Messages in this thread | | | Subject | Re: [PATCH v4 6/6] arm64: ftrace: add arch-specific stack tracer | From | AKASHI Takahiro <> | Date | Wed, 4 Nov 2015 17:01:58 +0900 |
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Jungseok,
On 11/01/2015 05:30 PM, Jungseok Lee wrote: > On Oct 30, 2015, at 2:25 PM, AKASHI Takahiro wrote: > > Hi Akashi, > >> Stack tracer on arm64, check_stack(), is uniqeue in the following >> points: >> * analyze a function prologue of a traced function to estimate a more >> accurate stack pointer value, replacing naive '<child's fp> + 0x10.' >> * use walk_stackframe(), instead of slurping stack contents as orignal >> check_stack() does, to identify a stack frame and a stack index (height) >> for every callsite. >> >> Regarding a function prologue analyzer, there is no guarantee that we can >> handle all the possible patterns of function prologue as gcc does not use >> any fixed templates to generate them. 'Instruction scheduling' is another >> issue here. >> Nevertheless, the current version will surely cover almost all the cases >> in the kernel image and give us useful information on stack pointers. > > Can I get an idea on how to test the function prologue analyzer? It pretty > tough to compare stack trace data with objdump one. Is there an easier way > to observe this enhancement without objdump?
It is quite difficult to give an evidence of the correctness of my function prologue analyzer. I only checked the outputs from stack tracer, one by one (every function), by comparing it against its disassembled code.
Thanks, -Takahiro AKASHI
> Best Regards > Jungseok Lee >
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