diff --git a/include/tdep-x86_64/libunwind_i.h b/include/tdep-x86_64/libunwind_i.h
index c4c6960..46762e4 100644
--- a/include/tdep-x86_64/libunwind_i.h
+++ b/include/tdep-x86_64/libunwind_i.h
@@ -50,12 +50,24 @@ unw_tdep_frame_type_t;
 typedef struct
   {
     uint64_t virtual_address;
-    int64_t frame_type     : 2;  /* unw_tdep_frame_type_t classification */
-    int64_t last_frame     : 1;  /* non-zero if last frame in chain */
-    int64_t cfa_reg_rsp    : 1;  /* cfa dwarf base register is rsp vs. rbp */
-    int64_t cfa_reg_offset : 30; /* cfa is at this offset from base register value */
-    int64_t rbp_cfa_offset : 15; /* rbp saved at this offset from cfa (-1 = not saved) */
-    int64_t rsp_cfa_offset : 15; /* rsp saved at this offset from cfa (-1 = not saved) */
+    union
+      {
+	struct
+	  {
+	    int64_t frame_type     : 2;  /* unw_tdep_frame_type_t classification */
+	    int64_t last_frame     : 1;  /* non-zero if last frame in chain */
+	    int64_t cfa_reg_rsp    : 1;  /* cfa dwarf base register is rsp vs. rbp */
+	    int64_t cfa_reg_offset : 30; /* cfa is at this offset from base register value */
+	    int64_t rbp_cfa_offset : 15; /* rbp saved at this offset from cfa (-1 = not saved) */
+	    int64_t rsp_cfa_offset : 15; /* rsp saved at this offset from cfa (-1 = not saved) */
+	  };
+	struct
+	  {
+	    int64_t x_frame_type   :  2;  /* unw_tdep_frame_type_t classification */
+	    int64_t sigcontext_addr: 62;  /* addr of sigcontext passed into
+					     SIGRETURN frame.  */
+	  };
+      };
   }
 unw_tdep_frame_t;
 
diff --git a/src/x86_64/Gstash_frame.c b/src/x86_64/Gstash_frame.c
index 2f81cc0..3412369 100644
--- a/src/x86_64/Gstash_frame.c
+++ b/src/x86_64/Gstash_frame.c
@@ -82,11 +82,15 @@ tdep_stash_frame (struct dwarf_cursor *d, struct dwarf_reg_state *rs)
   else if (f->frame_type == UNW_X86_64_FRAME_SIGRETURN)
   {
     assert (f->cfa_reg_offset == -1);
-    f->cfa_reg_offset = d->cfa - c->sigcontext_addr;
-    f->rbp_cfa_offset = DWARF_GET_LOC(d->loc[RBP]) - d->cfa;
-    f->rsp_cfa_offset = DWARF_GET_LOC(d->loc[RSP]) - d->cfa;
-    Debug (4, " sigreturn frame rbpoff %d rspoff %d\n",
-	   f->rbp_cfa_offset, f->rsp_cfa_offset);
+    f->sigcontext_addr = c->sigcontext_addr;
+    if (unlikely (f->sigcontext_addr != c->sigcontext_addr))
+      {
+	Debug (4, " sigreturn frame offset overflow\n");
+	f->frame_type = UNW_X86_64_FRAME_OTHER;
+	return;
+      }
+    Debug (4, " sigreturn frame sigcontext_addr %zu\n",
+	   f->sigcontext_addr);
   }
 
   /* PLT and guessed RBP-walked frames are handled in unw_step(). */
diff --git a/src/x86_64/Gtrace.c b/src/x86_64/Gtrace.c
index f10737f..9e84010 100644
--- a/src/x86_64/Gtrace.c
+++ b/src/x86_64/Gtrace.c
@@ -35,12 +35,6 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
 /* Initial hash table size. Table expands by 2 bits (times four). */
 #define HASH_MIN_BITS 14
 
-/* There's not enough space to store RIP's location in a signal
-   frame, but we can calculate it relative to RBP's (or RSP's)
-   position in mcontext structure.  Note we don't want to use
-   the UC_MCONTEXT_GREGS_* directly since we rely on DWARF info. */
-#define dRIP (UC_MCONTEXT_GREGS_RIP - UC_MCONTEXT_GREGS_RBP)
-
 typedef struct
 {
   unw_tdep_frame_t *frames;
@@ -50,7 +44,8 @@ typedef struct
 			 been called. */
 } unw_trace_cache_t;
 
-static const unw_tdep_frame_t empty_frame = { 0, UNW_X86_64_FRAME_OTHER, -1, -1, 0, -1, -1 };
+static const unw_tdep_frame_t empty_frame = {
+  0, {{UNW_X86_64_FRAME_OTHER, -1, -1, 0, -1, -1 }}};
 static pthread_mutex_t trace_init_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_once_t trace_cache_once = PTHREAD_ONCE_INIT;
 static sig_atomic_t trace_cache_once_happen;
@@ -497,15 +492,14 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
 
     case UNW_X86_64_FRAME_SIGRETURN:
       /* Advance standard signal frame, whose CFA points above saved
-         registers (ucontext) among other things.  We know the info
-	 is stored at some unknown constant offset off inner frame's
-	 CFA.  We determine the actual offset from DWARF unwind info. */
-      cfa = cfa + f->cfa_reg_offset;
-      ACCESS_MEM_FAST(ret, c->validate, d, cfa + f->rbp_cfa_offset + dRIP, rip);
-      if (likely(ret >= 0))
-        ACCESS_MEM_FAST(ret, c->validate, d, cfa + f->rbp_cfa_offset, rbp);
-      if (likely(ret >= 0))
-        ACCESS_MEM_FAST(ret, c->validate, d, cfa + f->rsp_cfa_offset, rsp);
+         registers (ucontext) among other things.  */
+      {
+	unw_word_t sigcontext_addr = f->sigcontext_addr;
+
+	ACCESS_MEM_FAST(ret, 0, d, sigcontext_addr + UC_MCONTEXT_GREGS_RIP, rip);
+	ACCESS_MEM_FAST(ret, 0, d, sigcontext_addr + UC_MCONTEXT_GREGS_RBP, rbp);
+	ACCESS_MEM_FAST(ret, 0, d, sigcontext_addr + UC_MCONTEXT_GREGS_RSP, rsp);
+      }
 
       /* Resume stack at signal restoration point. The stack is not
          necessarily continuous here, especially with sigaltstack(). */