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author | Roman I Khimov <khimov@altell.ru> | 2010-05-04 14:00:47 +0400 |
---|---|---|
committer | Austin Foxley <austinf@cetoncorp.com> | 2010-05-05 08:43:22 -0700 |
commit | 0b7acfa800444525498442032b47bfd7d066c72b (patch) | |
tree | 0a01157af61958014f0b0dc957d1dd5061df5d26 /libc/unistd/sysconf.c | |
parent | c1505e73d00ed26b7c250e331b213e63a948b1dd (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 'libc/unistd/sysconf.c')
0 files changed, 0 insertions, 0 deletions