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  1. 08 1月, 2018 1 次提交
    • J
      perf report: Fix a wrong offset issue when using /proc/kcore · 935f5a9d
      由 Jin Yao 提交于 
      When a valid vmlinux is not found, 'perf report' falls back to look at
/proc/kcore. In this case, it will report the impossible large offset.

For example:

  # perf record -b -e cycles:k find /etc/ > /dev/null
  # perf report --stdio --branch-history

    22.77%  _vm_normal_page+18446603336221188162
            |
            ---page_remove_rmap +18446603336221188324
               page_remove_rmap +18446603336221188487 (cycles:5)
               unlock_page_memcg +18446603336221188096
               page_remove_rmap +18446603336221188327 (cycles:1)

The issue is the value which is passed to parameter 'addr' in
__get_srcline() is the objdump address. It's not correct if we calculate
the offset by using 'addr - sym->start'.

This patch creates a new parameter 'ip' in __get_srcline(). It is not
converted to objdump address.

With this patch, the perf report output is:

    22.77%  _vm_normal_page+66
            |
            ---page_remove_rmap +228
               page_remove_rmap +391 (cycles:5)
               unlock_page_memcg +0
               page_remove_rmap +231 (cycles:1)
               page_remove_rmap +236

Committer testing:

Make sure you get any valid vmlinux out of the way, using '-v' on the
'perf report' case and deleting it from places where perf searches them,
like your kernel build dir and the build-id cache, in ~/.debug/.
Reported-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJin Yao <yao.jin@linux.intel.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1514564812-17344-1-git-send-email-yao.jin@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      935f5a9d
  3. 27 12月, 2017 3 次提交
  5. 05 12月, 2017 1 次提交
  7. 29 11月, 2017 1 次提交
  9. 17 11月, 2017 10 次提交
  11. 13 11月, 2017 13 次提交
  13. 26 10月, 2017 1 次提交
    • R
      perf symbols: Fix memory corruption because of zero length symbols · 331c7cb3
      由 Ravi Bangoria 提交于 
      Perf top is often crashing at very random locations on powerpc.  After
investigating, I found the crash only happens when sample is of zero
length symbol. Powerpc kernel has many such symbols which does not
contain length details in vmlinux binary and thus start and end
addresses of such symbols are same.

Structure

  struct sym_hist {
        u64                   nr_samples;
        u64                   period;
        struct sym_hist_entry addr[0];
  };

has last member 'addr[]' of size zero. 'addr[]' is an array of addresses
that belongs to one symbol (function). If function consist of 100
instructions, 'addr' points to an array of 100 'struct sym_hist_entry'
elements. For zero length symbol, it points to the *empty* array, i.e.
no members in the array and thus offset 0 is also invalid for such
array.

  static int __symbol__inc_addr_samples(...)
  {
        ...
        offset = addr - sym->start;
        h = annotation__histogram(notes, evidx);
        h->nr_samples++;
        h->addr[offset].nr_samples++;
        h->period += sample->period;
        h->addr[offset].period += sample->period;
        ...
  }

Here, when 'addr' is same as 'sym->start', 'offset' becomes 0, which is
valid for normal symbols but *invalid* for zero length symbols and thus
updating h->addr[offset] causes memory corruption.

Fix this by adding one dummy element for zero length symbols.

Link: https://lkml.org/lkml/2016/10/10/148
Fixes: edee44be ("perf annotate: Don't throw error for zero length symbols")
Signed-off-by: NRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Taeung Song <treeze.taeung@gmail.com>
Link: http://lkml.kernel.org/r/1508854806-10542-1-git-send-email-ravi.bangoria@linux.vnet.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      331c7cb3
  15. 23 10月, 2017 1 次提交
  17. 18 8月, 2017 1 次提交
  19. 28 7月, 2017 1 次提交
  21. 27 7月, 2017 1 次提交
  23. 26 7月, 2017 1 次提交
  25. 25 7月, 2017 1 次提交
  27. 21 7月, 2017 4 次提交