From 4b335e1e0d6f8fa91dac615a44b123c9f26e93d3 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Thu, 7 Jul 2022 14:39:00 +0530 Subject: [PATCH] perf trace: Fix SIGSEGV when processing syscall args On powerpc, 'perf trace' is crashing with a SIGSEGV when trying to process a perf.data file created with 'perf trace record -p': #0 0x00000001225b8988 in syscall_arg__scnprintf_augmented_string at builtin-trace.c:1492 #1 syscall_arg__scnprintf_filename at builtin-trace.c:1492 #2 syscall_arg__scnprintf_filename at builtin-trace.c:1486 #3 0x00000001225bdd9c in syscall_arg_fmt__scnprintf_val at builtin-trace.c:1973 #4 syscall__scnprintf_args at builtin-trace.c:2041 #5 0x00000001225bff04 in trace__sys_enter at builtin-trace.c:2319 That points to the below code in tools/perf/builtin-trace.c: /* * If this is raw_syscalls.sys_enter, then it always comes with the 6 possible * arguments, even if the syscall being handled, say "openat", uses only 4 arguments * this breaks syscall__augmented_args() check for augmented args, as we calculate * syscall->args_size using each syscalls:sys_enter_NAME tracefs format file, * so when handling, say the openat syscall, we end up getting 6 args for the * raw_syscalls:sys_enter event, when we expected just 4, we end up mistakenly * thinking that the extra 2 u64 args are the augmented filename, so just check * here and avoid using augmented syscalls when the evsel is the raw_syscalls one. */ if (evsel != trace->syscalls.events.sys_enter) augmented_args = syscall__augmented_args(sc, sample, &augmented_args_size, trace->raw_augmented_syscalls_args_size); As the comment points out, we should not be trying to augment the args for raw_syscalls. However, when processing a perf.data file, we are not initializing those properly. Fix the same. Reported-by: Claudio Carvalho Signed-off-by: Naveen N. Rao Cc: Jiri Olsa Cc: Namhyung Kim Link: http://lore.kernel.org/lkml/20220707090900.572584-1-naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 897fc504918b91..f075cf37a65ef8 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -4280,6 +4280,7 @@ static int trace__replay(struct trace *trace) goto out; evsel = evlist__find_tracepoint_by_name(session->evlist, "raw_syscalls:sys_enter"); + trace->syscalls.events.sys_enter = evsel; /* older kernels have syscalls tp versus raw_syscalls */ if (evsel == NULL) evsel = evlist__find_tracepoint_by_name(session->evlist, "syscalls:sys_enter"); @@ -4292,6 +4293,7 @@ static int trace__replay(struct trace *trace) } evsel = evlist__find_tracepoint_by_name(session->evlist, "raw_syscalls:sys_exit"); + trace->syscalls.events.sys_exit = evsel; if (evsel == NULL) evsel = evlist__find_tracepoint_by_name(session->evlist, "syscalls:sys_exit"); if (evsel &&