ladybird/AK/StackUnwinder.h

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/*
* Copyright (c) 2024, Sönke Holz <sholz8530@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Concepts.h>
#include <AK/Error.h>
#include <AK/Types.h>
namespace AK {
struct StackFrame {
FlatPtr return_address;
FlatPtr previous_frame_pointer;
};
// This function only returns errors if on_stack_frame returns an error.
// It doesn't return an error on failed memory reads, since the last frame record sometimes contains invalid addresses when using frame pointer-based unwinding.
ErrorOr<void> unwind_stack_from_frame_pointer(FlatPtr frame_pointer, CallableAs<ErrorOr<FlatPtr>, FlatPtr> auto read_memory, CallableAs<ErrorOr<IterationDecision>, StackFrame> auto on_stack_frame)
{
// aarch64/x86_64 frame record layout:
// fp/rbp+8: return address
// fp/rbp+0: previous base/frame pointer
// riscv64 frame record layout:
// fp-8: return address
// fp-16: previous frame pointer
#if ARCH(AARCH64) || ARCH(X86_64)
static constexpr ptrdiff_t FRAME_POINTER_RETURN_ADDRESS_OFFSET = 8;
static constexpr ptrdiff_t FRAME_POINTER_PREVIOUS_FRAME_POINTER_OFFSET = 0;
#elif ARCH(RISCV64)
static constexpr ptrdiff_t FRAME_POINTER_RETURN_ADDRESS_OFFSET = -8;
static constexpr ptrdiff_t FRAME_POINTER_PREVIOUS_FRAME_POINTER_OFFSET = -16;
#else
# error Unknown architecture
#endif
FlatPtr current_frame_pointer = frame_pointer;
while (current_frame_pointer != 0) {
StackFrame stack_frame;
auto maybe_return_address = read_memory(current_frame_pointer + FRAME_POINTER_RETURN_ADDRESS_OFFSET);
if (maybe_return_address.is_error())
return {};
stack_frame.return_address = maybe_return_address.value();
if (stack_frame.return_address == 0)
return {};
auto maybe_previous_frame_pointer = read_memory(current_frame_pointer + FRAME_POINTER_PREVIOUS_FRAME_POINTER_OFFSET);
if (maybe_previous_frame_pointer.is_error())
return {};
stack_frame.previous_frame_pointer = maybe_previous_frame_pointer.value();
if (TRY(on_stack_frame(stack_frame)) == IterationDecision::Break)
return {};
current_frame_pointer = maybe_previous_frame_pointer.value();
}
return {};
}
}