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Recognise and unwind through PLT.

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This commit is contained in:
Lassi Tuura 2010-04-20 23:13:14 +02:00 committed by Arun Sharma
parent a9dce3c06e
commit f252f5ff4e
1 changed files with 33 additions and 3 deletions
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36
src/x86_64/Gstep.c
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@ -28,14 +28,38 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#include "unwind_i.h" #include "unwind_i.h"
#include <signal.h> #include <signal.h>
/* Recognise PLT entries such as:
3bdf0: ff 25 e2 49 13 00 jmpq *0x1349e2(%rip)
3bdf6: 68 ae 03 00 00 pushq $0x3ae
3bdfb: e9 00 c5 ff ff jmpq 38300 <_init+0x18> */
static int
is_plt_entry (struct dwarf_cursor *c)
{
unw_word_t w0, w1;
unw_accessors_t *a;
int ret;
a = unw_get_accessors (c->as);
if ((ret = (*a->access_mem) (c->as, c->ip, &w0, 0, c->as_arg)) < 0
|| (ret = (*a->access_mem) (c->as, c->ip + 8, &w1, 0, c->as_arg)) < 0)
return 0;
ret = (((w0 & 0xffff) == 0x25ff)
&& (((w0 >> 48) & 0xff) == 0x68)
&& (((w1 >> 24) & 0xff) == 0xe9));
Debug (14, "ip=0x%lx => 0x%016lx 0x%016lx, ret = %d\n", c->ip, w0, w1, ret);
return ret;
}
PROTECTED int PROTECTED int
unw_step (unw_cursor_t *cursor) unw_step (unw_cursor_t *cursor)
{ {
struct cursor *c = (struct cursor *) cursor; struct cursor *c = (struct cursor *) cursor;
int ret, i; int ret, i;
Debug (1, "(cursor=%p, ip=0x%016llx)\n", Debug (1, "(cursor=%p, ip=0x%016lx, cfa=0x%016lx)\n",
c, (unsigned long long) c->dwarf.ip); c, c->dwarf.ip, c->dwarf.cfa);
/* Try DWARF-based unwinding... */ /* Try DWARF-based unwinding... */
c->sigcontext_format = X86_64_SCF_NONE; c->sigcontext_format = X86_64_SCF_NONE;
@ -86,6 +110,12 @@ unw_step (unw_cursor_t *cursor)
return 0; return 0;
} }
} }
else if (is_plt_entry (&c->dwarf))
{
Debug (2, "found plt entry\n");
c->dwarf.loc[RIP] = DWARF_LOC (c->dwarf.cfa, 0);
c->dwarf.cfa += 8;
}
else else
{ {
unw_word_t rbp; unw_word_t rbp;
@ -133,7 +163,7 @@ unw_step (unw_cursor_t *cursor)
c->dwarf.ret_addr_column = RIP; c->dwarf.ret_addr_column = RIP;
if (!DWARF_IS_NULL_LOC (c->dwarf.loc[RBP])) if (!DWARF_IS_NULL_LOC (c->dwarf.loc[RIP]))
{ {
ret = dwarf_get (&c->dwarf, c->dwarf.loc[RIP], &c->dwarf.ip); ret = dwarf_get (&c->dwarf, c->dwarf.loc[RIP], &c->dwarf.ip);
Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n", Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n",