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i386: Allow "lea foo@GOT, %reg" in PIC

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"lea foo@GOT, %reg" is OK in PIC since it only loads the GOT offset
into register, which can be used later with a GOT base register to
get the value in the GOT entry.

bfd/

	PR ld/21168
	* elf32-i386.c (elf_i386_relocate_section): Allow
	"lea foo@GOT, %reg" in PIC.

ld/

	PR ld/21168
	* testsuite/ld-i386/i386.exp: Run pr21168.
	* testsuite/ld-i386/pr21168a.c: New file.
	* testsuite/ld-i386/pr21168b.S: Likewise.
This commit is contained in:
H.J. Lu 2017-02-15 11:39:30 -08:00
parent a5def14f1c
commit 2a5684011e
6 changed files with 86 additions and 4 deletions
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6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2017-02-15 H.J. Lu <hongjiu.lu@intel.com>
PR ld/21168
* elf32-i386.c (elf_i386_relocate_section): Allow
"lea foo@GOT, %reg" in PIC.
2017-02-15 H.J. Lu <hongjiu.lu@intel.com>
PR ld/20244

12
bfd/elf32-i386.c
View File

@ -4074,7 +4074,9 @@ elf_i386_relocate_section (bfd *output_bfd,
- gotplt->output_section->vma
- gotplt->output_offset);
if ((*(contents + rel->r_offset - 1) & 0xc7) == 0x5)
if (rel->r_offset > 1
&& (*(contents + rel->r_offset - 1) & 0xc7) == 0x5
&& *(contents + rel->r_offset - 2) != 0x8d)
{
if (bfd_link_pic (info))
goto disallow_got32;
@ -4345,13 +4347,15 @@ r_386_got32:
relocation = (htab->elf.sgot->output_section->vma
+ htab->elf.sgot->output_offset + off);
if ((*(contents + rel->r_offset - 1) & 0xc7) == 0x5)
if (rel->r_offset > 1
&& (*(contents + rel->r_offset - 1) & 0xc7) == 0x5
&& *(contents + rel->r_offset - 2) != 0x8d)
{
if (bfd_link_pic (info))
{
/* For PIC, disallow R_386_GOT32 without a base
register since we don't know what the GOT base
is. */
register, except for "lea foo@GOT, %reg", since
we don't know what the GOT base is. */
const char *name;
disallow_got32:

7
ld/ChangeLog
View File

@ -1,3 +1,10 @@
2017-02-15 H.J. Lu <hongjiu.lu@intel.com>
PR ld/21168
* testsuite/ld-i386/i386.exp: Run pr21168.
* testsuite/ld-i386/pr21168a.c: New file.
* testsuite/ld-i386/pr21168b.S: Likewise.
2017-02-15 H.J. Lu <hongjiu.lu@intel.com>
PR ld/20244

22
ld/testsuite/ld-i386/i386.exp
View File

@ -835,6 +835,20 @@ if { [isnative]
"-fPIC -O2 -g" \
{ ifunc-1a.c ifunc-1b.S ifunc-1c.S ifunc-1d.S } \
] \
[list \
"Build pr21168a.o" \
"" \
"" \
{ pr21168a.c } \
] \
[list \
"Build pr21168.so" \
"-shared" \
"" \
{ pr21168b.S } \
"" \
"pr21168.so" \
] \
]
run_ld_link_exec_tests [list \
@ -856,6 +870,14 @@ if { [isnative]
"ifunc-1b" \
"pass.out" \
] \
[list \
"Run pr21168" \
"tmpdir/pr21168a.o tmpdir/pr21168.so" \
"" \
{ dummy.c } \
"pr21168" \
"pass.out" \
] \
]
}

14
ld/testsuite/ld-i386/pr21168a.c Normal file
View File

@ -0,0 +1,14 @@
#include <stdio.h>
int foo = 1;
extern int *bar (void);
extern int bar_ifunc (void);
int
main (void)
{
if (bar () == &foo && bar_ifunc () == 0xbadbeef)
printf ("PASS\n");
return 0;
}

29
ld/testsuite/ld-i386/pr21168b.S Normal file
View File

@ -0,0 +1,29 @@
.text
.globl bar
.type bar, @function
bar:
call __x86.get_pc_thunk.ax
addl $_GLOBAL_OFFSET_TABLE_, %eax
lea foo@GOT, %ecx
mov (%eax,%ecx,1), %eax
ret
.globl bar_ifunc
.type bar_ifunc, @function
bar_ifunc:
call __x86.get_pc_thunk.ax
addl $_GLOBAL_OFFSET_TABLE_, %eax
lea ifunc@GOT, %ecx
mov (%eax,%ecx,1), %eax
ret
.type ifunc, @gnu_indirect_function
ifunc:
mov $0xbadbeef, %eax
ret
.section .text.__x86.get_pc_thunk.ax,"axG",@progbits,__x86.get_pc_thunk.ax,comdat
.globl __x86.get_pc_thunk.ax
.hidden __x86.get_pc_thunk.ax
.type __x86.get_pc_thunk.ax, @function
__x86.get_pc_thunk.ax:
movl (%esp), %eax
ret
.section .note.GNU-stack,"",@progbits