linux-toradex.git/tools/perf/util/machine.c, branch v5.18

perf unwind: Don't show unwind error messages when augmenting frame pointer stack

2022-04-09T15:34:29+00:00

Commit Fixes: b9f6fbb3b2c29736 ("perf arm64: Inject missing frames when
using 'perf record --call-graph=fp'") intended to add a 'best effort'
DWARF unwind that improved the frame pointer stack in most scenarios.

It's expected that the unwind will fail sometimes, but this shouldn't be
reported as an error. It only works when the return address can be
determined from the contents of the link register alone.

Fix the error shown when the unwinder requires extra registers by adding
a new flag that suppresses error messages. This flag is not set in the
normal --call-graph=dwarf unwind mode so that behavior is not changed.

Fixes: b9f6fbb3b2c29736 ("perf arm64: Inject missing frames when using 'perf record --call-graph=fp'")
Reported-by: John Garry 
Signed-off-by: James Clark 
Tested-by: John Garry 
Cc: Alexander Shishkin 
Cc: Alexandre Truong 
Cc: German Gomez 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/r/20220406145651.1392529-1-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf maps: Use a pointer for kmaps

2022-02-14T19:47:13+00:00

struct maps is reference counted, using a pointer is more idiomatic.

Committer notes:

Delay:

   maps = machine__kernel_maps(&vmlinux);

To after:

  machine__init(&vmlinux, "", HOST_KERNEL_ID);

To avoid this on f34:

  In file included from /var/home/acme/git/perf/tools/perf/util/build-id.h:10,
                   from /var/home/acme/git/perf/tools/perf/util/dso.h:13,
                   from tests/vmlinux-kallsyms.c:8:
  In function ‘machine__kernel_maps’,
      inlined from ‘test__vmlinux_matches_kallsyms’ at tests/vmlinux-kallsyms.c:122:22:
  /var/home/acme/git/perf/tools/perf/util/machine.h:86:23: error: ‘vmlinux.kmaps’ is used uninitialized [-Werror=uninitialized]
     86 |         return machine->kmaps;
        |                ~~~~~~~^~~~~~~
  tests/vmlinux-kallsyms.c: In function ‘test__vmlinux_matches_kallsyms’:
  tests/vmlinux-kallsyms.c:121:34: note: ‘vmlinux’ declared here
    121 |         struct machine kallsyms, vmlinux;
        |                                  ^~~~~~~
  cc1: all warnings being treated as errors

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Alexey Bayduraev 
Cc: Andi Kleen 
Cc: Andrew Morton 
Cc: André Almeida 
Cc: Andy Shevchenko 
Cc: Darren Hart 
Cc: Davidlohr Bueso 
Cc: Dmitriy Vyukov 
Cc: Eric Dumazet 
Cc: German Gomez 
Cc: Hao Luo 
Cc: James Clark 
Cc: Jin Yao 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kajol Jain 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Masami Hiramatsu 
Cc: Miaoqian Lin 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Riccardo Mancini 
Cc: Shunsuke Nakamura 
Cc: Song Liu 
Cc: Stephane Eranian 
Cc: Stephen Brennan 
Cc: Steven Rostedt (VMware) 
Cc: Thomas Gleixner 
Cc: Thomas Richter 
Cc: Yury Norov 
Link: http://lore.kernel.org/lkml/20220211103415.2737789-6-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Apply correct label to user/kernel symbols in branch mode

2022-02-06T12:03:06+00:00

In branch mode, the branch symbols were being displayed with incorrect
cpumode labels. So fix this.

For example, before:
  # perf record -b -a -- sleep 1
  # perf report -b

  Overhead  Command  Source Shared Object  Source Symbol               Target Symbol
     0.08%  swapper  [kernel.kallsyms]     [k] rcu_idle_enter          [k] cpuidle_enter_state
 ==> 0.08%  cmd0     [kernel.kallsyms]     [.] psi_group_change        [.] psi_group_change
     0.08%  cmd1     [kernel.kallsyms]     [k] psi_group_change        [k] psi_group_change

After:
  # perf report -b

  Overhead  Command  Source Shared Object  Source Symbol               Target Symbol
     0.08%  swapper  [kernel.kallsyms]     [k] rcu_idle_enter          [k] cpuidle_enter_state
     0.08%  cmd0     [kernel.kallsyms]     [k] psi_group_change        [k] pei_group_change
     0.08%  cmd1     [kernel.kallsyms]     [k] psi_group_change        [k] psi_group_change

Reviewed-by: James Clark 
Signed-off-by: German Gomez 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/r/20220126105927.3411216-1-german.gomez@arm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Use path__join() to compose a path instead of snprintf(dir, '/', filename)

2022-01-19T16:54:57+00:00

Its more intention revealing, and if we're interested in the odd cases
where this may end up truncating we can do debug checks at one
centralized place.

Motivation, of all the container builds, fedora rawhide started
complaining of:

  util/machine.c: In function ‘machine__create_modules’:
  util/machine.c:1419:50: error: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
   1419 |                 snprintf(path, sizeof(path), "%s/%s", dir_name, dent->d_name);
        |                                                  ^~
  In file included from /usr/include/stdio.h:894,
                   from util/branch.h:9,
                   from util/callchain.h:8,
                   from util/machine.c:7:
  In function ‘snprintf’,
      inlined from ‘maps__set_modules_path_dir’ at util/machine.c:1419:3,
      inlined from ‘machine__set_modules_path’ at util/machine.c:1473:9,
      inlined from ‘machine__create_modules’ at util/machine.c:1519:7:
  /usr/include/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 2 and 4352 bytes into a destination of size 4096

There are other places where we should use path__join(), but lets get rid of
this one first.

Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Acked-by: Ian Rogers 
Link: Link: https://lore.kernel.org/r/YebZKjwgfdOz0lAs@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf arm64: Inject missing frames when using 'perf record --call-graph=fp'

2021-12-21T21:37:13+00:00

When unwinding using frame pointers on ARM64, the return address of the
current function may not have been pushed into the stack when a function
was interrupted, which makes perf show an incorrect call graph to the
user.

Consider the following example program:

  void leaf() {
      /* long computation */
  }

  void parent() {
      // (1)
      leaf();
      // (2)
  }

  ... could be compiled into (using gcc -fno-inline -fno-omit-frame-pointer):

  leaf:
      /* long computation */
      nop
      ret
  parent:
      // (1)
      stp     x29, x30, [sp, -16]!
      mov     x29, sp
      bl      parent
      nop
      ldp     x29, x30, [sp], 16
      // (2)
      ret

If the program is interrupted at (1), (2), or any point in "leaf:", the
call graph will skip the callers of the current function. We can unwind
using the dwarf info and check if the return addr is the same as the LR
register, and inject the missing frame into the call graph.

Before this patch, the above example shows the following call-graph when
recording using "--call-graph fp" mode in ARM64:

  # Children      Self  Command   Shared Object     Symbol
  # ........  ........  ........  ................  ......................
  #
      99.86%    99.86%  program3  program3          [.] leaf
  	    |
  	    ---_start
  	       __libc_start_main
  	       main
  	       leaf

As can be seen, the "parent" function is missing. This is specially
problematic in "leaf" because for leaf functions the compiler may always
omit pushing the return addr into the stack. After this patch, it shows
the correct graph:

  # Children      Self  Command   Shared Object     Symbol
  # ........  ........  ........  ................  ......................
  #
      99.86%    99.86%  program3  program3          [.] leaf
  	    |
  	    ---_start
  	       __libc_start_main
  	       main
  	       parent
  	       leaf

Reviewed-by: James Clark 
Signed-off-by: Alexandre Truong 
Acked-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Mathieu Poirier 
Cc: Namhyung Kim 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20211217154521.80603-7-german.gomez@arm.com
Signed-off-by: German Gomez 
[ Rename machine__normalize_is() to machine__normalized_is(), as suggested by James Clark ]
Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Add a mechanism to inject stack frames

2021-12-21T21:35:34+00:00

Add a mechanism for platforms to inject stack frames for the leaf
frame caller if there is enough information to determine a frame
is missing from dwarf or other post processing mechanisms.

Reviewed-by: James Clark 
Signed-off-by: Alexandre Truong 
Acked-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Mathieu Poirier 
Cc: Namhyung Kim 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20211217154521.80603-3-german.gomez@arm.com
Signed-off-by: German Gomez 
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add support for PERF_RECORD_AUX_OUTPUT_HW_ID

2021-10-20T14:22:27+00:00

The PERF_RECORD_AUX_OUTPUT_HW_ID event provides a way to match AUX output
data like Intel PT PEBS-via-PT back to the event that it came from, by
providing a hardware ID that is present in the AUX output.

Reviewed-by: Alexander Shishkin 
Reviewed-by: Andi Kleen 
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Peter Zijlstra 
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/20210907163903.11820-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Initialize srcline string member in add_location struct

2021-09-18T20:43:05+00:00

It's later supposed to be either a correct address or NULL. Without the
initialization, it may contain an undefined value which results in the
following segmentation fault:

  # perf top --sort comm -g --ignore-callees=do_idle

terminates with:

  #0  0x00007ffff56b7685 in __strlen_avx2 () from /lib64/libc.so.6
  #1  0x00007ffff55e3802 in strdup () from /lib64/libc.so.6
  #2  0x00005555558cb139 in hist_entry__init (callchain_size=, sample_self=true, template=0x7fffde7fb110, he=0x7fffd801c250) at util/hist.c:489
  #3  hist_entry__new (template=template@entry=0x7fffde7fb110, sample_self=sample_self@entry=true) at util/hist.c:564
  #4  0x00005555558cb4ba in hists__findnew_entry (hists=hists@entry=0x5555561d9e38, entry=entry@entry=0x7fffde7fb110, al=al@entry=0x7fffde7fb420,
      sample_self=sample_self@entry=true) at util/hist.c:657
  #5  0x00005555558cba1b in __hists__add_entry (hists=hists@entry=0x5555561d9e38, al=0x7fffde7fb420, sym_parent=, bi=bi@entry=0x0, mi=mi@entry=0x0,
      sample=sample@entry=0x7fffde7fb4b0, sample_self=true, ops=0x0, block_info=0x0) at util/hist.c:288
  #6  0x00005555558cbb70 in hists__add_entry (sample_self=true, sample=0x7fffde7fb4b0, mi=0x0, bi=0x0, sym_parent=, al=, hists=0x5555561d9e38)
      at util/hist.c:1056
  #7  iter_add_single_cumulative_entry (iter=0x7fffde7fb460, al=) at util/hist.c:1056
  #8  0x00005555558cc8a4 in hist_entry_iter__add (iter=iter@entry=0x7fffde7fb460, al=al@entry=0x7fffde7fb420, max_stack_depth=, arg=arg@entry=0x7fffffff7db0)
      at util/hist.c:1231
  #9  0x00005555557cdc9a in perf_event__process_sample (machine=, sample=0x7fffde7fb4b0, evsel=, event=, tool=0x7fffffff7db0)
      at builtin-top.c:842
  #10 deliver_event (qe=, qevent=) at builtin-top.c:1202
  #11 0x00005555558a9318 in do_flush (show_progress=false, oe=0x7fffffff80e0) at util/ordered-events.c:244
  #12 __ordered_events__flush (oe=oe@entry=0x7fffffff80e0, how=how@entry=OE_FLUSH__TOP, timestamp=timestamp@entry=0) at util/ordered-events.c:323
  #13 0x00005555558a9789 in __ordered_events__flush (timestamp=, how=, oe=) at util/ordered-events.c:339
  #14 ordered_events__flush (how=OE_FLUSH__TOP, oe=0x7fffffff80e0) at util/ordered-events.c:341
  #15 ordered_events__flush (oe=oe@entry=0x7fffffff80e0, how=how@entry=OE_FLUSH__TOP) at util/ordered-events.c:339
  #16 0x00005555557cd631 in process_thread (arg=0x7fffffff7db0) at builtin-top.c:1114
  #17 0x00007ffff7bb817a in start_thread () from /lib64/libpthread.so.0
  #18 0x00007ffff5656dc3 in clone () from /lib64/libc.so.6

If you look at the frame #2, the code is:

488	 if (he->srcline) {
489          he->srcline = strdup(he->srcline);
490          if (he->srcline == NULL)
491              goto err_rawdata;
492	 }

If he->srcline is not NULL (it is not NULL if it is uninitialized rubbish),
it gets strdupped and strdupping a rubbish random string causes the problem.

