[PATCH 011/107] perf augmented_raw_syscalls: Add handler for "openat"

Arnaldo Carvalho de Melo
2019-07-30T02:56:58Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

I.e. for a syscall that has its second argument being a string, its
difficult these days to find 'open' being used in the wild :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-yf3kbzirqrukd3fb2sp5qx4p@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-trace.c | 1 +
.../perf/examples/bpf/augmented_raw_syscalls.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 872c9cc982a5..a681b8c2ee4e 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -836,6 +836,7 @@ static struct syscall_fmt {
.arg = { [0] = { .scnprintf = SCA_FDAT, /* dfd */ },
[2] = { .scnprintf = SCA_OPEN_FLAGS, /* flags */ }, }, },
{ .name = "openat",
+ .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_openat", },
.arg = { [0] = { .scnprintf = SCA_FDAT, /* dfd */ },
[2] = { .scnprintf = SCA_OPEN_FLAGS, /* flags */ }, }, },
{ .name = "perf_event_open",
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index c66474a6ccf4..661936f90fe0 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -131,6 +131,23 @@ int sys_enter_open(struct syscall_enter_args *args)
return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);
}

+SEC("!syscalls:sys_enter_openat")
+int sys_enter_openat(struct syscall_enter_args *args)
+{
+ int key = 0;
+ struct augmented_args_filename *augmented_args = bpf_map_lookup_elem(&augmented_filename_map, &key);
+ const void *filename_arg = (const void *)args->args[1];
+ unsigned int len = sizeof(augmented_args->args);
+
+ if (augmented_args == NULL)
+ return 1; /* Failure: don't filter */
+
+ len += augmented_filename__read(&augmented_args->filename, filename_arg, sizeof(augmented_args->filename.value));
+
+ /* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
+ return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);
+}
+
SEC("raw_syscalls:sys_enter")
int sys_enter(struct syscall_enter_args *args)
{
--
2.21.0