From 4b21b3e7ef86aff7ff961bf28b2c17ee4204da16 Mon Sep 17 00:00:00 2001 From: Athira Rajeev Date: Mon, 16 Jan 2023 10:31:30 +0530 Subject: perf buildid-cache: Fix the file mode with copyfile() while adding file to build-id cache MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- tools/perf/util/build-id.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index a839b30c981b..ea9c083ab1e3 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -715,9 +715,13 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam } else if (nsi && nsinfo__need_setns(nsi)) { if (copyfile_ns(name, filename, nsi)) goto out_free; - } else if (link(realname, filename) && errno != EEXIST && - copyfile(name, filename)) - goto out_free; + } else if (link(realname, filename) && errno != EEXIST) { + struct stat f_stat; + + if (!(stat(name, &f_stat) < 0) && + copyfile_mode(name, filename, f_stat.st_mode)) + goto out_free; + } } /* Some binaries are stripped, but have .debug files with their symbol -- cgit v1.2.3