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| author | Maxime COQUELIN <maxime.coquelin@st.com> | 2014-11-06 10:54:19 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-12-06 15:55:39 -0800 |
| commit | 42be4e5c4a5da3f9e27d6e1420612c3aea11f658 (patch) | |
| tree | a9c5ef54c0375fecfd7f7dfdce49d15113d26b55 /include | |
| parent | a35b403e0ad0a6dfcbc4eb4d307d9d2aaa60d914 (diff) | |
| download | lwn-42be4e5c4a5da3f9e27d6e1420612c3aea11f658.tar.gz lwn-42be4e5c4a5da3f9e27d6e1420612c3aea11f658.zip | |
bitops: Fix shift overflow in GENMASK macros
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@st.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux@rasmusvillemoes.dk
Cc: gong.chen@linux.intel.com
Cc: John Sullivan <jsrhbz@kanargh.force9.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Fixes: 10ef6b0dffe4 ("bitops: Introduce a more generic BITMASK macro")
Link: http://lkml.kernel.org/r/1415267659-10563-1-git-send-email-maxime.coquelin@st.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bitops.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index be5fd38bd5a0..5d858e02997f 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); |