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perf augmented_syscalls: Use pid_filter

tip:perf/core tip-bot for Arnaldo Carvalho de Melo 1 participant 1 message Nov 22, 2018 perf events

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Commit-ID:  ed9a77ba7703f7da8f106d241cd0c734f8664b4d
Gitweb:     https://git.kernel.org/tip/ed9a77ba7703f7da8f106d241cd0c734f8664b4d
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Tue, 6 Nov 2018 16:09:06 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 21 Nov 2018 12:00:31 -0300

perf augmented_syscalls: Use pid_filter

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 <[email protected]>
Cc David Ahern <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Wang Nan <[email protected]>
Link https://lkml.kernel.org/n/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/examples/bpf/augmented_raw_syscalls.c | 34 ++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)
tools/perf/examples/bpf/augmented_raw_syscalls.c +32 -2
index 7d729319618c..5fed1eff889d 100644
@@ -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);