Re: [PATCH v2 5/9] libperf: Add support for user space counter access

From: Jiri Olsa <jolsa@redhat.com>
To: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Raphael Gault <raphael.gault@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Ian Rogers <irogers@google.com>,
	honnappa.nagarahalli@arm.com
Subject: Re: [PATCH v2 5/9] libperf: Add support for user space counter access
Date: Mon, 31 Aug 2020 11:11:34 +0200	[thread overview]
Message-ID: <20200831091134.GC406859@krava> (raw)
In-Reply-To: <20200828205614.3391252-6-robh@kernel.org>

On Fri, Aug 28, 2020 at 02:56:10PM -0600, Rob Herring wrote:

SNIP

>  
> +void *perf_evsel__mmap(struct perf_evsel *evsel)
> +{
> +	int ret;
> +	struct perf_mmap *map;
> +	struct perf_mmap_param mp = {
> +		.mask = -1,
> +		.prot = PROT_READ | PROT_WRITE,
> +	};
> +
> +	if (FD(evsel, 0, 0) < 0)
> +		return NULL;
> +
> +	map = zalloc(sizeof(*map));
> +	if (!map)
> +		return NULL;
> +
> +	perf_mmap__init(map, NULL, false, NULL);
> +
> +	ret = perf_mmap__mmap(map, &mp, FD(evsel, 0, 0), 0);
> +	if (ret) {
> +		free(map);
> +		return NULL;
> +	}
> +
> +	evsel->mmap = map;
> +	return map->base;
> +}

so this only maps first page, I think we should use different
name and keep perf_evsel__mmap for some generic map with size

perf_evsel__mmap_user
perf_evsel__mmap_zero
...?

not sure.. or we could add size argument

jirka