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Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 vdso updates from Ingo Molnar:
 "Further simplifications and improvements to the VDSO code, by Andy
  Lutomirski"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86_64/vsyscall: Fix warn_bad_vsyscall log output
  x86/vdso: Set VM_MAYREAD for the vvar vma
  x86, vdso: Get rid of the fake section mechanism
  x86, vdso: Move the vvar area before the vdso text
This commit is contained in:
Linus Torvalds 2014-08-04 17:27:47 -07:00
parent 5637a2a3e9 53b884ac37
commit 98a96f2022
8 changed files with 192 additions and 290 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
arch/x86/include/asm/vdso.h
View File

@ -18,15 +18,15 @@ struct vdso_image {
unsigned long alt, alt_len;
unsigned long sym_end_mapping; /* Total size of the mapping */
long sym_vvar_start; /* Negative offset to the vvar area */
unsigned long sym_vvar_page;
unsigned long sym_hpet_page;
unsigned long sym_VDSO32_NOTE_MASK;
unsigned long sym___kernel_sigreturn;
unsigned long sym___kernel_rt_sigreturn;
unsigned long sym___kernel_vsyscall;
unsigned long sym_VDSO32_SYSENTER_RETURN;
long sym_vvar_page;
long sym_hpet_page;
long sym_VDSO32_NOTE_MASK;
long sym___kernel_sigreturn;
long sym___kernel_rt_sigreturn;
long sym___kernel_vsyscall;
long sym_VDSO32_SYSENTER_RETURN;
};
#ifdef CONFIG_X86_64

8
arch/x86/kernel/vsyscall_64.c
View File

@ -81,10 +81,10 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
if (!show_unhandled_signals)
return;
pr_notice_ratelimited("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, current->comm, task_pid_nr(current),
message, regs->ip, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
printk_ratelimited("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, current->comm, task_pid_nr(current),
message, regs->ip, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
}
static int addr_to_vsyscall_nr(unsigned long addr)

16
arch/x86/vdso/Makefile
View File

@ -10,7 +10,7 @@ VDSO32-$(CONFIG_X86_32) := y
VDSO32-$(CONFIG_COMPAT) := y
# files to link into the vdso
vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vdso-fakesections.o
vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
# files to link into kernel
obj-y += vma.o
@ -37,7 +37,8 @@ vdso_img_sodbg := $(vdso_img-y:%=vdso%.so.dbg)
obj-y += $(vdso_img_objs)
targets += $(vdso_img_cfiles)
targets += $(vdso_img_sodbg)
.SECONDARY: $(vdso_img-y:%=$(obj)/vdso-image-%.c)
.SECONDARY: $(vdso_img-y:%=$(obj)/vdso-image-%.c) \
$(vdso_img-y:%=$(obj)/vdso%.so)
export CPPFLAGS_vdso.lds += -P -C
@ -54,10 +55,10 @@ hostprogs-y += vdso2c
quiet_cmd_vdso2c = VDSO2C $@
define cmd_vdso2c
$(obj)/vdso2c $< $@
$(obj)/vdso2c $< $(<:%.dbg=%) $@
endef
$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso2c FORCE
$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
$(call if_changed,vdso2c)
#
@ -113,6 +114,10 @@ $(obj)/%-x32.o: $(obj)/%.o FORCE
targets += vdsox32.lds $(vobjx32s-y)
$(obj)/%.so: OBJCOPYFLAGS := -S
$(obj)/%.so: $(obj)/%.so.dbg
$(call if_changed,objcopy)
$(obj)/vdsox32.so.dbg: $(src)/vdsox32.lds $(vobjx32s) FORCE
$(call if_changed,vdso)
@ -134,7 +139,7 @@ override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
targets += vdso32/vdso32.lds
targets += vdso32/note.o vdso32/vclock_gettime.o $(vdso32.so-y:%=vdso32/%.o)
targets += vdso32/vclock_gettime.o vdso32/vdso-fakesections.o
targets += vdso32/vclock_gettime.o
$(obj)/vdso32.o: $(vdso32-images:%=$(obj)/%)
@ -156,7 +161,6 @@ $(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
$(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
$(obj)/vdso32/vdso32.lds \
$(obj)/vdso32/vclock_gettime.o \
$(obj)/vdso32/vdso-fakesections.o \
$(obj)/vdso32/note.o \
$(obj)/vdso32/%.o
$(call if_changed,vdso)

