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    SubjectRe: [PATCH v2] perf trace: Fix SIGSEGV when processing syscall args
    Em Thu, Jul 07, 2022 at 02:39:00PM +0530, Naveen N. Rao escreveu:
    > 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 <snip> at builtin-trace.c:1492
    > #1 syscall_arg__scnprintf_filename <snip> at builtin-trace.c:1492
    > #2 syscall_arg__scnprintf_filename <snip> at builtin-trace.c:1486
    > #3 0x00000001225bdd9c in syscall_arg_fmt__scnprintf_val <snip> at builtin-trace.c:1973
    > #4 syscall__scnprintf_args <snip> at builtin-trace.c:2041
    > #5 0x00000001225bff04 in trace__sys_enter <snip> 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.

    Thanks, applied.

    - Arnaldo


    > Reported-by: Claudio Carvalho <cclaudio@linux.ibm.com>
    > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
    > ---
    > 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 &&
    >
    > base-commit: 52f28b7bac75da9b8508f17438c9a8d83ab48e5d
    > --
    > 2.36.1

    --

    - Arnaldo

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