Commit 6466ec14 authored May 14, 2019 by Kan Liang Committed by Arnaldo Carvalho de Melo May 16, 2019

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>

parent af785e75

tools/perf/arch/x86/include/perf_regs.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

tools/perf/arch/x86/util/perf_regs.c

+28 −0

Original line number	Diff line number	Diff line
		@@ -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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