On Wed, Aug 02, 2023 at 10:03:27AM +0200, Alexandre Ghiti wrote:
> riscv now supports mmaping hardware counters so add what's needed to
> take advantage of that in libperf.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>
> ---
> tools/lib/perf/mmap.c | 66 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 66 insertions(+)
>
> diff --git a/tools/lib/perf/mmap.c b/tools/lib/perf/mmap.c
> index 0d1634cedf44..2184814b37dd 100644
> --- a/tools/lib/perf/mmap.c
> +++ b/tools/lib/perf/mmap.c
> @@ -392,6 +392,72 @@ static u64 read_perf_counter(unsigned int counter)
>
> static u64 read_timestamp(void) { return read_sysreg(cntvct_el0); }
>
> +/* __riscv_xlen contains the witdh of the native base integer, here 64-bit */
> +#elif defined(__riscv) && __riscv_xlen == 64
> +
> +/* TODO: implement rv32 support */
It'd be easy to implement the rv32 support now (even if it's premature for
use), in order to avoid the TODO (which will likely be forgotten). I think
we just need to drop the __riscv_xlen == 64 above and then extend the
csr_read() macro something like the untested code below. (I'm not sure if
a TODO or premature, likely untested, code is worse though.)
> +
> +#define CSR_CYCLE 0xc00
> +#define CSR_TIME 0xc01
> +
> +#define csr_read(csr) \
> +({ \
u64 __value;
> + register unsigned long __v; \
> + __asm__ __volatile__ ("csrr %0, %1" \
> + : "=r" (__v) \
> + : "i" (csr) : ); \
__value = __v;
#if __riscv_xlen == 32
{
int csrh = (csr) - CSR_CYCLE + CSR_CYCLEH;
__asm__ __volatile__ ("csrr %0, %1" : "=r" (__v) : "i" (csrh));
__value |= (u64)__v << 32;
}
#endif
__value;
> +})
> +
> +static unsigned long csr_read_num(int csr_num)
static u64 csr_read_num(int csr_num)
> +{
> +#define switchcase_csr_read(__csr_num, __val) {\
> + case __csr_num: \
> + __val = csr_read(__csr_num); \
> + break; }
> +#define switchcase_csr_read_2(__csr_num, __val) {\
> + switchcase_csr_read(__csr_num + 0, __val) \
> + switchcase_csr_read(__csr_num + 1, __val)}
> +#define switchcase_csr_read_4(__csr_num, __val) {\
> + switchcase_csr_read_2(__csr_num + 0, __val) \
> + switchcase_csr_read_2(__csr_num + 2, __val)}
> +#define switchcase_csr_read_8(__csr_num, __val) {\
> + switchcase_csr_read_4(__csr_num + 0, __val) \
> + switchcase_csr_read_4(__csr_num + 4, __val)}
> +#define switchcase_csr_read_16(__csr_num, __val) {\
> + switchcase_csr_read_8(__csr_num + 0, __val) \
> + switchcase_csr_read_8(__csr_num + 8, __val)}
> +#define switchcase_csr_read_32(__csr_num, __val) {\
> + switchcase_csr_read_16(__csr_num + 0, __val) \
> + switchcase_csr_read_16(__csr_num + 16, __val)}
> +
> + unsigned long ret = 0;
> +
> + switch (csr_num) {
> + switchcase_csr_read_32(CSR_CYCLE, ret)
> + default:
> + break;
> + }
> +
> + return ret;
> +#undef switchcase_csr_read_32
> +#undef switchcase_csr_read_16
> +#undef switchcase_csr_read_8
> +#undef switchcase_csr_read_4
> +#undef switchcase_csr_read_2
> +#undef switchcase_csr_read
> +}
> +
> +static u64 read_perf_counter(unsigned int counter)
> +{
> + return csr_read_num(CSR_CYCLE + counter);
> +}
> +
> +static u64 read_timestamp(void)
> +{
> + return csr_read_num(CSR_TIME);
> +}
> +
> #else
> static u64 read_perf_counter(unsigned int counter __maybe_unused) { return 0; }
> static u64 read_timestamp(void) { return 0; }
> --
> 2.39.2
>
Thanks,
drew
