// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/profiler/frame_pointer_unwinder.h"
#include <memory>
#include "base/profiler/module_cache.h"
#include "base/profiler/stack_sampling_profiler_test_util.h"
#include "base/profiler/unwinder.h"
#include "build/buildflag.h"
#include "testing/gtest/include/gtest/gtest.h"
#if BUILDFLAG(IS_APPLE)
#include "base/mac/mac_util.h"
#endif
namespace base {
namespace {
constexpr uintptr_t kModuleStart = 0x1000;
constexpr size_t kModuleSize = 0x1000;
constexpr uintptr_t kNonNativeModuleStart = 0x4000;
// Used to construct test stacks. If `relative` is true, the value should be the
// address `offset` positions from the bottom of the stack (at 8-byte alignment)
// Otherwise, `offset` is added to the stack as an absolute address/value.
// For example, when creating a stack with bottom 0x2000, {false, 0xf00d} will
// become 0xf00d, and {true, 0x3} will become 0x2018.
struct StackEntrySpec {
bool relative;
uintptr_t offset;
};
// Enables constructing a stack buffer that has pointers to itself
// and provides convenience methods for calling the unwinder.
struct InputStack {
explicit InputStack(const std::vector<StackEntrySpec>& offsets)
: buffer(offsets.size()) {
size_t size = offsets.size();
for (size_t i = 0; i < size; ++i) {
auto spec = offsets[i];
if (spec.relative) {
buffer[i] = bottom() + (spec.offset * sizeof(uintptr_t));
} else {
buffer[i] = spec.offset;
}
}
}
uintptr_t bottom() const {
return reinterpret_cast<uintptr_t>(buffer.data());
}
uintptr_t top() const { return bottom() + buffer.size() * sizeof(uintptr_t); }
private:
std::vector<uintptr_t> buffer;
};
} // namespace
class FramePointerUnwinderTest : public testing::Test {
protected:
FramePointerUnwinderTest() {
#if BUILDFLAG(IS_APPLE)
if (__builtin_available(iOS 12, *)) {
#else
{
#endif
unwinder_ = std::make_unique<FramePointerUnwinder>();
auto test_module =
std::make_unique<TestModule>(kModuleStart, kModuleSize);
module_ = test_module.get();
module_cache_.AddCustomNativeModule(std::move(test_module));
auto non_native_module = std::make_unique<TestModule>(
kNonNativeModuleStart, kModuleSize, false);
non_native_module_ = non_native_module.get();
std::vector<std::unique_ptr<const ModuleCache::Module>> wrapper;
wrapper.push_back(std::move(non_native_module));
module_cache()->UpdateNonNativeModules({}, std::move(wrapper));
unwinder_->Initialize(&module_cache_);
}
}
ModuleCache* module_cache() { return &module_cache_; }
ModuleCache::Module* module() { return module_; }
ModuleCache::Module* non_native_module() { return non_native_module_; }
Unwinder* unwinder() { return unwinder_.get(); }
private:
std::unique_ptr<Unwinder> unwinder_;
base::ModuleCache module_cache_;
raw_ptr<ModuleCache::Module> module_;
raw_ptr<ModuleCache::Module> non_native_module_;
};
TEST_F(FramePointerUnwinderTest, FPPointsOutsideOfStack) {
InputStack input({
{false, 0x1000},
{false, 0x1000},
{false, 0x1000},
{false, 0x1000},
{false, 0x1000},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = 0x1;
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({{kModuleStart, module()}}), stack);
RegisterContextFramePointer(&context) = input.bottom() - sizeof(uintptr_t);
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({{kModuleStart, module()}}), stack);
RegisterContextFramePointer(&context) = input.top();
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({{kModuleStart, module()}}), stack);
}
TEST_F(FramePointerUnwinderTest, FPPointsToSelf) {
InputStack input({
{true, 0},
{false, kModuleStart + 0x10},
{true, 4},
{false, kModuleStart + 0x20},
{false, 0},
{false, 0},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({
{kModuleStart, module()},
}),
stack);
}
// Tests that two frame pointers that point to each other can't create an
// infinite loop
TEST_F(FramePointerUnwinderTest, FPCycle) {
InputStack input({
{true, 2},
{false, kModuleStart + 0x10},
{true, 0},
{false, kModuleStart + 0x20},
{true, 4},
{false, kModuleStart + 0x30},
{false, 0},
{false, 0},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({
{kModuleStart, module()},
{kModuleStart + 0x10, module()},
}),
stack);
}
TEST_F(FramePointerUnwinderTest, NoModuleForIP) {
uintptr_t not_in_module = kModuleStart - 0x10;
InputStack input({
{true, 2},
{false, not_in_module},
{true, 4},
{true, kModuleStart + 0x10},
{false, 0},
{false, 0},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(
std::vector<Frame>({{kModuleStart, module()}, {not_in_module, nullptr}}),
stack);
}
// Tests that testing that checking if there's space to read two values from the
// stack doesn't overflow.
