This is a note to let you know that I've just added the patch titled
bitops: Fix shift overflow in GENMASK macros
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bitops-fix-shift-overflow-in-genmask-macros.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 00b4d9a14125f1e51874def2b9de6092e007412d Mon Sep 17 00:00:00 2001
From: Maxime COQUELIN <maxime.coquelin@xxxxxx>
Date: Thu, 6 Nov 2014 10:54:19 +0100
Subject: bitops: Fix shift overflow in GENMASK macros
From: Maxime COQUELIN <maxime.coquelin@xxxxxx>
commit 00b4d9a14125f1e51874def2b9de6092e007412d upstream.
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.
Reported-by: Eric Paire <eric.paire@xxxxxx>
Suggested-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Maxime Coquelin <maxime.coquelin@xxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: linux@xxxxxxxxxxxxxxxxxx
Cc: gong.chen@xxxxxxxxxxxxxxx
Cc: John Sullivan <jsrhbz@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Fixes: 10ef6b0dffe4 ("bitops: Introduce a more generic BITMASK macro")
Link: http://lkml.kernel.org/r/1415267659-10563-1-git-send-email-maxime.coquelin@xxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/bitops.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- 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);
Patches currently in stable-queue which might be from maxime.coquelin@xxxxxx are
queue-3.17/bitops-fix-shift-overflow-in-genmask-macros.patch
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