Re: [PATCH v6 09/10] tools: lib: perf: Implement riscv mmap support

[Andrew Jones]

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 */
> +
> +#define CSR_CYCLE	0xc00
> +#define CSR_TIME	0xc01
> +
> +#define csr_read(csr)						\
> +({								\
> +	register unsigned long __v;				\
> +		__asm__ __volatile__ ("csrr %0, %1"		\
> +		 : "=r" (__v)					\
> +		 : "i" (csr) : );				\
> +		 __v;						\

nit: no need for the indentation or line wrap,

({
	register unsigned long __v;
	__asm__ __volatile__ ("csrr %0, %1" : "=r" (__v) : "i" (csr));
	__v;
})

Thanks,
drew