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From: James Clark <james.clark@arm.com>
To: mathieu.poirier@linaro.org, coresight@lists.linaro.org
Cc: suzuki.poulose@arm.com, James Clark <james.clark@arm.com>,
	Mike Leach <mike.leach@linaro.org>, Leo Yan <leo.yan@linaro.org>,
	John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] perf cs-etm: Remove duplicate and incorrect aux size checks
Date: Wed,  8 Dec 2021 11:54:35 +0000	[thread overview]
Message-ID: <20211208115435.610101-1-james.clark@arm.com> (raw)

There are two checks, one is for size when running without admin, but
this one is covered by the driver and reported on in more detail here
(builtin-record.c):

  pr_err("Permission error mapping pages.\n"
         "Consider increasing "
         "/proc/sys/kernel/perf_event_mlock_kb,\n"
         "or try again with a smaller value of -m/--mmap_pages.\n"
         "(current value: %u,%u)\n",

This had the effect of artificially limiting the aux buffer size to a
value smaller than what was allowed because perf_event_mlock_kb wasn't
taken into account.

The second is to check for a power of two, but this is covered here
(evlist.c):

  pr_info("rounding mmap pages size to %s (%lu pages)\n",
          buf, pages);

Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/arch/arm/util/cs-etm.c | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 293a23bf8be3..8a3d54a86c9c 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -407,25 +407,6 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
 
 	}
 
-	/* Validate auxtrace_mmap_pages provided by user */
-	if (opts->auxtrace_mmap_pages) {
-		unsigned int max_page = (KiB(128) / page_size);
-		size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
-
-		if (!privileged &&
-		    opts->auxtrace_mmap_pages > max_page) {
-			opts->auxtrace_mmap_pages = max_page;
-			pr_err("auxtrace too big, truncating to %d\n",
-			       max_page);
-		}
-
-		if (!is_power_of_2(sz)) {
-			pr_err("Invalid mmap size for %s: must be a power of 2\n",
-			       CORESIGHT_ETM_PMU_NAME);
-			return -EINVAL;
-		}
-	}
-
 	if (opts->auxtrace_snapshot_mode)
 		pr_debug2("%s snapshot size: %zu\n", CORESIGHT_ETM_PMU_NAME,
 			  opts->auxtrace_snapshot_size);
-- 
2.28.0


             reply	other threads:[~2021-12-08 11:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-08 11:54 James Clark [this message]
2021-12-08 13:17 ` Leo Yan
2021-12-08 14:08   ` James Clark
2021-12-09 13:44     ` Leo Yan
2021-12-09 14:16       ` James Clark
2021-12-10 16:54         ` Mathieu Poirier
2021-12-10 17:55           ` Arnaldo Carvalho de Melo
2021-12-10 19:03         ` Arnaldo Carvalho de Melo

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