kernel.git/tools/perf/util/symbol.c, branch linux-4.4.y

perf symbols: Fix debuginfo search for Ubuntu

2020-06-20T08:23:25Z

commit 85afd35575a3c1a3a905722dde5ee70b49282e70 upstream. Reportedly, from 19.10 Ubuntu has begun mixing up the location of some debug symbol files, putting files expected to be in /usr/lib/debug/usr/lib into /usr/lib/debug/lib instead. Fix by adding another dso_binary_type. Example on Ubuntu 20.04 Before: $ perf record -e intel_pt//u uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.030 MB perf.data ] $ perf script --call-trace | head -5 uname 14003 [005] 15321.764958566: cbr: 42 freq: 4219 MHz (156%) uname 14003 [005] 15321.764958566: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) 7f1e71cc4100 uname 14003 [005] 15321.764961566: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) 7f1e71cc4df0 uname 14003 [005] 15321.764961900: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) 7f1e71cc4e18 uname 14003 [005] 15321.764963233: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) 7f1e71cc5128 After: $ perf script --call-trace | head -5 uname 14003 [005] 15321.764958566: cbr: 42 freq: 4219 MHz (156%) uname 14003 [005] 15321.764958566: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) _start uname 14003 [005] 15321.764961566: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) _dl_start uname 14003 [005] 15321.764961900: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) _dl_start uname 14003 [005] 15321.764963233: (/usr/lib/x86_64-linux-gnu/ld-2.31.so ) _dl_start Reported-by: Travis Downs Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Link: http://lore.kernel.org/lkml/20200526155207.9172-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf symbols: Fix symbols__fixup_end heuristic for corner cases

2017-12-20T09:04:56Z

[ Upstream commit e7ede72a6d40cb3a30c087142d79381ca8a31dab ] The current symbols__fixup_end() heuristic for the last entry in the rb tree is suboptimal as it leads to not being able to recognize the symbol in the call graph in a couple of corner cases, for example: i) If the symbol has a start address (f.e. exposed via kallsyms) that is at a page boundary, then the roundup(curr->start, 4096) for the last entry will result in curr->start == curr->end with a symbol length of zero. ii) If the symbol has a start address that is shortly before a page boundary, then also here, curr->end - curr->start will just be very few bytes, where it's unrealistic that we could perform a match against. Instead, change the heuristic to roundup(curr->start, 4096) + 4096, so that we can catch such corner cases and have a better chance to find that specific symbol. It's still just best effort as the real end of the symbol is unknown to us (and could even be at a larger offset than the current range), but better than the current situation. Alexei reported that he recently run into case i) with a JITed eBPF program (these are all page aligned) as the last symbol which wasn't properly shown in the call graph (while other eBPF program symbols in the rb tree were displayed correctly). Since this is a generic issue, lets try to improve the heuristic a bit. Reported-and-Tested-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Fixes: 2e538c4a1847 ("perf tools: Improve kernel/modules symbol lookup") Link: http://lkml.kernel.org/r/bb5c80d27743be6f12afc68405f1956a330e1bc9.1489614365.git.daniel@iogearbox.net Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

perf symbols: Fixup symbol sizes before picking best ones

2016-10-31T10:14:01Z

commit 432746f8e0b6a82ba832b771afe31abd51af6752 upstream. When we call symbol__fixup_duplicate() we use algorithms to pick the "best" symbols for cases where there are various functions/aliases to an address, and those check zero size symbols, which, before calling symbol__fixup_end() are _all_ symbols in a just parsed kallsyms file. So first fixup the end, then fixup the duplicates. Found while trying to figure out why 'perf test vmlinux' failed, see the output of 'perf test -v vmlinux' to see cases where the symbols picked as best for vmlinux don't match the ones picked for kallsyms. Cc: Anton Blanchard Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Wang Nan Fixes: 694bf407b061 ("perf symbols: Add some heuristics for choosing the best duplicate symbol") Link: http://lkml.kernel.org/n/tip-rxqvdgr0mqjdxee0kf8i2ufn@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf symbols: Check symbol_conf.allow_aliases for kallsyms loading too

2016-10-31T10:14:01Z

commit c97b40e4d15f13a36cd037d598e45cbe9e1e5757 upstream. We can allow aliases to be kept, but we were checking this just when loading vmlinux files, be consistent, do it for any symbol table loading code that calls symbol__fixup_duplicate() by making this function check .allow_aliases instead. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Wang Nan Fixes: 680d926a8cb0 ("perf symbols: Allow symbol alias when loading map for symbol name") Link: http://lkml.kernel.org/n/tip-z0avp0s6cfjckc4xj3pdfjdz@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf symbols: Allow forcing reading of non-root owned files by root

2015-11-12T21:58:18Z

When the root user tries to read a file owned by some other user we get: # ls -la perf.data -rw-------. 1 acme acme 20032 Nov 12 15:50 perf.data # perf report File perf.data not owned by current user or root (use -f to override) # perf report -f | grep -v ^# | head -2 30.96% ls [kernel.vmlinux] [k] do_set_pte 28.24% ls libc-2.20.so [.] intel_check_word # That wasn't happening when the symbol code tried to read a JIT map, where the same check was done but no forcing was possible, fix it. Reported-by: Brendan Gregg Tested-by: Brendan Gregg Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: http://permalink.gmane.org/gmane.linux.kernel.perf.user/2380 Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Rebuild rbtree when adjusting symbols for kcore

2015-11-12T21:58:17Z

Normally symbols are read from the DSO and adjusted, if need be, so that the symbol start matches the file offset in the DSO file (we want the file offset because that is what we know from MMAP events). That is done by dso__load_sym() which inserts the symbols *after* adjusting them. In the case of kcore, the symbols have been read from kallsyms and the symbol start is the memory address. The symbols have to be adjusted to match the kcore file offsets. dso__split_kallsyms_for_kcore() does that, but now the adjustment is being done *after* the symbols have been inserted. It appears dso__split_kallsyms_for_kcore() was assuming that changing the symbol start would not change the order in the rbtree - which is, of course, not guaranteed. Signed-off-by: Adrian Hunter Tested-by: Wang Nan Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/563CB241.2090701@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Fix endless loop in dso__split_kallsyms_for_kcore

2015-10-28T14:19:30Z

Currently we split symbols based on the map comparison, but symbols are stored within dso objects and maps could point into same dso objects (kernel maps). Hence we could end up changing rbtree we are currently iterating and mess it up. It's easily reproduced on s390x by running: $ perf record -a -- sleep 3 $ perf buildid-list -i perf.data --with-hits The fix is to compare dso objects instead. Reported-by: Michael Petlan Signed-off-by: Jiri Olsa Acked-by: Adrian Hunter Cc: Andi Kleen Cc: Kan Liang Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20151026135130.GA26003@krava.brq.redhat.com Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: we can now read separate debug-info files based on a build ID

2015-10-28T13:04:27Z

Recent GDB (at least on a vanilla Debian box) looks for debug information in /usr/lib/debug/.build-id/nn/nnnnnnn where nn/nnnnnn is the build-id of the stripped ELF binary. This is documented here: https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html This was not working in perf because we didn't read the build id until AFTER we searched for the separate debug information file. This patch reads the build ID and THEN does the search. Signed-off-by: Dima Kogan Link: http://lkml.kernel.org/r/87si6pfwz4.fsf@secretsauce.net Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Try the .debug/ DSO cache as a last resort

2015-10-12T16:52:27Z

Not as the first attempt at finding a vmlinux for the running kernel, this way we get a more informative filename to present in tools, it will check that the build-id is the same as the one previously loaded in the DSO in dso->build_id, reading from /sys/kernel/notes, for instance. E.g. in the annotation TUI, going from 'perf top', for the scsi_sg_alloc kernel function, in the first line: Before: scsi_sg_alloc /root/.debug/.build-id/28/2777c262e6b3c0451375163c9a81c893218ab1 After: scsi_sg_alloc /lib/modules/4.3.0-rc1+/build/vmlinux And: # ls -la /root/.debug/.build-id/28/2777c262e6b3c0451375163c9a81c893218ab1 lrwxrwxrwx. 1 root root 81 Sep 22 16:11 /root/.debug/.build-id/28/2777c262e6b3c0451375163c9a81c893218ab1 -> ../../home/git/build/v4.3.0-rc1+/vmlinux/282777c262e6b3c0451375163c9a81c893218ab1 # file ~/.debug/home/git/build/v4.3.0-rc1+/vmlinux/282777c262e6b3c0451375163c9a81c893218ab1 /root/.debug/home/git/build/v4.3.0-rc1+/vmlinux/282777c262e6b3c0451375163c9a81c893218ab1: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=282777c262e6b3c0451375163c9a81c893218ab1, not stripped # The same as: # file /lib/modules/4.3.0-rc1+/build/vmlinux /lib/modules/4.3.0-rc1+/build/vmlinux: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=282777c262e6b3c0451375163c9a81c893218ab1, not stripped Furthermore: # sha256sum /lib/modules/4.3.0-rc1+/build/vmlinux e7a789bbdc61029ec09140c228e1dd651271f38ef0b8416c0b7d5ff727b98be2 /lib/modules/4.3.0-rc1+/build/vmlinux # sha256sum ~/.debug/home/git/build/v4.3.0-rc1+/vmlinux/282777c262e6b3c0451375163c9a81c893218ab1 e7a789bbdc61029ec09140c228e1dd651271f38ef0b8416c0b7d5ff727b98be2 /root/.debug/home/git/build/v4.3.0-rc1+/vmlinux/282777c262e6b3c0451375163c9a81c893218ab1 [root@zoo new]# Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: http://lkml.kernel.org/n/tip-9y42ikzq3jisiddoi6f07n8z@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

tools lib symbol: Rename kallsyms2elf_type to kallsyms2elf_binding

2015-09-30T21:34:30Z

It is about binding, not type, we have just a letter in kallsyms that should map both for the ELF type (STT_FUNC, etc) and to the ELF symbol binding (STB_WEAK, STB_GLOBAL, etc), so rename it now before introducing kallsyms2_elf_type() Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: http://lkml.kernel.org/n/tip-uu5vj343ms1q2wm55690on6v@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo