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* [glibc/release/2.35/master] m68k: Handle fewer relocations for RTLD_BOOTSTRAP (#BZ29071)
@ 2022-04-20 21:55 Fangrui Song
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From: Fangrui Song @ 2022-04-20 21:55 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d3feff2232ec27f05ca619ca8b314155d9018224
commit d3feff2232ec27f05ca619ca8b314155d9018224
Author: Fangrui Song <maskray@google.com>
Date: Wed Apr 20 10:24:15 2022 -0700
m68k: Handle fewer relocations for RTLD_BOOTSTRAP (#BZ29071)
m68k is a non-PI_STATIC_AND_HIDDEN arch which uses a GOT relocation when
loading the address of a jump table. The GOT load may be reordered
before processing R_68K_RELATIVE relocations, leading to an
unrelocated/incorrect jump table, which will cause a crash.
The foolproof approach is to add an optimization barrier (e.g. calling
an non-inlinable function after relative relocations are resolved). That
is non-trivial 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.
Reviewed-by: Adheemrval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit a8e9b5b8079d18116ca69c9797e77804ecf2ee7e)
Diff:
---
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;
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