| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BACKTRACE_REQUEST_BACKTRACE_REQUEST_H_ |
| #define BACKTRACE_REQUEST_BACKTRACE_REQUEST_H_ |
| |
| #include <stdint.h> |
| |
| // Special value we put in the first register to let the exception handler know |
| // that we are just requesting a backtrace and we should resume the thread. |
| #define BACKTRACE_REQUEST_MAGIC ((uint64_t)0xee726573756d65ee) |
| |
| // Prints a backtrace, resuming the thread without killing the process. |
| __attribute__((always_inline)) static inline void backtrace_request(void) { |
| // Two instructions: one that sets a software breakpoint ("int3" on x64, |
| // "brk" on arm64) and one that writes the "magic" value in the first |
| // register ("a" on x64, "x0" on arm64). |
| // |
| // We set a software breakpoint to trigger the exception handling in |
| // crashsvc, which will print the debug info, including the backtrace. |
| // |
| // We write the "magic" value in the first register so that the exception |
| // handler can check for it and resume the thread if present. |
| #ifdef __x86_64__ |
| __asm__("int3" : : "a"(BACKTRACE_REQUEST_MAGIC)); |
| #endif |
| #ifdef __aarch64__ |
| // This is what gdb uses. |
| __asm__( |
| "mov x0, %0\n" |
| "\tbrk 0" |
| : |
| : "r"(BACKTRACE_REQUEST_MAGIC) |
| : "x0"); |
| #endif |
| } |
| |
| #endif // BACKTRACE_REQUEST_BACKTRACE_REQUEST_H_ |
