无帧指针获取调用堆栈 [英] Getting call stack without frame pointers
问题描述
我正在尝试获取调用堆栈回溯。不能包含execinfo.h因此不能使用 int backtrace（void ** buffer，int size）; 。
另外，尝试使用 __ builtin_return_address（），但是按照： http://codingrelic.geekhold.com/2009/05/pre-mortem-backtracing.html
...在某些体系结构中，包括我喜欢的MIPS，只有__builtin_return_address（0）有效.MIPS没有帧指针，因此难以走回堆栈。
如何获得完整的通话记录？
<我已经成功地使用了@Erki A所建议的方法，并且描述了 解决方案
stack-without-a-frame-pointer.htmlrel =nofollow noreferrer> here 。
以下是该方法的简短摘要：
问题：
无需调用堆栈一个帧指针。
解决方案的主要思想：
从汇编代码中得出调试器从调试信息中理解的内容。
我们需要的信息：
1.保留返回地址。
2.堆栈指针减少的数量
要重现整个堆栈跟踪，需要：
1.获取当前的$ sp和$ ra
2.扫描函数的开头并查找addui
sp，sp，spofft 命令（spofft <0）
3. Reprodece prev。 $ sp（sp-spofft）
4.向前扫描并查找sw r31，raofft（sp）
5.上一页。返回地址存储在[sp + raofft]
上面我描述了一次迭代。
如何获得第一个$ ra？
__builtin_return_address（0）
如何获得第一个$ sp？
寄存器unsigned sp asm（29）;
asm（：= r（sp））;
***由于我的大多数文件是使用微型mips优化编译的，所以我不得不处理micro- MIPS-ISA。
当我试图分析使用microMips优化编译的代码时，出现了很多问题（请记住，每一步的目标是重现prev。ra和prev。sp）：
它让事情变得更多一点复杂：
1. ra（$ 31）寄存器包含未对齐的返回地址。
您可以在链接问题中找到更多信息。
unaligned ra帮助你理解你运行在不同的
ISA（micro-mips-isa）
上2.有些函数不会移动sp。你可以找到更多的
信息[这里] [3]。
（如果leaf函数只修改临时寄存器并将
返回给其调用者代码中的返回语句，则不需要更改
$ ra，并且存在不需要
函数的堆栈框架。）
3.不存储ra
的函数4. MicroMips指令可以是 - 16位和32位：运行在
通讯使用不存在的短*。
5.有一些函数执行addiu sp，sp，spofft不止一次
6. micro-mips-isa对于相同命令
有几个变体，例如：addiu，addiusp 。
我决定忽略部分问题，这就是为什么95％ 。
I am trying to get call stack backtrace. Can't include "execinfo.h" therefore can't use int backtrace(void **buffer, int size);.
Also, tried to use __builtin_return_address() but acording to :http://codingrelic.geekhold.com/2009/05/pre-mortem-backtracing.html
...Also on some architectures, including my beloved MIPS, only __builtin_return_address(0) works.MIPS has no frame pointer, making it difficult to walk back up the stack. Frame 0 can use the return address register directly.
How can I get full call satck?
I have successfully used the method suggested by @Erki A and described here. Here is a short summary of the method:
The problem:
get a call stack without a frame pointer.
Solution main idea:
conclude from the assembly code what the debugger understood from debug info.
The information we need:
1. Where the return address is kept.
2. What amount the stack pointer is decremented.
To reproduce the whole stack trace one need to:
1. Get the current $sp and $ra
2. Scan towards the beginning of the function and look for "addui
sp,sp,spofft" command (spofft<0)
3. Reprodece prev. $sp (sp- spofft)
4. Scan forward and look for "sw r31,raofft(sp)"
5. Prev. return address stored at [sp+ raofft]
Above I described one iteration. You stop when the $ra is 0. How to get the first $ra?
__builtin_return_address(0)
How to get the first $sp?
register unsigned sp asm("29");
asm("" : "=r" (sp));
***Since most of my files compiled with micro-mips optimisation I had to deal with micro-mips-ISA. A lot of issues arose when I tried to analyze code that compiled with microMips optimization(remember that the goal at each step is to reproduce prev. ra and prev. sp): It makes things a bit more complicated:
1. ra ($31) register contain unaligned return address.
You may find more information at Linked questions.
The unaligned ra helps you understand that you run over different
ISA(micro-mips-isa)
2. There are functions that do not move the sp. You can find more
information [here][3].
(If a "leaf" function only modifies the temporary registers and returns
to a return statement in its caller's code, then there is no need for
$ra to be changed, and there is no need for a stack frame for that
function.)
3. Functions that do not store the ra
4. MicroMips instructions can be both - 16bit and 32bit: run over the
commnds using unsinged short*.
5. There are functions that perform "addiu sp, sp, spofft" more than once
6. micro-mips-isa has couple variations for the same command
for example: addiu,addiusp.
I have decided to ignore part of the issues and that is why it works for 95% of the cases.
这篇关于无帧指针获取调用堆栈的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
