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Subject[PATCH 07/77] perf trace: Augment the 'open' syscall 'filename' arg
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

As described in the previous cset, all we had to do was to touch the
augmented_syscalls.c eBPF program, fire up 'perf trace' with that new
eBPF script in system wide mode and wait for 'open' syscalls, in
addition to 'openat' ones to see that it works:

# perf trace -e tools/perf/examples/bpf/augmented_syscalls.c
0.000 StreamT~s #200/16150 openat(dfd: CWD, filename: /home/acme/.mozilla/firefox/fqxhj76d.default/prefs.js, flags: CREAT|EXCL|TRUNC|WRONLY, mode: IRUSR|IWUSR)
0.065 StreamT~s #200/16150 openat(dfd: CWD, filename: /home/acme/.mozilla/firefox/fqxhj76d.default/prefs-1.js, flags: CREAT|EXCL|TRUNC|WRONLY, mode: IRUSR|IWUSR)
0.435 StreamT~s #200/16150 openat(dfd: CWD, filename: /home/acme/.mozilla/firefox/fqxhj76d.default/prefs-1.js, flags: CREAT|TRUNC|WRONLY, mode: IRUSR|IWUSR)
1.875 perf/16772 openat(dfd: CWD, filename: /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat/form)
1227.260 gnome-shell/1463 openat(dfd: CWD, filename: /proc/self/stat)
1227.397 gnome-shell/2125 openat(dfd: CWD, filename: /proc/self/stat)
7227.619 gnome-shell/1463 openat(dfd: CWD, filename: /proc/self/stat)
7227.661 gnome-shell/2125 openat(dfd: CWD, filename: /proc/self/stat)
10018.079 gnome-shell/1463 openat(dfd: CWD, filename: /proc/self/stat)
10018.514 perf/16772 openat(dfd: CWD, filename: /proc/1237/status)
10018.568 perf/16772 openat(dfd: CWD, filename: /proc/1237/status)
10022.409 gnome-shell/2125 openat(dfd: CWD, filename: /proc/self/stat)
10090.044 NetworkManager/1237 openat(dfd: CWD, filename: /proc/2125/stat)
10090.351 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
10090.407 perf/16772 openat(dfd: CWD, filename: /sys/kernel/debug/tracing/events/syscalls/sys_enter_open/format)
10091.763 NetworkManager/1237 openat(dfd: CWD, filename: /proc/2125/stat)
10091.812 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
10092.807 NetworkManager/1237 openat(dfd: CWD, filename: /proc/2125/stat)
10092.851 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
10094.650 NetworkManager/1237 openat(dfd: CWD, filename: /proc/1463/stat)
10094.926 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
10096.010 NetworkManager/1237 openat(dfd: CWD, filename: /proc/1463/stat)
10096.057 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
10097.056 NetworkManager/1237 openat(dfd: CWD, filename: /proc/1463/stat)
10097.099 NetworkManager/1237 open(filename: /etc/passwd, flags: CLOEXEC)
13228.345 gnome-shell/1463 openat(dfd: CWD, filename: /proc/self/stat)
13232.734 gnome-shell/2125 openat(dfd: CWD, filename: /proc/self/stat)
15198.956 lighttpd/16748 open(filename: /proc/loadavg, mode: ISGID|IXOTH)
^C#

It even catches 'perf' itself looking at the sys_enter_open and
sys_enter_openat tracefs format dictionaries when it first finds them in
the trace... :-)

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-upmogc57uatljr6el6u8537l@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/examples/bpf/augmented_syscalls.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/tools/perf/examples/bpf/augmented_syscalls.c b/tools/perf/examples/bpf/augmented_syscalls.c
index 93960e891478..154379463c95 100644
--- a/tools/perf/examples/bpf/augmented_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_syscalls.c
@@ -61,4 +61,31 @@ int syscall_enter(openat)(struct syscall_enter_openat_args *args)
return 0;
}

+struct syscall_enter_open_args {
+ unsigned long long common_tp_fields;
+ long syscall_nr;
+ char *filename_ptr;
+ long flags;
+ long mode;
+};
+
+struct augmented_enter_open_args {
+ struct syscall_enter_open_args args;
+ struct augmented_filename filename;
+};
+
+int syscall_enter(open)(struct syscall_enter_open_args *args)
+{
+ struct augmented_enter_open_args augmented_args = { .filename.reserved = 0, };
+
+ probe_read(&augmented_args.args, sizeof(augmented_args.args), args);
+ augmented_args.filename.size = probe_read_str(&augmented_args.filename.value,
+ sizeof(augmented_args.filename.value),
+ args->filename_ptr);
+ perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU,
+ &augmented_args,
+ sizeof(augmented_args) - sizeof(augmented_args.filename.value) + augmented_args.filename.size);
+ return 0;
+}
+
license(GPL);
--
2.14.4
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