Also, if you look at the commit 1fb7d06a509e, it adds the srcline property
into the struct, but not initializing it everywhere needed.

Committer notes:

Now I see, when using --ignore-callees=do_idle we end up here at line
2189 in add_callchain_ip():

2181         if (al.sym != NULL) {
2182                 if (perf_hpp_list.parent && !*parent &&
2183                     symbol__match_regex(al.sym, &parent_regex))
2184                         *parent = al.sym;
2185                 else if (have_ignore_callees && root_al &&
2186                   symbol__match_regex(al.sym, &ignore_callees_regex)) {
2187                         /* Treat this symbol as the root,
2188                            forgetting its callees. */
2189                         *root_al = al;
2190                         callchain_cursor_reset(cursor);
2191                 }
2192         }

And the al that doesn't have the ->srcline field initialized will be
copied to the root_al, so then, back to:

1211 int hist_entry_iter__add(struct hist_entry_iter *iter, struct addr_location *al,
1212                          int max_stack_depth, void *arg)
1213 {
1214         int err, err2;
1215         struct map *alm = NULL;
1216
1217         if (al)
1218                 alm = map__get(al->map);
1219
1220         err = sample__resolve_callchain(iter->sample, &callchain_cursor, &iter->parent,
1221                                         iter->evsel, al, max_stack_depth);
1222         if (err) {
1223                 map__put(alm);
1224                 return err;
1225         }
1226
1227         err = iter->ops->prepare_entry(iter, al);
1228         if (err)
1229                 goto out;
1230
1231         err = iter->ops->add_single_entry(iter, al);
1232         if (err)
1233                 goto out;
1234

That al at line 1221 is what hist_entry_iter__add() (called from
sample__resolve_callchain()) saw as 'root_al', and then:

        iter->ops->add_single_entry(iter, al);

will go on with al->srcline with a bogus value, I'll add the above
sequence to the cset and apply, thanks!

Signed-off-by: Michael Petlan 
CC: Milian Wolff 
Cc: Jiri Olsa 
Fixes: 1fb7d06a509e ("perf report Use srcline from callchain for hist entries")
Link: https //lore.kernel.org/r/20210719145332.29747-1-mpetlan@redhat.com
Reported-by: Juri Lelli 
Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Fix refcount usage when processing PERF_RECORD_KSYMBOL

2021-06-19T13:06:46+00:00

ASan reported a memory leak of BPF-related ksymbols map and dso. The
leak is caused by refount never reaching 0, due to missing __put calls
in the function machine__process_ksymbol_register.

Once the dso is inserted in the map, dso__put() should be called
(map__new2() increases the refcount to 2).

The same thing applies for the map when it's inserted into maps
(maps__insert() increases the refcount to 2).

  $ sudo ./perf record -- sleep 5
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.025 MB perf.data (8 samples) ]

  =================================================================
  ==297735==ERROR: LeakSanitizer: detected memory leaks

  Direct leak of 6992 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x8e4e53 in map__new2 /home/user/linux/tools/perf/util/map.c:216:20
      #2 0x8cf68c in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:778:10
      [...]

  Indirect leak of 8702 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x8728d7 in dso__new_id /home/user/linux/tools/perf/util/dso.c:1256:20
      #2 0x872015 in dso__new /home/user/linux/tools/perf/util/dso.c:1295:9
      #3 0x8cf623 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:774:21
      [...]

  Indirect leak of 1520 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23
      #2 0x888954 in map__process_kallsym_symbol /home/user/linux/tools/perf/util/symbol.c:710:8
      [...]

  Indirect leak of 1406 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23
      #2 0x8cfbd8 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:803:8
      [...]

Signed-off-by: Riccardo Mancini 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: Ian Rogers 
Cc: Jiapeng Chong 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Tommi Rantala 
Link: http://lore.kernel.org/lkml/20210612173751.188582-1-rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Fix various typos in comments

2021-03-23T20:13:43+00:00

Fix ~124 single-word typos and a few spelling errors in the perf tooling code,
accumulated over the years.

Signed-off-by: Ingo Molnar 
Cc: Peter Zijlstra 
Link: https://lore.kernel.org/r/20210321113734.GA248990@gmail.com
Link: http://lore.kernel.org/lkml/20210323160915.GA61903@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo