From d80406453ad4a69932dc17a617d5b7bc7ae80b8f Mon Sep 17 00:00:00 2001 From: Paul Clarke Date: Tue, 25 Apr 2017 13:15:49 -0500 Subject: perf symbols: Allow user probes on versioned symbols Symbol versioning, as in glibc, results in symbols being defined as: @[@] (Note that "@@" identifies a default symbol, if the symbol name is repeated.) perf is currently unable to deal with this, and is unable to create user probes at such symbols: -- $ nm /lib/powerpc64le-linux-gnu/libpthread.so.0 | grep pthread_create 0000000000008d30 t __pthread_create_2_1 0000000000008d30 T pthread_create@@GLIBC_2.17 $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create probe-definition(0): pthread_create symbol:pthread_create file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Open Debuginfo file: /usr/lib/debug/lib/powerpc64le-linux-gnu/libpthread-2.19.so Try to find probe point from debuginfo. Probe point 'pthread_create' not found. Error: Failed to add events. Reason: No such file or directory (Code: -2) -- One is not able to specify the fully versioned symbol, either, due to syntactic conflicts with other uses of "@" by perf: -- $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create@@GLIBC_2.17 probe-definition(0): pthread_create@@GLIBC_2.17 Semantic error :SRC@SRC is not allowed. 0 arguments Error: Command Parse Error. Reason: Invalid argument (Code: -22) -- This patch ignores versioning for default symbols, thus allowing probes to be created for these symbols: -- $ /usr/bin/sudo ./perf probe -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create Added new event: probe_libpthread:pthread_create (on pthread_create in /lib/powerpc64le-linux-gnu/libpthread-2.19.so) You can now use it in all perf tools, such as: perf record -e probe_libpthread:pthread_create -aR sleep 1 $ /usr/bin/sudo ./perf record -e probe_libpthread:pthread_create -aR ./test 2 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.052 MB perf.data (2 samples) ] $ /usr/bin/sudo ./perf script test 2915 [000] 19124.260729: probe_libpthread:pthread_create: (3fff99248d38) test 2916 [000] 19124.260962: probe_libpthread:pthread_create: (3fff99248d38) $ /usr/bin/sudo ./perf probe --del=probe_libpthread:pthread_create Removed event: probe_libpthread:pthread_create -- Committer note: Change the variable storing the result of strlen() to 'int', to fix the build on debian:experimental-x-mipsel, fedora:24-x-ARC-uClibc, ubuntu:16.04-x-arm, etc: util/symbol.c: In function 'symbol__match_symbol_name': util/symbol.c:422:11: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare] if (len < versioning - name) ^ Signed-off-by: Paul A. Clarke Tested-by: Arnaldo Carvalho de Melo Acked-by: Masami Hiramatsu Cc: David Ahern Link: http://lkml.kernel.org/r/c2b18d9c-17f8-9285-4868-f58b6359ccac@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/perf/util/symbol.h') diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h index 7acd70fce68e..41ebba9a2eb2 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -348,8 +348,19 @@ void arch__sym_update(struct symbol *s, GElf_Sym *sym); #define SYMBOL_A 0 #define SYMBOL_B 1 +int arch__compare_symbol_names(const char *namea, const char *nameb); +int arch__compare_symbol_names_n(const char *namea, const char *nameb, + unsigned int n); int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb); +enum symbol_tag_include { + SYMBOL_TAG_INCLUDE__NONE = 0, + SYMBOL_TAG_INCLUDE__DEFAULT_ONLY +}; + +int symbol__match_symbol_name(const char *namea, const char *nameb, + enum symbol_tag_include includes); + /* structure containing an SDT note's info */ struct sdt_note { char *name; /* name of the note*/ -- cgit v1.2.3