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Subject[tip:perf/core] perf regs x86: Add X86 specific arch__intr_reg_mask()
Commit-ID:  6466ec14aaf44ff14a05369dcf0929d0f01171c6
Gitweb: https://git.kernel.org/tip/6466ec14aaf44ff14a05369dcf0929d0f01171c6
Author: Kan Liang <kan.liang@linux.intel.com>
AuthorDate: Tue, 14 May 2019 13:19:34 -0700
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 16 May 2019 14:17:23 -0300

perf regs x86: Add X86 specific arch__intr_reg_mask()

XMM registers can be collected on Icelake and later platforms.

Add specific arch__intr_reg_mask(), which creating an event to check if
the kernel and hardware can collect XMM registers.

Test on Skylake which doesn't support XMM registers collection. There is
nothing changed.

#perf record -I?
available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9
R10 R11 R12 R13 R14 R15

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

#perf record -I
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.905 MB perf.data (2520 samples) ]

#perf evlist -v
cycles: size: 112, { sample_period, sample_freq }: 4000, sample_type:
IP|TID|TIME|CPU|PERIOD|REGS_INTR, read_format: ID, disabled: 1,
inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3,
sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol:
1, bpf_event: 1, sample_regs_intr: 0xff0fff

Test on Icelake which support XMM registers collection.

#perf record -I?
available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9 R10
R11 R12 R13 R14 R15 XMM0 XMM1 XMM2 XMM3 XMM4 XMM5 XMM6 XMM7 XMM8 XMM9
XMM10 XMM11 XMM12 XMM13 XMM14 XMM15

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

#perf record -I
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.800 MB perf.data (318 samples) ]

#perf evlist -v
cycles: size: 112, { sample_period, sample_freq }: 4000, sample_type:
IP|TID|TIME|CPU|PERIOD|REGS_INTR, read_format: ID, disabled: 1,
inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3,
sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol:
1, bpf_event: 1, sample_regs_intr: 0xffffffff00ff0fff

Committer notes:

Don't set attr.sample_period as a named struct init, as it is part of an
unnamed union in 'struct perf_event_attr', and doing so breaks the build
on older gcc versions, such as:

gcc version 4.1.2 20080704 (Red Hat 4.1.2-55)
gcc version 4.4.7 20120313 (Red Hat 4.4.7-23) (GCC)

arch/x86/util/perf_regs.c: In function 'arch__intr_reg_mask':
arch/x86/util/perf_regs.c:279: error: unknown field 'sample_period' specified in initializer
cc1: warnings being treated as errors
arch/x86/util/perf_regs.c:279: warning: missing braces around initializer
arch/x86/util/perf_regs.c:279: warning: (near initialization for 'attr.<anonymous>')

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
[ Only on a lenovo t480s, a skylake machine, where the XMM registers didn't show up in -I?/--user-regs=? as expected ]
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1557865174-56264-3-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/arch/x86/include/perf_regs.h | 1 +
tools/perf/arch/x86/util/perf_regs.c | 28 ++++++++++++++++++++++++++++
2 files changed, 29 insertions(+)

diff --git a/tools/perf/arch/x86/include/perf_regs.h b/tools/perf/arch/x86/include/perf_regs.h
index b7321337d100..b7cd91a9014f 100644
--- a/tools/perf/arch/x86/include/perf_regs.h
+++ b/tools/perf/arch/x86/include/perf_regs.h
@@ -9,6 +9,7 @@
void perf_regs_load(u64 *regs);

#define PERF_REGS_MAX PERF_REG_X86_XMM_MAX
+#define PERF_XMM_REGS_MASK (~((1ULL << PERF_REG_X86_XMM0) - 1))
#ifndef HAVE_ARCH_X86_64_SUPPORT
#define PERF_REGS_MASK ((1ULL << PERF_REG_X86_32_MAX) - 1)
#define PERF_SAMPLE_REGS_ABI PERF_SAMPLE_REGS_ABI_32
diff --git a/tools/perf/arch/x86/util/perf_regs.c b/tools/perf/arch/x86/util/perf_regs.c
index 71d7604dbf0b..7886ca5263e3 100644
--- a/tools/perf/arch/x86/util/perf_regs.c
+++ b/tools/perf/arch/x86/util/perf_regs.c
@@ -270,3 +270,31 @@ int arch_sdt_arg_parse_op(char *old_op, char **new_op)

return SDT_ARG_VALID;
}
+
+uint64_t arch__intr_reg_mask(void)
+{
+ struct perf_event_attr attr = {
+ .type = PERF_TYPE_HARDWARE,
+ .config = PERF_COUNT_HW_CPU_CYCLES,
+ .sample_type = PERF_SAMPLE_REGS_INTR,
+ .sample_regs_intr = PERF_XMM_REGS_MASK,
+ .precise_ip = 1,
+ .disabled = 1,
+ .exclude_kernel = 1,
+ };
+ int fd;
+ /*
+ * In an unnamed union, init it here to build on older gcc versions
+ */
+ attr.sample_period = 1;
+
+ event_attr_init(&attr);
+
+ fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
+ if (fd != -1) {
+ close(fd);
+ return (PERF_XMM_REGS_MASK | PERF_REGS_MASK);
+ }
+
+ return PERF_REGS_MASK;
+}
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