linux-sg2042/scripts/link-vmlinux.sh

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#!/bin/sh
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
#
# link vmlinux
#
# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
# (not within --whole-archive), and do not require symbol indexes added.
#
# vmlinux
# ^
# |
# +--< $(KBUILD_VMLINUX_OBJS)
# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
# |
# +--< $(KBUILD_VMLINUX_LIBS)
# | +--< lib/lib.a + more
# |
# +-< ${kallsymso} (see description in KALLSYMS section)
#
# vmlinux version (uname -v) cannot be updated during normal
# descending-into-subdirs phase since we do not yet know if we need to
# update vmlinux.
# Therefore this step is delayed until just before final link of vmlinux.
#
# System.map is generated to document addresses of all kernel symbols
# Error out on error
set -e
# Nice output in kbuild format
# Will be supressed by "make -s"
info()
{
if [ "${quiet}" != "silent_" ]; then
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
printf " %-7s %s\n" "${1}" "${2}"
fi
}
# Link of vmlinux.o used for section mismatch analysis
# ${1} output file
modpost_link()
{
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
local objects
objects="--whole-archive \
${KBUILD_VMLINUX_OBJS} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group"
${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
}
# Link of vmlinux
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
# ${1} - output file
# ${2}, ${3}, ... - optional extra .o files
vmlinux_link()
{
local lds="${objtree}/${KBUILD_LDS}"
local output=${1}
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
local objects
Kbuild updates for v5.4 - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups -----BEGIN PGP SIGNATURE----- iQJSBAABCgA8FiEEbmPs18K1szRHjPqEPYsBB53g2wYFAl1+OnoeHHlhbWFkYS5t YXNhaGlyb0Bzb2Npb25leHQuY29tAAoJED2LAQed4NsGoKEQAKcid9lDacMe5KWT 4Ic93hANMFKZ9Qy8WoxivnOr1a93NcloZ0Bhka96QUt7hYUkLmDCs99eMbxKuMfP m/ViHepojOBPzq+VtAGWOiIyPMCA7XDrTPph4wcPDKeOURTreK1PZ20fxDoAR4to +qaqKZJGdRcNf2DpJN1yIosz8Wj0Sa2LQrRi9jgUHi3bzgvLfL7P9WM2xyZMggAc GaSktCEFL0UzMFlMpYyDrKh2EV6ryOnN8+bVAKbmWP89tuU3njutycKdWOoL+bsj tH2kjFThxQyIcZGNHS1VzNunYAFE2q5nj2q47O1EDN6sjTYUoRn5cHwPam6x3Kly NH88xDEtJ7sUUc9GZEIXADWWD0f08QIhAH5x+jxFg3529lNgyrNHRSQ2XceYNAnG i/GnMJ0EhODOFKusXw7sNlWFKtukep+8/pwnvfTXWQu6plEm5EQ3a3RL5SESubVo mHzXsQDFCE0x/UrsJxEAww+3YO3pQEelfVi74W9z0cckpbRF8FuUq/69ltOT15l4 X+gCz80lXMWBKw/kNoR4GQoAJo3KboMEociawwoj72HXEHTPLJnCdUOsAf3n+opj xuz/UPZ4WYSgKdnbmmDbJ+1POA1NqtARZZXpMVyKVVCOiLafbJkLQYwLKEpE2mOO TP9igzP1i3/jPWec8cJ6Fa8UwuGh =VGqV -----END PGP SIGNATURE----- Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups * tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits) genksyms: convert to SPDX License Identifier for lex.l and parse.y modpost: use __section in the output to *.mod.c modpost: use MODULE_INFO() for __module_depends export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols export.h: remove defined(__KERNEL__), which is no longer needed kbuild: allow Clang to find unused static inline functions for W=1 build kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN kbuild: refactor scripts/Makefile.extrawarn merge_config.sh: ignore unwanted grep errors kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj) modpost: add NOFAIL to strndup modpost: add guid_t type definition kbuild: add $(BASH) to run scripts with bash-extension kbuild: remove ARCH_{CPP,A,C}FLAGS kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC kbuild: Do not enable -Wimplicit-fallthrough for clang for now kbuild: clean up subdir-ymn calculation in Makefile.clean kbuild: remove unneeded '+' marker from cmd_clean kbuild: remove clean-dirs syntax kbuild: check clean srctree even earlier ...
