From: Leo Yan leo.yan@linaro.org
[ Upstream commit 03e9a5d8eb552a1bf692a9c8a5ecd50f4e428006 ]
On Arm64 a case is perf tools fails to find the corresponding trace point folder for system calls listed in the table 'syscalltbl_arm64', e.g. the generated system call table contains "lookup_dcookie" but we cannot find out the matched trace point folder for it.
We need to figure out if there have any issue for the generated system call table, on the other hand, we need to handle the case when trace point folder is missed under sysfs, this patch sets the flag syscall::nonexistent as true and returns the error from trace__read_syscall_info().
Another problem is for trace__syscall_info(), it returns two different values if a system call doesn't exist: at the first time calling trace__syscall_info() it returns NULL when the system call doesn't exist, later if call trace__syscall_info() again for the same missed system call, it returns pointer of syscall. trace__syscall_info() checks the condition 'syscalls.table[id].name == NULL', but the name will be assigned in the first invoking even the system call is not found.
So checking system call's name in trace__syscall_info() is not the right thing to do, this patch simply checks flag syscall::nonexistent to make decision if a system call exists or not, finally trace__syscall_info() returns the consistent result (NULL) if a system call doesn't existed.
Fixes: b8b1033fcaa091d8 ("perf trace: Mark syscall ids that are not allocated to avoid unnecessary error messages") Signed-off-by: Leo Yan leo.yan@linaro.org Acked-by: Ian Rogers irogers@google.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: bpf@vger.kernel.org Cc: Ingo Molnar mingo@redhat.com Cc: Jiri Olsa jolsa@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: https://lore.kernel.org/r/20221121075237.127706-4-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-trace.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 40123f5688b2..3dcf6aed1ef7 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1811,13 +1811,19 @@ static int trace__read_syscall_info(struct trace *trace, int id) sc->tp_format = trace_event__tp_format("syscalls", tp_name); }
+ /* + * Fails to read trace point format via sysfs node, so the trace point + * doesn't exist. Set the 'nonexistent' flag as true. + */ + if (IS_ERR(sc->tp_format)) { + sc->nonexistent = true; + return PTR_ERR(sc->tp_format); + } + if (syscall__alloc_arg_fmts(sc, IS_ERR(sc->tp_format) ? RAW_SYSCALL_ARGS_NUM : sc->tp_format->format.nr_fields)) return -ENOMEM;
- if (IS_ERR(sc->tp_format)) - return PTR_ERR(sc->tp_format); - sc->args = sc->tp_format->format.fields; /* * We need to check and discard the first variable '__syscall_nr' @@ -2134,11 +2140,8 @@ static struct syscall *trace__syscall_info(struct trace *trace, (err = trace__read_syscall_info(trace, id)) != 0) goto out_cant_read;
- if (trace->syscalls.table[id].name == NULL) { - if (trace->syscalls.table[id].nonexistent) - return NULL; + if (trace->syscalls.table && trace->syscalls.table[id].nonexistent) goto out_cant_read; - }
return &trace->syscalls.table[id];