m68k: Handle fewer relocations for RTLD_BOOTSTRAP (#BZ29071)
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Check |
Description |
| dj/TryBot-apply_patch |
success
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Patch applied to master at the time it was sent
|
| dj/TryBot-32bit |
success
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Build for i686
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Commit Message
m68k is a non-PI_STATIC_AND_HIDDEN arch which uses a GOT relocation when
loading a jump table. The GOT load may be reordered before processing
R_68K_RELATIVE relocations, leading to an unrelocated/incorrect jump
table. The foolproof approach is to add an optimization barrier (e.g.
calling a function after relative relocations are resolved). That isn't
suitable given the current code structure, so just use the simple
approach to avoid the jump table: handle only the essential reloctions
for RTLD_BOOTSTRAP code.
This is based on Andreas Schwab's patch and fixed ld.so crash on m68k.
---
sysdeps/m68k/dl-machine.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
Comments
On 19/04/2022 23:35, Fangrui Song wrote:
> m68k is a non-PI_STATIC_AND_HIDDEN arch which uses a GOT relocation when
> loading a jump table. The GOT load may be reordered before processing
> R_68K_RELATIVE relocations, leading to an unrelocated/incorrect jump
> table. The foolproof approach is to add an optimization barrier (e.g.
> calling a function after relative relocations are resolved). That isn't
> suitable given the current code structure, so just use the simple
> approach to avoid the jump table: handle only the essential reloctions
> for RTLD_BOOTSTRAP code.
>
> This is based on Andreas Schwab's patch and fixed ld.so crash on m68k.
LGTM, thanks. The loader does not triggers a segfault anymore.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> sysdeps/m68k/dl-machine.h | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/sysdeps/m68k/dl-machine.h b/sysdeps/m68k/dl-machine.h
> index c44ab055aa..bb51b4198c 100644
> --- a/sysdeps/m68k/dl-machine.h
> +++ b/sysdeps/m68k/dl-machine.h
> @@ -234,6 +234,11 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
>
> switch (r_type)
> {
> + case R_68K_GLOB_DAT:
> + case R_68K_JMP_SLOT:
> + *reloc_addr = value;
> + break;
> +#ifndef RTLD_BOOTSTRAP
> case R_68K_COPY:
> if (sym == NULL)
> /* This can happen in trace mode if an object could not be
> @@ -252,10 +257,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
> memcpy (reloc_addr_arg, (void *) value,
> MIN (sym->st_size, refsym->st_size));
> break;
> - case R_68K_GLOB_DAT:
> - case R_68K_JMP_SLOT:
> - *reloc_addr = value;
> - break;
> case R_68K_8:
> *(char *) reloc_addr = value + reloc->r_addend;
> break;
> @@ -276,7 +277,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
> case R_68K_PC32:
> *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
> break;
> -#ifndef RTLD_BOOTSTRAP
> case R_68K_TLS_DTPMOD32:
> /* Get the information from the link map returned by the
> resolv function. */
> @@ -294,9 +294,9 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
> *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
> }
> break;
> -#endif /* !RTLD_BOOTSTRAP */
> case R_68K_NONE: /* Alright, Wilbur. */
> break;
> +#endif /* !RTLD_BOOTSTRAP */
> default:
> _dl_reloc_bad_type (map, r_type, 0);
> break;
@@ -234,6 +234,11 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
switch (r_type)
{
+ case R_68K_GLOB_DAT:
+ case R_68K_JMP_SLOT:
+ *reloc_addr = value;
+ break;
+#ifndef RTLD_BOOTSTRAP
case R_68K_COPY:
if (sym == NULL)
/* This can happen in trace mode if an object could not be
@@ -252,10 +257,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
memcpy (reloc_addr_arg, (void *) value,
MIN (sym->st_size, refsym->st_size));
break;
- case R_68K_GLOB_DAT:
- case R_68K_JMP_SLOT:
- *reloc_addr = value;
- break;
case R_68K_8:
*(char *) reloc_addr = value + reloc->r_addend;
break;
@@ -276,7 +277,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
case R_68K_PC32:
*reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
break;
-#ifndef RTLD_BOOTSTRAP
case R_68K_TLS_DTPMOD32:
/* Get the information from the link map returned by the
resolv function. */
@@ -294,9 +294,9 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
}
break;
-#endif /* !RTLD_BOOTSTRAP */
case R_68K_NONE: /* Alright, Wilbur. */
break;
+#endif /* !RTLD_BOOTSTRAP */
default:
_dl_reloc_bad_type (map, r_type, 0);
break;