21
arch/x86/vdso/vdso-fakesections.c
View File

@ -1,21 +0,0 @@
/*
* Copyright 2014 Andy Lutomirski
* Subject to the GNU Public License, v.2
*
* String table for loadable section headers. See vdso2c.h for why
* this exists.
*/
const char fake_shstrtab[] __attribute__((section(".fake_shstrtab"))) =
".hash\0"
".dynsym\0"
".dynstr\0"
".gnu.version\0"
".gnu.version_d\0"
".dynamic\0"
".rodata\0"
".fake_shstrtab\0" /* Yay, self-referential code. */
".note\0"
".eh_frame_hdr\0"
".eh_frame\0"
".text";

44
arch/x86/vdso/vdso-layout.lds.S
View File

@ -18,6 +18,25 @@
SECTIONS
{
/*
* User/kernel shared data is before the vDSO. This may be a little
* uglier than putting it after the vDSO, but it avoids issues with
* non-allocatable things that dangle past the end of the PT_LOAD
* segment.
*/
vvar_start = . - 2 * PAGE_SIZE;
vvar_page = vvar_start;
/* Place all vvars at the offsets in asm/vvar.h. */
#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
#undef __VVAR_KERNEL_LDS
#undef EMIT_VVAR
hpet_page = vvar_start + PAGE_SIZE;
. = SIZEOF_HEADERS;
.hash : { *(.hash) } :text
@ -74,31 +93,6 @@ SECTIONS
.altinstructions : { *(.altinstructions) } :text
.altinstr_replacement : { *(.altinstr_replacement) } :text
/*
* The remainder of the vDSO consists of special pages that are
* shared between the kernel and userspace. It needs to be at the
* end so that it doesn't overlap the mapping of the actual
* vDSO image.
*/
. = ALIGN(PAGE_SIZE);
vvar_page = .;
/* Place all vvars at the offsets in asm/vvar.h. */
#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
#undef __VVAR_KERNEL_LDS
#undef EMIT_VVAR
. = vvar_page + PAGE_SIZE;
hpet_page = .;
. = . + PAGE_SIZE;
. = ALIGN(PAGE_SIZE);
end_mapping = .;
/DISCARD/ : {
*(.discard)
*(.discard.*)

128
arch/x86/vdso/vdso2c.c
View File

@ -1,3 +1,53 @@
/*
* vdso2c - A vdso image preparation tool
* Copyright (c) 2014 Andy Lutomirski and others
* Licensed under the GPL v2
*
* vdso2c requires stripped and unstripped input. It would be trivial
* to fully strip the input in here, but, for reasons described below,
* we need to write a section table. Doing this is more or less
* equivalent to dropping all non-allocatable sections, but it's
* easier to let objcopy handle that instead of doing it ourselves.
* If we ever need to do something fancier than what objcopy provides,
* it would be straightforward to add here.
*
* We're keep a section table for a few reasons:
*
* The Go runtime had a couple of bugs: it would read the section
* table to try to figure out how many dynamic symbols there were (it
* shouldn't have looked at the section table at all) and, if there
* were no SHT_SYNDYM section table entry, it would use an
* uninitialized value for the number of symbols. An empty DYNSYM
* table would work, but I see no reason not to write a valid one (and
* keep full performance for old Go programs). This hack is only
* needed on x86_64.
*
* The bug was introduced on 2012-08-31 by:
* https://code.google.com/p/go/source/detail?r=56ea40aac72b
* and was fixed on 2014-06-13 by:
* https://code.google.com/p/go/source/detail?r=fc1cd5e12595
*
* Binutils has issues debugging the vDSO: it reads the section table to
* find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which
* would break build-id if we removed the section table. Binutils
* also requires that shstrndx != 0. See:
* https://sourceware.org/bugzilla/show_bug.cgi?id=17064
*
* elfutils might not look for PT_NOTE if there is a section table at
* all. I don't know whether this matters for any practical purpose.
*
* For simplicity, rather than hacking up a partial section table, we
* just write a mostly complete one. We omit non-dynamic symbols,
* though, since they're rather large.
*
* Once binutils gets fixed, we might be able to drop this for all but
* the 64-bit vdso, since build-id only works in kernel RPMs, and
* systems that update to new enough kernel RPMs will likely update
* binutils in sync. build-id has never worked for home-built kernel
* RPMs without manual symlinking, and I suspect that no one ever does
* that.
*/
#include <inttypes.h>
#include <stdint.h>
#include <unistd.h>
@ -20,9 +70,9 @@ const char *outfilename;
/* Symbols that we need in vdso2c. */
enum {
sym_vvar_start,
sym_vvar_page,
sym_hpet_page,
sym_end_mapping,
sym_VDSO_FAKE_SECTION_TABLE_START,
sym_VDSO_FAKE_SECTION_TABLE_END,
};
@ -38,9 +88,9 @@ struct vdso_sym {
};
struct vdso_sym required_syms[] = {
[sym_vvar_start] = {"vvar_start", true},
[sym_vvar_page] = {"vvar_page", true},
[sym_hpet_page] = {"hpet_page", true},
[sym_end_mapping] = {"end_mapping", true},
[sym_VDSO_FAKE_SECTION_TABLE_START] = {
"VDSO_FAKE_SECTION_TABLE_START", false
},
@ -61,7 +111,8 @@ static void fail(const char *format, ...)
va_start(ap, format);
fprintf(stderr, "Error: ");
vfprintf(stderr, format, ap);
unlink(outfilename);
if (outfilename)
unlink(outfilename);
exit(1);
va_end(ap);
}
@ -96,9 +147,11 @@ extern void bad_put_le(void);
#define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))
#define BITSFUNC3(name, bits) name##bits
#define BITSFUNC2(name, bits) BITSFUNC3(name, bits)
#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS)
#define BITSFUNC3(name, bits, suffix) name##bits##suffix
#define BITSFUNC2(name, bits, suffix) BITSFUNC3(name, bits, suffix)
#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS, )
#define INT_BITS BITSFUNC2(int, ELF_BITS, _t)
#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
@ -112,30 +165,53 @@ extern void bad_put_le(void);
#include "vdso2c.h"
#undef ELF_BITS
static void go(void *addr, size_t len, FILE *outfile, const char *name)
static void go(void *raw_addr, size_t raw_len,
void *stripped_addr, size_t stripped_len,
FILE *outfile, const char *name)
{
Elf64_Ehdr *hdr = (Elf64_Ehdr *)addr;
Elf64_Ehdr *hdr = (Elf64_Ehdr *)raw_addr;
if (hdr->e_ident[EI_CLASS] == ELFCLASS64) {
go64(addr, len, outfile, name);
go64(raw_addr, raw_len, stripped_addr, stripped_len,
outfile, name);
} else if (hdr->e_ident[EI_CLASS] == ELFCLASS32) {
go32(addr, len, outfile, name);
go32(raw_addr, raw_len, stripped_addr, stripped_len,
outfile, name);
} else {
fail("unknown ELF class\n");
}
}
static void map_input(const char *name, void **addr, size_t *len, int prot)
{
off_t tmp_len;
int fd = open(name, O_RDONLY);
if (fd == -1)
err(1, "%s", name);
tmp_len = lseek(fd, 0, SEEK_END);
if (tmp_len == (off_t)-1)
err(1, "lseek");
*len = (size_t)tmp_len;
*addr = mmap(NULL, tmp_len, prot, MAP_PRIVATE, fd, 0);
if (*addr == MAP_FAILED)
err(1, "mmap");
close(fd);
}
int main(int argc, char **argv)
{
int fd;
off_t len;
void *addr;
size_t raw_len, stripped_len;
void *raw_addr, *stripped_addr;
FILE *outfile;
char *name, *tmp;
int namelen;
if (argc != 3) {
printf("Usage: vdso2c INPUT OUTPUT\n");
if (argc != 4) {
printf("Usage: vdso2c RAW_INPUT STRIPPED_INPUT OUTPUT\n");
return 1;
}
@ -143,7 +219,7 @@ int main(int argc, char **argv)
* Figure out the struct name. If we're writing to a .so file,
* generate raw output insted.
*/
name = strdup(argv[2]);
name = strdup(argv[3]);
namelen = strlen(name);
if (namelen >= 3 && !strcmp(name + namelen - 3, ".so")) {
name = NULL;
@ -159,26 +235,18 @@ int main(int argc, char **argv)
*tmp = '_';
}
fd = open(argv[1], O_RDONLY);
if (fd == -1)
err(1, "%s", argv[1]);
map_input(argv[1], &raw_addr, &raw_len, PROT_READ);
map_input(argv[2], &stripped_addr, &stripped_len, PROT_READ);
len = lseek(fd, 0, SEEK_END);
if (len == (off_t)-1)
err(1, "lseek");
addr = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
if (addr == MAP_FAILED)
err(1, "mmap");
outfilename = argv[2];
outfilename = argv[3];
outfile = fopen(outfilename, "w");
if (!outfile)
err(1, "%s", argv[2]);
go(addr, (size_t)len, outfile, name);
go(raw_addr, raw_len, stripped_addr, stripped_len, outfile, name);
munmap(addr, len);
munmap(raw_addr, raw_len);
munmap(stripped_addr, stripped_len);
fclose(outfile);
return 0;

