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Date:   Wed, 10 Oct 2018 09:54:15 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     Anthony LaTorre <tlatorre9@gmail.com>,
        andipan Das <sandipan@linux.ibm.com>, peterz@infradead.org,
        mingo@redhat.com, jolsa@kernel.org,
        alexander.shishkin@linux.intel.com, namhyung@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: perf report segfault
Message-ID: <20181010125415.GG10775@kernel.org>
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Em Wed, Oct 10, 2018 at 12:20:04AM +0200, Jiri Olsa escreveu:
> On Tue, Oct 09, 2018 at 04:47:31PM -0500, Anthony LaTorre wrote:
> > I can try building perf from the latest sources. I've attached the
> > perf.data and perf.data.tar.bz2 from the test program I sent earlier.
> 
> cool, reproduced.. it seems to get introduced by:
>   2a9d5050dc84 perf script: Show correct offsets for DWARF-based unwinding
> 
> reverting that patch fixes the issue for me, but looks like
> we could just make th attached check and prevent the crash
> 
> adding Sandipan Das to the loop, the author of that commit, any idea?

commit ff4ce2885af8f9e8e99864d78dbeb4673f089c76
Author: Milian Wolff <milian.wolff@kdab.com>
Date:   Wed Sep 26 15:52:05 2018 +0200

    perf report: Don't try to map ip to invalid map
    
    Fixes a crash when the report encounters an address that could not be
    associated with an mmaped region:
    
      #0  0x00005555557bdc4a in callchain_srcline (ip=<error reading variable: Cannot access memory at address 0x38>, sym=0x0, map=0x0) at util/machine.c:2329
      #1  unwind_entry (entry=entry@entry=0x7fffffff9180, arg=arg@entry=0x7ffff5642498) at util/machine.c:2329
      #2  0x00005555558370af in entry (arg=0x7ffff5642498, cb=0x5555557bdb50 <unwind_entry>, thread=<optimized out>, ip=18446744073709551615) at util/unwind-libunwind-local.c:586
      #3  get_entries (ui=ui@entry=0x7fffffff9620, cb=0x5555557bdb50 <unwind_entry>, arg=0x7ffff5642498, max_stack=<optimized out>) at util/unwind-libunwind-local.c:703
      #4  0x0000555555837192 in _unwind__get_entries (cb=<optimized out>, arg=<optimized out>, thread=<optimized out>, data=<optimized out>, max_stack=<optimized out>) at util/unwind-libunwind-
local.c:725
      #5  0x00005555557c310f in thread__resolve_callchain_unwind (max_stack=127, sample=0x7fffffff9830, evsel=0x555555c7b3b0, cursor=0x7ffff5642498, thread=0x555555c7f6f0) at util/machine.c:235
1
      #6  thread__resolve_callchain (thread=0x555555c7f6f0, cursor=0x7ffff5642498, evsel=0x555555c7b3b0, sample=0x7fffffff9830, parent=0x7fffffff97b8, root_al=0x7fffffff9750, max_stack=127) at 
util/machine.c:2378
      #7  0x00005555557ba4ee in sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fffffff97b8, evsel=<optimized out>, al=al@entry=0x7fffffff9750,
          max_stack=<optimized out>) at util/callchain.c:1085
    
    Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
    Tested-by: Sandipan Das <sandipan@linux.ibm.com>
    Acked-by: Jiri Olsa <jolsa@kernel.org>
    Cc: Jin Yao <yao.jin@linux.intel.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Fixes: 2a9d5050dc84 ("perf script: Show correct offsets for DWARF-based unwinding")
    Link: http://lkml.kernel.org/r/20180926135207.30263-1-milian.wolff@kdab.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>