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Re: [PATCH] Implement x86 SIZE32/SIZE64 relocations
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Andreas Jaeger <aj at suse dot com>
- Cc: libc-alpha at sourceware dot org
- Date: Wed, 16 Jan 2013 07:39:21 -0800
- Subject: Re: [PATCH] Implement x86 SIZE32/SIZE64 relocations
- References: <20130115214514.GA12687@intel.com><2336492.Cv7ONmYlGe@byrd>
On Wed, Jan 16, 2013 at 1:19 AM, Andreas Jaeger <aj@suse.com> wrote:
> On Tuesday, January 15, 2013 13:45:14 H.J. Lu wrote:
>> Hi
>>
>> Back to 2005, Solaris added R_386_SIZE32, R_X86_64_SIZE32 and
>> R_X86_64_SIZE64, which are resolved to symbol size plus addend. But
>> they aren't implemented in glibc. This patch implements them. They
>> can used to improve address sanitizer for global common symbols:
>>
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55739
>>
>> OK to install?
>>
>> BTW, I will also implement them in binutils.
>>
Here is the updated patch with feedbacks. OK to install?
Thanks.
--
H.J.
---
* elf/elf.h (R_386_SIZE32): New relocation.
* sysdeps/i386/dl-machine.h (elf_machine_rel): Handle
R_386_SIZE32.
(elf_machine_rela): Likewise.
* sysdeps/x86_64/dl-machine.h (elf_machine_rela): Handle
R_X86_64_SIZE64 and R_X86_64_SIZE32.
diff --git a/elf/elf.h b/elf/elf.h
index 9a31373..9bc5004 100644
--- a/elf/elf.h
+++ b/elf/elf.h
@@ -1229,7 +1229,7 @@ typedef struct
#define R_386_TLS_DTPMOD32 35 /* ID of module containing symbol */
#define R_386_TLS_DTPOFF32 36 /* Offset in TLS block */
#define R_386_TLS_TPOFF32 37 /* Negated offset in static TLS block */
-/* 38? */
+#define R_386_SIZE32 38 /* 32-bit symbol size */
#define R_386_TLS_GOTDESC 39 /* GOT offset for TLS descriptor. */
#define R_386_TLS_DESC_CALL 40 /* Marker of call through TLS
descriptor for
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 9e36687..a1e40d8 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -348,6 +348,12 @@ elf_machine_rel (struct link_map *map, const
Elf32_Rel *reloc,
switch (r_type)
{
+# ifndef RTLD_BOOTSTRAP
+ case R_386_SIZE32:
+ /* Set to symbol size plus addend. */
+ *reloc_addr += sym->st_size;
+ break;
+# endif
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
*reloc_addr = value;
@@ -507,6 +513,9 @@ elf_machine_rela (struct link_map *map, const
Elf32_Rela *reloc,
switch (ELF32_R_TYPE (reloc->r_info))
{
+ case R_386_SIZE32:
+ /* Set to symbol size plus addend. */
+ value = sym->st_size;
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
case R_386_32:
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index 660f1aa..4768c69 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -286,6 +286,21 @@ elf_machine_rela (struct link_map *map, const
ElfW(Rela) *reloc,
switch (r_type)
{
+# ifndef RTLD_BOOTSTRAP
+# ifdef __ILP32__
+ case R_X86_64_SIZE64:
+ /* Set to symbol size plus addend. */
+ *(Elf64_Addr *) (uintptr_t) reloc_addr
+ = (Elf64_Addr) sym->st_size + reloc->r_addend;
+ break;
+
+ case R_X86_64_SIZE32:
+# else
+ case R_X86_64_SIZE64:
+# endif
+ /* Set to symbol size plus addend. */
+ value = sym->st_size;
+# endif
case R_X86_64_GLOB_DAT:
case R_X86_64_JUMP_SLOT:
*reloc_addr = value + reloc->r_addend;
@@ -394,6 +409,11 @@ elf_machine_rela (struct link_map *map, const
ElfW(Rela) *reloc,
relocation updates the whole 64-bit entry. */
*(Elf64_Addr *) reloc_addr = (Elf64_Addr) value + reloc->r_addend;
break;
+# ifndef __ILP32__
+ case R_X86_64_SIZE32:
+ /* Set to symbol size plus addend. */
+ value = sym->st_size;
+# endif
case R_X86_64_32:
value += reloc->r_addend;
*(unsigned int *) reloc_addr = value;