TEST_F(FramePointerUnwinderTest, FPAdditionOverflows) {
uintptr_t will_overflow = std::numeric_limits<uintptr_t>::max() - 1;
InputStack input({
{true, 2},
{false, kModuleStart + 0x10},
{false, 0},
{false, 0},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = will_overflow;
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kAborted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({
{kModuleStart, module()},
}),
stack);
}
// Tests the happy path: a successful unwind with no non-native modules.
TEST_F(FramePointerUnwinderTest, RegularUnwind) {
InputStack input({
{true, 4}, // fp of frame 1
{false, kModuleStart + 0x20}, // ip of frame 1
{false, 0xaaaa},
{false, 0xaaaa},
{true, 8}, // fp of frame 2
{false, kModuleStart + 0x42}, // ip of frame 2
{false, 0xaaaa},
{false, 0xaaaa},
{false, 0},
{false, 1},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kCompleted,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({
{kModuleStart, module()},
{kModuleStart + 0x20, module()},
{kModuleStart + 0x42, module()},
}),
stack);
}
// Tests that if a V8 frame is encountered, unwinding stops and
// kUnrecognizedFrame is returned to facilitate continuing with the V8 unwinder.
TEST_F(FramePointerUnwinderTest, NonNativeFrame) {
InputStack input({
{true, 4}, // fp of frame 1
{false, kModuleStart + 0x20}, // ip of frame 1
{false, 0xaaaa},
{false, 0xaaaa},
{true, 8}, // fp of frame 2
{false, kNonNativeModuleStart + 0x42}, // ip of frame 2
{false, 0xaaaa},
{false, 0xaaaa},
{true, 12}, // fp of frame 3
{false, kModuleStart + 0x10}, // ip of frame 3
{true, 0xaaaa},
{true, 0xaaaa},
{false, 0},
{false, 1},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kUnrecognizedFrame,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
EXPECT_EQ(std::vector<Frame>({
{kModuleStart, module()},
{kModuleStart + 0x20, module()},
{kNonNativeModuleStart + 0x42, non_native_module()},
}),
stack);
}
// Tests that a V8 frame with an unaligned frame pointer correctly returns
// kUnrecognizedFrame and not kAborted.
TEST_F(FramePointerUnwinderTest, NonNativeUnaligned) {
InputStack input({
{true, 4}, // fp of frame 1
{false, kModuleStart + 0x20}, // ip of frame 1
{false, 0xaaaa},
{false, 0xaaaa},
{true, 7}, // fp of frame 2
{false, kNonNativeModuleStart + 0x42}, // ip of frame 2
{false, 0xaaaa},
{true, 10}, // fp of frame 3
{false, kModuleStart + 0x10}, // ip of frame 3
{true, 0xaaaa},
{false, 0},
{false, 1},
});
RegisterContext context;
RegisterContextStackPointer(&context) = input.bottom();
RegisterContextInstructionPointer(&context) = kModuleStart;
RegisterContextFramePointer(&context) = input.bottom();
std::vector<Frame> stack = {
Frame(RegisterContextInstructionPointer(&context), module())};
EXPECT_EQ(UnwindResult::kUnrecognizedFrame,
unwinder()->TryUnwind(/*state_capture=*/nullptr, &context,
input.top(), &stack));
}
} // namespace base
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