linux-kernel - Re: [PATCH v6] perf: __kmod_path__parse: deal with kernel module names in '[]' correctly.

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Message-ID: <20150529000045.GA8405@sejong>
Date:	Fri, 29 May 2015 09:00:45 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	jolsa@...hat.com, acme@...nel.org, jolsa@...nel.org,
	mingo@...hat.com, lizefan@...wei.com, pi3orama@....com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] perf: __kmod_path__parse: deal with kernel module
 names in '[]' correctly.

Hi,

Sorry for being late, I forgot about this email..


On Tue, Apr 21, 2015 at 05:28:51PM +0800, Wang Nan wrote:
> On 2015/4/21 13:16, Namhyung Kim wrote:
> > Hi Wang,
> > 
> > On Tue, Apr 21, 2015 at 03:33:10AM +0000, Wang Nan wrote:
> >> Before patch ba92732e9808df679ddf75c5ea1c0caae6d7dce2 ('perf kmaps:
> >> Check kmaps to make code more robust'), perf report and perf annotate
> >> will segfault if trace data contains kernel module information like
> >> this:
> >>
> >>  # perf report -D -i ./perf.data
> >>  ...
> >>  0 0 0x188 [0x50]: PERF_RECORD_MMAP -1/0: [0xffffffbff1018000(0xf068000) @ 0]: x [test_module]
> >>  ...
> >>
> >>  # perf report -i ./perf.data --objdump=/path/to/objdump --kallsyms=/path/to/kallsyms
> >>
> >>  perf: Segmentation fault
> >>  -------- backtrace --------
> >>  /path/to/perf[0x503478]
> >>  /lib64/libc.so.6(+0x3545f)[0x7fb201f3745f]
> >>  /path/to/perf[0x499b56]
> >>  /path/to/perf(dso__load_kallsyms+0x13c)[0x49b56c]
> >>  /path/to/perf(dso__load+0x72e)[0x49c21e]
> >>  /path/to/perf(map__load+0x6e)[0x4ae9ee]
> >>  /path/to/perf(thread__find_addr_map+0x24c)[0x47deec]
> >>  /path/to/perf(perf_event__preprocess_sample+0x88)[0x47e238]
> >>  /path/to/perf[0x43ad02]
> >>  /path/to/perf[0x4b55bc]
> >>  /path/to/perf(ordered_events__flush+0xca)[0x4b57ea]
> >>  /path/to/perf[0x4b1a01]
> >>  /path/to/perf(perf_session__process_events+0x3be)[0x4b428e]
> >>  /path/to/perf(cmd_report+0xf11)[0x43bfc1]
> >>  /path/to/perf[0x474702]
> >>  /path/to/perf(main+0x5f5)[0x42de95]
> >>  /lib64/libc.so.6(__libc_start_main+0xf4)[0x7fb201f23bd4]
> >>  /path/to/perf[0x42dfc4]
> >>
> >> This is because __kmod_path__parse treats '[' leading names as kernel
> >> name instead of names of kernel module. If perf.data contains build
> >> information and the buildid of such modules can be found, the DSO of
> >> it will be treated as kernel, not kernel module.
> > 
> > Sorry if I missed some prior discussion on it, but any chance to treat
> > them as modules instead of kernel binaries?
> 
> Sorry, I tried but failed to understand your question. What this patch do
> is to treat them as modules instead of kernel binaries (or binary?
> since kernel is a whole binary and kernel modules are DSOs).

It seems I misunderstood your point.  So this patch makes DSOs have
correct dso_kernel_type, right?  Then I'm fine with this change..

Thanks,
Namhyung
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