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ld/x86: Add -z report-relative-reloc

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Linker generated relative relocations don't have symbol info:

[hjl@gnu-cfl-2 tmpdir]$ readelf -rW dump

Relocation section '.rela.dyn' at offset 0x180 contains 2 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
00002f70  00000008 R_X86_64_RELATIVE                 1000
00002f68  00000025 R_X86_64_IRELATIVE                1007
[hjl@gnu-cfl-2 tmpdir]$

Add -z report-relative-reloc to x86 ELF linker to report dynamic relative
relocations:

[hjl@gnu-cfl-2 tmpdir]$ ../ld-new -pie -melf32_x86_64 -z report-relative-reloc -o dump report-reloc-1.o
dump: R_X86_64_IRELATIVE (offset: 0x00002f68, info: 0x00000025, addend: 0x00001007) against 'ifunc' for section '.data.rel.ro.local' in report-reloc-1.o
dump: R_X86_64_RELATIVE (offset: 0x00002f70, info: 0x00000008, addend: 0x00001000) against '_start' for section '.data.rel.ro.local' in report-reloc-1.o
[hjl@gnu-cfl-2 tmpdir]$

It can be used to map relative relocations to corresponding symbols.

bfd/

	* elf-linker-x86.h (elf_linker_x86_params): Add
	report_relative_reloc.
	* elf32-i386.c (elf_i386_relocate_section): Call
	_bfd_x86_elf_link_report_relative_reloc to report relative
	relocations for -z report-relative-reloc.
	(elf_i386_finish_dynamic_symbol): Likewse.
	* elf64-x86-64.c (elf_x86_64_relocate_section): Likewse.
	(elf_x86_64_finish_dynamic_symbol): Likewse.
	* elfxx-x86.c (_bfd_x86_elf_link_report_relative_reloc): New
	function.
	* elfxx-x86.h (_bfd_x86_elf_link_report_relative_reloc): New
	prototype.

ld/

	* NEWS: Mention -z report-relative-reloc.
	* ld.texi: Document -z report-relative-reloc.
	* emulparams/elf32_x86_64.sh: Source x86-report-relative.sh.
	* emulparams/elf_i386.sh: Likewse.
	* emulparams/elf_x86_64.sh: Likewse.
	* emulparams/x86-report-relative.sh: New file.
	* testsuite/ld-i386/report-reloc-1.d: Likewse.
	* testsuite/ld-i386/report-reloc-1.l: Likewse.
	* testsuite/ld-i386/report-reloc-1.s: Likewse.
	* testsuite/ld-x86-64/report-reloc-1-x32.d: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.d: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.l: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.s: Likewse.
	* testsuite/ld-i386/i386.exp: Run report-reloc-1.
	* testsuite/ld-x86-64/x86-64.exp: Run report-reloc-1 and
	report-reloc-1-x32.
This commit is contained in:
H.J. Lu 2021-01-15 18:06:48 -08:00
parent ad92f33d38
commit 68b007788a
22 changed files with 239 additions and 0 deletions
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15
bfd/ChangeLog
View File

@ -1,3 +1,18 @@
2021-01-15 H.J. Lu <hongjiu.lu@intel.com>
* elf-linker-x86.h (elf_linker_x86_params): Add
report_relative_reloc.
* elf32-i386.c (elf_i386_relocate_section): Call
_bfd_x86_elf_link_report_relative_reloc to report relative
relocations for -z report-relative-reloc.
(elf_i386_finish_dynamic_symbol): Likewse.
* elf64-x86-64.c (elf_x86_64_relocate_section): Likewse.
(elf_x86_64_finish_dynamic_symbol): Likewse.
* elfxx-x86.c (_bfd_x86_elf_link_report_relative_reloc): New
function.
* elfxx-x86.h (_bfd_x86_elf_link_report_relative_reloc): New
prototype.
2021-01-16 Alan Modra <amodra@gmail.com>
* compress.c (decompress_contents): Tidy inflateEnd result test.

