[Libunwind-devel] [PATCH 1/2] Add support for RT signal frame detection on ARM.

[Ken Werner]

This patch adds a few more patterns to the check that detects if the IP
points to a sigreturn sequence.

Signed-off-by: Ken Werner <address@hidden>
---
 src/arm/Gis_signal_frame.c |   30 +++++++++++++++++++++++-------
 1 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/arm/Gis_signal_frame.c b/src/arm/Gis_signal_frame.c
index e472185..284289f 100644
--- a/src/arm/Gis_signal_frame.c
+++ b/src/arm/Gis_signal_frame.c
@@ -29,11 +29,21 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
SOFTWARE.  */
 #ifdef __linux__
 #include <sys/syscall.h>
 
+/* ARM EABI sigreturn (the syscall number is loaded into r7) */
+#define MOV_R7_SIGRETURN (0xe3a07000UL | __NR_sigreturn)
+#define MOV_R7_RT_SIGRETURN (0xe3a07000UL | __NR_rt_sigreturn)
+
+/* ARM OABI sigreturn (using SWI) */
 #define ARM_SIGRETURN (0xef000000UL |(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
-#define THUMB_SIGRETURN (0xdf00UL  << 16 | 0x2700 | (__NR_sigreturn - 
__NR_SYSCALL_BASE))
-#define MOV_R7_SIGRETURN (0xe3a07000UL  | (__NR_sigreturn - __NR_SYSCALL_BASE))
+#define ARM_RT_SIGRETURN (0xef000000UL 
|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
+
+/* Thumb sigreturn (two insns, syscall number is loaded into r7) */
+#define THUMB_SIGRETURN (0xdf00UL  << 16 | 0x2700 | __NR_sigreturn)
+#define THUMB_RT_SIGRETURN (0xdf00UL  << 16 | 0x2700 | __NR_rt_sigreturn)
 #endif
 
+/* Returns 1 in case of a non-RT signal frame and 2 in case of a RT signal
+   frame. */
 PROTECTED int
 unw_is_signal_frame (unw_cursor_t *cursor)
 {
@@ -50,13 +60,19 @@ unw_is_signal_frame (unw_cursor_t *cursor)
   arg = c->dwarf.as_arg;
 
   ip = c->dwarf.ip;
+
   if ((ret = (*a->access_mem) (as, ip, &w0, 0, arg)) < 0)
     return ret;
-  ret = (w0 == ARM_SIGRETURN) || (w0 == MOV_R7_SIGRETURN)
-    || (w0 == THUMB_SIGRETURN);
-  fprintf (stderr, "w0=%8.8x ret=%d\n", w0, ret);
-  Debug (16, "returning %d\n", ret);
-  return ret;
+
+  /* Return 1 if the IP points to a non-RT sigreturn sequence.  */
+  if (w0 == MOV_R7_SIGRETURN || w0 == ARM_SIGRETURN || w0 == THUMB_SIGRETURN)
+    return 1;
+  /* Return 2 if the IP points to a RT sigreturn sequence.  */
+  else if (w0 == MOV_R7_RT_SIGRETURN || w0 == ARM_RT_SIGRETURN
+           || w0 == THUMB_RT_SIGRETURN)
+    return 2;
+
+  return 0;
 #else
   printf ("%s: implement me\n", __FUNCTION__);
   return -UNW_ENOINFO;
-- 
1.7.4.1