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Date: Wed, 29 May 2019 17:12:48 +0300
From: Alexey Budankov <alexey.budankov@...ux.intel.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Andi Kleen <ak@...ux.intel.com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: perf record: collect user registers set jointly with dwarf stacks
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 -- stack_test2.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. IP and SP registers (dwarf_regs)
are collected anyways regardless of the --user-regs option value provided
from the command line:
-g call-graph dwarf,K full_regs
-g call-graph dwarf,K --user-regs=user_regs user_regs + dwarf_regs
--user-regs=user_regs user_regs
$ perf record -g --call-graph dwarf,1024 --user-regs=BP -- ls
WARNING: specified --user-regs register set doesn't include registers needed by also specified --call-graph=dwarf, auto adding IP, SP registers.
arch COPYING Documentation include Kbuild lbuild MAINTAINERS modules.builtin Module.symvers perf.data.old scripts System.map virt
block CREDITS drivers init Kconfig lib Makefile modules.builtin.modinfo net README security tools vmlinux
certs crypto fs ipc kernel LICENSES mm modules.order perf.data samples sound usr vmlinux.o
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]
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
Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
---
tools/perf/util/evsel.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index a6f572a40deb..426dfefeecda 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -669,6 +669,9 @@ int perf_evsel__group_desc(struct perf_evsel *evsel, char *buf, size_t size)
return ret;
}
+#define DWARF_REGS_MASK ((1ULL << PERF_REG_IP) | \
+ (1ULL << PERF_REG_SP))
+
static void __perf_evsel__config_callchain(struct perf_evsel *evsel,
struct record_opts *opts,
struct callchain_param *param)
@@ -702,7 +705,13 @@ 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 |= DWARF_REGS_MASK;
+ pr_warning("WARNING: specified --user-regs register set doesn't include registers "
+ "needed by also specified --call-graph=dwarf, auto adding IP, SP registers.\n");
+ } else {
+ 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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