linux-kernel - [PATCH V1] perf tools: Get correct max value of format attribute

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Date:   Wed, 20 Dec 2017 15:46:23 -0800
From:   Megha Dey <megha.dey@...ux.intel.com>
To:     linux-kernel@...r.kernel.org
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, yu-cheng.yu@...el.com, megha.dey@...el.com,
        Megha Dey <megha.dey@...ux.intel.com>
Subject: [PATCH V1] perf tools: Get correct max value of format attribute

Currently, the maximum value of every format attribute is not being
correctly set.

For eg:
cat /sys/devices/cpu/format/umask
config:8-15

This implies the max_value of umask should be 0xff

./perf stat –e cpu/umask=0x100/ sleep 1
Performance counter stats for '../rets-128.bin':

                 0      cpu/umask=0x100/

       0.109157272 seconds time elapsed

works just fine(0x100 > 0xff). Whereas,

./perf stat –e cpu/umask=0xff01/ sleep 1
event syntax error: 'cpu/umask=0xff01/'
                               \___ value too big for format, maximum is
65280(0xff00)

The maximum value is set to 0xff00 instead of 0xff.

This patch fixes the pmu_format_max_value() function to return the
correct maximum value.

Acked-by: Jiri Olsa <jolsa@...nel.org>
Signed-off-by: Megha Dey <megha.dey@...ux.intel.com>
---
 tools/perf/util/pmu.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 2fffc3a..2bf7a7d 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -777,13 +777,7 @@ static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
 
 static __u64 pmu_format_max_value(const unsigned long *format)
 {
-	__u64 w = 0;
-	int fbit;
-
-	for_each_set_bit(fbit, format, PERF_PMU_FORMAT_BITS)
-		w |= (1ULL << fbit);
-
-	return w;
+	return (1ULL << bitmap_weight(format, PERF_PMU_FORMAT_BITS)) - 1;
 }
 
 /*
-- 
1.9.1