---
src/x86_64/Gstep.c | 36 +++++++++++++++++++++++++++++++++---
1 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/src/x86_64/Gstep.c b/src/x86_64/Gstep.c
index 01022a1..d691aa6 100644
--- a/src/x86_64/Gstep.c
+++ b/src/x86_64/Gstep.c
@@ -28,14 +28,38 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE. */
#include "unwind_i.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
unw_step (unw_cursor_t *cursor)
{
struct cursor *c = (struct cursor *) cursor;
int ret, i;
- Debug (1, "(cursor=%p, ip=0x%016llx)\n",
- c, (unsigned long long) c->dwarf.ip);
+ Debug (1, "(cursor=%p, ip=0x%016lx, cfa=0x%016lx)\n",
+ c, c->dwarf.ip, c->dwarf.cfa);
/* Try DWARF-based unwinding... */
c->sigcontext_format = X86_64_SCF_NONE;
@@ -86,6 +110,12 @@ unw_step (unw_cursor_t *cursor)
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
{
unw_word_t rbp;
@@ -133,7 +163,7 @@ unw_step (unw_cursor_t *cursor)
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);
Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n",
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