c++ - 如何使用向后 cpp 在 ARM 上获取堆栈跟踪

Question

我正在尝试使用 backward-cpp 在 ARM 机器上抛出异常后恢复我的程序堆栈跟踪图书馆。在 AMD64 机器上运行简单程序时，以下代码返回预期的堆栈跟踪:

#include <backward/backward.hpp>

backward::SignalHandling sh{};

int main() {
    throw 1;
}

terminate called after throwing an instance of 'int'
Stack trace (most recent call last):
#9    Object "", at 0xffffffffffffffff, in 
#8    Object "/home/uy/Sandbox/SimpleC++/cmake-build-debug---native/main", at 0x556929e5308d, in 
#7    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7fb8a1e8c0b2, in __libc_start_main
#6    Source "/home/uy/Sandbox/SimpleC++/main.cpp", line 7, in int main() [0x556929e53174]
          4: backward::SignalHandling sh{};
          5: 
          6: int main() {
      >   7:     throw 1;
          8: }
#5    Object "/lib/x86_64-linux-gnu/libstdc++.so.6", at 0x7fb8a211c798, in __cxa_throw
#4    Object "/lib/x86_64-linux-gnu/libstdc++.so.6", at 0x7fb8a211c4e6, in std::terminate()
#3    Object "/lib/x86_64-linux-gnu/libstdc++.so.6", at 0x7fb8a211c47b, in 
#2    Object "/lib/x86_64-linux-gnu/libstdc++.so.6", at 0x7fb8a2110950, in 
#1    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7fb8a1e8a858, in abort
#0    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7fb8a1eab18b, in gsignal
Aborted (Signal sent by tkill() 32939 1000)

但是，在 ARM 机器上运行相同的代码时，程序给出的堆栈跟踪并不是特别有用:

terminate called after throwing an instance of 'int'
Stack trace (most recent call last):
#7    Object "/lib/arm-linux-gnueabihf/libc.so.6", at 0xb6d08e9f, in gsignal
#6    Object "/lib/arm-linux-gnueabihf/libc.so.6", at 0xb6cf9c65, in gnu_get_libc_version
#5    Object "/lib/arm-linux-gnueabihf/libc.so.6", at 0xb6d09cbf, in __default_sa_restorer
#4    Source "/home/uy/Sandbox/SimpleC++/backward-cpp/include/backward/backward.hpp", line 3972, in backward::SignalHandling::sig_handler(int signo, siginfo_t *info, void *_ctx) [0x7f5a2429]
#3    Source "/home/uy/Sandbox/SimpleC++/backward-cpp/include/backward/backward.hpp", line 3947, in backward::SignalHandling::handleSignal(int, siginfo_t *info, void *_ctx) [0x7f5a2371]
#2    Source "/home/uy/Sandbox/SimpleC++/backward-cpp/include/backward/backward.hpp", line 823, in size_t backward::StackTraceImpl<backward::system_tag::linux_tag>::load_from(void *addr, size_t depth) [0x7f59d44f]
#1    Source "/home/uy/Sandbox/SimpleC++/backward-cpp/include/backward/backward.hpp", line 817, in size_t backward::StackTraceImpl<backward::system_tag::linux_tag>::load_here(size_t depth) [0x7f59d3d3]
#0    Source "/home/uy/Sandbox/SimpleC++/backward-cpp/include/backward/backward.hpp", line 802, in size_t backward::details::unwind<backward::StackTraceImpl<backward::system_tag::linux_tag>::callback>(callback f, size_t depth) [0x7f5a2df3]
Aborted (Signal sent by tkill() 8424 1000)
Aborted

我如何获得类似于我在 AMD64 机器上获得的堆栈跟踪？

Answer 1

这是可行的，但需要访问 libgcc 如何实现 _Unwind_Backtrace 函数的内部细节。幸运的是，代码是开源的，但是依赖于这些内部细节是脆弱的，因为它可能会在没有任何通知的情况下在 future 的 armgcc 版本中崩溃。
通常，通过读取 libgcc 的源代码进行回溯，它会创建 CPU 内核寄存器的内存虚拟表示，然后使用此表示向上走栈，模拟异常抛出。 _Unwind_Backtrace 做的第一件事就是从当前 CPU 寄存器填充这个上下文，然后调用一个内部实现函数。
在大多数情况下，从堆栈异常结构手动创建该上下文足以伪造从处理程序模式向上通过调用堆栈的回溯。这是一些示例代码(来自 https://github.com/bakerstu/openmrn/blob/62683863e8621cef35e94c9dcfe5abcaf996d7a2/src/freertos_drivers/common/cpu_profile.hxx#L162 ):