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Merge branch 'x86/ld-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 linker bug workarounds from Peter Anvin.

GNU ld-2.22.52.0.[12] (*) has an unfortunate bug where it incorrectly
turns certain relocation entries absolute.  Section-relative symbols
that are part of otherwise empty sections are silently changed them to
absolute.  We rely on section-relative symbols staying section-relative,
and actually have several sections in the linker script solely for this
purpose.

See for example

   http://sourceware.org/bugzilla/show_bug.cgi?id=14052

We could just black-list the buggy linker, but it appears that it got
shipped in at least F17, and possibly other distros too, so it's sadly
not some rare unusual case.

This backports the workaround from the x86/trampoline branch, and as
Peter says: "This is not a minimal fix, not at all, but it is a tested
code base."

* 'x86/ld-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, relocs: When printing an error, say relative or absolute
  x86, relocs: Workaround for binutils 2.22.52.0.1 section bug
  x86, realmode: 16-bit real-mode code support for relocs tool

(*) That's a manly release numbering system. Stupid, sure. But manly.
This commit is contained in:
Linus Torvalds 2012-05-19 15:28:22 -07:00
commit 5d1204582e
7 changed files with 205 additions and 65 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Makefile
View File

@ -442,7 +442,7 @@ asm-generic:
no-dot-config-targets := clean mrproper distclean \
cscope gtags TAGS tags help %docs check% coccicheck \
include/linux/version.h headers_% archheaders \
include/linux/version.h headers_% archheaders archscripts \
kernelversion %src-pkg
config-targets := 0
@ -979,7 +979,7 @@ prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
include/config/auto.conf
$(cmd_crmodverdir)
archprepare: archheaders prepare1 scripts_basic
archprepare: archheaders archscripts prepare1 scripts_basic
prepare0: archprepare FORCE
$(Q)$(MAKE) $(build)=.
@ -1049,8 +1049,11 @@ hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)
PHONY += archheaders
archheaders:
PHONY += archscripts
archscripts:
PHONY += __headers
__headers: include/linux/version.h scripts_basic asm-generic archheaders FORCE
__headers: include/linux/version.h scripts_basic asm-generic archheaders archscripts FORCE
$(Q)$(MAKE) $(build)=scripts build_unifdef
PHONY += headers_install_all

3
arch/x86/Makefile
View File

@ -134,6 +134,9 @@ KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
KBUILD_CFLAGS += $(mflags-y)
KBUILD_AFLAGS += $(mflags-y)
archscripts:
$(Q)$(MAKE) $(build)=arch/x86/tools relocs
###
# Syscall table generation

9
arch/x86/boot/compressed/Makefile
View File

@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
targets += vmlinux.bin.all vmlinux.relocs
targets += vmlinux.bin.all vmlinux.relocs relocs
hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs
CMD_RELOCS = arch/x86/tools/relocs
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux FORCE
$(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin

1
arch/x86/tools/.gitignore vendored Normal file
View File

@ -0,0 +1 @@
relocs

4
arch/x86/tools/Makefile
View File

@ -36,3 +36,7 @@ HOSTCFLAGS_insn_sanity.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x
$(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
$(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-y += relocs
relocs: $(obj)/relocs

