[tip:perf/core] perf trace: Use the raw_syscalls:sys_enter for the augmented syscalls
From: tip-bot for Arnaldo Carvalho de Melo
Date: Thu Sep 06 2018 - 09:48:19 EST
Commit-ID: b1a9e2535e20cdd6cd14eec8128278bc5d97843c
Gitweb: https://git.kernel.org/tip/b1a9e2535e20cdd6cd14eec8128278bc5d97843c
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Mon, 3 Sep 2018 16:29:39 -0300
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 4 Sep 2018 16:51:12 -0300
perf trace: Use the raw_syscalls:sys_enter for the augmented syscalls
Now we combine what comes from the "bpf-output" event, i.e. what is
added in the augmented_syscalls.c BPF program via the
__augmented_syscalls__ BPF map, i.e. the payload we get with
raw_syscalls:sys_enter tracepoints plus the pointer contents, right
after that payload, with the raw_syscall:sys_exit also added, without
augmentation, in the augmented_syscalls.c program.
The end result is that for the hooked syscalls, we get strace like
output with pointer expansion, something that wasn't possible before
with just raw_syscalls:sys_enter + raw_syscalls:sys_exit.
E.g.:
# perf trace -e tools/perf/examples/bpf/augmented_syscalls.c ping -c 2 ::1
0.000 ( 0.008 ms): ping/19573 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
0.036 ( 0.006 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libcap.so.2, flags: CLOEXEC) = 3
0.070 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libidn.so.11, flags: CLOEXEC) = 3
0.095 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libcrypto.so.1.1, flags: CLOEXEC) = 3
0.127 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libresolv.so.2, flags: CLOEXEC) = 3
0.156 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libm.so.6, flags: CLOEXEC) = 3
0.181 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
0.212 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libz.so.1, flags: CLOEXEC) = 3
0.242 ( 0.004 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libdl.so.2, flags: CLOEXEC) = 3
0.266 ( 0.003 ms): ping/19573 openat(dfd: CWD, filename: /lib64/libpthread.so.0, flags: CLOEXEC) = 3
0.709 ( 0.006 ms): ping/19573 open(filename: /usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
PING ::1(::1) 56 data bytes
1.133 ( 0.011 ms): ping/19573 connect(fd: 5, uservaddr: { .family: INET6, port: 1025, addr: ::1 }, addrlen: 28) = 0
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.033 ms
1.234 ( 0.036 ms): ping/19573 sendto(fd: 4<socket:[1498931]>, buff: 0x555e5b975720, len: 64, addr: { .family: INET6, port: 58, addr: ::1 }, addr_len: 28) = 64
64 bytes from ::1: icmp_seq=2 ttl=64 time=0.120 ms
--- ::1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.033/0.076/0.120/0.044 ms
1002.060 ( 0.129 ms): ping/19573 sendto(fd: 4<socket:[1498931]>, buff: 0x555e5b975720, len: 64, flags: CONFIRM, addr: { .family: INET6, port: 58, addr: ::1 }, addr_len: 28) = 64
#
# perf trace -e tools/perf/examples/bpf/augmented_syscalls.c cat tools/perf/examples/bpf/hello.c
#include <stdio.h>
int syscall_enter(openat)(void *args)
{
puts("Hello, world\n");
return 0;
}
license(GPL);
0.000 ( 0.008 ms): cat/20054 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
0.020 ( 0.005 ms): cat/20054 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
0.176 ( 0.011 ms): cat/20054 open(filename: /usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
0.243 ( 0.006 ms): cat/20054 openat(dfd: CWD, filename: tools/perf/examples/bpf/hello.c) = 3
#
Now to think how to hook on all syscalls, fallbacking to the non-augmented
raw_syscalls:sys_enter payload.
Probably the best way is to use a BPF_MAP_TYPE_PROG_ARRAY just like
samples/bpf/tracex5_kern.c does.
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-nlt60y69o26xi59z5vtpdrj5@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-trace.c | 41 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 36 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 2b99a02355cf..7ce277d22a91 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -288,6 +288,13 @@ static int perf_evsel__init_augmented_syscall_tp_args(struct perf_evsel *evsel)
return __tp_field__init_ptr(&sc->args, sc->id.offset + sizeof(u64));
}
+static int perf_evsel__init_augmented_syscall_tp_ret(struct perf_evsel *evsel)
+{
+ struct syscall_tp *sc = evsel->priv;
+
+ return __tp_field__init_uint(&sc->ret, sizeof(u64), sc->id.offset + sizeof(u64), evsel->needs_swap);
+}
+
static int perf_evsel__init_raw_syscall_tp(struct perf_evsel *evsel, void *handler)
{
evsel->priv = malloc(sizeof(struct syscall_tp));
@@ -3346,12 +3353,8 @@ int cmd_trace(int argc, const char **argv)
goto out;
}
- if (evsel) {
- if (perf_evsel__init_augmented_syscall_tp(evsel) ||
- perf_evsel__init_augmented_syscall_tp_args(evsel))
- goto out;
+ if (evsel)
trace.syscalls.events.augmented = evsel;
- }
err = bpf__setup_stdout(trace.evlist);
if (err) {
@@ -3396,6 +3399,34 @@ int cmd_trace(int argc, const char **argv)
}
}
+ /*
+ * If we are augmenting syscalls, then combine what we put in the
+ * __augmented_syscalls__ BPF map with what is in the
+ * syscalls:sys_exit_FOO tracepoints, i.e. just like we do without BPF,
+ * combining raw_syscalls:sys_enter with raw_syscalls:sys_exit.
+ *
+ * We'll switch to look at two BPF maps, one for sys_enter and the
+ * other for sys_exit when we start augmenting the sys_exit paths with
+ * buffers that are being copied from kernel to userspace, think 'read'
+ * syscall.
+ */
+ if (trace.syscalls.events.augmented) {
+ evsel = trace.syscalls.events.augmented;
+
+ if (perf_evsel__init_augmented_syscall_tp(evsel) ||
+ perf_evsel__init_augmented_syscall_tp_args(evsel))
+ goto out;
+ evsel->handler = trace__sys_enter;
+
+ evlist__for_each_entry(trace.evlist, evsel) {
+ if (strstarts(perf_evsel__name(evsel), "syscalls:sys_exit_")) {
+ perf_evsel__init_augmented_syscall_tp(evsel);
+ perf_evsel__init_augmented_syscall_tp_ret(evsel);
+ evsel->handler = trace__sys_exit;
+ }
+ }
+ }
+
if ((argc >= 1) && (strcmp(argv[0], "record") == 0))
return trace__record(&trace, argc-1, &argv[1]);