CFI: Add diagnostic information to likely CFI violation stack traces.

base/debug/stack_trace_posix.cc

Index: base/debug/stack_trace_posix.cc
diff --git a/base/debug/stack_trace_posix.cc b/base/debug/stack_trace_posix.cc
index 9593962d3aa838019b839c3df8a36ff9facd2a83..fe8934a2ae9830971623b98ea8150673e3eb899e 100644
--- a/base/debug/stack_trace_posix.cc
+++ b/base/debug/stack_trace_posix.cc
@@ -281,6 +281,17 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
   }
   PrintToStderr("\n");
 
+#if defined(CFI_ENFORCEMENT)
+  if (signal == SIGILL && info->si_code == ILL_ILLOPN) {
+    PrintToStderr(
+        "CFI: Most likely a control flow integrity violation; for more "
+        "information see:\n");
+    PrintToStderr(
+        "https://sites.google.com/a/chromium.org/dev/developers/testing/"
+        "control-flow-integrity\n");

[Avi (use Gerrit), 2015/08/05 15:19:35]

FYI, rather than the sites page URL, use

https://www.chromium.org/developers/testing/control-flow-integrity

instead.

[pcc1, 2015/08/05 19:58:15]

Done.

+  }
+#endif
+
   debug::StackTrace().Print();
 
 #if defined(OS_LINUX)
@@ -395,6 +406,13 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
   write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
 #endif  // ARCH_CPU_32_BITS
 #endif  // defined(OS_MACOSX)
+
+#if defined(CFI_ENFORCEMENT)
+  if (signal == SIGILL && info->si_code == ILL_ILLOPN) {
+    PrintToStderr("CFI: Aborting\n");
+  }
+#endif
+
   _exit(1);
 }