When synthesizing build-ids, for build ID mmap2 events, they will be
added for data mmaps if -d/--data is specified. The files opened for
their build IDs may block on the open causing perf to hang during
synthesis. There is some robustness in existing calls to
filename__read_build_id by checking the file path is to a regular
file, which unfortunately fails for symlinks. Rather than adding more
is_regular_file calls, switch filename__read_build_id to take a
"block" argument and specify O_NONBLOCK when this is false. The
existing is_regular_file checking callers and the event synthesis
callers are made to pass false and thereby avoiding the hang.
Fixes: 53b00ff358 ("perf record: Make --buildid-mmap the default")
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250823000024.724394-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
It post-processes samples to find which DSO has samples. Based on that
info, it can save used DSOs in the build-ID cache directory. But for
some reason, it saves all DSOs without checking the hit mark. Skipping
unused DSOs can give some speedup especially with --buildid-mmap being
default.
On my idle machine, `time perf record -a sleep 1` goes down from 3 sec
to 1.5 sec with this change.
Fixes: e29386c8f7 ("perf record: Add --buildid-mmap option to enable PERF_RECORD_MMAP2's build id")
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20250731070330.57116-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The dso_id previously contained the major, minor, inode and inode
generation information from a mmap2 event - the inode generation would
be zero when reading from /proc/pid/maps. The build_id was in the
dso. With build ID mmap2 events these fields wouldn't be initialized
which would largely mean the special empty case where any dso would
match for equality. This isn't desirable as if a dso is replaced we
want the comparison to yield a difference.
To support detecting the difference between DSOs based on build_id,
move the build_id out of the DSO and into the dso_id. The dso_id is
also stored in the DSO so nothing is lost. Capture in the dso_id what
parts have been initialized and rename dso_id__inject to
dso_id__improve_id so that it is clear the dso_id is being improved
upon with additional information. With the build_id in the dso_id, use
memcmp to compare for equality.
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250724163302.596743-7-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The build-id events written at the end of the record session are broken
due to unexpected data. The write_buildid() writes the fixed length
event first and then variable length filename.
But a recent change made it write more data in the padding area
accidentally. So readers of the event see zero-filled data for the
next entry and treat it incorrectly. This resulted in wrong kernel
symbols because the kernel DSO loaded a random vmlinux image in the
path as it didn't have a valid build-id.
Fixes: ae39ba1655 ("perf inject: Fix build ID injection")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/Z0aRFFW9xMh3mqKB@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The test "build id cache operations" fails on powerpc as below:
Adding 5a0fd882b53084224ba47b624c55a469 ./tests/shell/../pe-file.exe: Ok
build id: 5a0fd882b53084224ba47b624c55a469
link: /tmp/perf.debug.ZTu/.build-id/5a/0fd882b53084224ba47b624c55a469
file: /tmp/perf.debug.ZTu/.build-id/5a/../../root/linux/tools/perf/tests/pe-file.exe/5a0fd882b53084224ba47b624c55a469/elf
failed: file /tmp/perf.debug.ZTu/.build-id/5a/../../root/linux/tools/perf/tests/pe-file.exe/5a0fd882b53084224ba47b624c55a469/elf does not exist
test child finished with -1
---- end ----
build id cache operations: FAILED!
The failing test is when trying to add pe-file.exe to build id cache.
'perf buildid-cache' can be used to add/remove/manage files from the
build-id cache. "-a" option is used to add a file to the build-id cache.
Simple command to do so for a PE exe file:
# ls -ltr tests/pe-file.exe
-rw-r--r--. 1 root root 75595 Jan 10 23:35 tests/pe-file.exe
The file is in home directory.
# mkdir /tmp/perf.debug.TeY1
# perf --buildid-dir /tmp/perf.debug.TeY1 buildid-cache -v -a tests/pe-file.exe
The above will create ".build-id" folder in build id directory, which is
/tmp/perf.debug.TeY1. Also adds file to this folder under build id.
