linux-toradex.git/tools/perf/jvmti, branch master

perf tools: Use const for variables receiving str{str,r?chr}() returns

2025-12-17T12:30:37+00:00

Newer glibc versions return const char for str{str,chr}() where the
haystack/s is const so to avoid warnings like these on fedora 44 change
some variables to const:

  36     8.17 fedora:44                     : FAIL gcc version 15.2.1 20251111 (Red Hat 15.2.1-4) (GCC)
    libbpf.c: In function 'kallsyms_cb':
    libbpf.c:8489:13: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
     8489 |         res = strstr(sym_name, ".llvm.");

Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20251211221756.96294-4-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf: Fix libjvmti.c sign compare error

2025-06-10T05:12:08+00:00

Fix the compile errors when compiling with -Werror=sign-compare.

This is a follow-up patch to a previous patch series for a separate
issue.  Link: https://lore.kernel.org/lkml/aC9lXhPFcs5fkHWH@x1/

Signed-off-by: Yuzhuo Jing 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250604173632.2362759-1-yuzhuo@google.com
Signed-off-by: Namhyung Kim

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

perf jvmti: Remove redundant jitdump line table entries

2020-05-29T19:51:38+00:00

For each PC/BCI pair in the JVMTI compiler inlining record table, the
jitdump plugin emits debug line table entries for every source line in
the method preceding that BCI. Instead only emit one source line per
PC/BCI pair. Reported by Ian Rogers. This reduces the .dump size for
SPECjbb from ~230MB to ~40MB.

Signed-off-by: Nick Gasson 
Acked-by: Ian Rogers 
Cc: Jiri Olsa 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lore.kernel.org/lkml/20200528054049.13662-1-nick.gasson@arm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jvmti: Do not report error when missing debug information

2020-05-28T13:03:28+00:00

If the Java sources are compiled with -g:none to disable debug
information the perf JVMTI plugin reports a lot of errors like:

  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION

Instead if GetLineNumberTable returns JVMTI_ERROR_ABSENT_INFORMATION
simply skip emitting line number information for that method. Unlike the
previous patch these errors don't affect the jitdump generation, they
just generate a lot of noise.

Similarly for native methods which also don't have line tables.

Signed-off-by: Nick Gasson 
Reviewed-by: Ian Rogers 
Tested-by: Ian Rogers 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lore.kernel.org/lkml/20200427061520.24905-3-nick.gasson@arm.com
[ Moved || operator to the end of the line, not at the start of 2nd if condition ]
Signed-off-by: Arnaldo Carvalho de Melo

perf jvmti: Fix jitdump for methods without debug info

2020-05-28T13:03:28+00:00

If a Java class is compiled with -g:none to omit debug information, the
JVMTI plugin won't write jitdump entries for any method in this class
and prints a lot of errors like:

    java: GetSourceFileName failed with JVMTI_ERROR_ABSENT_INFORMATION

The call to GetSourceFileName is used to derive the file name `fn`, but
this value is not actually used since commit ca58d7e64bdf ("perf jvmti:
Generate correct debug information for inlined code") which moved the
file name lookup into fill_source_filenames(). So the call to
GetSourceFileName and related code can be safely removed.

Signed-off-by: Nick Gasson 
Reviewed-by: Ian Rogers 
Tested-by: Ian Rogers 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lore.kernel.org/lkml/20200427061520.24905-2-nick.gasson@arm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jvmti: Link against tools/lib/ctype.h to have weak strlcpy()

2019-10-15T14:47:38+00:00

The build of file libperf-jvmti.so succeeds but the resulting
object fails to load:

 # ~/linux/tools/perf/perf record -k mono -- java  \
      -XX:+PreserveFramePointer \
      -agentpath:/root/linux/tools/perf/libperf-jvmti.so \
       hog 100000 123450
  Error occurred during initialization of VM
  Could not find agent library /root/linux/tools/perf/libperf-jvmti.so
      in absolute path, with error:
      /root/linux/tools/perf/libperf-jvmti.so: undefined symbol: _ctype

Add the missing _ctype symbol into the build script.

