<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/tools/perf/util/sort.c, branch v5.10.257</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.257</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.257'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2024-08-19T03:40:49+00:00</updated>
<entry>
<title>perf report: Fix condition in sort__sym_cmp()</title>
<updated>2024-08-19T03:40:49+00:00</updated>
<author>
<name>Namhyung Kim</name>
<email>namhyung@kernel.org</email>
</author>
<published>2024-06-21T17:05:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=6ef4f1e98154d9938b4161f56c94013b55b9dacf'/>
<id>urn:sha1:6ef4f1e98154d9938b4161f56c94013b55b9dacf</id>
<content type='text'>
[ Upstream commit cb39d05e67dc24985ff9f5150e71040fa4d60ab8 ]

It's expected that both hist entries are in the same hists when
comparing two.  But the current code in the function checks one without
dso sort key and other with the key.  This would make the condition true
in any case.

I guess the intention of the original commit was to add '!' for the
right side too.  But as it should be the same, let's just remove it.

Fixes: 69849fc5d2119 ("perf hists: Move sort__has_dso into struct perf_hpp_list")
Reviewed-by: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: https://lore.kernel.org/r/20240621170528.608772-2-namhyung@kernel.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>perf map: Delete two variable initialisations before null pointer checks in sort__sym_from_cmp()</title>
<updated>2023-05-17T09:48:13+00:00</updated>
<author>
<name>Markus Elfring</name>
<email>Markus.Elfring@web.de</email>
</author>
<published>2023-04-13T12:46:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=be3517ae6b8093baa5c7e04cd4c8713c6e6eacaa'/>
<id>urn:sha1:be3517ae6b8093baa5c7e04cd4c8713c6e6eacaa</id>
<content type='text'>
[ Upstream commit c160118a90d4acf335993d8d59b02ae2147a524e ]

Addresses of two data structure members were determined before
corresponding null pointer checks in the implementation of the function
“sort__sym_from_cmp”.

Thus avoid the risk for undefined behaviour by removing extra
initialisations for the local variables “from_l” and “from_r” (also
because they were already reassigned with the same value behind this
pointer check).

This issue was detected by using the Coccinelle software.

Fixes: 1b9e97a2a95e4941 ("perf tools: Fix report -F symbol_from for data without branch info")
Signed-off-by: &lt;elfring@users.sourceforge.net&gt;
Acked-by: Ian Rogers &lt;irogers@google.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: German Gomez &lt;german.gomez@arm.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: https://lore.kernel.org/cocci/54a21fea-64e3-de67-82ef-d61b90ffad05@web.de/
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>perf report: Free generated help strings for sort option</title>
<updated>2021-07-28T12:35:35+00:00</updated>
<author>
<name>Riccardo Mancini</name>
<email>rickyman7@gmail.com</email>
</author>
<published>2021-07-15T16:07:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=51077d315a4698eaba72010cf0781b6189a8bf8c'/>
<id>urn:sha1:51077d315a4698eaba72010cf0781b6189a8bf8c</id>
<content type='text'>
[ Upstream commit a37338aad8c4d8676173ead14e881d2ec308155c ]

ASan reports the memory leak of the strings allocated by sort_help() when
running perf report.

This patch changes the returned pointer to char* (instead of const
char*), saves it in a temporary variable, and finally deallocates it at
function exit.

Signed-off-by: Riccardo Mancini &lt;rickyman7@gmail.com&gt;
Fixes: 702fb9b415e7c99b ("perf report: Show all sort keys in help output")
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/a38b13f02812a8a6759200b9063c6191337f44d4.1626343282.git.rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>perf report: Fix -F for branch &amp; mem modes</title>
<updated>2021-03-17T16:06:17+00:00</updated>
<author>
<name>Ravi Bangoria</name>
<email>ravi.bangoria@linux.ibm.com</email>
</author>
<published>2021-03-04T06:29:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=f9a87999bdd9aa03df63959542bbb1627adf4efc'/>
<id>urn:sha1:f9a87999bdd9aa03df63959542bbb1627adf4efc</id>
<content type='text'>
commit 6740a4e70e5d1b9d8e7fe41fd46dd5656d65dadf upstream.

perf report fails to add valid additional fields with -F when
used with branch or mem modes. Fix it.