Example:
# ls -ltr /tmp/perf.debug.TeY1/.build-id/5a/0fd882b53084224ba47b624c55a469/
total 76
-rw-r--r--. 1 root root 0 Jan 11 00:38 probes
-rwxr-xr-x. 1 root root 75595 Jan 11 00:38 elf
We can see in the results that file mode for original file and file in
build id directory is different. ie, build id file has executable
permission whereas original file doesn’t have.
The code path and function (build_id_cache__add to add a file to the
cache is in "util/build-id.c". In build_id_cache__add() function, it
first attempts to link the original file to destination cache folder.
If linking the file fails (which can happen if the destination and
source is on a different mount points), it will copy the file to
destination. Here copyfile() routine explicitly uses mode as "755" and
hence file in the destination will have executable permission.
Code snippet:
if (link(realname, filename) && errno != EEXIST && copyfile(name, filename))
strace logs:
172285 link("/home/<user_name>/linux/tools/perf/tests/pe-file.exe", "/tmp/perf.debug.TeY1/home/<user_name>/linux/tools/perf/tests/pe-file.exe/5a0fd882b53084224ba47b624c55a469/elf") = -1 EXDEV (Invalid cross-device link)
172285 newfstatat(AT_FDCWD, "tests/pe-file.exe", {st_mode=S_IFREG|0644, st_size=75595, ...}, 0) = 0
172285 openat(AT_FDCWD, "/tmp/perf.debug.TeY1/home/<user_name>/linux/tools/perf/tests/pe-file.exe/5a0fd882b53084224ba47b624c55a469/.elf.KbAnsl", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
172285 fchmod(3, 0755) = 0
172285 openat(AT_FDCWD, "tests/pe-file.exe", O_RDONLY) = 4
172285 mmap(NULL, 75595, PROT_READ, MAP_PRIVATE, 4, 0) = 0x7fffa5cd0000
172285 pwrite64(3, "MZ\220\0\3\0\0\0\4\0\0\0\377\377\0\0\270\0\0\0\0\0\0\0@\0\0\0\0\0\0\0"..., 75595, 0) = 75595
Whereas if the link succeeds, it succeeds in the first attempt itself
and the file in the build-id dir will have same permission as original
file.
Example, above uses /tmp. Instead if we use "--buildid-dir /home/build",
linking will work here since mount points are same. Hence the
destination file will not have executable permission.
Since the testcase "tests/shell/buildid.sh" always looks for executable
file, test fails in powerpc environment when test is run from /root.
The patch adds a change in build_id_cache__add() to use copyfile_mode()
which also passes the file’s original mode as argument. This way the
destination file mode also will be same as original file.
Signed-off-by: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Disha Goel <disgoel@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nageswara R Sastry <rnsastry@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230116050131.17221-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Build ID events associate a file name with a build ID. However, when
using perf inject, there is no guarantee that the file on the current
machine at the current time has that build ID. Fix by comparing the
build IDs and skip adding to the cache if they are different.
Example:
$ echo "int main() {return 0;}" > prog.c
$ gcc -o prog prog.c
$ perf record --buildid-all ./prog
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.019 MB perf.data ]
$ file-buildid() { file $1 | awk -F= '{print $2}' | awk -F, '{print $1}' ; }
$ file-buildid prog
444ad9be165d8058a48ce2ffb4e9f55854a3293e
$ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf
444ad9be165d8058a48ce2ffb4e9f55854a3293e
$ echo "int main() {return 1;}" > prog.c
$ gcc -o prog prog.c
$ file-buildid prog
885524d5aaa24008a3e2b06caa3ea95d013c0fc5
Before:
$ perf buildid-cache --purge $(pwd)/prog
$ perf inject -i perf.data -o junk
$ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf
885524d5aaa24008a3e2b06caa3ea95d013c0fc5
$
After:
$ perf buildid-cache --purge $(pwd)/prog
$ perf inject -i perf.data -o junk
$ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf
$
Fixes: 454c407ec1 ("perf: add perf-inject builtin")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Link: https://lore.kernel.org/r/20220621125144.5623-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We do not store size with build ids in perf data, but there's enough
space to do it. Adding misc bit PERF_RECORD_MISC_BUILD_ID_SIZE to mark
build id event with size.
