108 lines
3.9 KiB
C++
108 lines
3.9 KiB
C++
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// Copyright 2021 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/profiler/frame_pointer_unwinder.h"
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#include "base/check_op.h"
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#include "base/notreached.h"
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#include "base/numerics/clamped_math.h"
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#include "base/profiler/module_cache.h"
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#include "build/build_config.h"
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#if BUILDFLAG(IS_APPLE)
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#include <pthread/stack_np.h>
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#endif
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namespace {
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// Given a frame pointer, returns the frame pointer of the calling stack
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// frame and places the return address of the calling stack frame into
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// `return_address`. Shim around `pthread_stack_frame_decode_np` where
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// available since it handles pointer authentication on supported platforms.
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// NB: The caller *must* ensure that there are 2+ uintptr_t's worth of memory at
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// `frame_pointer`.
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uintptr_t DecodeFrame(uintptr_t frame_pointer, uintptr_t* return_address) {
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#if BUILDFLAG(IS_APPLE)
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if (__builtin_available(macOS 10.14, iOS 12, *))
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return pthread_stack_frame_decode_np(frame_pointer, return_address);
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#endif
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const uintptr_t* fp = reinterpret_cast<uintptr_t*>(frame_pointer);
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uintptr_t next_frame = *fp;
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*return_address = *(fp + 1);
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return next_frame;
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}
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} // namespace
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namespace base {
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FramePointerUnwinder::FramePointerUnwinder() = default;
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bool FramePointerUnwinder::CanUnwindFrom(const Frame& current_frame) const {
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return current_frame.module && current_frame.module->IsNative();
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}
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UnwindResult FramePointerUnwinder::TryUnwind(RegisterContext* thread_context,
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uintptr_t stack_top,
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std::vector<Frame>* stack) {
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// We expect the frame corresponding to the |thread_context| register state to
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// exist within |stack|.
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DCHECK_GT(stack->size(), 0u);
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#if defined(ARCH_CPU_ARM64)
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constexpr uintptr_t align_mask = 0x1;
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#elif defined(ARCH_CPU_X86_64)
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constexpr uintptr_t align_mask = 0xf;
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#endif
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uintptr_t next_frame = RegisterContextFramePointer(thread_context);
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uintptr_t frame_lower_bound = RegisterContextStackPointer(thread_context);
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const auto is_fp_valid = [&](uintptr_t fp) {
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// Ensure there's space on the stack to read two values: the caller's
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// frame pointer and the return address.
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return next_frame >= frame_lower_bound &&
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ClampAdd(next_frame, sizeof(uintptr_t) * 2) <= stack_top &&
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(next_frame & align_mask) == 0;
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};
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if (!is_fp_valid(next_frame))
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return UnwindResult::kAborted;
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for (;;) {
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if (!stack->back().module) {
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return UnwindResult::kAborted;
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}
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if (!stack->back().module->IsNative()) {
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// This is a non-native module associated with the auxiliary unwinder
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// (e.g. corresponding to a frame in V8 generated code). Report as
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// UNRECOGNIZED_FRAME to allow that unwinder to unwind the frame.
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return UnwindResult::kUnrecognizedFrame;
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}
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uintptr_t retaddr;
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uintptr_t frame = next_frame;
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next_frame = DecodeFrame(frame, &retaddr);
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frame_lower_bound = frame + 1;
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// If `next_frame` is 0, we've hit the root and `retaddr` isn't useful.
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// Bail without recording the frame.
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if (next_frame == 0)
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return UnwindResult::kCompleted;
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const ModuleCache::Module* module =
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module_cache()->GetModuleForAddress(retaddr);
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// V8 doesn't conform to the x86_64 ABI re: stack alignment. For V8 frames,
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// let the V8 unwinder determine whether the FP is valid or not.
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bool is_non_native_module = module && !module->IsNative();
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// If the FP doesn't look correct, don't record this frame.
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if (!is_non_native_module && !is_fp_valid(next_frame))
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return UnwindResult::kAborted;
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RegisterContextFramePointer(thread_context) = next_frame;
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RegisterContextInstructionPointer(thread_context) = retaddr;
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RegisterContextStackPointer(thread_context) = frame + sizeof(uintptr_t) * 2;
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stack->emplace_back(retaddr, module);
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}
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NOTREACHED();
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return UnwindResult::kCompleted;
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}
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} // namespace base
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