Re: [PATCH v11 perf, bpf-next 7/9] perf tools: synthesize PERF_RECORD_* for loaded BPF programs

From: Arnaldo Carvalho de Melo
Date: Tue Jan 22 2019 - 09:13:26 EST


Em Fri, Jan 18, 2019 at 11:46:55AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Jan 17, 2019 at 08:15:19AM -0800, Song Liu escreveu:
> > This patch synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for
> > BPF programs loaded before perf-record. This is achieved by gathering
> > information about all BPF programs via sys_bpf.
>
> Ditto

This is breaking 'perf sched', see below, the fix seems trivial:

[root@quaco ~]# perf sched record -a sleep 2
[ perf record: Woken up 1 times to write data ]
0x5b60 [0x138]: failed to process type: 17
[ perf record: Captured and wrote 1.539 MB perf.data ]
[root@quaco ~]# perf sched lat
0x5b60 [0x138]: failed to process type: 17
Failed to process events, error -22
[root@quaco ~]#

[acme@quaco perf]$ git bisect good
7b612e291a5affb12b9d0b87332c71bcbe9c5db4 is the first bad commit
commit 7b612e291a5affb12b9d0b87332c71bcbe9c5db4
Author: Song Liu <songliubraving@xxxxxx>
Date: Thu Jan 17 08:15:19 2019 -0800

perf tools: Synthesize PERF_RECORD_* for loaded BPF programs

This patch synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for
BPF programs loaded before perf-record. This is achieved by gathering
information about all BPF programs via sys_bpf.

Committer notes:

Fix the build on some older systems such as amazonlinux:1 where it was
breaking with:

util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
util/bpf-event.c:52:9: error: missing initializer for field 'type' of 'struct bpf_prog_info' [-Werror=missing-field-initializers]
struct bpf_prog_info info = {};
^
In file included from /git/linux/tools/lib/bpf/bpf.h:26:0,
from util/bpf-event.c:3:
/git/linux/tools/include/uapi/linux/bpf.h:2699:8: note: 'type' declared here
__u32 type;
^
cc1: all warnings being treated as errors

Further fix on a centos:6 system:

cc1: warnings being treated as errors
util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
util/bpf-event.c:50: error: 'func_info_rec_size' may be used uninitialized in this function

The compiler is wrong, but to silence it, initialize that variable to
zero.

One more fix, this time for debian:experimental-x-mips, x-mips64 and
x-mipsel:

util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
util/bpf-event.c:93:16: error: implicit declaration of function 'calloc' [-Werror=implicit-function-declaration]
func_infos = calloc(sub_prog_cnt, func_info_rec_size);
^~~~~~
util/bpf-event.c:93:16: error: incompatible implicit declaration of built-in function 'calloc' [-Werror]
util/bpf-event.c:93:16: note: include '<stdlib.h>' or provide a declaration of 'calloc'

Add the missing header.

Committer testing:

# perf record --bpf-event sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.021 MB perf.data (7 samples) ]
# perf report -D | grep PERF_RECORD_BPF_EVENT | nl
1 0 0x4b10 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 13
2 0 0x4c60 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 14
3 0 0x4db0 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 15
4 0 0x4f00 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 16
5 0 0x5050 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 17
6 0 0x51a0 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 18
7 0 0x52f0 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 21
8 0 0x5440 [0x18]: PERF_RECORD_BPF_EVENT bpf event with type 1, flags 0, id 22
# bpftool prog
13: cgroup_skb tag 7be49e3934a125ba gpl
loaded_at 2019-01-19T09:09:43-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 13,14
14: cgroup_skb tag 2a142ef67aaad174 gpl
loaded_at 2019-01-19T09:09:43-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 13,14
15: cgroup_skb tag 7be49e3934a125ba gpl
loaded_at 2019-01-19T09:09:43-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 15,16
16: cgroup_skb tag 2a142ef67aaad174 gpl
loaded_at 2019-01-19T09:09:43-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 15,16
17: cgroup_skb tag 7be49e3934a125ba gpl
loaded_at 2019-01-19T09:09:44-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 17,18
18: cgroup_skb tag 2a142ef67aaad174 gpl
loaded_at 2019-01-19T09:09:44-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 17,18
21: cgroup_skb tag 7be49e3934a125ba gpl
loaded_at 2019-01-19T09:09:45-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 21,22
22: cgroup_skb tag 2a142ef67aaad174 gpl
loaded_at 2019-01-19T09:09:45-0300 uid 0
xlated 296B jited 229B memlock 4096B map_ids 21,22
#