Before patch:

  $ perf record -b
  $ perf report -b -F +srcline_from --stdio
  Error:
  Invalid --fields key: `srcline_from'

After patch:

  $ perf report -b -F +srcline_from --stdio
  # Samples: 8K of event 'cycles'
  # Event count (approx.): 8784
  ...

Committer notes:

There was an inversion: when looking at branch stack dimensions (keys)
it was checking if the sort mode was 'mem', not 'branch'.

Fixes: aa6b3c99236b ("perf report: Make -F more strict like -s")
Reported-by: Athira Jajeev &lt;atrajeev@linux.vnet.ibm.com&gt;
Signed-off-by: Ravi Bangoria &lt;ravi.bangoria@linux.ibm.com&gt;
Reviewed-by: Athira Jajeev &lt;atrajeev@linux.vnet.ibm.com&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Tested-by: Athira Jajeev &lt;atrajeev@linux.vnet.ibm.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: http://lore.kernel.org/lkml/20210304062958.85465-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>perf util: Fix memory leak of prefix_if_not_in</title>
<updated>2020-05-28T13:03:27+00:00</updated>
<author>
<name>Xie XiuQi</name>
<email>xiexiuqi@huawei.com</email>
</author>
<published>2020-05-21T13:32:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=07e9a6f538cbeecaf5c55b6f2991416f873cdcbd'/>
<id>urn:sha1:07e9a6f538cbeecaf5c55b6f2991416f873cdcbd</id>
<content type='text'>
Need to free "str" before return when asprintf() failed to avoid memory
leak.

Signed-off-by: Xie XiuQi &lt;xiexiuqi@huawei.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Hongbo Yao &lt;yaohongbo@huawei.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Li Bin &lt;huawei.libin@huawei.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: http://lore.kernel.org/lkml/20200521133218.30150-4-liwei391@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
<entry>
<title>perf symbol: Fix kernel symbol address display</title>
<updated>2020-05-05T19:35:32+00:00</updated>
<author>
<name>Thomas Richter</name>
<email>tmricht@linux.ibm.com</email>
</author>
<published>2020-04-15T07:07:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=51d9635582c55479bf7904fa47e39aef2b323a50'/>
<id>urn:sha1:51d9635582c55479bf7904fa47e39aef2b323a50</id>
<content type='text'>
Running commands

   ./perf record -e rb0000 -- find .
   ./perf report -v

reveals symbol names and its addresses. There is a mismatch between
kernel symbol and address. Here is an example for kernel symbol
check_chain_key:

 3.55%  find /lib/modules/.../build/vmlinux  0xf11ec  v [k] check_chain_key

This address is off by 0xff000 as can be seen with:

[root@t35lp46 ~]# fgrep check_chain_key /proc/kallsyms
00000000001f00d0 t check_chain_key
[root@t35lp46 ~]# objdump -t ~/linux/vmlinux| fgrep check_chain_key
00000000001f00d0 l     F .text	00000000000001e8 check_chain_key
[root@t35lp46 ~]#

This function is located in main memory 0x1f00d0 - 0x1f02b4. It has
several entries in the perf data file with the correct address:

[root@t35lp46 perf]# ./perf report -D -i perf.data.find-bad | \
				fgrep SAMPLE| fgrep 0x1f01ec
PERF_RECORD_SAMPLE(IP, 0x1): 22228/22228: 0x1f01ec period: 1300000 addr: 0
PERF_RECORD_SAMPLE(IP, 0x1): 22228/22228: 0x1f01ec period: 1300000 addr: 0

The root cause happens when reading symbol tables during perf report.
A long gdb call chain leads to

   machine__deliver_events
     perf_evlist__deliver_event
       perf_evlist__deliver_sample
         build_id__mark_dso_hits
	   thread__find_map(1)      Read correct address from sample entry
	     map__load
	       dso__load            Some more functions to end up in
	         ....
		 dso__load_sym.

