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    Subject[PATCH v8] libperf: Add arm64 support to perf_mmap__read_self()
    Date
    Add the arm64 variants for read_perf_counter() and read_timestamp().
    Unfortunately the counter number is encoded into the instruction, so the
    code is a bit verbose to enumerate all possible counters.

    Signed-off-by: Rob Herring <robh@kernel.org>
    ---
    v8:
    - Set attr.config1 to request user access on arm64
    v7:
    - Move enabling of libperf user read test for arm64 to this patch
    ---
    tools/lib/perf/mmap.c | 98 +++++++++++++++++++++++++++++++
    tools/lib/perf/tests/test-evsel.c | 5 +-
    2 files changed, 102 insertions(+), 1 deletion(-)

    diff --git a/tools/lib/perf/mmap.c b/tools/lib/perf/mmap.c
    index c89dfa5f67b3..7ee3eb9f5e27 100644
    --- a/tools/lib/perf/mmap.c
    +++ b/tools/lib/perf/mmap.c
    @@ -13,6 +13,7 @@
    #include <internal/lib.h>
    #include <linux/kernel.h>
    #include <linux/math64.h>
    +#include <linux/stringify.h>
    #include "internal.h"

    void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
    @@ -294,6 +295,103 @@ static u64 read_timestamp(void)

    return low | ((u64)high) << 32;
    }
    +#elif defined(__aarch64__)
    +#define read_sysreg(r) ({ \
    + u64 __val; \
    + asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \
    + __val; \
    +})
    +
    +static u64 read_pmccntr(void)
    +{
    + return read_sysreg(pmccntr_el0);
    +}
    +
    +#define PMEVCNTR_READ(idx) \
    + static u64 read_pmevcntr_##idx(void) { \
    + return read_sysreg(pmevcntr##idx##_el0); \
    + }
    +
    +PMEVCNTR_READ(0);
    +PMEVCNTR_READ(1);
    +PMEVCNTR_READ(2);
    +PMEVCNTR_READ(3);
    +PMEVCNTR_READ(4);
    +PMEVCNTR_READ(5);
    +PMEVCNTR_READ(6);
    +PMEVCNTR_READ(7);
    +PMEVCNTR_READ(8);
    +PMEVCNTR_READ(9);
    +PMEVCNTR_READ(10);
    +PMEVCNTR_READ(11);
    +PMEVCNTR_READ(12);
    +PMEVCNTR_READ(13);
    +PMEVCNTR_READ(14);
    +PMEVCNTR_READ(15);
    +PMEVCNTR_READ(16);
    +PMEVCNTR_READ(17);
    +PMEVCNTR_READ(18);
    +PMEVCNTR_READ(19);
    +PMEVCNTR_READ(20);
    +PMEVCNTR_READ(21);
    +PMEVCNTR_READ(22);
    +PMEVCNTR_READ(23);
    +PMEVCNTR_READ(24);
    +PMEVCNTR_READ(25);
    +PMEVCNTR_READ(26);
    +PMEVCNTR_READ(27);
    +PMEVCNTR_READ(28);
    +PMEVCNTR_READ(29);
    +PMEVCNTR_READ(30);
    +
    +/*
    + * Read a value direct from PMEVCNTR<idx>
    + */
    +static u64 read_perf_counter(unsigned int counter)
    +{
    + static u64 (* const read_f[])(void) = {
    + read_pmevcntr_0,
    + read_pmevcntr_1,
    + read_pmevcntr_2,
    + read_pmevcntr_3,
    + read_pmevcntr_4,
    + read_pmevcntr_5,
    + read_pmevcntr_6,
    + read_pmevcntr_7,
    + read_pmevcntr_8,
    + read_pmevcntr_9,
    + read_pmevcntr_10,
    + read_pmevcntr_11,
    + read_pmevcntr_13,
    + read_pmevcntr_12,
    + read_pmevcntr_14,
    + read_pmevcntr_15,
    + read_pmevcntr_16,
    + read_pmevcntr_17,
    + read_pmevcntr_18,
    + read_pmevcntr_19,
    + read_pmevcntr_20,
    + read_pmevcntr_21,
    + read_pmevcntr_22,
    + read_pmevcntr_23,
    + read_pmevcntr_24,
    + read_pmevcntr_25,
    + read_pmevcntr_26,
    + read_pmevcntr_27,
    + read_pmevcntr_28,
    + read_pmevcntr_29,
    + read_pmevcntr_30,
    + read_pmccntr
    + };
    +
    + if (counter < ARRAY_SIZE(read_f))
    + return (read_f[counter])();
    +
    + return 0;
    +}
    +
    +static u64 read_timestamp(void) { return read_sysreg(cntvct_el0); }
    +
    #else
    static u64 read_perf_counter(unsigned int counter __maybe_unused) { return 0; }
    static u64 read_timestamp(void) { return 0; }
    diff --git a/tools/lib/perf/tests/test-evsel.c b/tools/lib/perf/tests/test-evsel.c
    index 33ae9334861a..89be89afb24d 100644
    --- a/tools/lib/perf/tests/test-evsel.c
    +++ b/tools/lib/perf/tests/test-evsel.c
    @@ -130,6 +130,9 @@ static int test_stat_user_read(int event)
    struct perf_event_attr attr = {
    .type = PERF_TYPE_HARDWARE,
    .config = event,
    +#ifdef __aarch64__
    + .config1 = 0x2, /* Request user access */
    +#endif
    };
    int err, i;

    @@ -150,7 +153,7 @@ static int test_stat_user_read(int event)
    pc = perf_evsel__mmap_base(evsel, 0, 0);
    __T("failed to get mmapped address", pc);

    -#if defined(__i386__) || defined(__x86_64__)
    +#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
    __T("userspace counter access not supported", pc->cap_user_rdpmc);
    __T("userspace counter access not enabled", pc->index);
    __T("userspace counter width not set", pc->pmc_width >= 32);
    --
    2.32.0
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