242
arch/x86/boot/compressed/relocs.c → arch/x86/tools/relocs.c
View File

@ -18,6 +18,8 @@ static void die(char *fmt, ...);
static Elf32_Ehdr ehdr;
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;
static unsigned long reloc16_count, reloc16_idx;
static unsigned long *relocs16;
struct section {
Elf32_Shdr shdr;
@ -28,52 +30,86 @@ struct section {
};
static struct section *secs;
enum symtype {
S_ABS,
S_REL,
S_SEG,
S_LIN,
S_NSYMTYPES
};
static const char * const sym_regex_kernel[S_NSYMTYPES] = {
/*
* Following symbols have been audited. There values are constant and do
* not change if bzImage is loaded at a different physical address than
* the address for which it has been compiled. Don't warn user about
* absolute relocations present w.r.t these symbols.
*/
static const char abs_sym_regex[] =
[S_ABS] =
"^(xen_irq_disable_direct_reloc$|"
"xen_save_fl_direct_reloc$|"
"VDSO|"
"__crc_)";
static regex_t abs_sym_regex_c;
static int is_abs_reloc(const char *sym_name)
{
return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0);
}
"__crc_)",
/*
* These symbols are known to be relative, even if the linker marks them
* as absolute (typically defined outside any section in the linker script.)
*/
static const char rel_sym_regex[] =
"^_end$";
static regex_t rel_sym_regex_c;
static int is_rel_reloc(const char *sym_name)
[S_REL] =
"^(__init_(begin|end)|"
"__x86_cpu_dev_(start|end)|"
"(__parainstructions|__alt_instructions)(|_end)|"
"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
"_end)$"
};
static const char * const sym_regex_realmode[S_NSYMTYPES] = {
/*
* These are 16-bit segment symbols when compiling 16-bit code.
*/
[S_SEG] =
"^real_mode_seg$",
/*
* These are offsets belonging to segments, as opposed to linear addresses,
* when compiling 16-bit code.
*/
[S_LIN] =
"^pa_",
};
static const char * const *sym_regex;
static regex_t sym_regex_c[S_NSYMTYPES];
static int is_reloc(enum symtype type, const char *sym_name)
{
return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0);
return sym_regex[type] &&
!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
}
static void regex_init(void)
static void regex_init(int use_real_mode)
{
char errbuf[128];
int err;
err = regcomp(&abs_sym_regex_c, abs_sym_regex,
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf);
die("%s", errbuf);
}
int i;
err = regcomp(&rel_sym_regex_c, rel_sym_regex,
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &rel_sym_regex_c, errbuf, sizeof errbuf);
die("%s", errbuf);
if (use_real_mode)
sym_regex = sym_regex_realmode;
else
sym_regex = sym_regex_kernel;
for (i = 0; i < S_NSYMTYPES; i++) {
if (!sym_regex[i])
continue;
err = regcomp(&sym_regex_c[i], sym_regex[i],
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
die("%s", errbuf);
}
}
}
@ -154,6 +190,10 @@ static const char *rel_type(unsigned type)
REL_TYPE(R_386_RELATIVE),
REL_TYPE(R_386_GOTOFF),
REL_TYPE(R_386_GOTPC),
REL_TYPE(R_386_8),
REL_TYPE(R_386_PC8),
REL_TYPE(R_386_16),
REL_TYPE(R_386_PC16),
#undef REL_TYPE
};
const char *name = "unknown type rel type name";
@ -189,7 +229,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
name = sym_strtab + sym->st_name;
}
else {
name = sec_name(secs[sym->st_shndx].shdr.sh_name);
name = sec_name(sym->st_shndx);
}
return name;
}
@ -472,7 +512,7 @@ static void print_absolute_relocs(void)
* Before warning check if this absolute symbol
* relocation is harmless.
*/
if (is_abs_reloc(name) || is_rel_reloc(name))
if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
continue;
if (!printed) {
@ -496,7 +536,8 @@ static void print_absolute_relocs(void)
printf("\n");
}
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
int use_real_mode)
{
int i;
/* Walk through the relocations */
@ -521,30 +562,67 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
Elf32_Rel *rel;
Elf32_Sym *sym;
unsigned r_type;
const char *symname;
int shn_abs;
rel = &sec->reltab[j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info);
/* Don't visit relocations to absolute symbols */
if (sym->st_shndx == SHN_ABS &&
!is_rel_reloc(sym_name(sym_strtab, sym))) {
continue;
}
shn_abs = sym->st_shndx == SHN_ABS;
switch (r_type) {
case R_386_NONE:
case R_386_PC32:
case R_386_PC16:
case R_386_PC8:
/*
* NONE can be ignored and and PC relative
* relocations don't need to be adjusted.
*/
break;
case R_386_16:
symname = sym_name(sym_strtab, sym);
if (!use_real_mode)
goto bad;
if (shn_abs) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_SEG, symname))
goto bad;
} else {
if (is_reloc(S_LIN, symname))
goto bad;
else
break;
}
visit(rel, sym);
break;
case R_386_32:
/* Visit relocations that need to be adjusted */
symname = sym_name(sym_strtab, sym);