# perf report -D | grep -B22 PERF_RECORD_KSYMBOL
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 ff 44 06 c0 ff ff ff ff ......8..D......
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 37 62 65 34 39 65 33 39 33 34 61 31 32 35 62 _7be49e3934a125b
. 0030: 61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 7b e4 9e 39 34 a1 25 ba 00 00 00 00 00 00 00 00 {..94.%.........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x49d8 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc00644ff len 229 type 1 flags 0x0 name bpf_prog_7be49e3934a125ba
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 48 6d 06 c0 ff ff ff ff ......8.Hm......
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 32 61 31 34 32 65 66 36 37 61 61 61 64 31 37 _2a142ef67aaad17
. 0030: 34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 2a 14 2e f6 7a aa d1 74 00 00 00 00 00 00 00 00 *...z..t........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x4b28 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0066d48 len 229 type 1 flags 0x0 name bpf_prog_2a142ef67aaad174
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 04 cf 03 c0 ff ff ff ff ......8.........
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 37 62 65 34 39 65 33 39 33 34 61 31 32 35 62 _7be49e3934a125b
. 0030: 61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 7b e4 9e 39 34 a1 25 ba 00 00 00 00 00 00 00 00 {..94.%.........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x4c78 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc003cf04 len 229 type 1 flags 0x0 name bpf_prog_7be49e3934a125ba
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 96 28 04 c0 ff ff ff ff ......8..(......
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 32 61 31 34 32 65 66 36 37 61 61 61 64 31 37 _2a142ef67aaad17
. 0030: 34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 2a 14 2e f6 7a aa d1 74 00 00 00 00 00 00 00 00 *...z..t........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x4dc8 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0042896 len 229 type 1 flags 0x0 name bpf_prog_2a142ef67aaad174
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 05 13 17 c0 ff ff ff ff ......8.........
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 37 62 65 34 39 65 33 39 33 34 61 31 32 35 62 _7be49e3934a125b
. 0030: 61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 7b e4 9e 39 34 a1 25 ba 00 00 00 00 00 00 00 00 {..94.%.........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x4f18 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0171305 len 229 type 1 flags 0x0 name bpf_prog_7be49e3934a125ba
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 0a 8c 23 c0 ff ff ff ff ......8...#.....
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 32 61 31 34 32 65 66 36 37 61 61 61 64 31 37 _2a142ef67aaad17
. 0030: 34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 2a 14 2e f6 7a aa d1 74 00 00 00 00 00 00 00 00 *...z..t........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x5068 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0238c0a len 229 type 1 flags 0x0 name bpf_prog_2a142ef67aaad174
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 2a a5 a4 c0 ff ff ff ff ......8.*.......
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 37 62 65 34 39 65 33 39 33 34 61 31 32 35 62 _7be49e3934a125b
. 0030: 61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 7b e4 9e 39 34 a1 25 ba 00 00 00 00 00 00 00 00 {..94.%.........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x51b8 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0a4a52a len 229 type 1 flags 0x0 name bpf_prog_7be49e3934a125ba
--
. ... raw event: size 312 bytes
. 0000: 11 00 00 00 00 00 38 01 9b c9 a4 c0 ff ff ff ff ......8.........
. 0010: e5 00 00 00 01 00 00 00 62 70 66 5f 70 72 6f 67 ........bpf_prog
. 0020: 5f 32 61 31 34 32 65 66 36 37 61 61 61 64 31 37 _2a142ef67aaad17
. 0030: 34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4...............
<SNIP zeroes>
. 0110: 00 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
. 0120: 2a 14 2e f6 7a aa d1 74 00 00 00 00 00 00 00 00 *...z..t........
. 0130: 00 00 00 00 00 00 00 00 ........

0 0x5308 [0x138]: PERF_RECORD_KSYMBOL ksymbol event with addr ffffffffc0a4c99b len 229 type 1 flags 0x0 name bpf_prog_2a142ef67aaad174

Signed-off-by: Song Liu <songliubraving@xxxxxx>
Reviewed-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: kernel-team@xxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190117161521.1341602-8-songliubraving@xxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

:040000 040000 811377248529490fc3977be729bd1ac6ab515920 3f1cc9a3e8c92d0d5a23a21c33286b7cdf758534 M tools
[acme@quaco perf]$