Hi libunwind team,
I'm making a profiler using the perf_event_open system call.
I try to record callchain information for each function.
One option is to use PERF_SAMPLE_CALLCHAIN to get callchain information
attached to a sample.
Unfortunately, when sample occurs in the system or some external
libraries (openMP, MPI...) callchain info are missing.
To retrieve them, I read in the perf_event_open documentation that I can
use PERF_SAMPLE_STACK_USER and PERF_SAMPLE_REGS_USER to do stack unwinding.
So now, for one sample I have the CPU register state and the stack
(actually a part of the stack).
Now I have to use libunwind in remote mode to retrieve the callchain.
I supposed that I have to create the address space with the
unw_create_addr_space function.
In the documentation, I see 8 call-back routines :
- find_proc_info
- put_unwind_info
- get_dyn_info_list_addr
- access_mem
- access_reg
- access_fpreg
- resume
- get_proc_name
Do I need to implement every routines to retrieve the callchain ?
Do you know where I can have more information about the implementation
of these routines ?
Thank you for your help,
Jean-Baptiste.
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