if (shn_abs) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_REL, symname))
goto bad;
} else {
if (use_real_mode &&
!is_reloc(S_LIN, symname))
break;
}
visit(rel, sym);
break;
default:
die("Unsupported relocation type: %s (%d)\n",
rel_type(r_type), r_type);
break;
bad:
symname = sym_name(sym_strtab, sym);
die("Invalid %s %s relocation: %s\n",
shn_abs ? "absolute" : "relative",
rel_type(r_type), symname);
}
}
}
@ -552,13 +630,19 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
reloc_count += 1;
if (ELF32_R_TYPE(rel->r_info) == R_386_16)
reloc16_count++;
else
reloc_count++;
}
static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
/* Remember the address that needs to be adjusted. */
relocs[reloc_idx++] = rel->r_offset;
if (ELF32_R_TYPE(rel->r_info) == R_386_16)
relocs16[reloc16_idx++] = rel->r_offset;
else
relocs[reloc_idx++] = rel->r_offset;
}
static int cmp_relocs(const void *va, const void *vb)
@ -568,23 +652,41 @@ static int cmp_relocs(const void *va, const void *vb)
return (*a == *b)? 0 : (*a > *b)? 1 : -1;
}
static void emit_relocs(int as_text)
static int write32(unsigned int v, FILE *f)
{
unsigned char buf[4];
put_unaligned_le32(v, buf);
return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
}
static void emit_relocs(int as_text, int use_real_mode)
{
int i;
/* Count how many relocations I have and allocate space for them. */
reloc_count = 0;
walk_relocs(count_reloc);
walk_relocs(count_reloc, use_real_mode);
relocs = malloc(reloc_count * sizeof(relocs[0]));
if (!relocs) {
die("malloc of %d entries for relocs failed\n",
reloc_count);
}
relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
if (!relocs16) {
die("malloc of %d entries for relocs16 failed\n",
reloc16_count);
}
/* Collect up the relocations */
reloc_idx = 0;
walk_relocs(collect_reloc);
walk_relocs(collect_reloc, use_real_mode);
if (reloc16_count && !use_real_mode)
die("Segment relocations found but --realmode not specified\n");
/* Order the relocations for more efficient processing */
qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
/* Print the relocations */
if (as_text) {
@ -593,58 +695,83 @@ static void emit_relocs(int as_text)
*/
printf(".section \".data.reloc\",\"a\"\n");
printf(".balign 4\n");
for (i = 0; i < reloc_count; i++) {
printf("\t .long 0x%08lx\n", relocs[i]);
if (use_real_mode) {
printf("\t.long %lu\n", reloc16_count);
for (i = 0; i < reloc16_count; i++)
printf("\t.long 0x%08lx\n", relocs16[i]);
printf("\t.long %lu\n", reloc_count);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
} else {
/* Print a stop */
printf("\t.long 0x%08lx\n", (unsigned long)0);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
}
printf("\n");
}
else {
unsigned char buf[4];
/* Print a stop */
fwrite("\0\0\0\0", 4, 1, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++) {
put_unaligned_le32(relocs[i], buf);
fwrite(buf, 4, 1, stdout);
if (use_real_mode) {
write32(reloc16_count, stdout);
for (i = 0; i < reloc16_count; i++)
write32(relocs16[i], stdout);
write32(reloc_count, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++)
write32(relocs[i], stdout);
} else {
/* Print a stop */
write32(0, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++) {
write32(relocs[i], stdout);
}
}
}
}
static void usage(void)
{
die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
}
int main(int argc, char **argv)
{
int show_absolute_syms, show_absolute_relocs;
int as_text;
int as_text, use_real_mode;
const char *fname;
FILE *fp;
int i;
regex_init();
show_absolute_syms = 0;
show_absolute_relocs = 0;
as_text = 0;
use_real_mode = 0;
fname = NULL;
for (i = 1; i < argc; i++) {
char *arg = argv[i];
if (*arg == '-') {
if (strcmp(argv[1], "--abs-syms") == 0) {
if (strcmp(arg, "--abs-syms") == 0) {
show_absolute_syms = 1;
continue;
}
if (strcmp(argv[1], "--abs-relocs") == 0) {
if (strcmp(arg, "--abs-relocs") == 0) {
show_absolute_relocs = 1;
continue;
}
else if (strcmp(argv[1], "--text") == 0) {
if (strcmp(arg, "--text") == 0) {
as_text = 1;
continue;
}
if (strcmp(arg, "--realmode") == 0) {
use_real_mode = 1;
continue;
}
}
else if (!fname) {
fname = arg;
@ -655,6 +782,7 @@ int main(int argc, char **argv)
if (!fname) {
usage();
}
regex_init(use_real_mode);
fp = fopen(fname, "r");
if (!fp) {
die("Cannot open %s: %s\n",
@ -673,6 +801,6 @@ int main(int argc, char **argv)
print_absolute_relocs();
return 0;
}
emit_relocs(as_text);
emit_relocs(as_text, use_real_mode);
return 0;
}

2
scripts/Makefile
View File

@ -8,6 +8,8 @@
# conmakehash: Create arrays for initializing the kernel console tables
# docproc: Used in Documentation/DocBook
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-$(CONFIG_KALLSYMS) += kallsyms
hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash