linux-stable.git/tools/perf/util/annotate.c, branch v4.14.2

perf symbols: Fix memory corruption because of zero length symbols

2017-10-25T16:01:09+00:00

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: edee44be5919 ("perf annotate: Don't throw error for zero length symbols")
Signed-off-by: Ravi Bangoria 
Acked-by: Jiri Olsa 
Acked-by: Namhyung Kim 
Cc: Alexander Shishkin 
Cc: Jin Yao 
Cc: Kim Phillips 
Cc: Naveen N. Rao 
Cc: Peter Zijlstra 
Cc: Taeung Song 
Link: http://lkml.kernel.org/r/1508854806-10542-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate stdio: Support --show-nr-samples option

2017-08-18T13:31:53+00:00

Add --show-nr-samples option to "perf annotate" so that it matches "perf
report".

Committer note:

Note that it can't be used together with --show-total-period, which
seems like a silly limitation, that can be lifted at some point.

Made it bail out if not on --stdio.

Signed-off-by: Taeung Song 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Milian Wolff 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/1503046008-5511-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Fix storing per line sym_hist_entry

2017-07-28T15:53:05+00:00

The existing loop incremented the offset while using it as the array
index, when we went to an array of sym_hist_entry instances, we
should've moved the increment to outside of the array element reference,
oops, fix it.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Taeung Song 
Cc: Wang Nan 
Fixes: 461c17f00f40 ("perf annotate: Store the sample period in each histogram bucket")
Link: http://lkml.kernel.org/n/tip-s3dm6uyrazlpag3f0psfia07@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate stdio: Set enough columns for --show-total-period

2017-07-26T20:16:46+00:00

Now that we set the first column header according to wether
--show-total-period is being used, we need to size it accordingly.

Based-on-a-patch-by: Taeung Song 
Cc: Jiri Olsa 
Cc: Milian Wolff 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/n/tip-pu504ffnit4m334k09hxcbs3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate stdio: Fix column header when using --show-total-period

2017-07-26T01:46:37+00:00

Currently the first column header is always "Percent", fix it to show
correct column name based on given options, i.e. if using
--show-total-period, show "Event count" as a first column.

Reported-by: Milian Wolff 
Signed-off-by: Taeung Song 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/c3c902e7-95bc-16d4-366f-12eb034c5c8d@gmail.com
[ Extracted from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate stdio: Fix --show-total-period

2017-07-25T14:23:36+00:00

We were showing the total number of samples, not the total period as
asked by the user, fix it.

Reported-by: Namhyung Kim 
Cc: Jiri Olsa 
Cc: Martin Liška 
Cc: Milian Wolff 
Link: http://lkml.kernel.org/n/tip-lh2nh89rtqn5x5vbfthw6qml@git.kernel.org
Fixes: 0c4a5bcea460 ("perf annotate: Display total number of samples with --show-total-period")
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Store the sample period in each histogram bucket

2017-07-21T15:02:38+00:00

We'll use it soon, when fixing --show-total-period.

Signed-off-by: Taeung Song 
Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/1500500215-16646-1-git-send-email-treeze.taeung@gmail.com
[ split from a larger patch, do the math in __symbol__inc_addr_samples() ]
Signed-off-by: Arnaldo Carvalho de Melo

perf hists: Pass perf_sample to symbolinc_addr_samples()

2017-07-21T11:23:50+00:00

To pave the way to use perf_sample fields in the annotate code, storing
sample->period in sym_hist->addr->period and its sum in
sym_hist->period.

Signed-off-by: Taeung Song 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/1500500215-16646-1-git-send-email-treeze.taeung@gmail.com
[ split and adjusted from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Rename 'sum' to 'nr_samples' in struct sym_hist

2017-07-21T11:23:49+00:00

To make it more clear that it is the sum of all the nr_samples fields in the
addr[] entries, i.e.:

  sym_hist->nr_samples = sum(sym_hist->addr[0 ..  symbol__size(sym)]->nr_samples)

Committer notes:

Taeung had renamed it to total_samples, but using nr_samples, as in the
added explanation above, looks clearer and establishes the direct
connection, making clear it is about the _number_ of samples.

Signed-off-by: Taeung Song 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/1500500211-16599-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Introduce struct sym_hist_entry

2017-07-21T11:23:38+00:00

struct sym_hist has addr[] but it should have not only number of samples
but also the sample period.  So use new struct symhist_entry to pave the
way to have that.

Committer notes:

This initial patch will only introduce the struct sym_hist_entry and use
only the nr_samples member, which makes the code clearer and paves the
way to save the period as well.

Signed-off-by: Taeung Song 
Suggested-by: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/1500500205-16553-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo