From 26bbf45fc81dc1bcb29a9b4721d3ec6c3804003d Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 10 Jul 2020 22:11:04 +0900 Subject: perf probe: Avoid setting probes on the same address for the same event There is a case that several same-name symbols points to the same address. In that case, 'perf probe' returns an error. E.g. # perf probe -x /lib64/libc-2.30.so -v -a "memcpy arg1=%di" probe-definition(0): memcpy arg1=%di symbol:memcpy file:(null) line:0 offset:0 return:0 lazy:(null) parsing arg: arg1=%di into name:arg1 %di 1 arguments symbol:setjmp file:(null) line:0 offset:0 return:0 lazy:(null) symbol:longjmp file:(null) line:0 offset:0 return:0 lazy:(null) symbol:longjmp_target file:(null) line:0 offset:0 return:0 lazy:(null) symbol:lll_lock_wait_private file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_arena_max file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_arena_test file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_tunable_tcache_max_bytes file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_tunable_tcache_count file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_tunable_tcache_unsorted_limit file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_trim_threshold file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_top_pad file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_mmap_threshold file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_mmap_max file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_perturb file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_mxfast file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_heap_new file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_arena_reuse_free_list file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_arena_reuse file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_arena_reuse_wait file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_arena_new file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_arena_retry file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_sbrk_less file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_heap_free file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_heap_less file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_tcache_double_free file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_heap_more file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_sbrk_more file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_malloc_retry file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_memalign_retry file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt_free_dyn_thresholds file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_realloc_retry file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_calloc_retry file:(null) line:0 offset:0 return:0 lazy:(null) symbol:memory_mallopt file:(null) line:0 offset:0 return:0 lazy:(null) Open Debuginfo file: /usr/lib/debug/usr/lib64/libc-2.30.so.debug Try to find probe point from debuginfo. Opening /sys/kernel/debug/tracing//README write=0 Failed to find the location of the '%di' variable at this address. Perhaps it has been optimized out. Use -V with the --range option to show '%di' location range. An error occurred in debuginfo analysis (-2). Trying to use symbols. Opening /sys/kernel/debug/tracing//uprobe_events write=1 Writing event: p:probe_libc/memcpy /usr/lib64/libc-2.30.so:0x914c0 arg1=%di Writing event: p:probe_libc/memcpy /usr/lib64/libc-2.30.so:0x914c0 arg1=%di Failed to write event: File exists Error: Failed to add events. Reason: File exists (Code: -17) You can see that perf tried to write completely the same probe definition twice, which caused an error. To fix this issue, check the symbol list and drop duplicated symbols (which has the same symbol name and address) from it. With this patch: # perf probe -x /lib64/libc-2.30.so -a "memcpy arg1=%di" Failed to find the location of the '%di' variable at this address. Perhaps it has been optimized out. Use -V with the --range option to show '%di' location range. Added new events: probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di) probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di) You can now use it in all perf tools, such as: perf record -e probe_libc:memcpy -aR sleep 1 Committer notes: Fix this build error on 32-bit arches by using PRIx64 for symbol->start, that is an u64: In file included from util/probe-event.c:27: util/probe-event.c: In function 'find_probe_trace_events_from_map': util/probe-event.c:2978:14: error: format '%lx' expects argument of type 'long unsigned int', but argument 5 has type 'u64' {aka 'long long unsigned int'} [-Werror=format=] pr_debug("Found duplicated symbol %s @ %lx\n", ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ util/debug.h:17:21: note: in definition of macro 'pr_fmt' #define pr_fmt(fmt) fmt ^~~ util/probe-event.c:2978:5: note: in expansion of macro 'pr_debug' pr_debug("Found duplicated symbol %s @ %lx\n", ^~~~~~~~ Reported-by: Andi Kleen Signed-off-by: Masami Hiramatsu Reviewed-by: Srikar Dronamraju Cc: Andi Kleen Cc: Oleg Nesterov Link: http://lore.kernel.org/lkml/159438666401.62703.15196394835032087840.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-event.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'tools/perf/util') diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index df713a5d1e26..4316348961c4 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -2968,6 +2968,16 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, for (j = 0; j < num_matched_functions; j++) { sym = syms[j]; + /* There can be duplicated symbols in the map */ + for (i = 0; i < j; i++) + if (sym->start == syms[i]->start) { + pr_debug("Found duplicated symbol %s @ %" PRIx64 "\n", + sym->name, sym->start); + break; + } + if (i != j) + continue; + tev = (*tevs) + ret; tp = &tev->point; if (ret == num_matched_functions) { -- cgit v1.2.3