3
bfd/elf-linker-x86.h
View File

@ -61,6 +61,9 @@ struct elf_linker_x86_params
/* TRUE if --dynamic-linker is passed at command-line. */
unsigned int has_dynamic_linker : 1;
/* Report relative relocations. */
unsigned int report_relative_reloc : 1;
/* X86-64 ISA level needed. */
unsigned int isa_level;

36
bfd/elf32-i386.c
View File

@ -2409,6 +2409,12 @@ elf_i386_relocate_section (bfd *output_bfd,
/* This symbol is resolved locally. */
outrel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym,
"R_386_IRELATIVE", &outrel);
bfd_put_32 (output_bfd,
(h->root.u.def.value
+ h->root.u.def.section->output_section->vma
@ -2532,6 +2538,12 @@ elf_i386_relocate_section (bfd *output_bfd,
+ htab->elf.sgot->output_offset
+ off);
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym, "R_386_RELATIVE",
&outrel);
elf_append_rel (output_bfd, s, &outrel);
}
@ -2738,6 +2750,11 @@ elf_i386_relocate_section (bfd *output_bfd,
/* This symbol is local, or marked to become local. */
relocate = TRUE;
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym, "R_386_RELATIVE",
&outrel);
}
sreloc = elf_section_data (input_section)->sreloc;
@ -2769,6 +2786,12 @@ elf_i386_relocate_section (bfd *output_bfd,
+ input_section->output_section->vma
+ input_section->output_offset;
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym, "R_386_RELATIVE",
&outrel);
sreloc = elf_section_data (input_section)->sreloc;
if (sreloc == NULL)
abort ();
@ -3664,6 +3687,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
+ h->root.u.def.section->output_offset),
gotplt->contents + got_offset);
rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, relplt, h, sym, "R_386_IRELATIVE", &rel);
/* R_386_IRELATIVE comes last. */
plt_index = htab->next_irelative_index--;
}
@ -3762,6 +3790,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
{
Elf_Internal_Rela rel;
asection *relgot = htab->elf.srelgot;
const char *relative_reloc_name = NULL;
/* This symbol has an entry in the global offset table. Set it
up. */
@ -3802,6 +3831,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
+ h->root.u.def.section->output_offset),
htab->elf.sgot->contents + h->got.offset);
rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
relative_reloc_name = "R_386_IRELATIVE";
}
else
goto do_glob_dat;
@ -3844,6 +3874,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
{
BFD_ASSERT((h->got.offset & 1) != 0);
rel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
relative_reloc_name = "R_386_RELATIVE";
}
else
{
@ -3854,6 +3885,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
rel.r_info = ELF32_R_INFO (h->dynindx, R_386_GLOB_DAT);
}
if (relative_reloc_name != NULL
&& htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, relgot, h, sym, relative_reloc_name, &rel);
elf_append_rel (output_bfd, relgot, &rel);
}

33
bfd/elf64-x86-64.c
View File

@ -2784,6 +2784,11 @@ elf_x86_64_relocate_section (bfd *output_bfd,
outrel.r_addend = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym,
"R_X86_64_IRELATIVE", &outrel);
}
else
{
@ -2940,6 +2945,12 @@ elf_x86_64_relocate_section (bfd *output_bfd,
+ off);
outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
outrel.r_addend = relocation;
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym, "R_X86_64_RELATIVE",
&outrel);
elf_append_rela (output_bfd, s, &outrel);
}
@ -3221,6 +3232,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
Elf_Internal_Rela outrel;
bfd_boolean skip, relocate;
asection *sreloc;
const char *relative_reloc_name = NULL;
/* When generating a shared object, these relocations
are copied into the output file to be resolved at run
@ -3259,6 +3271,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
relocate = TRUE;
outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
outrel.r_addend = relocation + rel->r_addend;
relative_reloc_name = "R_X86_64_RELATIVE";
}
else if (r_type == R_X86_64_64
&& !ABI_64_P (output_bfd))
@ -3267,6 +3280,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
outrel.r_info = htab->r_info (0,
R_X86_64_RELATIVE64);
outrel.r_addend = relocation + rel->r_addend;
relative_reloc_name = "R_X86_64_RELATIVE64";
/* Check addend overflow. */
if ((outrel.r_addend & 0x80000000)
!= (rel->r_addend & 0x80000000))
@ -3333,6 +3347,12 @@ elf_x86_64_relocate_section (bfd *output_bfd,
goto check_relocation_error;
}
if (relative_reloc_name
&& htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, input_section, h, sym, relative_reloc_name,
&outrel);
elf_append_rela (output_bfd, sreloc, &outrel);
/* If this reloc is against an external symbol, we do
@ -4292,6 +4312,11 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
rela.r_addend = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
if (htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, relplt, h, sym, "R_X86_64_IRELATIVE", &rela);
/* R_X86_64_IRELATIVE comes last. */
plt_index = htab->next_irelative_index--;
}
@ -4409,6 +4434,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
{
Elf_Internal_Rela rela;
asection *relgot = htab->elf.srelgot;
const char *relative_reloc_name = NULL;
/* This symbol has an entry in the global offset table. Set it
up. */
@ -4447,6 +4473,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
rela.r_addend = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
relative_reloc_name = "R_X86_64_IRELATIVE";
}
else
goto do_glob_dat;
@ -4494,6 +4521,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
rela.r_addend = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
relative_reloc_name = "R_X86_64_RELATIVE";
}
else
{
@ -4505,6 +4533,11 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
rela.r_addend = 0;
}
if (relative_reloc_name != NULL
&& htab->params->report_relative_reloc)
_bfd_x86_elf_link_report_relative_reloc
(info, relgot, h, sym, relative_reloc_name, &rela);
elf_append_rela (output_bfd, relgot, &rela);
}

