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OpenCloudOS-Kernel/arch/x86/entry/vdso/vdso2c.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
/*
* This file is included twice from vdso2c.c. It generates code for 32-bit
* and 64-bit vDSOs. We need both for 64-bit builds, since 32-bit vDSOs
* are built for 32-bit userspace.
*/
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
void *stripped_addr, size_t stripped_len,
x86/vdso: Rename variable to fix -Wshadow warning The go32() and go64() functions has an argument and a local variable called ‘name’. Rename both to clarify the code and to fix a warning with -Wshadow. Signed-off-by: Leonardo Brás <leobras.c@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David.Laight@aculab.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: helen@koikeco.de Cc: linux-kbuild@vger.kernel.org Cc: lkcamp@lists.libreplanetbr.org Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlash Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-23 09:10:22 +08:00
FILE *outfile, const char *image_name)
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
{
int found_load = 0;
unsigned long load_size = -1; /* Work around bogus warning */
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
unsigned long mapping_size;
ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
int i;
unsigned long j;
x86/vdso2c: Use better macros for ELF bitness Rather than using a separate macro for each replacement, use generic macros. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/d953cd2e70ceee1400985d091188cdd65fba2f05.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:47 +08:00
ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
*alt_sec = NULL;
x86/vdso2c: Use better macros for ELF bitness Rather than using a separate macro for each replacement, use generic macros. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/d953cd2e70ceee1400985d091188cdd65fba2f05.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:47 +08:00
ELF(Dyn) *dyn = 0, *dyn_end = 0;
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
const char *secstrings;
x86, vdso: Move the vvar area before the vdso text Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:15 +08:00
INT_BITS syms[NSYMS] = {};
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff));
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
x86/vdso: Fix building on big endian host We need to call GET_LE to read hdr->e_type. Fixes: 57f90c3dfc75 ("x86/vdso: Error out if the vDSO isn't a valid DSO") Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: linux-next@vger.kernel.org Link: http://lkml.kernel.org/r/20160929193442.GA16617@gate.crashing.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-29 19:51:00 +08:00
if (GET_LE(&hdr->e_type) != ET_DYN)
x86/vdso: Error out if the vDSO isn't a valid DSO Some distros has been playing with toolchain changes that can affect the type of ELF objects built. Occasionally, this goes wrong and the vDSO ends up not being a DSO at all. This causes the kernel to end up broken in a surprisingly subtle way -- glibc apparently silently ignores a vDSO that isn't a DSO, so everything works, albeit slowly, until users try a different libc implementation. Make the kernel build process a bit more robust: fail outright if the vDSO isn't ET_DYN or is missing its PT_DYNAMIC segment. I've never seen this in an unmodified kernel. See: https://github.com/docker/docker/issues/23378 Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/8a30e0a07c3b47ff917a8daa2df5e407cc0c6698.1468878336.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-19 05:46:35 +08:00
fail("input is not a shared object\n");
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
/* Walk the segment table. */
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
if (GET_LE(&pt[i].p_type) == PT_LOAD) {
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
if (found_load)
fail("multiple PT_LOAD segs\n");
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
if (GET_LE(&pt[i].p_offset) != 0 ||
GET_LE(&pt[i].p_vaddr) != 0)
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fail("PT_LOAD in wrong place\n");
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz))
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fail("cannot handle memsz != filesz\n");
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
load_size = GET_LE(&pt[i].p_memsz);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
found_load = 1;
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
} else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) {
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
dyn = raw_addr + GET_LE(&pt[i].p_offset);
dyn_end = raw_addr + GET_LE(&pt[i].p_offset) +
