linux-toradex.git/tools/perf/util/build-id.c, branch v6.3

perf buildid-cache: Fix the file mode with copyfile() while adding file to build-id cache

2023-01-18T13:39:16+00:00

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//linux/tools/perf/tests/pe-file.exe", "/tmp/perf.debug.TeY1/home//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//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 
Cc: Andi Kleen 
Cc: Disha Goel 
Cc: Ian Rogers 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Madhavan Srinivasan 
Cc: Michael Ellerman 
Cc: Nageswara R Sastry 
Cc: Namhyung Kim 
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

perf dso: Hold lock when accessing nsinfo

2022-10-04T11:55:20+00:00

There may be threads racing to update dso->nsinfo:

  https://lore.kernel.org/linux-perf-users/CAP-5=fWZH20L4kv-BwVtGLwR=Em3AOOT+Q4QGivvQuYn5AsPRg@mail.gmail.com/

Holding the dso->lock avoids use-after-free, memory leaks and other such
bugs. Apply the fix in:

  https://lore.kernel.org/linux-perf-users/20211118193714.2293728-1-irogers@google.com/

of there being a missing nsinfo__put now that the accesses are data race
free. Fixes test "Lookup mmap thread" when compiled with address
sanitizer.

Signed-off-by: Ian Rogers 
Reviewed-by: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Alexandre Truong 
Cc: Alexey Bayduraev 
Cc: Andi Kleen 
Cc: Andres Freund 
Cc: Andrii Nakryiko 
Cc: André Almeida 
Cc: Athira Jajeev 
Cc: Christophe JAILLET 
Cc: Colin Ian King 
Cc: Dario Petrillo 
Cc: Darren Hart 
Cc: Dave Marchevsky 
Cc: Davidlohr Bueso 
Cc: Fangrui Song 
Cc: Hewenliang 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jason Wang 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Kim Phillips 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Martin Liška 
Cc: Masami Hiramatsu 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Pavithra Gurushankar 
Cc: Peter Zijlstra 
Cc: Quentin Monnet 
Cc: Ravi Bangoria 
Cc: Remi Bernon 
Cc: Riccardo Mancini 
Cc: Song Liu 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Thomas Richter 
Cc: Tom Rix 
Cc: Weiguo Li 
Cc: Wenyu Liu 
Cc: William Cohen 
Cc: Zechuan Chen 
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Cc: yaowenbin 
Link: https://lore.kernel.org/r/20220826164242.43412-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf build-id: Print debuginfod queries if -v option is used

2022-08-12T13:27:20+00:00

When ending a 'perf record' session, the querying of a debuginfod server
can take quite some time. Inform a user about it when -v options is
used.

Signed-off-by: Martin Liška 
Link: http://lore.kernel.org/lkml/325871cf-b71f-6237-8793-82182272ece8@suse.cz
Signed-off-by: Arnaldo Carvalho de Melo

perf build-id: Fix coding style, replace 8 spaces by tabs

2022-08-12T13:22:49+00:00

Use tabs instead of 8 spaces for the indentation.

Signed-off-by: Martin Liška 
Link: http://lore.kernel.org/lkml/2983e2e0-6850-ad59-79d8-efe83b22cffe@suse.cz
Signed-off-by: Arnaldo Carvalho de Melo

perf buildid-cache: Do not require purge files to also be in the file system

2022-07-20T14:07:58+00:00

realname() returns NULL if the file is not in the file system, but we can
still remove it from the build ID cache in that case, so continue and
attempt the purge with the name provided.

Signed-off-by: Adrian Hunter 
Cc: Andi Kleen 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-10-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf buildid-cache: Add guestmount'd files to the build ID cache

2022-07-20T14:07:53+00:00

When the guestmount option is used, a guest machine's file system mount
point is recorded in machine->root_dir.

perf already iterates guest machines when adding files to the build ID
cache, but does not take machine->root_dir into account.

Use machine->root_dir to find files for guest build IDs, and add them to
the build ID cache using the "proper" name i.e. relative to the guest root
directory not the host root directory.

Signed-off-by: Adrian Hunter 
Acked-by: Ian Rogers 
Cc: Andi Kleen 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-9-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Export dsos__for_each_with_build_id()

2022-07-20T14:07:02+00:00

Export dsos__for_each_with_build_id() so it can be used elsewhere.

Signed-off-by: Adrian Hunter 
Acked-by: Ian Rogers 
Cc: Andi Kleen 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf build-id: Fix caching files with a wrong build ID

2022-06-26T15:32:55+00:00

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: 454c407ec17a0c63 ("perf: add perf-inject builtin")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Tom Zanussi 
Link: https://lore.kernel.org/r/20220621125144.5623-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf build-id: Fix spelling mistake "Cant" -> "Can't"

2022-03-22T21:27:56+00:00

There is a spelling mistake in a pr_err message. Fix it.

Signed-off-by: Colin Ian King 
Acked-by: Ian Rogers 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: kernel-janitors@vger.kernel.org
Link: https://lore.kernel.org/r/20220316232452.53062-1-colin.i.king@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf namespaces: Add functions to access nsinfo

2022-02-11T17:31:22+00:00

Having functions to access nsinfo reduces the places where reference
counting checking needs to be added.

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/20220211103415.2737789-14-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo