Re: [PATCH v3] perf tools: Introduce perf_thread for backtrace

From: Jiri Olsa
Date: Wed Dec 02 2015 - 11:27:30 EST


On Thu, Dec 03, 2015 at 12:33:40AM +0900, Namhyung Kim wrote:
> Backtrace is a crucial info for debugging. And upcoming refcnt
> tracking facility also wants to use it.
>
> So instead of relying on glibc's backtrace_symbols[_fd] which misses
> some (static) functions , use our own symbol searching mechanism. To
> do that, add perf_thread global variable to keep its maps and symbols.
>
> The backtrace output from TUI is changed like below. (I made a key
> action to generate a segfault):
>
> Before:
> perf: Segmentation fault
> -------- backtrace --------
> perf[0x544a8b]
> /usr/lib/libc.so.6(+0x33680)[0x7fc46420b680]
> perf[0x54041b]
> perf(perf_evlist__tui_browse_hists+0x91)[0x5432e1]
> perf(cmd_report+0x1d20)[0x43cb10]
> perf[0x487073]
> perf(main+0x62f)[0x42cb1f]
> /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7fc4641f8610]
> perf(_start+0x29)[0x42cc39]
>
> After:
> perf: Segmentation fault
> -------- backtrace --------
> perf_evsel__hists_browse(+0x43b) in perf [0x54066b]
> perf_evlist__tui_browse_hists(+0x91) in perf [0x543531]
> cmd_report(+0x1d20) in perf [0x43cb50]
> run_builtin(+0x53) in perf [0x4870b3]
> main(+0x634) in perf [0x42cb54]
> __libc_start_main(+0xf0) in libc-2.22.so [0x7fea3577c610]
> _start(+0x29) in perf [0x42cc79]
>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> ---
> v3) check return value of create_perf_thread()

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

thanks,
jirka
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