[PATCH 12/91] perf script: Remove extraneous newline in perf_sample__fprintf_regs()

Arnaldo Carvalho de Melo
2020-05-06T15:23:35Z

From: Stephane Eranian <eranian@google.com>

When printing iregs, there was a double newline printed because
perf_sample__fprintf_regs() was printing its own and then at the end of
all fields, perf script was adding one. This was causing blank line in
the output:

Before:

$ perf script -Fip,iregs
401b8d ABI:2 DX:0x100 SI:0x4a8340 DI:0x4a9340

401b8d ABI:2 DX:0x100 SI:0x4a9340 DI:0x4a8340

401b8d ABI:2 DX:0x100 SI:0x4a8340 DI:0x4a9340

401b8d ABI:2 DX:0x100 SI:0x4a9340 DI:0x4a8340

After:

$ perf script -Fip,iregs
401b8d ABI:2 DX:0x100 SI:0x4a8340 DI:0x4a9340
401b8d ABI:2 DX:0x100 SI:0x4a9340 DI:0x4a8340
401b8d ABI:2 DX:0x100 SI:0x4a8340 DI:0x4a9340

Committer testing:

First we need to figure out how to request that registers be recorded,
so we use:

# perf record -h reg

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-I, --intr-regs[=<any register>]
sample selected machine registers on interrupt, use '-I?' to list register names
--buildid-all Record build-id of all DSOs regardless of hits
--user-regs[=<any register>]
sample selected machine registers on interrupt, use '--user-regs=?' to list register names

#

Ok, now lets ask for them all:

# perf record -a --intr-regs --user-regs sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 4.105 MB perf.data (2760 samples) ]
#

Lets look at the first 6 output lines:

# perf script -Fip,iregs | head -6
ffffffff8a06f2f4 ABI:2 AX:0xffffd168fee0a980 BX:0xffff8a23b087f000 CX:0xfffeb69aaeb25d73 DX:0xffff8a253e8310f0 SI:0xfffffff9bafe7359 DI:0xffffb1690204fb10 BP:0xffffd168fee0a950 SP:0xffffb1690204fb88 IP:0xffffffff8a06f2f4 FLAGS:0x4e CS:0x10 SS:0x18 R8:0x1495f0a91129a R9:0xffff8a23b087f000 R10:0x1 R11:0xffffffff R12:0x0 R13:0xffff8a253e827e00 R14:0xffffd168fee0aa5c R15:0xffffd168fee0a980

ffffffff8a06f2f4 ABI:2 AX:0x0 BX:0xffffd168fee0a950 CX:0x5684cc1118491900 DX:0x0 SI:0xffffd168fee0a9d0 DI:0x202 BP:0xffffb1690204fd70 SP:0xffffb1690204fd20 IP:0xffffffff8a06f2f4 FLAGS:0x24e CS:0x10 SS:0x18 R8:0x0 R9:0xffffd168fee0a9d0 R10:0x1 R11:0xffffffff R12:0xffffffff8a23e480 R13:0xffff8a23b087f240 R14:0xffff8a23b087f000 R15:0xffffd168fee0a950

ffffffff8a06f2f4 ABI:2 AX:0x0 BX:0x0 CX:0x7f25f334335b DX:0x0 SI:0x2400 DI:0x4 BP:0x7fff5f264570 SP:0x7fff5f264538 IP:0xffffffff8a06f2f4 FLAGS:0x24e CS:0x10 SS:0x2b R8:0x0 R9:0x2312d20 R10:0x0 R11:0x246 R12:0x22cc0e0 R13:0x0 R14:0x0 R15:0x22d0780

#

Reproduced, apply the patch and:

