From 33ac04a215a70d2f39f1ddec1bba5a42c0fd8bee Mon Sep 17 00:00:00 2001
From: Yabin Cui <yabinc@google.com>
Date: Tue, 22 Sep 2015 11:16:15 -0700
Subject: [PATCH] Increase alternative signal stack size on 64-bit devices.

Bug: 23041777
Bug: 24187462
Change-Id: I7d84c0cc775a74753a3e8e101169c0fb5dbf7437
---
 libc/bionic/pthread_internal.h |  7 ++++++-
 tests/pthread_test.cpp         | 24 ++++++++++++++++++++++++
 tests/stack_unwinding_test.cpp |  2 +-
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 3b91e6a19..6a39a214a 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -130,8 +130,13 @@ __LIBC_HIDDEN__ void pthread_key_clean_all(void);
  */
 #define PTHREAD_STACK_SIZE_DEFAULT ((1 * 1024 * 1024) - SIGSTKSZ)
 
-/* Leave room for a guard page in the internally created signal stacks. */
+// Leave room for a guard page in the internally created signal stacks.
+#if defined(__LP64__)
+// SIGSTKSZ is not big enough for 64-bit arch. See http://b/23041777.
+#define SIGNAL_STACK_SIZE (16 * 1024 + PAGE_SIZE)
+#else
 #define SIGNAL_STACK_SIZE (SIGSTKSZ + PAGE_SIZE)
+#endif
 
 /* Needed by fork. */
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_prepare();
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 3c686ef20..11afad141 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -27,6 +27,7 @@
 #include <sys/syscall.h>
 #include <time.h>
 #include <unistd.h>
+#include <unwind.h>
 
 #include <atomic>
 #include <regex>
@@ -1632,3 +1633,26 @@ TEST_F(pthread_DeathTest, pthread_mutex_unlock_null_64) {
   GTEST_LOG_(INFO) << "This test tests bionic implementation details on 64 bit devices.";
 #endif
 }
+
+extern _Unwind_Reason_Code FrameCounter(_Unwind_Context* ctx, void* arg);
+
+static volatile bool signal_handler_on_altstack_done;
+
+static void SignalHandlerOnAltStack(int signo, siginfo_t*, void*) {
+  ASSERT_EQ(SIGUSR1, signo);
+  // Check if we have enough stack space for unwinding.
+  int count = 0;
+  _Unwind_Backtrace(FrameCounter, &count);
+  ASSERT_GT(count, 0);
+  // Check if we have enough stack space for logging.
+  std::string s(2048, '*');
+  GTEST_LOG_(INFO) << s;
+  signal_handler_on_altstack_done = true;
+}
+
+TEST(pthread, big_enough_signal_stack_for_64bit_arch) {
+  signal_handler_on_altstack_done = false;
+  ScopedSignalHandler handler(SIGUSR1, SignalHandlerOnAltStack, SA_SIGINFO | SA_ONSTACK);
+  kill(getpid(), SIGUSR1);
+  ASSERT_TRUE(signal_handler_on_altstack_done);
+}
diff --git a/tests/stack_unwinding_test.cpp b/tests/stack_unwinding_test.cpp
index d1b3402cd..afd9e7f0e 100644
--- a/tests/stack_unwinding_test.cpp
+++ b/tests/stack_unwinding_test.cpp
@@ -34,7 +34,7 @@
 #define noinline __attribute__((__noinline__))
 #define __unused __attribute__((__unused__))
 
-static _Unwind_Reason_Code FrameCounter(_Unwind_Context* ctx __unused, void* arg) {
+_Unwind_Reason_Code FrameCounter(_Unwind_Context* ctx __unused, void* arg) {
   int* count_ptr = reinterpret_cast<int*>(arg);
 
 #if SHOW_FRAME_LOCATIONS