Fixes: 79743bc927f6 ("perf jvmti: Link against tools/lib/string.o to have weak strlcpy()")
Signed-off-by: Thomas Richter 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Link: http://lore.kernel.org/lkml/20191008093841.59387-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jvmti: Link against tools/lib/string.o to have weak strlcpy()

2019-09-20T12:18:45+00:00

That is needed in systems such some S/390 distros.

  $ readelf -s /tmp/build/perf/jvmti/jvmti-in.o | grep strlcpy
	452: 0000000000002990   125 FUNC    WEAK   DEFAULT  119 strlcpy
  $

Thanks to Jiri Olsa for fixing up my initial stab at this, I forgot how
Makefiles are picky about spaces versus tabs.

Reported-by: Thomas Richter 
Cc: Adrian Hunter 
Cc: Andreas Krebbel 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Sergey Melnikov 
Link: https://lkml.kernel.org/n/tip-x8vg9sffgb2t1tzqmhkrulh7@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools build: Check if gettid() is available before providing helper

2019-06-17T18:57:19+00:00

Laura reported that the perf build failed in fedora when we got a glibc
that provides gettid(), which I reproduced using fedora rawhide with the
glibc-devel-2.29.9000-26.fc31.x86_64 package.

Add a feature check to avoid providing a gettid() helper in such
systems.

On a fedora rawhide system with this patch applied we now get:

  [root@7a5f55352234 perf]# grep gettid /tmp/build/perf/FEATURE-DUMP
  feature-gettid=1
  [root@7a5f55352234 perf]# cat /tmp/build/perf/feature/test-gettid.make.output
  [root@7a5f55352234 perf]# ldd /tmp/build/perf/feature/test-gettid.bin
          linux-vdso.so.1 (0x00007ffc6b1f6000)
          libc.so.6 => /lib64/libc.so.6 (0x00007f04e0a74000)
          /lib64/ld-linux-x86-64.so.2 (0x00007f04e0c47000)
  [root@7a5f55352234 perf]# nm /tmp/build/perf/feature/test-gettid.bin | grep -w gettid
                   U gettid@@GLIBC_2.30
  [root@7a5f55352234 perf]#

While on a fedora:29 system:

  [acme@quaco perf]$ grep gettid /tmp/build/perf/FEATURE-DUMP
  feature-gettid=0
  [acme@quaco perf]$ cat /tmp/build/perf/feature/test-gettid.make.output
  test-gettid.c: In function ‘main’:
  test-gettid.c:8:9: error: implicit declaration of function ‘gettid’; did you mean ‘getgid’? [-Werror=implicit-function-declaration]
    return gettid();
           ^~~~~~
           getgid
  cc1: all warnings being treated as errors
  [acme@quaco perf]$

Reported-by: Laura Abbott 
Tested-by: Laura Abbott 
Acked-by: Jiri Olsa 
Cc: Adrian Hunter 
Cc: Florian Weimer 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Link: https://lkml.kernel.org/n/tip-yfy3ch53agmklwu9o7rlgf9c@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf jvmti: Address gcc string overflow warning for strncpy()

2019-06-05T12:51:26+00:00

We are getting false positive gcc warning when we compile with gcc9 (9.1.1):

     CC       jvmti/libjvmti.o
   In file included from /usr/include/string.h:494,
                    from jvmti/libjvmti.c:5:
   In function ‘strncpy’,
       inlined from ‘copy_class_filename.constprop’ at jvmti/libjvmti.c:166:3:
   /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound depends on the length of the source argument [-Werror=stringop-overflow=]
     106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
         |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   jvmti/libjvmti.c: In function ‘copy_class_filename.constprop’:
   jvmti/libjvmti.c:165:26: note: length computed here
     165 |   size_t file_name_len = strlen(file_name);
         |                          ^~~~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors

As per Arnaldo's suggestion use strlcpy(), which does the same thing and keeps
gcc silent.

Suggested-by: Arnaldo Carvalho de Melo 
Signed-off-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: Ben Gainey 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/r/20190531131321.GB1281@krava
Signed-off-by: Arnaldo Carvalho de Melo