Guard against frames across pages, in the profiler.

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index de2afea156800d813254301cd5df6486242ec88a..2960583d7f95a19ee84fc3e6d1384228b5ec04b9 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -1687,7 +1687,9 @@ class ProfilerNativeStackWalker : public ValueObject {
       // Stack pointer should not be above frame pointer.
       return 1;
     }
-    intptr_t gap = original_fp_ - original_sp_;
+    const intptr_t kPageMask = ~(kMaxStep - 1);
+    const intptr_t gap =

[Cutch, 2014/05/23 11:44:29]

#ifdef PLATFORM_WINDOWS
const intptr_t gap = (original_fp_ & kPageMask) - (original_sp_ & kPageMask);
#else
const intptr_t gap = original_fp_ - original_sp_;
#endif

[Anders Johnsen, 2014/05/26 08:27:55]

Done.

+        (original_fp_ & kPageMask) - (original_sp_ & kPageMask);
     if (gap >= kMaxStep) {
       // Gap between frame pointer and stack pointer is
       // too large.
@@ -1699,7 +1701,9 @@ class ProfilerNativeStackWalker : public ValueObject {
       lower_bound_ = original_sp_;
     }
     // Store the PC marker for the top frame.
-    sample_->set_pc_marker(GetCurrentFramePcMarker(fp));
+    if (gap > 0) {
+      sample_->set_pc_marker(GetCurrentFramePcMarker(fp));
+    }
     int i = 0;
     for (; i < FLAG_profile_depth; i++) {
       if (FLAG_profile_verify_stack_walk) {