2019-09-20 23:36:47 +08:00
info LD ${output}
# skip output file argument
shift
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
${KBUILD_VMLINUX_OBJS} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group \
${@}"
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
-o ${output} \
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
${KBUILD_VMLINUX_OBJS} \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
-Wl,--end-group \
${@}"
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
${CC} ${CFLAGS_vmlinux} \
-o ${output} \
-Wl,-T,${lds} \
${objects} \
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 20:29:19 +08:00
-lutil -lrt -lpthread
rm -f linux
fi
}
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
# generate .BTF typeinfo from DWARF debuginfo
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
# ${1} - vmlinux image
# ${2} - file to dump raw BTF data into
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
gen_btf()
{
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
local pahole_ver
local bin_arch
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
if ! [ -x "$(command -v ${PAHOLE})" ]; then
info "BTF" "${1}: pahole (${PAHOLE}) is not available"
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
return 1
fi
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
if [ "${pahole_ver}" -lt "113" ]; then
info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
return 1
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
fi
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
info "BTF" ${2}
vmlinux_link ${1}
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
# dump .BTF section into raw binary file to link with final vmlinux
bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
cut -d, -f1 | cut -d' ' -f2)
bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
awk '{print $4}')
${OBJCOPY} --change-section-address .BTF=0 \
--set-section-flags .BTF=alloc -O binary \
--only-section=.BTF ${1} .btf.vmlinux.bin
${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
--rename-section .data=.BTF .btf.vmlinux.bin ${2}
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
}
# Create ${2} .o file with all symbols from the ${1} object file
kallsyms()
{
info KSYM ${2}
local kallsymopt;
if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
kallsymopt="${kallsymopt} --all-symbols"
fi
if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
kallsyms: fix percpu vars on x86-64 with relocation. x86-64 has a problem: per-cpu variables are actually represented by their absolute offsets within the per-cpu area, but the symbols are not emitted as absolute. Thus kallsyms naively creates them as offsets from _text, meaning their values change if the kernel is relocated (especially noticeable with CONFIG_RANDOMIZE_BASE): $ egrep ' (gdt_|_(stext|_per_cpu_))' /root/kallsyms.nokaslr 0000000000000000 D __per_cpu_start 0000000000004000 D gdt_page 0000000000014280 D __per_cpu_end ffffffff810001c8 T _stext ffffffff81ee53c0 D __per_cpu_offset $ egrep ' (gdt_|_(stext|_per_cpu_))' /root/kallsyms.kaslr1 000000001f200000 D __per_cpu_start 000000001f204000 D gdt_page 000000001f214280 D __per_cpu_end ffffffffa02001c8 T _stext ffffffffa10e53c0 D __per_cpu_offset Making them absolute symbols is the Right Thing, but requires fixes to the relocs tool. So for the moment, we add a --absolute-percpu option which makes them absolute from a kallsyms perspective: $ egrep ' (gdt_|_(stext|_per_cpu_))' /proc/kallsyms # no KASLR 0000000000000000 A __per_cpu_start 000000000000a000 A gdt_page 0000000000013040 A __per_cpu_end ffffffff802001c8 T _stext ffffffff8099b180 D __per_cpu_offset ffffffff809a3000 D __per_cpu_load $ egrep ' (gdt_|_(stext|_per_cpu_))' /proc/kallsyms # With KASLR 0000000000000000 A __per_cpu_start 000000000000a000 A gdt_page 0000000000013040 A __per_cpu_end ffffffff89c001c8 T _stext ffffffff8a39d180 D __per_cpu_offset ffffffff8a3a5000 D __per_cpu_load Based-on-the-original-screenplay-by: Andy Honig <ahonig@google.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Kees Cook <keescook@chromium.org>
2014-03-17 11:35:46 +08:00
kallsymopt="${kallsymopt} --absolute-percpu"
fi
kallsyms: add support for relative offsets in kallsyms address table Similar to how relative extables are implemented, it is possible to emit the kallsyms table in such a way that it contains offsets relative to some anchor point in the kernel image rather than absolute addresses. On 64-bit architectures, it cuts the size of the kallsyms address table in half, since offsets between kernel symbols can typically be expressed in 32 bits. This saves several hundreds of kilobytes of permanent .rodata on average. In addition, the kallsyms address table is no longer subject to dynamic relocation when CONFIG_RELOCATABLE is in effect, so the relocation work done after decompression now doesn't have to do relocation updates for all these values. This saves up to 24 bytes (i.e., the size of a ELF64 RELA relocation table entry) per value, which easily adds up to a couple of megabytes of uncompressed __init data on ppc64 or arm64. Even if these relocation entries typically compress well, the combined size reduction of 2.8 MB uncompressed for a ppc64_defconfig build (of which 2.4 MB is __init data) results in a ~500 KB space saving in the compressed image. Since it is useful for some architectures (like x86) to retain the ability to emit absolute values as well, this patch also adds support for capturing both absolute and relative values when KALLSYMS_ABSOLUTE_PERCPU is in effect, by emitting absolute per-cpu addresses as positive 32-bit values, and addresses relative to the lowest encountered relative symbol as negative values, which are subtracted from the runtime address of this base symbol to produce the actual address. Support for the above is enabled by default for all architectures except IA-64 and Tile-GX, whose symbols are too far apart to capture in this manner. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Ingo Molnar <mingo@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-16 05:58:19 +08:00
if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
kallsymopt="${kallsymopt} --base-relative"
fi
local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
local afile="`basename ${2} .o`.S"
${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
${CC} ${aflags} -c -o ${2} ${afile}
}
# Perform one step in kallsyms generation, including temporary linking of
# vmlinux.
kallsyms_step()
{
kallsymso_prev=${kallsymso}
kallsymso=.tmp_kallsyms${1}.o
kallsyms_vmlinux=.tmp_vmlinux${1}
Kbuild updates for v5.4 - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups -----BEGIN PGP SIGNATURE----- iQJSBAABCgA8FiEEbmPs18K1szRHjPqEPYsBB53g2wYFAl1+OnoeHHlhbWFkYS5t YXNhaGlyb0Bzb2Npb25leHQuY29tAAoJED2LAQed4NsGoKEQAKcid9lDacMe5KWT 4Ic93hANMFKZ9Qy8WoxivnOr1a93NcloZ0Bhka96QUt7hYUkLmDCs99eMbxKuMfP m/ViHepojOBPzq+VtAGWOiIyPMCA7XDrTPph4wcPDKeOURTreK1PZ20fxDoAR4to +qaqKZJGdRcNf2DpJN1yIosz8Wj0Sa2LQrRi9jgUHi3bzgvLfL7P9WM2xyZMggAc GaSktCEFL0UzMFlMpYyDrKh2EV6ryOnN8+bVAKbmWP89tuU3njutycKdWOoL+bsj tH2kjFThxQyIcZGNHS1VzNunYAFE2q5nj2q47O1EDN6sjTYUoRn5cHwPam6x3Kly NH88xDEtJ7sUUc9GZEIXADWWD0f08QIhAH5x+jxFg3529lNgyrNHRSQ2XceYNAnG i/GnMJ0EhODOFKusXw7sNlWFKtukep+8/pwnvfTXWQu6plEm5EQ3a3RL5SESubVo mHzXsQDFCE0x/UrsJxEAww+3YO3pQEelfVi74W9z0cckpbRF8FuUq/69ltOT15l4 X+gCz80lXMWBKw/kNoR4GQoAJo3KboMEociawwoj72HXEHTPLJnCdUOsAf3n+opj xuz/UPZ4WYSgKdnbmmDbJ+1POA1NqtARZZXpMVyKVVCOiLafbJkLQYwLKEpE2mOO TP9igzP1i3/jPWec8cJ6Fa8UwuGh =VGqV -----END PGP SIGNATURE----- Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups * tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits) genksyms: convert to SPDX License Identifier for lex.l and parse.y modpost: use __section in the output to *.mod.c modpost: use MODULE_INFO() for __module_depends export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols export.h: remove defined(__KERNEL__), which is no longer needed kbuild: allow Clang to find unused static inline functions for W=1 build kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN kbuild: refactor scripts/Makefile.extrawarn merge_config.sh: ignore unwanted grep errors kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj) modpost: add NOFAIL to strndup modpost: add guid_t type definition kbuild: add $(BASH) to run scripts with bash-extension kbuild: remove ARCH_{CPP,A,C}FLAGS kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC kbuild: Do not enable -Wimplicit-fallthrough for clang for now kbuild: clean up subdir-ymn calculation in Makefile.clean kbuild: remove unneeded '+' marker from cmd_clean kbuild: remove clean-dirs syntax kbuild: check clean srctree even earlier ...