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&pt[i].p_memsz);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
}
if (!found_load)
fail("no PT_LOAD seg\n");
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
if (stripped_len < load_size)
fail("stripped input is too short\n");
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
x86/vdso: Error out if the vDSO isn't a valid DSO Some distros has been playing with toolchain changes that can affect the type of ELF objects built. Occasionally, this goes wrong and the vDSO ends up not being a DSO at all. This causes the kernel to end up broken in a surprisingly subtle way -- glibc apparently silently ignores a vDSO that isn't a DSO, so everything works, albeit slowly, until users try a different libc implementation. Make the kernel build process a bit more robust: fail outright if the vDSO isn't ET_DYN or is missing its PT_DYNAMIC segment. I've never seen this in an unmodified kernel. See: https://github.com/docker/docker/issues/23378 Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/8a30e0a07c3b47ff917a8daa2df5e407cc0c6698.1468878336.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-19 05:46:35 +08:00
if (!dyn)
fail("input has no PT_DYNAMIC section -- your toolchain is buggy\n");
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
/* Walk the dynamic table */
x86/vdso, build: Make LE access macros clearer, host-safe Make it a little clearer what the littleendian access macros in vdso2c.[ch] actually do. This way they can probably also be moved to a central location (e.g. tools/include) for the benefit of other host tools. We should avoid implementation namespace symbols when writing code that is compiling for the compiler host, so avoid names starting with double underscore or underscore-capital. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2cf258df123cb24bad63c274c8563c050547d99d.1401464755.git.luto@amacapital.net
2014-05-31 08:03:22 +08:00
for (i = 0; dyn + i < dyn_end &&
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&dyn[i].d_tag) != DT_NULL; i++) {
typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag);
x86/vdso: Error out in vdso2c if DT_RELA is present vdso2c was checking for various types of relocations to detect when the vdso had undefined symbols or was otherwise dependent on relocation at load time. Undefined symbols in the vdso would fail if accessed at runtime, and certain implementation errors (e.g. branch profiling or incorrect symbol visibilities) could result in data access through the GOT that requires relocations. This could be as simple as: extern char foo; return foo; Without some kind of visibility control, the compiler would assume that foo could be interposed at load time and would generate a relocation. x86-64 and x32 (as opposed to i386) use explicit-addent (RELA) instead of implicit-addent (REL) relocations for data access, and vdso2c forgot to detect those. Whether these bad relocations would actually fail at runtime depends on what the linker sticks in the unrelocated references. Nonetheless, these relocations have no business existing in the vDSO and should be fixed rather than silently ignored. This error could trigger on some configurations due to branch profiling. The previous patch fixed that. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/74ef0c00b4d2a3b573e00a4113874e62f772e348.1403642755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-25 04:46:53 +08:00
if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA ||
x86/vdso, build: Fix cross-compilation from big-endian architectures This adds a macro GET(x) to convert x from big-endian to little-endian. Hopefully I put it everywhere it needs to go and got all the cases needed for everyone's linux/elf.h. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2cf258df123cb24bad63c274c8563c050547d99d.1401464755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-30 23:48:49 +08:00
tag == DT_RELENT || tag == DT_TEXTREL)
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fail("vdso image contains dynamic relocations\n");
}
/* Walk the section table */
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset);
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) +
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&hdr->e_shentsize) * i;
if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
symtab_hdr = sh;
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
if (!strcmp(secstrings + GET_LE(&sh->sh_name),
x86/vdso, build: Make LE access macros clearer, host-safe Make it a little clearer what the littleendian access macros in vdso2c.[ch] actually do. This way they can probably also be moved to a central location (e.g. tools/include) for the benefit of other host tools. We should avoid implementation namespace symbols when writing code that is compiling for the compiler host, so avoid names starting with double underscore or underscore-capital. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2cf258df123cb24bad63c274c8563c050547d99d.1401464755.git.luto@amacapital.net
2014-05-31 08:03:22 +08:00
".altinstructions"))
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
alt_sec = sh;
}
x86/vdso, build: When vdso2c fails, unlink the output This avoids bizarre failures if make is run again. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/1764385fe9931e8940b9d001132515448ea89523.1401464755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-30 23:48:48 +08:00
if (!symtab_hdr)
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fail("no symbol table\n");
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
/* Walk the symbol table */
x86/vdso, build: Make LE access macros clearer, host-safe Make it a little clearer what the littleendian access macros in vdso2c.[ch] actually do. This way they can probably also be moved to a central location (e.g. tools/include) for the benefit of other host tools. We should avoid implementation namespace symbols when writing code that is compiling for the compiler host, so avoid names starting with double underscore or underscore-capital. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2cf258df123cb24bad63c274c8563c050547d99d.1401464755.git.luto@amacapital.net
2014-05-31 08:03:22 +08:00
for (i = 0;
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
x86/vdso, build: Fix cross-compilation from big-endian architectures This adds a macro GET(x) to convert x from big-endian to little-endian. Hopefully I put it everywhere it needs to go and got all the cases needed for everyone's linux/elf.h. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2cf258df123cb24bad63c274c8563c050547d99d.1401464755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-30 23:48:49 +08:00
i++) {
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
int k;
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) +
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
GET_LE(&symtab_hdr->sh_entsize) * i;
x86/vdso: Rename variable to fix -Wshadow warning The go32() and go64() functions has an argument and a local variable called ‘name’. Rename both to clarify the code and to fix a warning with -Wshadow. Signed-off-by: Leonardo Brás <leobras.c@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David.Laight@aculab.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: helen@koikeco.de Cc: linux-kbuild@vger.kernel.org Cc: lkcamp@lists.libreplanetbr.org Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlash Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-23 09:10:22 +08:00
const char *sym_name = raw_addr +
GET_LE(&strtab_hdr->sh_offset) +
GET_LE(&sym->st_name);
x86/vdso: Hack to keep 64-bit Go programs working The Go runtime has a buggy vDSO parser that currently segfaults. This writes an empty SHT_DYNSYM entry that causes Go's runtime to malfunction by thinking that the vDSO is empty rather than malfunctioning by running off the end and segfaulting. This affects x86-64 only as far as we know, so we do not need this for the i386 and x32 vdsos. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/d10618176c4bd39b457a5e85c497295c90cab1bc.1402620737.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2014-06-13 08:53:12 +08:00
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
for (k = 0; k < NSYMS; k++) {
x86/vdso: Rename variable to fix -Wshadow warning The go32() and go64() functions has an argument and a local variable called ‘name’. Rename both to clarify the code and to fix a warning with -Wshadow. Signed-off-by: Leonardo Brás <leobras.c@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David.Laight@aculab.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: helen@koikeco.de Cc: linux-kbuild@vger.kernel.org Cc: lkcamp@lists.libreplanetbr.org Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlash Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-23 09:10:22 +08:00
if (!strcmp(sym_name, required_syms[k].name)) {
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
if (syms[k]) {
fail("duplicate symbol %s\n",
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
required_syms[k].name);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
x86, vdso: Move the vvar area before the vdso text Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:15 +08:00
/*
* Careful: we use negative addresses, but
* st_value is unsigned, so we rely
* on syms[k] being a signed type of the
* correct width.