[root@five ~]# perf script -Fip,iregs | head -6
ffffffff8a06f2f4 ABI:2 AX:0xffffd168fee0a980 BX:0xffff8a23b087f000 CX:0xfffeb69aaeb25d73 DX:0xffff8a253e8310f0 SI:0xfffffff9bafe7359 DI:0xffffb1690204fb10 BP:0xffffd168fee0a950 SP:0xffffb1690204fb88 IP:0xffffffff8a06f2f4 FLAGS:0x4e CS:0x10 SS:0x18 R8:0x1495f0a91129a R9:0xffff8a23b087f000 R10:0x1 R11:0xffffffff R12:0x0 R13:0xffff8a253e827e00 R14:0xffffd168fee0aa5c R15:0xffffd168fee0a980
ffffffff8a06f2f4 ABI:2 AX:0x0 BX:0xffffd168fee0a950 CX:0x5684cc1118491900 DX:0x0 SI:0xffffd168fee0a9d0 DI:0x202 BP:0xffffb1690204fd70 SP:0xffffb1690204fd20 IP:0xffffffff8a06f2f4 FLAGS:0x24e CS:0x10 SS:0x18 R8:0x0 R9:0xffffd168fee0a9d0 R10:0x1 R11:0xffffffff R12:0xffffffff8a23e480 R13:0xffff8a23b087f240 R14:0xffff8a23b087f000 R15:0xffffd168fee0a950
ffffffff8a06f2f4 ABI:2 AX:0x0 BX:0x0 CX:0x7f25f334335b DX:0x0 SI:0x2400 DI:0x4 BP:0x7fff5f264570 SP:0x7fff5f264538 IP:0xffffffff8a06f2f4 FLAGS:0x24e CS:0x10 SS:0x2b R8:0x0 R9:0x2312d20 R10:0x0 R11:0x246 R12:0x22cc0e0 R13:0x0 R14:0x0 R15:0x22d0780
ffffffff8a24074b ABI:2 AX:0xcb BX:0xcb CX:0x0 DX:0x0 SI:0xffffb1690204ff58 DI:0xcb BP:0xffffb1690204ff58 SP:0xffffb1690204ff40 IP:0xffffffff8a24074b FLAGS:0x24e CS:0x10 SS:0x18 R8:0x0 R9:0x0 R10:0x0 R11:0x0 R12:0x0 R13:0x0 R14:0x0 R15:0x0
ffffffff8a310600 ABI:2 AX:0x0 BX:0xffffffff8b8c39a0 CX:0x0 DX:0xffff8a2503890300 SI:0xffffb1690204ff20 DI:0xffff8a23e4080000 BP:0xffff8a23e4080000 SP:0xffffb1690204fec0 IP:0xffffffff8a310600 FLAGS:0x28e CS:0x10 SS:0x18 R8:0x0 R9:0x0 R10:0x0 R11:0x0 R12:0xffffffffffffffea R13:0xffff8a23e4080020 R14:0x0 R15:0x0
ffffffff8a11b688 ABI:2 AX:0x0 BX:0xffff8a237b7c8800 CX:0xffffb1690204fae0 DX:0x78 SI:0xffff8a237b7c8800 DI:0xffffb1690204fa10 BP:0xffffb1690204fb00 SP:0xffffb1690204fa00 IP:0xffffffff8a11b688 FLAGS:0x8a CS:0x10 SS:0x18 R8:0x1495f0a917eba R9:0xffffd168fde19a48 R10:0xffffb1690204fd98 R11:0xffff8a253e82afb0 R12:0xffff8a237b7c8800 R13:0xffffb1690204fb00 R14:0x0 R15:0xffff8a237b7c8800
[root@five ~]#

To see it more clearly, lets get just two of those registers by sample:

# perf record -a --intr-regs=ax,bx --user-regs=cx,dx sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 3.502 MB perf.data (1653 samples) ]
#

Extra info, lets see what gets setup in that 'struct perf_event_attr':

# perf evlist -v
cycles: size: 120, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|REGS_USER|REGS_INTR, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 2, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, sample_regs_user: 0xc, sample_regs_intr: 0x3
#

Cook, some PERF_SAMPLE_REGS_USER|PERF_SAMPLE_REGS_INTR +
attr.sample_regs_user and attr.sample_regs_intr register masks, now lets
see if those newlines are gone in a more compact fashion:

# perf script -Fip,iregs,uregs
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a29b78d ABI:2 AX:0x2a20ffcd6000 BX:0x2ec7d9000 ABI:2 CX:0x7f204460e49b DX:0xf42920
#

And where was that?

# perf script -Fip,iregs,uregs,sym,dso
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a56df78 strrchr (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0xffff8a25137b6028 BX:0xffff8a2502f18000 ABI:2 CX:0x7f204460e49b DX:0xf42920
ffffffff8a29b78d __vma_link_rb (/lib/modules/5.7.0-rc2/build/vmlinux) ABI:2 AX:0x2a20ffcd6000 BX:0x2ec7d9000 ABI:2 CX:0x7f204460e49b DX:0xf42920
#

Signed-off-by: Stephane Eranian <eranian@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200418231908.152212-1-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index a2236542900d..3aadefd2791e 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -604,8 +604,6 @@ static int perf_sample__fprintf_regs(struct regs_dump *regs, uint64_t mask,
printed += fprintf(fp, "%5s:0x%"PRIx64" ", perf_reg_name(r), val);
}

- fprintf(fp, "\n");
-
return printed;
}

--
2.21.1