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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Subject: [PATCH 1/4] bitops: Fix shift overflow in GENMASK macros
Date: Wed,  3 Feb 2016 17:20:08 +0100	[thread overview]
Message-ID: <1454516411-22858-2-git-send-email-s.hauer@pengutronix.de> (raw)
In-Reply-To: <1454516411-22858-1-git-send-email-s.hauer@pengutronix.de>

From: Steffen Trumtrar <s.trumtrar@pengutronix.de>

Based on the original patch for linux:

	commit 00b4d9a14125f1e51874def2b9de6092e007412d
	Author: Maxime COQUELIN <maxime.coquelin@st.com>
	Date:   Thu Nov 6 10:54:19 2014

	On some 32 bits architectures, including x86, GENMASK(31, 0) returns 0
	instead of the expected ~0UL.

	This is the same on some 64 bits architectures with GENMASK_ULL(63, 0).

	This is due to an overflow in the shift operand, 1 << 32 for GENMASK,
	1 << 64 for GENMASK_ULL.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 include/linux/bitops.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index f3a740c..31345c2 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -18,8 +18,11 @@
  * position @h. For example
  * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
  */
-#define GENMASK(h, l)		(((U32_C(1) << ((h) - (l) + 1)) - 1) << (l))
-#define GENMASK_ULL(h, l)	(((U64_C(1) << ((h) - (l) + 1)) - 1) << (l))
+#define GENMASK(h, l) \
+	(((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+
+#define GENMASK_ULL(h, l) \
+	(((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
 
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
-- 
2.7.0.rc3


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  reply	other threads:[~2016-02-03 16:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 16:20 [PATCH] Add regmap support Sascha Hauer
2016-02-03 16:20 ` Sascha Hauer [this message]
2016-02-03 16:20 ` [PATCH 2/4] Add initial " Sascha Hauer
2016-02-03 16:20 ` [PATCH 3/4] mfd: mc13xxx: Switch to " Sascha Hauer
2016-02-03 16:20 ` [PATCH 4/4] ARM: i.MX ocotp: " Sascha Hauer
2016-02-04  7:38   ` Stefan Christ
2016-02-04  7:43     ` Sascha Hauer

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