47
bfd/elfxx-x86.c
View File

@ -1742,6 +1742,53 @@ _bfd_x86_elf_link_fixup_ifunc_symbol (struct bfd_link_info *info,
}
}
/* Report relative relocation. */
void
_bfd_x86_elf_link_report_relative_reloc
(struct bfd_link_info *info, asection *asect,
struct elf_link_hash_entry *h, Elf_Internal_Sym *sym,
const char *reloc_name, const void *reloc)
{
const char *name;
bfd *abfd;
const Elf_Internal_Rela *rel = (const Elf_Internal_Rela *) reloc;
char r_offset[30], r_info[30];
/* Use the output BFD for linker created sections. */
if ((asect->flags & SEC_LINKER_CREATED) != 0)
abfd = info->output_bfd;
else
abfd = asect->owner;
if (h != NULL && h->root.root.string != NULL)
name = h->root.root.string;
else
name = bfd_elf_sym_name (abfd, &elf_symtab_hdr (abfd), sym, NULL);
bfd_sprintf_vma (abfd, r_offset, rel->r_offset);
bfd_sprintf_vma (abfd, r_info, rel->r_info);
if (asect->use_rela_p)
{
char r_addend[30];
bfd_sprintf_vma (abfd, r_addend, rel->r_addend);
info->callbacks->einfo
(_("%pB: %s (offset: 0x%s, info: 0x%s, addend: 0x%s) against "
"'%s' " "for section '%pA' in %pB\n"),
info->output_bfd, reloc_name, r_offset, r_info, r_addend,
name, asect, abfd);
}
else
info->callbacks->einfo
(_("%pB: %s (offset: 0x%s, info: 0x%s) against '%s' for section "
"'%pA' in %pB\n"),
info->output_bfd, reloc_name, r_offset, r_info, name,
asect, abfd);
}
/* Return TRUE if symbol should be hashed in the `.gnu.hash' section. */
bfd_boolean

4
bfd/elfxx-x86.h
View File

@ -686,6 +686,10 @@ extern void _bfd_x86_elf_link_fixup_ifunc_symbol
(struct bfd_link_info *, struct elf_x86_link_hash_table *,
struct elf_link_hash_entry *, Elf_Internal_Sym *sym);
extern void _bfd_x86_elf_link_report_relative_reloc
(struct bfd_link_info *, asection *, struct elf_link_hash_entry *,
Elf_Internal_Sym *, const char *, const void *);
#define bfd_elf64_mkobject \
_bfd_x86_elf_mkobject
#define bfd_elf32_mkobject \

