linux-kernel - [PATCH v2 1/1] perf: use hweight64 instead of hweight

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Message-Id: <29ad7947dc8fd1ff0abd2093a72cc27a2446be9f.1554186265.git.han_mao@c-sky.com>
Date:   Tue,  2 Apr 2019 14:35:42 +0800
From:   Mao Han <han_mao@...ky.com>
To:     linux-kernel@...r.kernel.org
Cc:     Mao Han <han_mao@...ky.com>, Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>, Guo Ren <guoren@...nel.org>
Subject: [PATCH v2 1/1] perf: use hweight64 instead of hweight_long

On 32-bits platform with more than 32 registers, the 64 bits mask is
truncate to the lower 32 bits and the return value of hweight_long will
always smaller than 32. When kernel outputs more than 32 registers, but
the user perf program only counts 32, there will be a data mismatch
result to overflow check fail.

CC: Peter Zijlstra <peterz@...radead.org>
CC: Ingo Molnar <mingo@...hat.com>
CC: Arnaldo Carvalho de Melo <acme@...nel.org>
CC: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
CC: Jiri Olsa <jolsa@...hat.com>
CC: Namhyung Kim <namhyung@...nel.org>
CC: Guo Ren <guoren@...nel.org>

Signed-off-by: Mao Han <han_mao@...ky.com>
---
 tools/perf/util/evsel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 7835e05..73c78be 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2322,7 +2322,7 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
 		if (data->user_regs.abi) {
 			u64 mask = evsel->attr.sample_regs_user;
 
-			sz = hweight_long(mask) * sizeof(u64);
+			sz = hweight64(mask) * sizeof(u64);
 			OVERFLOW_CHECK(array, sz, max_size);
 			data->user_regs.mask = mask;
 			data->user_regs.regs = (u64 *)array;
-- 
2.7.4