2019-09-20 23:36:47 +08:00
vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
kallsyms ${kallsyms_vmlinux} ${kallsymso}
}
# Create map file with all symbols from ${1}
# See mksymap for additional details
mksysmap()
{
${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
}
sortextable()
{
${objtree}/scripts/sortextable ${1}
}
# Delete output files in case of error
cleanup()
{
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
rm -f .btf.*
rm -f .tmp_System.map
rm -f .tmp_kallsyms*
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
rm -f vmlinux.o
}
on_exit()
{
if [ $? -ne 0 ]; then
cleanup
fi
}
trap on_exit EXIT
on_signals()
{
exit 1
}
trap on_signals HUP INT QUIT TERM
#
#
# Use "make V=1" to debug this script
case "${KBUILD_VERBOSE}" in
*1*)
set -x
;;
esac
if [ "$1" = "clean" ]; then
cleanup
exit 0
fi
# We need access to CONFIG_ symbols
. include/config/auto.conf
# Update version
info GEN .version
if [ -r .version ]; then
VERSION=$(expr 0$(cat .version) + 1)
echo $VERSION > .version
else
rm -f .version
echo 1 > .version
fi;
# final build of init/
${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
#link vmlinux.o
info LD vmlinux.o
modpost_link vmlinux.o
# modpost vmlinux.o to check for section mismatches
${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
moduleparam: Save information about built-in modules in separate file Problem: When a kernel module is compiled as a separate module, some important information about the kernel module is available via .modinfo section of the module. In contrast, when the kernel module is compiled into the kernel, that information is not available. Information about built-in modules is necessary in the following cases: 1. When it is necessary to find out what additional parameters can be passed to the kernel at boot time. 2. When you need to know which module names and their aliases are in the kernel. This is very useful for creating an initrd image. Proposal: The proposed patch does not remove .modinfo section with module information from the vmlinux at the build time and saves it into a separate file after kernel linking. So, the kernel does not increase in size and no additional information remains in it. Information is stored in the same format as in the separate modules (null-terminated string array). Because the .modinfo section is already exported with a separate modules, we are not creating a new API. It can be easily read in the userspace: $ tr '\0' '\n' < modules.builtin.modinfo ext4.softdep=pre: crc32c ext4.license=GPL ext4.description=Fourth Extended Filesystem ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others ext4.alias=fs-ext4 ext4.alias=ext3 ext4.alias=fs-ext3 ext4.alias=ext2 ext4.alias=fs-ext2 md_mod.alias=block-major-9-* md_mod.alias=md md_mod.description=MD RAID framework md_mod.license=GPL md_mod.parmtype=create_on_open:bool md_mod.parmtype=start_dirty_degraded:int ... Co-Developed-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org> Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org> Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> Acked-by: Jessica Yu <jeyu@kernel.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-04-30 00:11:14 +08:00
info MODINFO modules.builtin.modinfo
${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
btf_vmlinux_bin_o=""
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
btf_vmlinux_bin_o=.btf.vmlinux.bin.o
else
echo >&2 "Failed to generate BTF for vmlinux"
echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
exit 1
btf: expose BTF info through sysfs Make .BTF section allocated and expose its contents through sysfs. /sys/kernel/btf directory is created to contain all the BTFs present inside kernel. Currently there is only kernel's main BTF, represented as /sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported, each module will expose its BTF as /sys/kernel/btf/<module-name> file. Current approach relies on a few pieces coming together: 1. pahole is used to take almost final vmlinux image (modulo .BTF and kallsyms) and generate .BTF section by converting DWARF info into BTF. This section is not allocated and not mapped to any segment, though, so is not yet accessible from inside kernel at runtime. 2. objcopy dumps .BTF contents into binary file and subsequently convert binary file into linkable object file with automatically generated symbols _binary__btf_kernel_bin_start and _binary__btf_kernel_bin_end, pointing to start and end, respectively, of BTF raw data. 3. final vmlinux image is generated by linking this object file (and kallsyms, if necessary). sysfs_btf.c then creates /sys/kernel/btf/kernel file and exposes embedded BTF contents through it. This allows, e.g., libbpf and bpftool access BTF info at well-known location, without resorting to searching for vmlinux image on disk (location of which is not standardized and vmlinux image might not be even available in some scenarios, e.g., inside qemu during testing). Alternative approach using .incbin assembler directive to embed BTF contents directly was attempted but didn't work, because sysfs_proc.o is not re-compiled during link-vmlinux.sh stage. This is required, though, to update embedded BTF data (initially empty data is embedded, then pahole generates BTF info and we need to regenerate sysfs_btf.o with updated contents, but it's too late at that point). If BTF couldn't be generated due to missing or too old pahole, sysfs_btf.c handles that gracefully by detecting that _binary__btf_kernel_bin_start (weak symbol) is 0 and not creating /sys/kernel/btf at all. v2->v3: - added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H); - created proper kobject (btf_kobj) for btf directory (Greg K-H); - undo v2 change of reusing vmlinux, as it causes extra kallsyms pass due to initially missing __binary__btf_kernel_bin_{start/end} symbols; v1->v2: - allow kallsyms stage to re-use vmlinux generated by gen_btf(); Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-13 02:39:47 +08:00
fi
fi
kallsymso=""
kallsymso_prev=""
kallsyms_vmlinux=""