With this fix the dso with md5 build id will have correct build id data
and will be usable for debuginfod processing if needed (coming in
following patches).
Committer notes:
Use %zu with size_t to fix this error on 32-bit arches:
util/header.c: In function '__event_process_build_id':
util/header.c:2105:3: error: format '%lu' expects argument of type 'long unsigned int', but argument 6 has type 'size_t' [-Werror=format=]
pr_debug("build id event received for %s: %s [%lu]\n",
^
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20201013192441.1299447-8-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Passing build_id object to build_id__sprintf function, so it can operate
with the proper size of build id.
This will create proper md5 build id readable names,
like following:
a50e350e97c43b4708d09bcd85ebfff7
instead of:
a50e350e97c43b4708d09bcd85ebfff700000000
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20201013192441.1299447-5-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Replace build_id byte array with struct build_id object and all the code
that references it.
The objective is to carry size together with build id array, so it's
better to keep both together.
This is preparatory change for following patches, and there's no
functional change.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20201013192441.1299447-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
During a perf-record, use the -ldebuginfod API to query a debuginfod
server, should the debug data not be found in the usual system
locations. If successful, the usual $HOME/.debug dir is populated.
Tested with:
$ find .
.
./ctags-debuginfo-5.8-26.fc31.x86_64.rpm
./usr
./usr/lib
./usr/lib/debug
./usr/lib/debug/.build-id
./usr/lib/debug/.build-id/ca
./usr/lib/debug/.build-id/ca/46f6ae6a0cee57d85abc1d461c49074248908d
./usr/lib/debug/.build-id/ca/46f6ae6a0cee57d85abc1d461c49074248908d.debug
./usr/lib/debug/usr
./usr/lib/debug/usr/bin
./usr/lib/debug/usr/bin/ctags-5.8-26.fc31.x86_64.debug
$ debuginfod -F .
...
$ rm -rf ~/.debug/ ; mkdir ~/.debug
$ perf record make tags
BUILD: Doing 'make -j8' parallel build
GEN tags
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.107 MB perf.data (1483 samples) ]
$ find ~/.debug | grep ctags
/home/jolsa/.debug/usr/bin/ctags
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/elf
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/probes
$ rm -rf ~/.debug/ ; mkdir ~/.debug
$ DEBUGINFOD_URLS=http://localhost:8002 perf record make tags
BUILD: Doing 'make -j8' parallel build
GEN tags
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.108 MB perf.data (1531 samples) ]
$ find ~/.debug | grep ctag
/home/jolsa/.debug/usr/bin/ctags
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/debug
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/elf
/home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/probes
Note the 'debug' file is created in the last run.
Note that currently the debuginfo data are downloaded only on record path,
we still need add this support to perf build-id/report.. and test ;-)
Tested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We got the sane_ctype.h headers from git and kept using it so far, but
since that code originally came from the kernel sources to the git
sources, perhaps its better to just use the one in the kernel, so that
we can leverage tools/perf/check_headers.sh to be notified when our copy
gets out of sync, i.e. when fixes or goodies are added to the code we've
copied.
This will help with things like tools/lib/string.c where we want to have
more things in common with the kernel, such as strim(), skip_spaces(),
etc so as to go on removing the things that we have in tools/perf/util/
and instead using the code in the kernel, indirectly and removing things
like EXPORT_SYMBOL(), etc, getting notified when fixes and improvements
are made to the original code.
Hopefully this also should help with reducing the difference of code
hosted in tools/ to the one in the kernel proper.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-7k9868l713wqtgo01xxygn12@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