*/
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
syms[k] = GET_LE(&sym->st_value);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
}
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
}
x86, vdso: Move the 32-bit vdso special pages after the text This unifies the vdso mapping code and teaches it how to map special pages at addresses corresponding to symbols in the vdso image. The new code is used for all vdso variants, but so far only the 32-bit variants use the new vvar page position. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:35 +08:00
/* Validate mapping addresses. */
for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
x86/vdso: Fix vdso2c's special_pages[] error checking Stephen Rothwell's compiler did something amazing: it unrolled a loop, discovered that one iteration of that loop contained an always-true test, and emitted a warning that will IMO only serve to convince people to disable the warning. That bogus warning caused me to wonder what prompted such an absurdity from his compiler, and I discovered that the code in question was, in fact, completely wrong -- I was looking things up in the wrong array. This affects 3.16 as well, but the only effect is to screw up the error checking a bit. vdso2c's output is unaffected. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/53d96ad5.80ywqrbs33ZBCQej%25akpm@linux-foundation.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 05:59:49 +08:00
INT_BITS symval = syms[special_pages[i]];
if (!symval)
x86, vdso: Move the 32-bit vdso special pages after the text This unifies the vdso mapping code and teaches it how to map special pages at addresses corresponding to symbols in the vdso image. The new code is used for all vdso variants, but so far only the 32-bit variants use the new vvar page position. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:35 +08:00
continue; /* The mapping isn't used; ignore it. */
x86/vdso: Fix vdso2c's special_pages[] error checking Stephen Rothwell's compiler did something amazing: it unrolled a loop, discovered that one iteration of that loop contained an always-true test, and emitted a warning that will IMO only serve to convince people to disable the warning. That bogus warning caused me to wonder what prompted such an absurdity from his compiler, and I discovered that the code in question was, in fact, completely wrong -- I was looking things up in the wrong array. This affects 3.16 as well, but the only effect is to screw up the error checking a bit. vdso2c's output is unaffected. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/53d96ad5.80ywqrbs33ZBCQej%25akpm@linux-foundation.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 05:59:49 +08:00
if (symval % 4096)
x86, vdso: Move the 32-bit vdso special pages after the text This unifies the vdso mapping code and teaches it how to map special pages at addresses corresponding to symbols in the vdso image. The new code is used for all vdso variants, but so far only the 32-bit variants use the new vvar page position. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:35 +08:00
fail("%s must be a multiple of 4096\n",
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
required_syms[i].name);
x86/vdso: Fix vdso2c's special_pages[] error checking Stephen Rothwell's compiler did something amazing: it unrolled a loop, discovered that one iteration of that loop contained an always-true test, and emitted a warning that will IMO only serve to convince people to disable the warning. That bogus warning caused me to wonder what prompted such an absurdity from his compiler, and I discovered that the code in question was, in fact, completely wrong -- I was looking things up in the wrong array. This affects 3.16 as well, but the only effect is to screw up the error checking a bit. vdso2c's output is unaffected. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/53d96ad5.80ywqrbs33ZBCQej%25akpm@linux-foundation.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 05:59:49 +08:00
if (symval + 4096 < syms[sym_vvar_start])
fail("%s underruns vvar_start\n",
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
required_syms[i].name);
x86/vdso: Fix vdso2c's special_pages[] error checking Stephen Rothwell's compiler did something amazing: it unrolled a loop, discovered that one iteration of that loop contained an always-true test, and emitted a warning that will IMO only serve to convince people to disable the warning. That bogus warning caused me to wonder what prompted such an absurdity from his compiler, and I discovered that the code in question was, in fact, completely wrong -- I was looking things up in the wrong array. This affects 3.16 as well, but the only effect is to screw up the error checking a bit. vdso2c's output is unaffected. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/53d96ad5.80ywqrbs33ZBCQej%25akpm@linux-foundation.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 05:59:49 +08:00
if (symval + 4096 > 0)
x86, vdso: Move the vvar area before the vdso text Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:15 +08:00
fail("%s is on the wrong side of the vdso text\n",
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
required_syms[i].name);
x86, vdso: Move the 32-bit vdso special pages after the text This unifies the vdso mapping code and teaches it how to map special pages at addresses corresponding to symbols in the vdso image. The new code is used for all vdso variants, but so far only the 32-bit variants use the new vvar page position. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:35 +08:00
}
x86, vdso: Move the vvar area before the vdso text Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:15 +08:00
if (syms[sym_vvar_start] % 4096)
fail("vvar_begin must be a multiple of 4096\n");
x86, vdso: Move the 32-bit vdso special pages after the text This unifies the vdso mapping code and teaches it how to map special pages at addresses corresponding to symbols in the vdso image. The new code is used for all vdso variants, but so far only the 32-bit variants use the new vvar page position. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:35 +08:00
x86/vdso: Rename variable to fix -Wshadow warning The go32() and go64() functions has an argument and a local variable called ‘name’. Rename both to clarify the code and to fix a warning with -Wshadow. Signed-off-by: Leonardo Brás <leobras.c@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David.Laight@aculab.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: helen@koikeco.de Cc: linux-kbuild@vger.kernel.org Cc: lkcamp@lists.libreplanetbr.org Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlash Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-23 09:10:22 +08:00
if (!image_name) {
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
fwrite(stripped_addr, stripped_len, 1, outfile);
x86/vdso, build: When vdso2c fails, unlink the output This avoids bizarre failures if make is run again. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/1764385fe9931e8940b9d001132515448ea89523.1401464755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-30 23:48:48 +08:00
return;
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
mapping_size = (stripped_len + 4095) / 4096 * 4096;
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
fprintf(outfile, "#include <linux/linkage.h>\n");
fprintf(outfile, "#include <asm/page_types.h>\n");
fprintf(outfile, "#include <asm/vdso.h>\n");
fprintf(outfile, "\n");
fprintf(outfile,
x86/vdso: Mark the vDSO code read-only after init The vDSO does not need to be writable after __init, so mark it as __ro_after_init. The result kills the exploit method of writing to the vDSO from kernel space resulting in userspace executing the modified code, as shown here to bypass SMEP restrictions: http://itszn.com/blog/?p=21 The memory map (with added vDSO address reporting) shows the vDSO moving into read-only memory: Before: [ 0.143067] vDSO @ ffffffff82004000 [ 0.143551] vDSO @ ffffffff82006000 ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd 0xffffffff81e00000-0xffffffff81e05000 20K ro GLB NX pte 0xffffffff81e05000-0xffffffff82000000 2028K ro NX pte 0xffffffff82000000-0xffffffff8214f000 1340K RW GLB NX pte 0xffffffff8214f000-0xffffffff82281000 1224K RW NX pte 0xffffffff82281000-0xffffffff82400000 1532K RW GLB NX pte 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd 0xffffffff83200000-0xffffffffc0000000 974M pmd After: [ 0.145062] vDSO @ ffffffff81da1000 [ 0.146057] vDSO @ ffffffff81da4000 ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd 0xffffffff81e00000-0xffffffff81e0b000 44K ro GLB NX pte 0xffffffff81e0b000-0xffffffff82000000 2004K ro NX pte 0xffffffff82000000-0xffffffff8214c000 1328K RW GLB NX pte 0xffffffff8214c000-0xffffffff8227e000 1224K RW NX pte 0xffffffff8227e000-0xffffffff82400000 1544K RW GLB NX pte 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd 0xffffffff83200000-0xffffffffc0000000 974M pmd Based on work by PaX Team and Brad Spengler. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brad Spengler <spender@grsecurity.net> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Brown <david.brown@linaro.org> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Emese Revfy <re.emese@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathias Krause <minipli@googlemail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: PaX Team <pageexec@freemail.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-hardening@lists.openwall.com Cc: linux-arch <linux-arch@vger.kernel.org> Link: http://lkml.kernel.org/r/1455748879-21872-7-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-18 06:41:17 +08:00
"static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {",
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
mapping_size);
for (j = 0; j < stripped_len; j++) {
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
if (j % 10 == 0)
fprintf(outfile, "\n\t");
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
fprintf(outfile, "0x%02X, ",
(int)((unsigned char *)stripped_addr)[j]);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
fprintf(outfile, "\n};\n\n");
x86/vdso: Rename variable to fix -Wshadow warning The go32() and go64() functions has an argument and a local variable called ‘name’. Rename both to clarify the code and to fix a warning with -Wshadow. Signed-off-by: Leonardo Brás <leobras.c@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: David.Laight@aculab.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: helen@koikeco.de Cc: linux-kbuild@vger.kernel.org Cc: lkcamp@lists.libreplanetbr.org Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlash Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-23 09:10:22 +08:00
fprintf(outfile, "const struct vdso_image %s = {\n", image_name);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fprintf(outfile, "\t.data = raw_data,\n");
x86, vdso: Get rid of the fake section mechanism Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:16 +08:00
fprintf(outfile, "\t.size = %lu,\n", mapping_size);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
if (alt_sec) {
fprintf(outfile, "\t.alt = %lu,\n",
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
(unsigned long)GET_LE(&alt_sec->sh_offset));
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
fprintf(outfile, "\t.alt_len = %lu,\n",
x86, vdso: Use <tools/le_byteshift.h> for littleendian access There are no standard functions for littleendian data (unlike bigendian data.) Thus, use <tools/le_byteshift.h> to access littleendian data members. Those are fairly inefficient, but it doesn't matter for this purpose (and can be optimized later.) This avoids portability problems. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
2014-06-07 05:30:37 +08:00
(unsigned long)GET_LE(&alt_sec->sh_size));
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
for (i = 0; i < NSYMS; i++) {
x86/vdso: Improve the fake section headers Fully stripping the vDSO has other unfortunate side effects: - binutils is unable to find ELF notes without a SHT_NOTE section. - Even elfutils has trouble: it can find ELF notes without a section table at all, but if a section table is present, it won't look for PT_NOTE. - gdb wants section names to match between stripped DSOs and their symbols; otherwise it will corrupt symbol addresses. We're also breaking the rules: section 0 is supposed to be SHT_NULL. Fix these problems by building a better fake section table. While we're at it, we might as well let buggy Go versions keep working well by giving the SHT_DYNSYM entry the correct size. This is a bit unfortunate: it adds quite a bit of size to the vdso image. If/when binutils improves and the improved versions become widespread, it would be worth considering dropping most of this. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-06-19 06:59:48 +08:00
if (required_syms[i].export && syms[i])
x86, vdso: Move the vvar area before the vdso text Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-07-11 09:13:15 +08:00
fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
required_syms[i].name, (int64_t)syms[i]);
x86, vdso: Reimplement vdso.so preparation in build-time C Currently, vdso.so files are prepared and analyzed by a combination of objcopy, nm, some linker script tricks, and some simple ELF parsers in the kernel. Replace all of that with plain C code that runs at build time. All five vdso images now generate .c files that are compiled and linked in to the kernel image. This should cause only one userspace-visible change: the loaded vDSO images are stripped more heavily than they used to be. Everything outside the loadable segment is dropped. In particular, this causes the section table and section name strings to be missing. This should be fine: real dynamic loaders don't load or inspect these tables anyway. The result is roughly equivalent to eu-strip's --strip-sections option. The purpose of this change is to enable the vvar and hpet mappings to be moved to the page following the vDSO load segment. Currently, it is possible for the section table to extend into the page after the load segment, so, if we map it, it risks overlapping the vvar or hpet page. This happens whenever the load segment is just under a multiple of PAGE_SIZE. The only real subtlety here is that the old code had a C file with inline assembler that did 'call VDSO32_vsyscall' and a linker script that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most likely worked by accident: the linker script entry defines a symbol associated with an address as opposed to an alias for the real dynamic symbol __kernel_vsyscall. That caused ld to relocate the reference at link time instead of leaving an interposable dynamic relocation. Since the VDSO32_vsyscall hack is no longer needed, I now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it work. vdso2c will generate an error and abort the build if the resulting image contains any dynamic relocations, so we won't silently generate bad vdso images. (Dynamic relocations are a problem because nothing will even attempt to relocate the vdso.) Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-06 03:19:34 +08:00
}
fprintf(outfile, "};\n");
}