Bug 1353420: Register the JIT region with mozglue so it can avoid stack-walking that code. r=luke

js/src/jit/ProcessExecutableMemory.cpp

@@ -217,7 +217,10 @@ ReserveProcessExecutableMemory(size_t bytes)
         }
 
         p = (uint8_t*)p + pageSize;
+        bytes -= pageSize;
     }
+
+    RegisterJitCodeRegion((uint8_t*)p, bytes);
 # endif
 
     return p;
@@ -227,6 +230,8 @@ static void
 DeallocateProcessExecutableMemory(void* addr, size_t bytes)
 {
 # ifdef HAVE_64BIT_BUILD
+    UnregisterJitCodeRegion((uint8_t*)addr, bytes);
+
     if (sJitExceptionHandler) {
         size_t pageSize = gc::SystemPageSize();
         addr = (uint8_t*)addr - pageSize;

mozglue/misc/StackWalk.cpp

@@ -222,6 +222,11 @@ struct WalkStackData
 DWORD gStackWalkThread;
 CRITICAL_SECTION gDbgHelpCS;
 
+#ifdef _M_AMD64
+static uint8_t* sJitCodeRegionStart;
+static size_t sJitCodeRegionSize;
+#endif
+
 // Routine to print an error message to standard error.
 static void
 PrintError(const char* aPrefix)
@@ -397,6 +402,14 @@ WalkStackMain64(struct WalkStackData* aData)
     }
 
 #elif defined(_M_AMD64)
+    // If we reach a frame in JIT code, we don't have enough information to
+    // unwind, so we have to give up.
+    if (sJitCodeRegionStart &&
+        (uint8_t*)context.Rip >= sJitCodeRegionStart &&
+        (uint8_t*)context.Rip < sJitCodeRegionStart + sJitCodeRegionSize) {
+      break;
+    }
+
     // 64-bit frame unwinding.
     // Try to look up unwind metadata for the current function.
     ULONG64 imageBase;
@@ -500,6 +513,33 @@ ReleaseStackWalkWorkaroundLock()
 #endif
 }
 
+MFBT_API void
+RegisterJitCodeRegion(uint8_t* aStart, size_t aSize)
+{
+#ifdef _M_AMD64
+  // Currently we can only handle one JIT code region at a time
+  MOZ_RELEASE_ASSERT(!sJitCodeRegionStart);
+
+  sJitCodeRegionStart = aStart;
+  sJitCodeRegionSize = aSize;
+#endif
+}
+
+MFBT_API void
+UnregisterJitCodeRegion(uint8_t* aStart, size_t aSize)
+{
+#ifdef _M_AMD64
+  // Currently we can only handle one JIT code region at a time
+  MOZ_RELEASE_ASSERT(sJitCodeRegionStart &&
+                     sJitCodeRegionStart == aStart &&
+                     sJitCodeRegionSize == aSize);
+
+  sJitCodeRegionStart = nullptr;
+  sJitCodeRegionSize = 0;
+#endif
+}
+
+
 static unsigned int WINAPI
 WalkStackThread(void* aData)
 {

mozglue/misc/StackWalk_windows.h

@@ -18,4 +18,10 @@ TryAcquireStackWalkWorkaroundLock();
 MFBT_API void
 ReleaseStackWalkWorkaroundLock();
 
+MFBT_API void
+RegisterJitCodeRegion(uint8_t* aStart, size_t size);
+
+MFBT_API void
+UnregisterJitCodeRegion(uint8_t* aStart, size_t size);
+
 #endif // mozilla_StackWalk_windows_h