Re: [PATCH v8] libperf: Add arm64 support to perf_mmap__read_self()

From: Masayoshi Mizuma
Date: Wed Jan 12 2022 - 13:00:56 EST

On Tue, Dec 14, 2021 at 03:56:30PM -0600, Rob Herring wrote:
> 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@xxxxxxxxxx>

This patch works well on the aarch64 machine, thanks!
Please feel free to add:
Tested-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>

the log of make tests:
```
# echo 1 > /proc/sys/kernel/perf_user_access
# make tests V=1
make -f /src/linux/tools/build/Makefile.build dir=. obj=libperf
make -C /src/linux/tools/lib/api/ O= libapi.a
make -f /src/linux/tools/build/Makefile.build dir=./fd obj=libapi
make -f /src/linux/tools/build/Makefile.build dir=./fs obj=libapi
make -f /src/linux/tools/build/Makefile.build dir=. obj=tests
make -f /src/linux/tools/build/Makefile.build dir=./tests obj=tests
running static:
- running tests/test-cpumap.c...OK
- running tests/test-threadmap.c...OK
- running tests/test-evlist.c...OK
- running tests/test-evsel.c...
loop = 65536, count = 328191
loop = 131072, count = 655878
loop = 262144, count = 1311204
loop = 524288, count = 2640123
loop = 1048576, count = 5243358
loop = 65536, count = 1290820
loop = 131072, count = 2509179
loop = 262144, count = 5011308
loop = 524288, count = 9999221
loop = 1048576, count = 20136809
OK
running dynamic:
- running tests/test-cpumap.c...OK
- running tests/test-threadmap.c...OK
- running tests/test-evlist.c...OK
- running tests/test-evsel.c...
loop = 65536, count = 328219
loop = 131072, count = 655856
loop = 262144, count = 1311199
loop = 524288, count = 2633704
loop = 1048576, count = 5243402
loop = 65536, count = 1303460
loop = 131072, count = 2513614
loop = 262144, count = 5020097
loop = 524288, count = 10043687
loop = 1048576, count = 20101337
OK
#
```

- Masa

> ---
> 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
>