19
ld/ChangeLog
View File

@ -1,3 +1,22 @@
2021-01-15 H.J. Lu <hongjiu.lu@intel.com>
* NEWS: Mention -z report-relative-reloc.
* ld.texi: Document -z report-relative-reloc.
* emulparams/elf32_x86_64.sh: Source x86-report-relative.sh.
* emulparams/elf_i386.sh: Likewse.
* emulparams/elf_x86_64.sh: Likewse.
* emulparams/x86-report-relative.sh: New file.
* testsuite/ld-i386/report-reloc-1.d: Likewse.
* testsuite/ld-i386/report-reloc-1.l: Likewse.
* testsuite/ld-i386/report-reloc-1.s: Likewse.
* testsuite/ld-x86-64/report-reloc-1-x32.d: Likewse.
* testsuite/ld-x86-64/report-reloc-1.d: Likewse.
* testsuite/ld-x86-64/report-reloc-1.l: Likewse.
* testsuite/ld-x86-64/report-reloc-1.s: Likewse.
* testsuite/ld-i386/i386.exp: Run report-reloc-1.
* testsuite/ld-x86-64/x86-64.exp: Run report-reloc-1 and
report-reloc-1-x32.
2021-01-16 Alan Modra <amodra@gmail.com>
PR 26002

3
ld/NEWS
View File

@ -1,5 +1,8 @@
-*- text -*-
* Add -z report-relative-reloc to x86 ELF linker to report dynamic
relative relocations.
Changes in 2.36:
* Add libdep plugin, for linking dependencies of static libraries that

1
ld/emulparams/elf32_x86_64.sh
View File

@ -4,6 +4,7 @@ source_sh ${srcdir}/emulparams/dynamic_undefined_weak.sh
source_sh ${srcdir}/emulparams/reloc_overflow.sh
source_sh ${srcdir}/emulparams/call_nop.sh
source_sh ${srcdir}/emulparams/cet.sh
source_sh ${srcdir}/emulparams/x86-report-relative.sh
source_sh ${srcdir}/emulparams/x86-64-level.sh
source_sh ${srcdir}/emulparams/static.sh
SCRIPT_NAME=elf

1
ld/emulparams/elf_i386.sh
View File

@ -3,6 +3,7 @@ source_sh ${srcdir}/emulparams/extern_protected_data.sh
source_sh ${srcdir}/emulparams/dynamic_undefined_weak.sh
source_sh ${srcdir}/emulparams/call_nop.sh
source_sh ${srcdir}/emulparams/cet.sh
source_sh ${srcdir}/emulparams/x86-report-relative.sh
source_sh ${srcdir}/emulparams/x86-64-level.sh
source_sh ${srcdir}/emulparams/static.sh
SCRIPT_NAME=elf

1
ld/emulparams/elf_x86_64.sh
View File

@ -4,6 +4,7 @@ source_sh ${srcdir}/emulparams/dynamic_undefined_weak.sh
source_sh ${srcdir}/emulparams/reloc_overflow.sh
source_sh ${srcdir}/emulparams/call_nop.sh
source_sh ${srcdir}/emulparams/cet.sh
source_sh ${srcdir}/emulparams/x86-report-relative.sh
source_sh ${srcdir}/emulparams/x86-64-level.sh
source_sh ${srcdir}/emulparams/x86-64-lam.sh
source_sh ${srcdir}/emulparams/static.sh

11
ld/emulparams/x86-report-relative.sh Normal file
View File

@ -0,0 +1,11 @@
PARSE_AND_LIST_OPTIONS_X86_REPORT_RELATIVE='
fprintf (file, _("\
-z report-relative-reloc Report relative relocations\n"));
'
PARSE_AND_LIST_ARGS_CASE_Z_X86_REPORT_RELATIVE='
else if (strcmp (optarg, "report-relative-reloc") == 0)
params.report_relative_reloc = 1;
'
PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_X86_REPORT_RELATIVE"
PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_X86_REPORT_RELATIVE"

4
ld/ld.texi
View File

@ -1426,6 +1426,10 @@ relocation, if supported. Specifying @samp{common-page-size} smaller
than the system page size will render this protection ineffective.
Don't create an ELF @code{PT_GNU_RELRO} segment if @samp{norelro}.
@item report-relative-reloc
Report dynamic relative relocations generated by linker. Supported for
Linux/i386 and Linux/x86_64.
@item separate-code
@itemx noseparate-code
Create separate code @code{PT_LOAD} segment header in the object. This

1
ld/testsuite/ld-i386/i386.exp
View File

@ -506,6 +506,7 @@ run_dump_test "pr18815"
run_dump_test "pr19939a"
run_dump_test "pr19939b"
run_dump_test "tlsdesc2"
run_dump_test "report-reloc-1"
proc undefined_weak {cflags ldflags} {
set testname "Undefined weak symbol"