227
arch/x86/vdso/vdso2c.h
View File

@ -4,139 +4,23 @@
* are built for 32-bit userspace.
*/
/*
* We're writing a section table for a few reasons:
*
* The Go runtime had a couple of bugs: it would read the section
* table to try to figure out how many dynamic symbols there were (it
* shouldn't have looked at the section table at all) and, if there
* were no SHT_SYNDYM section table entry, it would use an
* uninitialized value for the number of symbols. An empty DYNSYM
* table would work, but I see no reason not to write a valid one (and
* keep full performance for old Go programs). This hack is only
* needed on x86_64.
*
* The bug was introduced on 2012-08-31 by:
* https://code.google.com/p/go/source/detail?r=56ea40aac72b
* and was fixed on 2014-06-13 by:
* https://code.google.com/p/go/source/detail?r=fc1cd5e12595
*
* Binutils has issues debugging the vDSO: it reads the section table to
* find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which
* would break build-id if we removed the section table. Binutils
* also requires that shstrndx != 0. See:
* https://sourceware.org/bugzilla/show_bug.cgi?id=17064
*
* elfutils might not look for PT_NOTE if there is a section table at
* all. I don't know whether this matters for any practical purpose.
*
* For simplicity, rather than hacking up a partial section table, we
* just write a mostly complete one. We omit non-dynamic symbols,
* though, since they're rather large.
*
* Once binutils gets fixed, we might be able to drop this for all but
* the 64-bit vdso, since build-id only works in kernel RPMs, and
* systems that update to new enough kernel RPMs will likely update
* binutils in sync. build-id has never worked for home-built kernel
* RPMs without manual symlinking, and I suspect that no one ever does
* that.
*/
struct BITSFUNC(fake_sections)
{
ELF(Shdr) *table;
unsigned long table_offset;
int count, max_count;
int in_shstrndx;
unsigned long shstr_offset;
const char *shstrtab;
size_t shstrtab_len;
int out_shstrndx;
};
static unsigned int BITSFUNC(find_shname)(struct BITSFUNC(fake_sections) *out,
const char *name)
{
const char *outname = out->shstrtab;
while (outname - out->shstrtab < out->shstrtab_len) {
if (!strcmp(name, outname))
return (outname - out->shstrtab) + out->shstr_offset;
outname += strlen(outname) + 1;
}
if (*name)
printf("Warning: could not find output name \"%s\"\n", name);
return out->shstr_offset + out->shstrtab_len - 1; /* Use a null. */
}
static void BITSFUNC(init_sections)(struct BITSFUNC(fake_sections) *out)
{
if (!out->in_shstrndx)
fail("didn't find the fake shstrndx\n");
memset(out->table, 0, out->max_count * sizeof(ELF(Shdr)));
if (out->max_count < 1)
fail("we need at least two fake output sections\n");
PUT_LE(&out->table[0].sh_type, SHT_NULL);
PUT_LE(&out->table[0].sh_name, BITSFUNC(find_shname)(out, ""));
out->count = 1;
}
static void BITSFUNC(copy_section)(struct BITSFUNC(fake_sections) *out,
int in_idx, const ELF(Shdr) *in,
const char *name)
{
uint64_t flags = GET_LE(&in->sh_flags);
bool copy = flags & SHF_ALLOC &&
(GET_LE(&in->sh_size) ||
(GET_LE(&in->sh_type) != SHT_RELA &&
GET_LE(&in->sh_type) != SHT_REL)) &&
strcmp(name, ".altinstructions") &&
strcmp(name, ".altinstr_replacement");
if (!copy)
return;
if (out->count >= out->max_count)
fail("too many copied sections (max = %d)\n", out->max_count);
if (in_idx == out->in_shstrndx)
out->out_shstrndx = out->count;
out->table[out->count] = *in;
PUT_LE(&out->table[out->count].sh_name,
BITSFUNC(find_shname)(out, name));
/* elfutils requires that a strtab have the correct type. */