Function dso__load_syms  checks for kernel relocation and symbol
adjustment for the kernel and results in kernel map adjustment of
	 kernel .text segment address (0x100000 on s390)
	 kernel .text segment offset in file (0x1000 on s390).
This results in all kernel symbol addresses to be changed by subtracting
0xff000 (on s390). For the symbol check_chain_key we end up with

    0x1f00d0 - 0x100000 + 0x1000 = 0xf11d0

and this address is saved in the perf symbol table. This calculation is
also applied by the mapping functions map__mapip() and map__unmapip()
to map IP addresses to dso mappings.

During perf report processing functions

   process_sample_event    (builtin-report.c)
     machine__resolve
       thread__find_map
     hist_entry_iter_add

are called. Function thread__find_map(1)
takes the correct sample address and applies the mapping function
map__mapip() from the kernel dso and saves the modified address
in struct addr_location for further reference. From now on this address
is used.

Funktion process_sample_event() then calls hist_entry_iter_add() to save
the address in member ip of struct hist_entry.

When samples are displayed using

    perf_evlist__tty_browse_hists
      hists__fprintf
        hist_entry__fprintf
	  hist_entry__snprintf
	    __hist_entry__snprintf
	      _hist_entry__sym_snprintf()

This simply displays the address of the symbol and ignores the dso &lt;-&gt; map
mappings done in function thread__find_map. This leads to the address
mismatch.

Output before:

ot@t35lp46 perf]# ./perf report -v | fgrep check_chain_key
     3.55%  find     /lib/modules/5.6.0d-perf+/build/vmlinux
     						0xf11ec v [k] check_chain_key
[root@t35lp46 perf]#

Output after:

[root@t35lp46 perf]# ./perf report -v | fgrep check_chain_key
     3.55%  find     /lib/modules/5.6.0d-perf+/build/vmlinux
     						0x1f01ec v [k] check_chain_key
[root@t35lp46 perf]#

Signed-off-by: Thomas Richter &lt;tmricht@linux.ibm.com&gt;
Acked-by: Sumanth Korikkar &lt;sumanthk@linux.ibm.com&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Link: http://lore.kernel.org/lkml/20200415070744.59919-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
<entry>
<title>perf evsel: Rename perf_evsel__{prev,next}() to evsel__{prev,next}()</title>
<updated>2020-05-05T19:35:31+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2020-04-30T14:06:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=e470daeaa36ad8058cb32616afb8c8d7cfba8456'/>
<id>urn:sha1:e470daeaa36ad8058cb32616afb8c8d7cfba8456</id>
<content type='text'>
As those are 'struct evsel' methods, not part of tools/lib/perf/, aka
libperf, to whom the perf_ prefix belongs.

Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
<entry>
<title>perf hist: Add fast path for duplicate entries check</title>
<updated>2020-04-18T12:05:01+00:00</updated>
<author>
<name>Kan Liang</name>
<email>kan.liang@linux.intel.com</email>
</author>
<published>2020-03-19T20:25:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=12e89e65f446476951f42aedeef56b6bd6f7f1e6'/>
<id>urn:sha1:12e89e65f446476951f42aedeef56b6bd6f7f1e6</id>
<content type='text'>
Perf checks the duplicate entries in a callchain before adding an entry.
However the check is very slow especially with deeper call stack.
Almost ~50% elapsed time of perf report is spent on the check when the
call stack is always depth of 32.

The hist_entry__cmp() is used to compare the new entry with the old
entries. It will go through all the available sorts in the sort_list,
and call the specific cmp of each sort, which is very slow.

