From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Wed, 4 Apr 2018 08:11:20 +0000 (+0200)
Subject: 4.16-stable patches
X-Git-Tag: v3.18.103~21
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c6b12c62899de819d6de9fdfd8888501ef7656be;p=thirdparty%2Fkernel%2Fstable-queue.git

4.16-stable patches

added patches:
	bitmap-fix-memset-optimization-on-big-endian-systems.patch
---

diff --git a/queue-4.16/bitmap-fix-memset-optimization-on-big-endian-systems.patch b/queue-4.16/bitmap-fix-memset-optimization-on-big-endian-systems.patch
new file mode 100644
index 00000000000..46fab95f668
--- /dev/null
+++ b/queue-4.16/bitmap-fix-memset-optimization-on-big-endian-systems.patch
@@ -0,0 +1,89 @@
+From 21035965f60b0502fc6537b232839389bb4ce664 Mon Sep 17 00:00:00 2001
+From: Omar Sandoval <osandov@fb.com>
+Date: Mon, 2 Apr 2018 15:58:31 -0700
+Subject: bitmap: fix memset optimization on big-endian systems
+
+From: Omar Sandoval <osandov@fb.com>
+
+commit 21035965f60b0502fc6537b232839389bb4ce664 upstream.
+
+Commit 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and
+bitmap_clear into memset when possible") introduced an optimization to
+bitmap_{set,clear}() which uses memset() when the start and length are
+constants aligned to a byte.
+
+This is wrong on big-endian systems; our bitmaps are arrays of unsigned
+long, so bit n is not at byte n / 8 in memory.  This was caught by the
+Btrfs selftests, but the bitmap selftests also fail when run on a
+big-endian machine.
+
+We can still use memset if the start and length are aligned to an
+unsigned long, so do that on big-endian.  The same problem applies to
+the memcmp in bitmap_equal(), so fix it there, too.
+
+Fixes: 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible")
+Fixes: 2c6deb01525a ("bitmap: use memcmp optimisation in more situations")
+Cc: stable@kernel.org
+Reported-by: "Erhard F." <erhard_f@mailbox.org>
+Cc: Matthew Wilcox <mawilcox@microsoft.com>
+Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
+Cc: Andrew Morton <akpm@linux-foundation.org>
+Cc: Arnd Bergmann <arnd@arndb.de>
+Signed-off-by: Omar Sandoval <osandov@fb.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ include/linux/bitmap.h |   22 +++++++++++++++++-----
+ 1 file changed, 17 insertions(+), 5 deletions(-)
+
+--- a/include/linux/bitmap.h
++++ b/include/linux/bitmap.h
+@@ -302,12 +302,20 @@ static inline void bitmap_complement(uns
+ 		__bitmap_complement(dst, src, nbits);
+ }
+ 
++#ifdef __LITTLE_ENDIAN
++#define BITMAP_MEM_ALIGNMENT 8
++#else
++#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
++#endif
++#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
++
+ static inline int bitmap_equal(const unsigned long *src1,
+ 			const unsigned long *src2, unsigned int nbits)
+ {
+ 	if (small_const_nbits(nbits))
+ 		return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
+-	if (__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
++	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
++	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
+ 		return !memcmp(src1, src2, nbits / 8);
+ 	return __bitmap_equal(src1, src2, nbits);
+ }
+@@ -358,8 +366,10 @@ static __always_inline void bitmap_set(u
+ {
+ 	if (__builtin_constant_p(nbits) && nbits == 1)
+ 		__set_bit(start, map);
+-	else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+-		 __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
++	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
++		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
++		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
++		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
+ 		memset((char *)map + start / 8, 0xff, nbits / 8);
+ 	else
+ 		__bitmap_set(map, start, nbits);
+@@ -370,8 +380,10 @@ static __always_inline void bitmap_clear
+ {
+ 	if (__builtin_constant_p(nbits) && nbits == 1)
+ 		__clear_bit(start, map);
+-	else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+-		 __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
++	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
++		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
++		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
++		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
+ 		memset((char *)map + start / 8, 0, nbits / 8);
+ 	else
+ 		__bitmap_clear(map, start, nbits);