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authorRoman I Khimov <khimov@altell.ru>2010-05-04 14:00:47 +0400
committerAustin Foxley <austinf@cetoncorp.com>2010-05-05 08:43:22 -0700
commit0b7acfa800444525498442032b47bfd7d066c72b (patch)
tree0a01157af61958014f0b0dc957d1dd5061df5d26 /ldso
parentc1505e73d00ed26b7c250e331b213e63a948b1dd (diff)
ldso: fix x86_64 R_X86_64_TPOFF64 and R_X86_64_DTPOFF64 relocations
R_X86_64_TPOFF64 revealed by trivial testcase: =================================================================== #include <stdio.h> #include <errno.h> int main() { void *a = &errno; printf("errno addr: %llx\n", a); __asm__("movq errno@gottpoff(%%rip), %0;\n" "add %%fs:0x0,%0;" : "=r"(a) ); printf("got errno addr: %llx\n", a); return 0; } =================================================================== The addresses application got with R_X86_64_TPOFF64 was different than the once libc internal __errno_location returned. R_X86_64_DTPOFF64 testcase is even simpler than that: =================================================================== #include <stdio.h> #include <errno.h> #include <netdb.h> #undef h_errno extern __thread int h_errno; int main() { printf("h_errno addr: %llx\n", &h_errno); printf("__h_errno_location addr: %llx\n", __h_errno_location()); return 0; } =================================================================== but needs to be linked with "-lpthread". This way we've got h_errno relocation via R_X86_64_TPOFF64 in application and h_errno relocation via R_X86_64_DTPOFF64 in libpthread which has its own __h_errno_location() (probably we can kill it later?). And addresses were different again. The problem is that both relocations resolve symbols in external modules and thus should use symbol_addr instead of sym->st_value. Signed-off-by: Roman I Khimov <khimov@altell.ru> Signed-off-by: Austin Foxley <austinf@cetoncorp.com>
Diffstat (limited to 'ldso')
-rw-r--r--ldso/ldso/x86_64/elfinterp.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/ldso/ldso/x86_64/elfinterp.c b/ldso/ldso/x86_64/elfinterp.c
index 54528d382..baf024d11 100644
--- a/ldso/ldso/x86_64/elfinterp.c
+++ b/ldso/ldso/x86_64/elfinterp.c
@@ -226,7 +226,7 @@ _dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
case R_X86_64_DTPOFF64:
/* During relocation all TLS symbols are defined and used.
* Therefore the offset is already correct. */
- *reloc_addr = sym->st_value + rpnt->r_addend;
+ *reloc_addr = symbol_addr + rpnt->r_addend;
break;
case R_X86_64_TPOFF64:
/* The offset is negative, forward from the thread pointer.
@@ -234,7 +234,7 @@ _dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
* It is a negative value which will be added to the
* thread pointer. */
CHECK_STATIC_TLS ((struct link_map *) tls_tpnt);
- *reloc_addr = sym->st_value - tls_tpnt->l_tls_offset + rpnt->r_addend;
+ *reloc_addr = symbol_addr - tls_tpnt->l_tls_offset + rpnt->r_addend;
break;
case R_X86_64_32:
*(unsigned int *) reloc_addr = symbol_addr + rpnt->r_addend;