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Date:   Wed, 2 Aug 2023 12:32:12 +0300
From:   Andrew Jones <ajones@ventanamicro.com>
To:     Alexandre Ghiti <alexghiti@rivosinc.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Atish Patra <atishp@atishpatra.org>,
        Anup Patel <anup@brainfault.org>,
        Will Deacon <will@kernel.org>, Rob Herring <robh@kernel.org>,
        =?utf-8?B?UsOpbWk=?= Denis-Courmont <remi@remlab.net>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, linux-riscv@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        Atish Patra <atishp@rivosinc.com>
Subject: Re: [PATCH v6 09/10] tools: lib: perf: Implement riscv mmap support
Message-ID: <20230802-7c19a712ae071f68030ab5f2@orel>
References: <20230802080328.1213905-1-alexghiti@rivosinc.com>
 <20230802080328.1213905-10-alexghiti@rivosinc.com>
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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@rivosinc.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Reviewed-by: Atish Patra <atishp@rivosinc.com>
> ---
>  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