Actually, for most cases, there are no duplicate entries in callchain.
The symbols are usually different. It's much faster to do a quick check
for symbols first. Only do the full cmp when the symbols are exactly the
same.

The quick check is only to check symbols, not dso. Export
_sort__sym_cmp.

  $ perf record --call-graph lbr ./tchain_edit_64

  Without the patch
  $time perf report --stdio
  real    0m21.142s
  user    0m21.110s
  sys     0m0.033s

  With the patch
  $time perf report --stdio
  real    0m10.977s
  user    0m10.948s
  sys     0m0.027s

Signed-off-by: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexey Budankov &lt;alexey.budankov@linux.intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Mathieu Poirier &lt;mathieu.poirier@linaro.org&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Pavel Gerasimov &lt;pavel.gerasimov@intel.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Ravi Bangoria &lt;ravi.bangoria@linux.ibm.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Vitaly Slobodskoy &lt;vitaly.slobodskoy@intel.com&gt;
Link: http://lore.kernel.org/lkml/20200319202517.23423-18-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
<entry>
<title>perf report: Add 'cgroup' sort key</title>
<updated>2020-04-03T12:37:55+00:00</updated>
<author>
<name>Namhyung Kim</name>
<email>namhyung@kernel.org</email>
</author>
<published>2020-03-25T12:45:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b629f3e9d01b4e4ad4e84c8f76fad514967a83da'/>
<id>urn:sha1:b629f3e9d01b4e4ad4e84c8f76fad514967a83da</id>
<content type='text'>
The cgroup sort key is to show cgroup membership of each task.
Currently it shows full path in the cgroupfs (not relative to the root
of cgroup namespace) since it'd be more intuitive IMHO.  Otherwise root
cgroup in different namespaces will all show same name - "/".

The cgroup sort key should come before cgroup_id otherwise
sort_dimension__add() will match it to cgroup_id as it only matches with
the given substring.

For example it will look like following.  Note that record patch adding
--all-cgroups patch will come later.

  $ perf record -a --namespace --all-cgroups  cgtest
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.208 MB perf.data (4090 samples) ]

  $ perf report -s cgroup_id,cgroup,pid
  ...
  # Overhead  cgroup id (dev/inode)  Cgroup          Pid:Command
  # ........  .....................  ..........  ...............
  #
      93.96%  0/0x0                  /                 0:swapper
       1.25%  3/0xeffffffb           /               278:looper0
       0.86%  3/0xf000015f           /sub/cgrp1      280:cgtest
       0.37%  3/0xf0000160           /sub/cgrp2      281:cgtest
       0.34%  3/0xf0000163           /sub/cgrp3      282:cgtest
       0.22%  3/0xeffffffb           /sub            278:looper0
       0.20%  3/0xeffffffb           /               280:cgtest
       0.15%  3/0xf0000163           /sub/cgrp3      285:looper3

Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20200325124536.2800725-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
<entry>
<title>perf report: Print al_addr when symbol is not found</title>
<updated>2020-03-23T14:08:29+00:00</updated>
<author>
<name>Jin Yao</name>
<email>yao.jin@linux.intel.com</email>
</author>
<published>2020-02-27T04:39:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=443bc639e518c6c4e8fc2e0456cccf3a04f6e77f'/>
<id>urn:sha1:443bc639e518c6c4e8fc2e0456cccf3a04f6e77f</id>
<content type='text'>
For branch mode, if the symbol is not found, it prints
the address.

For example, 0x0000555eee0365a0 in below output.

  Overhead  Command  Source Shared Object  Source Symbol                            Target Symbol
    17.55%  div      libc-2.27.so          [.] __random                             [.] __random
     6.11%  div      div                   [.] 0x0000555eee0365a0                   [.] rand
     6.10%  div      libc-2.27.so          [.] rand                                 [.] 0x0000555eee036769
     5.80%  div      libc-2.27.so          [.] __random_r                           [.] __random
     5.72%  div      libc-2.27.so          [.] __random                             [.] __random_r
     5.62%  div      libc-2.27.so          [.] __random_r                           [.] __random_r
     5.38%  div      libc-2.27.so          [.] __random                             [.] rand
     4.56%  div      libc-2.27.so          [.] __random                             [.] __random
     4.49%  div      div                   [.] 0x0000555eee036779                   [.] 0x0000555eee0365ff
     4.25%  div      div                   [.] 0x0000555eee0365fa                   [.] 0x0000555eee036760

But it's not very easy to understand what the instructions
are in the binary. So this patch uses the al_addr instead.

