| From 00b4d9a14125f1e51874def2b9de6092e007412d Mon Sep 17 00:00:00 2001 |
| From: Maxime COQUELIN <maxime.coquelin@st.com> |
| Date: Thu, 6 Nov 2014 10:54:19 +0100 |
| Subject: bitops: Fix shift overflow in GENMASK macros |
| |
| From: Maxime COQUELIN <maxime.coquelin@st.com> |
| |
| 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> |
| |
| 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); |
