linux-kernel - [PATCH] kcsan: use u64 instead of cycles

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Message-Id: <20210729142811.1309391-1-hca@linux.ibm.com>
Date:   Thu, 29 Jul 2021 16:28:11 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Marco Elver <elver@...gle.com>
Cc:     Ilya Leoshkevich <iii@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: [PATCH] kcsan: use u64 instead of cycles_t

cycles_t has a different type across architectures: unsigned int,
unsinged long, or unsigned long long. Depending on architecture this
will generate this warning:

kernel/kcsan/debugfs.c: In function ‘microbenchmark’:
./include/linux/kern_levels.h:5:25: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘cycles_t’ {aka ‘long unsigned int’} [-Wformat=]

To avoid this simple change the type of cycle to u64 in
microbenchmark(), since u64 is of type unsigned long long for all
architectures.

Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
 kernel/kcsan/debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index e65de172ccf7..1d1d1b0e4248 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -64,7 +64,7 @@ static noinline void microbenchmark(unsigned long iters)
 {
 	const struct kcsan_ctx ctx_save = current->kcsan_ctx;
 	const bool was_enabled = READ_ONCE(kcsan_enabled);
-	cycles_t cycles;
+	u64 cycles;
 
 	/* We may have been called from an atomic region; reset context. */
 	memset(&current->kcsan_ctx, 0, sizeof(current->kcsan_ctx));
-- 
2.25.1