With this patch, the output is

  Overhead  Command  Source Shared Object  Source Symbol                            Target Symbol
    17.55%  div      libc-2.27.so          [.] __random                             [.] __random
     6.11%  div      div                   [.] 0x00000000000005a0                   [.] rand
     6.10%  div      libc-2.27.so          [.] rand                                 [.] 0x0000000000000769
     5.80%  div      libc-2.27.so          [.] __random_r                           [.] __random
     5.72%  div      libc-2.27.so          [.] __random                             [.] __random_r
     5.62%  div      libc-2.27.so          [.] __random_r                           [.] __random_r
     5.38%  div      libc-2.27.so          [.] __random                             [.] rand
     4.56%  div      libc-2.27.so          [.] __random                             [.] __random
     4.49%  div      div                   [.] 0x0000000000000779                   [.] 0x00000000000005ff
     4.25%  div      div                   [.] 0x00000000000005fa                   [.] 0x0000000000000760

Now we can use objdump to dump the object starting from 0x5a0.

For example,
objdump -d --start-address 0x5a0 div

00000000000005a0 &lt;rand@plt&gt;:
 5a0:   ff 25 2a 0a 20 00       jmpq   *0x200a2a(%rip)        # 200fd0 &lt;__cxa_finalize@plt+0x200a20&gt;
 5a6:   68 02 00 00 00          pushq  $0x2
 5ab:   e9 c0 ff ff ff          jmpq   570 &lt;srand@plt-0x10&gt;
 ...

Committer testing:

  [root@seventh ~]# perf record -a -b sleep 1
  [root@seventh ~]# perf report --header-only | grep cpudesc
  # cpudesc : Intel(R) Core(TM) i5-7500 CPU @ 3.40GHz
  [root@seventh ~]# perf evlist -v
  cycles: size: 120, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|BRANCH_STACK, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, branch_sample_type: ANY
  [root@seventh ~]#

Before:

  [root@seventh ~]# perf report --stdio --dso libsystemd-shared-241.so | head -20
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 2K of event 'cycles'
  # Event count (approx.): 2240
  #
  # Overhead  Command          Source Shared Object      Source Symbol           Target Symbol           Basic Block Cycles
  # ........  ...............  ........................  ......................  ......................  ..................
  #
       0.13%  systemd-journal  libc-2.29.so              [.] cfree@GLIBC_2.2.5   [.] _int_free           1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00007fe406465c82  [.] 0x00007fe406465d80  1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00007fe406465ded  [.] 0x00007fe406465c30  1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00007fe406465e4e  [.] 0x00007fe406465de0  1
       0.09%  systemd-journal  systemd-journald          [.] free@plt            [.] cfree@GLIBC_2.2.5   1
       0.09%  systemd-journal  libc-2.29.so              [.] _int_free           [.] _int_free           18
       0.09%  systemd-journal  libc-2.29.so              [.] _int_free           [.] _int_free           2
       0.04%  systemd          libsystemd-shared-241.so  [.] bus_resolve@plt     [.] bus_resolve         204
       0.04%  systemd          libsystemd-shared-241.so  [.] getpid_cached@plt   [.] getpid_cached       7
  [root@seventh ~]#

After:

