[PATCH 07/28] perf augmented_syscalls: Use pid_filter

Arnaldo Carvalho de Melo
2018-11-22T03:36:49Z

Just to test filtering a bunch of pids, now its time to go and get that
hooked up in 'perf trace', right after we load the bpf program, if we
find a "pids_filtered" map defined, we'll populate it with the filtered
pids.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-1i9s27wqqdhafk3fappow84x@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/examples/bpf/augmented_raw_syscalls.c | 34 ++++++++++++++++++++++--
1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index 7d729319618c..5fed1eff889d 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -16,6 +16,7 @@

#include <stdio.h>
#include <unistd.h>
+#include <pid_filter.h>

/* bpf-output associated map */
struct bpf_map SEC("maps") __augmented_syscalls__ = {
@@ -48,6 +49,29 @@ struct augmented_filename {
#define SYS_POLL 7
#define SYS_OPENAT 257

+pid_filter(pids_filtered);
+
+static void pid_filter__init(void)
+{
+ /*
+ * Filter a bunch of pids: gnome-shell, kvm, firefox threads,
+ * avahi-daemon, etc, just for testing as we go along.
+ *
+ * These will come from 'perf trace --filter-pids' in a explicit way
+ * and also it will filter out itself, to avoid the feedback loop:
+ * syscalls 'perf trace' does gets caught, reported, causing new
+ * syscalls to get emitted, rinse repeat forever.
+ */
+ if (pid_filter__add(&pids_filtered, 2971))
+ return; /* pid_filter__init() was already called, bail out */
+ pid_filter__add(&pids_filtered, 20016);
+ pid_filter__add(&pids_filtered, 12018);
+ pid_filter__add(&pids_filtered, 2310);
+ pid_filter__add(&pids_filtered, 3759);
+ pid_filter__add(&pids_filtered, 25978);
+ pid_filter__add(&pids_filtered, 883);
+}
+
SEC("raw_syscalls:sys_enter")
int sys_enter(struct syscall_enter_args *args)
{
@@ -57,8 +81,14 @@ int sys_enter(struct syscall_enter_args *args)
} augmented_args;
unsigned int len = sizeof(augmented_args);
const void *filename_arg = NULL;
+ /*
+ * We still don't have a "main()" called first and only once
+ * call it always, it will exit as soon as it realizes the
+ * first hard coded filtered pid was already added.
+ */
+ pid_filter__init();

- if (getpid() == 2971)
+ if (pid_filter__has(&pids_filtered, getpid()))
return 0;

probe_read(&augmented_args.args, sizeof(augmented_args.args), args);
@@ -132,7 +162,7 @@ int sys_enter(struct syscall_enter_args *args)
SEC("raw_syscalls:sys_exit")
int sys_exit(struct syscall_exit_args *args)
{
- return getpid() != 2971;
+ return !pid_filter__has(&pids_filtered, getpid());
}

license(GPL);
--
2.14.5