if [ -n "${CONFIG_KALLSYMS}" ]; then
# kallsyms support
# Generate section listing all symbols and add it into vmlinux
# It's a three step process:
# 1) Link .tmp_vmlinux1 so it has all symbols and sections,
# but __kallsyms is empty.
# Running kallsyms on that gives us .tmp_kallsyms1.o with
# the right size
# 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
# the right size, but due to the added section, some
# addresses have shifted.
# From here, we generate a correct .tmp_kallsyms2.o
# 3) That link may have expanded the kernel image enough that
# more linker branch stubs / trampolines had to be added, which
# introduces new names, which further expands kallsyms. Do another
# pass if that is the case. In theory it's possible this results
# in even more stubs, but unlikely.
# KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
# other bugs.
# 4) The correct ${kallsymso} is linked into the final vmlinux.
#
# a) Verify that the System.map from vmlinux matches the map from
# ${kallsymso}.
kallsyms_step 1
kallsyms_step 2
# step 3
size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
kallsyms_step 3
fi
fi
Kbuild updates for v5.4 - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups -----BEGIN PGP SIGNATURE----- iQJSBAABCgA8FiEEbmPs18K1szRHjPqEPYsBB53g2wYFAl1+OnoeHHlhbWFkYS5t YXNhaGlyb0Bzb2Npb25leHQuY29tAAoJED2LAQed4NsGoKEQAKcid9lDacMe5KWT 4Ic93hANMFKZ9Qy8WoxivnOr1a93NcloZ0Bhka96QUt7hYUkLmDCs99eMbxKuMfP m/ViHepojOBPzq+VtAGWOiIyPMCA7XDrTPph4wcPDKeOURTreK1PZ20fxDoAR4to +qaqKZJGdRcNf2DpJN1yIosz8Wj0Sa2LQrRi9jgUHi3bzgvLfL7P9WM2xyZMggAc GaSktCEFL0UzMFlMpYyDrKh2EV6ryOnN8+bVAKbmWP89tuU3njutycKdWOoL+bsj tH2kjFThxQyIcZGNHS1VzNunYAFE2q5nj2q47O1EDN6sjTYUoRn5cHwPam6x3Kly NH88xDEtJ7sUUc9GZEIXADWWD0f08QIhAH5x+jxFg3529lNgyrNHRSQ2XceYNAnG i/GnMJ0EhODOFKusXw7sNlWFKtukep+8/pwnvfTXWQu6plEm5EQ3a3RL5SESubVo mHzXsQDFCE0x/UrsJxEAww+3YO3pQEelfVi74W9z0cckpbRF8FuUq/69ltOT15l4 X+gCz80lXMWBKw/kNoR4GQoAJo3KboMEociawwoj72HXEHTPLJnCdUOsAf3n+opj xuz/UPZ4WYSgKdnbmmDbJ+1POA1NqtARZZXpMVyKVVCOiLafbJkLQYwLKEpE2mOO TP9igzP1i3/jPWec8cJ6Fa8UwuGh =VGqV -----END PGP SIGNATURE----- Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - add modpost warn exported symbols marked as 'static' because 'static' and EXPORT_SYMBOL is an odd combination - break the build early if gold linker is used - optimize the Bison rule to produce .c and .h files by a single pattern rule - handle PREEMPT_RT in the module vermagic and UTS_VERSION - warn CONFIG options leaked to the user-space except