  [root@seventh ~]# perf report --stdio --dso libsystemd-shared-241.so | head -20
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 2K of event 'cycles'
  # Event count (approx.): 2240
  #
  # Overhead  Command          Source Shared Object      Source Symbol           Target Symbol           Basic Block Cycles
  # ........  ...............  ........................  ......................  ......................  ..................
  #
       0.13%  systemd-journal  libc-2.29.so              [.] cfree@GLIBC_2.2.5   [.] _int_free           1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00000000000f7c82  [.] 0x00000000000f7d80  1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00000000000f7ded  [.] 0x00000000000f7c30  1
       0.09%  systemd          libsystemd-shared-241.so  [.] 0x00000000000f7e4e  [.] 0x00000000000f7de0  1
       0.09%  systemd-journal  systemd-journald          [.] free@plt            [.] cfree@GLIBC_2.2.5   1
       0.09%  systemd-journal  libc-2.29.so              [.] _int_free           [.] _int_free           18
       0.09%  systemd-journal  libc-2.29.so              [.] _int_free           [.] _int_free           2
       0.04%  systemd          libsystemd-shared-241.so  [.] bus_resolve@plt     [.] bus_resolve         204
       0.04%  systemd          libsystemd-shared-241.so  [.] getpid_cached@plt   [.] getpid_cached       7
  [root@seventh ~]#

Lets use -v to get full paths and then try objdump on the unresolved address:

  [root@seventh ~]# perf report -v --stdio --dso libsystemd-shared-241.so |&amp; grep libsystemd-shared-241.so | tail -1
     0.04% systemd-journal /usr/lib/systemd/libsystemd-shared-241.so 0x80c1a B [.] 0x0000000000080c1a 0x80a95 B [.] 0x0000000000080a95 61
  [root@seventh ~]#

  [root@seventh ~]# objdump -d --start-address 0x00000000000f7d80 /usr/lib/systemd/libsystemd-shared-241.so | head -20

  /usr/lib/systemd/libsystemd-shared-241.so:     file format elf64-x86-64

  Disassembly of section .text:

  00000000000f7d80 &lt;proc_cmdline_parse_given@@SD_SHARED+0x330&gt;:
     f7d80:	41 39 11             	cmp    %edx,(%r9)
     f7d83:	0f 84 ff fe ff ff    	je     f7c88 &lt;proc_cmdline_parse_given@@SD_SHARED+0x238&gt;
     f7d89:	4c 8d 05 97 09 0c 00 	lea    0xc0997(%rip),%r8        # 1b8727 &lt;utf8_skip_data@@SD_SHARED+0x3147&gt;
     f7d90:	b9 49 00 00 00       	mov    $0x49,%ecx
     f7d95:	48 8d 15 c9 f5 0b 00 	lea    0xbf5c9(%rip),%rdx        # 1b7365 &lt;utf8_skip_data@@SD_SHARED+0x1d85&gt;
     f7d9c:	31 ff                	xor    %edi,%edi
     f7d9e:	48 8d 35 9b ff 0b 00 	lea    0xbff9b(%rip),%rsi        # 1b7d40 &lt;utf8_skip_data@@SD_SHARED+0x2760&gt;
     f7da5:	e8 a6 d6 f4 ff       	callq  45450 &lt;log_assert_failed_realm@plt&gt;
     f7daa:	66 0f 1f 44 00 00    	nopw   0x0(%rax,%rax,1)
     f7db0:	41 56                	push   %r14
     f7db2:	41 55                	push   %r13
     f7db4:	41 54                	push   %r12
     f7db6:	55                   	push   %rbp
  [root@seventh ~]#

If we tried the the reported address before this patch:

  [root@seventh ~]# objdump -d --start-address 0x00007fe406465d80 /usr/lib/systemd/libsystemd-shared-241.so | head -20

  /usr/lib/systemd/libsystemd-shared-241.so:     file format elf64-x86-64

  [root@seventh ~]#

Signed-off-by: Jin Yao &lt;yao.jin@linux.intel.com&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Tested-by: Ravi Bangoria &lt;ravi.bangoria@linux.ibm.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20200227043939.4403-2-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
</feed>
