diff --git a/libsanitizer/ChangeLog b/libsanitizer/ChangeLog
index 156aaebaf33cfef76574256e79dba51b32336aca..267aa42d4845b9c73fbb8dff2cf0325c2c9a47fd 100644
--- a/libsanitizer/ChangeLog
+++ b/libsanitizer/ChangeLog
@@ -1,3 +1,11 @@
+2012-11-16  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR other/55333
+	* include/sanitizer/common_interface_defs.h (uhwptr): New type
+	for hardware pointer.
+	* sanitizer_common/sanitizer_stacktrace.cc (StackTrace::FastUnwindStack):
+	Replace uptr with uhwptr for stack unwind.
+
 2012-11-16  Dodji Seketeli  <dodji@redhat.com>
 
 	* configure.tgt: Enable build on sparc linux.
diff --git a/libsanitizer/include/sanitizer/common_interface_defs.h b/libsanitizer/include/sanitizer/common_interface_defs.h
index 4ac7609c6759d9ec66f43a7e1d7cc5c625e8241c..d78d2802a2b8161ead1ea653ec4f5b9ccdbdc9b7 100644
--- a/libsanitizer/include/sanitizer/common_interface_defs.h
+++ b/libsanitizer/include/sanitizer/common_interface_defs.h
@@ -46,6 +46,13 @@ typedef signed   long long sptr;  // NOLINT
 typedef unsigned long uptr;  // NOLINT
 typedef signed   long sptr;  // NOLINT
 #endif  // defined(_WIN64)
+#if defined(__x86_64__)
+// Since x32 uses ILP32 data model in 64-bit hardware mode,  we must use
+// 64-bit pointer to unwind stack frame.
+typedef unsigned long long uhwptr;  // NOLINT
+#else
+typedef uptr uhwptr;   // NOLINT
+#endif
 typedef unsigned char u8;
 typedef unsigned short u16;  // NOLINT
 typedef unsigned int u32;
diff --git a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
index f6d7a0966c2a1d9464044d065f6eff9be5825c91..915c4b8050a5d0c63c460af9b0513d171b72b5f9 100644
--- a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
+++ b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
@@ -120,18 +120,18 @@ void StackTrace::FastUnwindStack(uptr pc, uptr bp,
                                  uptr stack_top, uptr stack_bottom) {
   CHECK(size == 0 && trace[0] == pc);
   size = 1;
-  uptr *frame = (uptr*)bp;
-  uptr *prev_frame = frame;
+  uhwptr *frame = (uhwptr *)bp;
+  uhwptr *prev_frame = frame;
   while (frame >= prev_frame &&
-         frame < (uptr*)stack_top - 2 &&
-         frame > (uptr*)stack_bottom &&
+         frame < (uhwptr *)stack_top - 2 &&
+         frame > (uhwptr *)stack_bottom &&
          size < max_size) {
-    uptr pc1 = frame[1];
+    uhwptr pc1 = frame[1];
     if (pc1 != pc) {
-      trace[size++] = pc1;
+      trace[size++] = (uptr) pc1;
     }
     prev_frame = frame;
-    frame = (uptr*)frame[0];
+    frame = (uhwptr *)frame[0];
   }
 }