crashpad/util/misc/capture_context.h
Thomas Gales 8dcf2b216f [fuchsia] Don't build CaptureContext
CaptureContext isn't actually used on Fuchsia and there is a desire to
remove `ucontext_t` from Fuchsia as it isn't a real concept on Fuchsia
and was only added as a placeholder. Moreover, `ucontext_t` won't ever
be added to Fuchsia for RISC-V.

Bug: fuchsia:123052
Fixed: fuchsia:131112
Fixed: fuchsia:127655
Tested: `fx test crashpad` on core.x64 emulator
Tested: `fx test crashpad` on ARM64 device
Tested: `fx shell crasher` @ 16b19a9891978487 on ARM64 device, ran
through Breakpad stackwalker locally as well
Tested: `fx build crashpad_tests` for minimal.riscv64
Change-Id: I4695054426df78a9deff8c9ea9c478b5bf9701b1
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4717085
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Thomas Gales <tgales@google.com>
2023-07-31 20:03:40 +00:00

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// Copyright 2014 The Crashpad Authors
//
// 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.
#ifndef CRASHPAD_UTIL_MISC_CAPTURE_CONTEXT_H_
#define CRASHPAD_UTIL_MISC_CAPTURE_CONTEXT_H_
#include "build/build_config.h"
#if BUILDFLAG(IS_APPLE)
#include <mach/mach.h>
#elif BUILDFLAG(IS_WIN)
#include <windows.h>
#elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
#include <ucontext.h>
#endif // BUILDFLAG(IS_APPLE)
namespace crashpad {
#if BUILDFLAG(IS_APPLE)
#if defined(ARCH_CPU_X86_FAMILY)
using NativeCPUContext = x86_thread_state;
#elif defined(ARCH_CPU_ARM64)
using NativeCPUContext = arm_unified_thread_state;
#endif
#elif BUILDFLAG(IS_WIN)
using NativeCPUContext = CONTEXT;
#elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
using NativeCPUContext = ucontext_t;
#endif // BUILDFLAG(IS_APPLE)
//! \brief Saves the CPU context.
//!
//! The CPU context will be captured as accurately and completely as possible,
//! containing an atomic snapshot at the point of this functions return. This
//! function does not modify any registers.
//!
//! This function is a replacement for `RtlCaptureContext()` and `getcontext()`
//! which contain bugs and/or limitations.
//!
//! On 32-bit x86, `RtlCaptureContext()` requires that `ebp` be used as a frame
//! pointer, and returns `ebp`, `esp`, and `eip` out of sync with the other
//! registers. Both the 32-bit x86 and 64-bit x86_64 versions of
//! `RtlCaptureContext()` capture only the state of the integer registers,
//! ignoring floating-point and vector state.
//!
//! CaptureContext isn't used on Fuchsia, nor does a concept of `ucontext_t`
//! exist on Fuchsia.
//!
//! \param[out] cpu_context The structure to store the context in.
//!
//! \note The ABI may require that this function's argument is passed by
//! register, preventing this fuction from saving the original value of that
//! register. This occurs in the following circumstances:
//!
//! OS | Architecture | Register
//! --------------------|--------------|---------
//! Win | x86_64 | `%%rcx`
//! macOS/Linux | x86_64 | `%%rdi`
//! Linux | ARM/ARM64 | `r0`/`x0`
//! Linux | MIPS/MIPS64 | `$a0`
//! Linux | RISCV64 | `a0`
//!
//! Additionally, the value `LR` on ARM/ARM64 will be the return address of
//! this function.
//!
//! If the value of these register prior to calling this function are needed
//! they must be obtained separately prior to calling this function. For
//! example:
//! \code
//! uint64_t rdi;
//! asm("movq %%rdi, %0" : "=m"(rdi));
//! \endcode
void CaptureContext(NativeCPUContext* cpu_context);
} // namespace crashpad
#endif // CRASHPAD_UTIL_MISC_CAPTURE_CONTEXT_H_