10
ld/testsuite/ld-i386/report-reloc-1.d Normal file
View File

@ -0,0 +1,10 @@
#source: report-reloc-1.s
#as: --32
#ld: -pie -melf_i386 -z report-relative-reloc
#warning_output: report-reloc-1.l
#readelf: -r --wide
Relocation section '.rel.dyn' at offset 0x[0-9a-f]+ contains 2 entries:
+Offset +Info +Type +Sym.* Value +Symbol's Name
[0-9a-f]+ +[0-9a-f]+ +R_386_RELATIVE +
[0-9a-f]+ +[0-9a-f]+ +R_386_IRELATIVE +

2
ld/testsuite/ld-i386/report-reloc-1.l Normal file
View File

@ -0,0 +1,2 @@
tmpdir/dump: R_386_IRELATIVE \(offset: 0x0+2000, info: 0x0+2a\) against 'ifunc' for section '.data.rel.ro.local' in tmpdir/report-reloc-1.o
tmpdir/dump: R_386_RELATIVE \(offset: 0x0+2004, info: 0x0+8\) against '_start' for section '.data.rel.ro.local' in tmpdir/report-reloc-1.o

12
ld/testsuite/ld-i386/report-reloc-1.s Normal file
View File

@ -0,0 +1,12 @@
.text
.globl _start
.type ifunc, @gnu_indirect_function
_start:
lea .Ljmp@GOTOFF(%ebx), %eax
ifunc:
jmp *(%eax)
.section .data.rel.ro.local,"aw",@progbits
.align 4
.Ljmp:
.long ifunc
.long _start

10
ld/testsuite/ld-x86-64/report-reloc-1-x32.d Normal file
View File

@ -0,0 +1,10 @@
#source: report-reloc-1.s
#as: --x32
#ld: -pie -melf32_x86_64 -z report-relative-reloc
#warning_output: report-reloc-1.l
#readelf: -r --wide
Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 2 entries:
+Offset +Info +Type +Sym.* Value +Symbol's Name \+ Addend
[0-9a-f]+ +[0-9a-f]+ +R_X86_64_RELATIVE +[0-9a-f]+
[0-9a-f]+ +[0-9a-f]+ +R_X86_64_IRELATIVE +[0-9a-f]+

10
ld/testsuite/ld-x86-64/report-reloc-1.d Normal file
View File

@ -0,0 +1,10 @@
#source: report-reloc-1.s
#as: --64
#ld: -pie -melf_x86_64 -z report-relative-reloc
#warning_output: report-reloc-1.l
#readelf: -r --wide
Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 2 entries:
+Offset +Info +Type +Sym.* Value +Symbol's Name \+ Addend
[0-9a-f]+ +[0-9a-f]+ +R_X86_64_RELATIVE +[0-9a-f]+
[0-9a-f]+ +[0-9a-f]+ +R_X86_64_IRELATIVE +[0-9a-f]+

2
ld/testsuite/ld-x86-64/report-reloc-1.l Normal file
View File

@ -0,0 +1,2 @@
tmpdir/dump: R_X86_64_IRELATIVE \(offset: 0x0+2000, info: 0x0+25, addend: 0x0+1007\) against 'ifunc' for section '.data.rel.ro.local' in tmpdir/report-reloc-1.o
tmpdir/dump: R_X86_64_RELATIVE \(offset: 0x0+2008, info: 0x0+8, addend: 0x0+1000\) against '_start' for section '.data.rel.ro.local' in tmpdir/report-reloc-1.o

12
ld/testsuite/ld-x86-64/report-reloc-1.s Normal file
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@ -0,0 +1,12 @@
.text
.globl _start
.type ifunc, @gnu_indirect_function
_start:
lea .Ljmp(%rip), %rax
ifunc:
jmp *(%rax)
.section .data.rel.ro.local,"aw",@progbits
.align 8
.Ljmp:
.quad ifunc
.quad _start

2
ld/testsuite/ld-x86-64/x86-64.exp
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@ -677,6 +677,8 @@ run_dump_test "pr26939"
run_dump_test "pr26939-x32"
run_dump_test "pr27016a"
run_dump_test "pr27016b"
run_dump_test "report-reloc-1"
run_dump_test "report-reloc-1-x32"
proc undefined_weak {cflags ldflags} {
set testname "Undefined weak symbol"