if (!strcmp(name, ".fake_shstrtab"))
PUT_LE(&out->table[out->count].sh_type, SHT_STRTAB);
out->count++;
}
static void BITSFUNC(go)(void *addr, size_t len,
static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
void *stripped_addr, size_t stripped_len,
FILE *outfile, const char *name)
{
int found_load = 0;
unsigned long load_size = -1; /* Work around bogus warning */
unsigned long data_size;
ELF(Ehdr) *hdr = (ELF(Ehdr) *)addr;
unsigned long mapping_size;
ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
int i;
unsigned long j;
ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
*alt_sec = NULL;
ELF(Dyn) *dyn = 0, *dyn_end = 0;
const char *secstrings;
uint64_t syms[NSYMS] = {};
INT_BITS syms[NSYMS] = {};
struct BITSFUNC(fake_sections) fake_sections = {};
ELF(Phdr) *pt = (ELF(Phdr) *)(addr + GET_LE(&hdr->e_phoff));
ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff));
/* Walk the segment table. */
for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
@ -154,14 +38,16 @@ static void BITSFUNC(go)(void *addr, size_t len,
load_size = GET_LE(&pt[i].p_memsz);
found_load = 1;
} else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) {
dyn = addr + GET_LE(&pt[i].p_offset);
dyn_end = addr + GET_LE(&pt[i].p_offset) +
dyn = raw_addr + GET_LE(&pt[i].p_offset);
dyn_end = raw_addr + GET_LE(&pt[i].p_offset) +
GET_LE(&pt[i].p_memsz);
}
}
if (!found_load)
fail("no PT_LOAD seg\n");
data_size = (load_size + 4095) / 4096 * 4096;
if (stripped_len < load_size)
fail("stripped input is too short\n");
/* Walk the dynamic table */
for (i = 0; dyn + i < dyn_end &&
@ -173,11 +59,11 @@ static void BITSFUNC(go)(void *addr, size_t len,
}
/* Walk the section table */
secstrings_hdr = addr + GET_LE(&hdr->e_shoff) +
secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
secstrings = addr + GET_LE(&secstrings_hdr->sh_offset);
secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset);
for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
ELF(Shdr) *sh = addr + GET_LE(&hdr->e_shoff) +
ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * i;
if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
symtab_hdr = sh;
@ -190,7 +76,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
if (!symtab_hdr)
fail("no symbol table\n");
strtab_hdr = addr + GET_LE(&hdr->e_shoff) +
strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
/* Walk the symbol table */
@ -198,9 +84,9 @@ static void BITSFUNC(go)(void *addr, size_t len,
i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
i++) {
int k;
ELF(Sym) *sym = addr + GET_LE(&symtab_hdr->sh_offset) +
ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) +
GET_LE(&symtab_hdr->sh_entsize) * i;
const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
const char *name = raw_addr + GET_LE(&strtab_hdr->sh_offset) +
GET_LE(&sym->st_name);
for (k = 0; k < NSYMS; k++) {
@ -209,52 +95,18 @@ static void BITSFUNC(go)(void *addr, size_t len,
fail("duplicate symbol %s\n",
required_syms[k].name);
}
/*
* Careful: we use negative addresses, but
* st_value is unsigned, so we rely
* on syms[k] being a signed type of the
* correct width.
*/
syms[k] = GET_LE(&sym->st_value);
}
}
if (!strcmp(name, "fake_shstrtab")) {
ELF(Shdr) *sh;
fake_sections.in_shstrndx = GET_LE(&sym->st_shndx);
fake_sections.shstrtab = addr + GET_LE(&sym->st_value);
fake_sections.shstrtab_len = GET_LE(&sym->st_size);
sh = addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) *
fake_sections.in_shstrndx;
fake_sections.shstr_offset = GET_LE(&sym->st_value) -
GET_LE(&sh->sh_addr);
}
}
/* Build the output section table. */
if (!syms[sym_VDSO_FAKE_SECTION_TABLE_START] ||
!syms[sym_VDSO_FAKE_SECTION_TABLE_END])
fail("couldn't find fake section table\n");
if ((syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
syms[sym_VDSO_FAKE_SECTION_TABLE_START]) % sizeof(ELF(Shdr)))
fail("fake section table size isn't a multiple of sizeof(Shdr)\n");
fake_sections.table = addr + syms[sym_VDSO_FAKE_SECTION_TABLE_START];
fake_sections.table_offset = syms[sym_VDSO_FAKE_SECTION_TABLE_START];
fake_sections.max_count = (syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
syms[sym_VDSO_FAKE_SECTION_TABLE_START]) /
sizeof(ELF(Shdr));
BITSFUNC(init_sections)(&fake_sections);
for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
ELF(Shdr) *sh = addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * i;
BITSFUNC(copy_section)(&fake_sections, i, sh,
secstrings + GET_LE(&sh->sh_name));
}
if (!fake_sections.out_shstrndx)
fail("didn't generate shstrndx?!?\n");
PUT_LE(&hdr->e_shoff, fake_sections.table_offset);
PUT_LE(&hdr->e_shentsize, sizeof(ELF(Shdr)));
PUT_LE(&hdr->e_shnum, fake_sections.count);
PUT_LE(&hdr->e_shstrndx, fake_sections.out_shstrndx);
/* Validate mapping addresses. */
for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
if (!syms[i])
@ -263,21 +115,23 @@ static void BITSFUNC(go)(void *addr, size_t len,
if (syms[i] % 4096)
fail("%s must be a multiple of 4096\n",
required_syms[i].name);
if (syms[i] < data_size)
fail("%s must be after the text mapping\n",
if (syms[sym_vvar_start] > syms[i] + 4096)
fail("%s underruns begin_vvar\n",
required_syms[i].name);
if (syms[sym_end_mapping] < syms[i] + 4096)
fail("%s overruns end_mapping\n",
if (syms[i] + 4096 > 0)
fail("%s is on the wrong side of the vdso text\n",
required_syms[i].name);
}
if (syms[sym_end_mapping] % 4096)
fail("end_mapping must be a multiple of 4096\n");
if (syms[sym_vvar_start] % 4096)
fail("vvar_begin must be a multiple of 4096\n");
if (!name) {
fwrite(addr, load_size, 1, outfile);
fwrite(stripped_addr, stripped_len, 1, outfile);
return;
}
mapping_size = (stripped_len + 4095) / 4096 * 4096;
fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
fprintf(outfile, "#include <linux/linkage.h>\n");
fprintf(outfile, "#include <asm/page_types.h>\n");
@ -285,20 +139,21 @@ static void BITSFUNC(go)(void *addr, size_t len,
fprintf(outfile, "\n");
fprintf(outfile,
"static unsigned char raw_data[%lu] __page_aligned_data = {",
data_size);
for (j = 0; j < load_size; j++) {
mapping_size);
for (j = 0; j < stripped_len; j++) {
if (j % 10 == 0)
fprintf(outfile, "\n\t");
fprintf(outfile, "0x%02X, ", (int)((unsigned char *)addr)[j]);
fprintf(outfile, "0x%02X, ",
(int)((unsigned char *)stripped_addr)[j]);
}
fprintf(outfile, "\n};\n\n");
fprintf(outfile, "static struct page *pages[%lu];\n\n",
data_size / 4096);
mapping_size / 4096);
fprintf(outfile, "const struct vdso_image %s = {\n", name);
fprintf(outfile, "\t.data = raw_data,\n");
fprintf(outfile, "\t.size = %lu,\n", data_size);
fprintf(outfile, "\t.size = %lu,\n", mapping_size);
fprintf(outfile, "\t.text_mapping = {\n");
fprintf(outfile, "\t\t.name = \"[vdso]\",\n");
fprintf(outfile, "\t\t.pages = pages,\n");
@ -311,8 +166,8 @@ static void BITSFUNC(go)(void *addr, size_t len,
}
for (i = 0; i < NSYMS; i++) {
if (required_syms[i].export && syms[i])
fprintf(outfile, "\t.sym_%s = 0x%" PRIx64 ",\n",
required_syms[i].name, syms[i]);
fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
required_syms[i].name, (int64_t)syms[i]);
}
fprintf(outfile, "};\n");
}

22
arch/x86/vdso/vma.c
View File

@ -93,7 +93,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long addr;
unsigned long addr, text_start;
int ret = 0;
static struct page *no_pages[] = {NULL};
static struct vm_special_mapping vvar_mapping = {
@ -103,26 +103,28 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
if (calculate_addr) {
addr = vdso_addr(current->mm->start_stack,
image->sym_end_mapping);
image->size - image->sym_vvar_start);
} else {
addr = 0;
}
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, addr, image->sym_end_mapping, 0, 0);
addr = get_unmapped_area(NULL, addr,
image->size - image->sym_vvar_start, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
current->mm->context.vdso = (void __user *)addr;
text_start = addr - image->sym_vvar_start;
current->mm->context.vdso = (void __user *)text_start;
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*/
vma = _install_special_mapping(mm,
addr,
text_start,
image->size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
@ -134,9 +136,9 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
}
vma = _install_special_mapping(mm,
addr + image->size,
image->sym_end_mapping - image->size,
VM_READ,
addr,
-image->sym_vvar_start,
VM_READ|VM_MAYREAD,
&vvar_mapping);
if (IS_ERR(vma)) {
@ -146,7 +148,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
if (image->sym_vvar_page)
ret = remap_pfn_range(vma,
addr + image->sym_vvar_page,
text_start + image->sym_vvar_page,
__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
PAGE_SIZE,
PAGE_READONLY);
@ -157,7 +159,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
#ifdef CONFIG_HPET_TIMER
if (hpet_address && image->sym_hpet_page) {
ret = io_remap_pfn_range(vma,
addr + image->sym_hpet_page,
text_start + image->sym_hpet_page,
hpet_address >> PAGE_SHIFT,
PAGE_SIZE,
pgprot_noncached(PAGE_READONLY));