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SubjectRe: [PATCH v1] perf record: collect user registers set jointly with dwarf stacks
On Mon, Apr 15, 2019 at 06:36:13PM +0300, Alexey Budankov wrote:
>
> When dwarf stacks are collected jointly with user specified register
> set using --user-regs option like below the full register context is
> still captured on a sample:
>
> $ perf record -g --call-graph dwarf,1024 --user-regs=IP,SP,BP -- matrix.gcc.g.O3
>
> 188143843893585 0x6b48 [0x4f8]: PERF_RECORD_SAMPLE(IP, 0x4002): 23828/23828: 0x401236 period: 1363819 addr: 0x7ffedbdd51ac
> ... FP chain: nr:0
> ... user regs: mask 0xff0fff ABI 64-bit
> .... AX 0x53b
> .... BX 0x7ffedbdd3cc0
> .... CX 0xffffffff
> .... DX 0x33d3a
> .... SI 0x7f09b74c38d0
> .... DI 0x0
> .... BP 0x401260
> .... SP 0x7ffedbdd3cc0
> .... IP 0x401236
> .... FLAGS 0x20a
> .... CS 0x33
> .... SS 0x2b
> .... R8 0x7f09b74c3800
> .... R9 0x7f09b74c2da0
> .... R10 0xfffffffffffff3ce
> .... R11 0x246
> .... R12 0x401070
> .... R13 0x7ffedbdd5db0
> .... R14 0x0
> .... R15 0x0
> ... ustack: size 1024, offset 0xe0
> . data_src: 0x5080021
> ... thread: stack_test2.g.O:23828
> ...... dso: /root/abudanko/stacks/stack_test2.g.O3
>
> After applying the change suggested in the patch the sample data contain
> only user specified register values:
>
> $ perf record -g --call-graph dwarf,1024 --user-regs=IP,SP,BP -- matrix.gcc.g.03
>
> 188368474305373 0x5e40 [0x470]: PERF_RECORD_SAMPLE(IP, 0x4002): 23839/23839: 0x401236 period: 1260507 addr: 0x7ffd3d85e96c
> ... FP chain: nr:0
> ... user regs: mask 0x1c0 ABI 64-bit
> .... BP 0x401260
> .... SP 0x7ffd3d85cc20
> .... IP 0x401236
> ... ustack: size 1024, offset 0x58
> . data_src: 0x5080021
> ... thread: stack_test2.g.O:23839
> ...... dso: /root/abudanko/stacks/stack_test2.g.O3
>
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
> tools/perf/util/evsel.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 84cfb9fe2fc6..29a223b4c699 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -702,7 +702,8 @@ static void __perf_evsel__config_callchain(struct perf_evsel *evsel,
> if (!function) {
> perf_evsel__set_sample_bit(evsel, REGS_USER);
> perf_evsel__set_sample_bit(evsel, STACK_USER);
> - attr->sample_regs_user |= PERF_REGS_MASK;
> + if (!opts->sample_user_regs)
> + attr->sample_regs_user |= PERF_REGS_MASK;
> attr->sample_stack_user = param->dump_size;
> attr->exclude_callchain_user = 1;
> } else {
> --
> 2.20.1
>

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