existing ones - make single targets work properly - rebuild modules when module linker scripts are updated - split the module final link stage into scripts/Makefile.modfinal - fix the missed error code in merge_config.sh - improve the error message displayed on the attempt of the O= build in unclean source tree - remove 'clean-dirs' syntax - disable -Wimplicit-fallthrough warning for Clang - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC - remove ARCH_{CPP,A,C}FLAGS variables - add $(BASH) to run bash scripts - change *CFLAGS_<basetarget>.o to take the relative path to $(obj) instead of the basename - stop suppressing Clang's -Wunused-function warnings when W=1 - fix linux/export.h to avoid genksyms calculating CRC of trimmed exported symbols - misc cleanups * tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits) genksyms: convert to SPDX License Identifier for lex.l and parse.y modpost: use __section in the output to *.mod.c modpost: use MODULE_INFO() for __module_depends export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols export.h: remove defined(__KERNEL__), which is no longer needed kbuild: allow Clang to find unused static inline functions for W=1 build kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN kbuild: refactor scripts/Makefile.extrawarn merge_config.sh: ignore unwanted grep errors kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj) modpost: add NOFAIL to strndup modpost: add guid_t type definition kbuild: add $(BASH) to run scripts with bash-extension kbuild: remove ARCH_{CPP,A,C}FLAGS kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC kbuild: Do not enable -Wimplicit-fallthrough for clang for now kbuild: clean up subdir-ymn calculation in Makefile.clean kbuild: remove unneeded '+' marker from cmd_clean kbuild: remove clean-dirs syntax kbuild: check clean srctree even earlier ...
2019-09-20 23:36:47 +08:00
vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
kbuild: add ability to generate BTF type info for vmlinux This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-03 00:49:50 +08:00
if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
info SORTEX vmlinux
sortextable vmlinux
fi
info SYSMAP System.map
mksysmap vmlinux System.map
# step a (see comment above)
if [ -n "${CONFIG_KALLSYMS}" ]; then
mksysmap ${kallsyms_vmlinux} .tmp_System.map
if ! cmp -s System.map .tmp_System.map; then
echo >&2 Inconsistent kallsyms data
echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
exit 1
fi
fi