Ian Rogers 533a06858b perf symbol: Fail to read phdr workaround
[ Upstream commit 6d518ac7be6223811ab947897273b1bbef846180 ]

The perf jvmti agent doesn't create program headers, in this case
fallback on section headers as happened previously.

Committer notes:

To test this, from a public post by Ian:

1) download a Java workload dacapo-9.12-MR1-bach.jar from
https://sourceforge.net/projects/dacapobench/

2) build perf such as "make -C tools/perf O=/tmp/perf NO_LIBBFD=1" it
should detect Java and create /tmp/perf/libperf-jvmti.so

3) run perf with the jvmti agent:

  perf record -k 1 java -agentpath:/tmp/perf/libperf-jvmti.so -jar dacapo-9.12-MR1-bach.jar -n 10 fop

4) run perf inject:

  perf inject -i perf.data -o perf-injected.data -j

5) run perf report

  perf report -i perf-injected.data | grep org.apache.fop

With this patch reverted I see lots of symbols like:

     0.00%  java             jitted-388040-4656.so  [.] org.apache.fop.fo.FObj.bind(org.apache.fop.fo.PropertyList)

With the patch (2d86612aacb7805f ("perf symbol: Correct address for bss
symbols")) I see lots of:

  dso__load_sym_internal: failed to find program header for symbol:
  Lorg/apache/fop/fo/FObj;bind(Lorg/apache/fop/fo/PropertyList;)V
  st_value: 0x40

Fixes: 2d86612aacb7805f ("perf symbol: Correct address for bss symbols")
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20220731164923.691193-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-17 14:24:13 +02:00
2022-06-22 14:22:03 +02:00
2021-10-18 20:22:03 -10:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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