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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <gtest/gtest.h>
#if defined(__BIONIC__)
#include <sys/mman.h>
#include "platform/bionic/android_unsafe_frame_pointer_chase.h"
// Prevent tail calls inside recurse.
__attribute__((weak, noinline)) size_t nop(size_t val) {
return val;
}
// Call android_unsafe_frame_pointer_chase inside count recurse stack frames.
__attribute__((weak, noinline)) int recurse(int count, uintptr_t* buf, size_t num_entries) {
if (count != 0) return nop(recurse(count - 1, buf, num_entries));
return nop(android_unsafe_frame_pointer_chase(buf, num_entries));
}
static constexpr size_t kNumFrames = 32;
static bool CheckFrames(uintptr_t* frames, size_t num_frames) {
// We expect one recurse frame calling android_unsafe_frame_pointer_chase, followed by kNumFrames identical
// recurse frames calling themselves, followed by at least one frame (the first caller of
// recurse).
if (num_frames < kNumFrames + 2) {
printf("num_frames (0x%zu) < kNumFrames + 2", num_frames);
return false;
}
if (frames[0] == frames[1]) {
printf("frames[0] == frames[1] (0x%zx)", frames[0]);
return false;
}
for (size_t i = 2; i <= kNumFrames; ++i) {
if (frames[i] != frames[1]) {
printf("frames[i] (0x%zx) != frames[1] (0x%zx)", frames[i], frames[1]);
return false;
}
}
if (frames[kNumFrames] == frames[kNumFrames + 1]) {
printf("frames[kNumFrames] == frames[kNumFrames + 1] (0x%zx)", frames[kNumFrames]);
return false;
}
return true;
}
TEST(android_unsafe_frame_pointer_chase, main_thread) {
size_t size = recurse(kNumFrames, 0, 0);
uintptr_t frames[kNumFrames + 2];
size_t size2 = recurse(kNumFrames, frames, kNumFrames + 2);
EXPECT_EQ(size2, size);
EXPECT_TRUE(CheckFrames(frames, size));
}
static const char* tester_func() {
size_t size = recurse(kNumFrames, 0, 0);
uintptr_t frames[kNumFrames + 2];
size_t size2 = recurse(kNumFrames, frames, kNumFrames + 2);
if (size2 != size) {
return "size2 != size";
}
if (!CheckFrames(frames, size)) {
return "CheckFrames failed";
}
return nullptr;
}
static void* BacktraceThread(void*) {
return (void*)tester_func();
}
TEST(android_unsafe_frame_pointer_chase, pthread) {
pthread_t t;
ASSERT_EQ(0, pthread_create(&t, nullptr, BacktraceThread, nullptr));
void* retval;
ASSERT_EQ(0, pthread_join(t, &retval));
EXPECT_EQ(nullptr, reinterpret_cast<char*>(retval));
}
static bool g_handler_called;
static const char* g_handler_tester_result;
static void BacktraceHandler(int) {
g_handler_called = true;
g_handler_tester_result = tester_func();
}
static constexpr size_t kStackSize = 16384;
static void* SignalBacktraceThread(void* sp) {
stack_t ss;
ss.ss_sp = sp;
ss.ss_flags = 0;
ss.ss_size = kStackSize;
sigaltstack(&ss, nullptr);
struct sigaction s = {};
s.sa_handler = BacktraceHandler;
s.sa_flags = SA_ONSTACK;
sigaction(SIGRTMIN, &s, nullptr);
raise(SIGRTMIN);
return nullptr;
}
TEST(android_unsafe_frame_pointer_chase, sigaltstack) {
// Create threads where the alternate stack appears both after and before the regular stack, and
// call android_unsafe_frame_pointer_chase from a signal handler. Without handling for the
// alternate signal stack, this would cause false negatives or potential false positives in the
// android_unsafe_frame_pointer_chase function.
void* stacks =
mmap(nullptr, kStackSize * 2, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
for (unsigned i = 0; i != 2; ++i) {
pthread_t t;
pthread_attr_t attr;
ASSERT_EQ(0, pthread_attr_init(&attr));
ASSERT_EQ(0, pthread_attr_setstack(&attr, reinterpret_cast<char*>(stacks) + kStackSize * i,
kStackSize));
ASSERT_EQ(0, pthread_create(&t, &attr, SignalBacktraceThread,
reinterpret_cast<char*>(stacks) + kStackSize * (1 - i)));
void* retval;
ASSERT_EQ(0, pthread_join(t, &retval));
EXPECT_TRUE(g_handler_called);
EXPECT_EQ(nullptr, g_handler_tester_result);
g_handler_called = false;
}
munmap(stacks, kStackSize * 2);
}
#endif // __BIONIC__
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