Merge branch 'akpm' (patches from Andrew)

Merge third patchbomb from Andrew Morton:

 - various misc things

 - a couple of lib/ optimisations

 - provide DIV_ROUND_CLOSEST_ULL()

 - checkpatch updates

 - rtc tree

 - befs, nilfs2, hfs, hfsplus, fatfs, adfs, affs, bfs

 - ptrace fixes

 - fork() fixes

 - seccomp cleanups

 - more mmap_sem hold time reductions from Davidlohr

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (138 commits)
  proc: show locks in /proc/pid/fdinfo/X
  docs: add missing and new /proc/PID/status file entries, fix typos
  drivers/rtc/rtc-at91rm9200.c: make IO endian agnostic
  Documentation/spi/spidev_test.c: fix warning
  drivers/rtc/rtc-s5m.c: allow usage on device type different than main MFD type
  .gitignore: ignore *.tar
  MAINTAINERS: add Mediatek SoC mailing list
  tomoyo: reduce mmap_sem hold for mm->exe_file
  powerpc/oprofile: reduce mmap_sem hold for exe_file
  oprofile: reduce mmap_sem hold for mm->exe_file
  mips: ip32: add platform data hooks to use DS1685 driver
  lib/Kconfig: fix up HAVE_ARCH_BITREVERSE help text
  x86: switch to using asm-generic for seccomp.h
  sparc: switch to using asm-generic for seccomp.h
  powerpc: switch to using asm-generic for seccomp.h
  parisc: switch to using asm-generic for seccomp.h
  mips: switch to using asm-generic for seccomp.h
  microblaze: use asm-generic for seccomp.h
  arm: use asm-generic for seccomp.h
  seccomp: allow COMPAT sigreturn overrides
  ...

9 files changed, 342 insertions, 464 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 87da53b..f544022 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -18,9 +18,8 @@ config HAVE_ARCH_BITREVERSE
 	default n
 	depends on BITREVERSE
 	help
-	  This option provides an config for the architecture which have instruction
-	  can do bitreverse operation, we use the hardware instruction if the architecture
-	  have this capability.
+	  This option enables the use of hardware bit-reversal instructions on
+	  architectures which support such operations.
 
 config RATIONAL
 	bool
diff --git a/lib/Makefile b/lib/Makefile
index 58f74d2..da6116b 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -25,7 +25,7 @@ obj-y	+= lockref.o
 obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
 	 bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
 	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
-	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
+	 bsearch.o find_bit.o llist.o memweight.o kfifo.o \
 	 percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o
 obj-y += string_helpers.o
 obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
diff --git a/lib/bitmap.c b/lib/bitmap.c
index d456f4c1..64c0926 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -42,36 +42,6 @@
  * for the best explanations of this ordering.
  */
 
-int __bitmap_empty(const unsigned long *bitmap, unsigned int bits)
-{
-	unsigned int k, lim = bits/BITS_PER_LONG;
-	for (k = 0; k < lim; ++k)
-		if (bitmap[k])
-			return 0;
-
-	if (bits % BITS_PER_LONG)
-		if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
-			return 0;
-
-	return 1;
-}
-EXPORT_SYMBOL(__bitmap_empty);
-
-int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
-{
-	unsigned int k, lim = bits/BITS_PER_LONG;
-	for (k = 0; k < lim; ++k)
-		if (~bitmap[k])
-			return 0;
-
-	if (bits % BITS_PER_LONG)
-		if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
-			return 0;
-
-	return 1;
-}
-EXPORT_SYMBOL(__bitmap_full);
-
 int __bitmap_equal(const unsigned long *bitmap1,
 		const unsigned long *bitmap2, unsigned int bits)
 {
diff --git a/lib/cpumask.c b/lib/cpumask.c
index b6513a9..5ab1553 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -37,10 +37,11 @@ EXPORT_SYMBOL(__next_cpu_nr);
 int cpumask_next_and(int n, const struct cpumask *src1p,
 		     const struct cpumask *src2p)
 {
-	while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
-		if (cpumask_test_cpu(n, src2p))
-			break;
-	return n;
+	struct cpumask tmp;
+
+	if (cpumask_and(&tmp, src1p, src2p))
+		return cpumask_next(n, &tmp);
+	return nr_cpu_ids;
 }
 EXPORT_SYMBOL(cpumask_next_and);
 
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 9722bd2..ae4b65e 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -361,7 +361,7 @@ static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
 	unsigned int range = 0;
 
 	while (range <= max_range) {
-		entry = __hash_bucket_find(*bucket, &index, containing_match);
+		entry = __hash_bucket_find(*bucket, ref, containing_match);
 
 		if (entry)
 			return entry;
diff --git a/lib/find_bit.c b/lib/find_bit.c
new file mode 100644
index 0000000..18072ea
--- /dev/null
+++ b/lib/find_bit.c
@@ -0,0 +1,193 @@
+/* bit search implementation
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * Copyright (C) 2008 IBM Corporation
+ * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
+ * (Inspired by David Howell's find_next_bit implementation)
+ *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+
+#if !defined(find_next_bit) || !defined(find_next_zero_bit)
+
+/*
+ * This is a common helper function for find_next_bit and
+ * find_next_zero_bit.  The difference is the "invert" argument, which
+ * is XORed with each fetched word before searching it for one bits.
+ */
+static unsigned long _find_next_bit(const unsigned long *addr,
+		unsigned long nbits, unsigned long start, unsigned long invert)
+{
+	unsigned long tmp;
+
+	if (!nbits || start >= nbits)
+		return nbits;
+
+	tmp = addr[start / BITS_PER_LONG] ^ invert;
+
+	/* Handle 1st word. */
+	tmp &= BITMAP_FIRST_WORD_MASK(start);
+	start = round_down(start, BITS_PER_LONG);
+
+	while (!tmp) {
+		start += BITS_PER_LONG;
+		if (start >= nbits)
+			return nbits;
+
+		tmp = addr[start / BITS_PER_LONG] ^ invert;
+	}
+
+	return min(start + __ffs(tmp), nbits);
+}
+#endif
+
+#ifndef find_next_bit
+/*
+ * Find the next set bit in a memory region.
+ */
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+			    unsigned long offset)
+{
+	return _find_next_bit(addr, size, offset, 0UL);
+}
+EXPORT_SYMBOL(find_next_bit);
+#endif
+
+#ifndef find_next_zero_bit
+unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
+				 unsigned long offset)
+{
+	return _find_next_bit(addr, size, offset, ~0UL);
+}
+EXPORT_SYMBOL(find_next_zero_bit);
+#endif
+
+#ifndef find_first_bit
+/*
+ * Find the first set bit in a memory region.
+ */
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+	unsigned long idx;
+
+	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+		if (addr[idx])
+			return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
+	}
+
+	return size;
+}
+EXPORT_SYMBOL(find_first_bit);
+#endif
+
+#ifndef find_first_zero_bit
+/*
+ * Find the first cleared bit in a memory region.
+ */
+unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+	unsigned long idx;
+
+	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+		if (addr[idx] != ~0UL)
+			return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
+	}
+
+	return size;
+}
+EXPORT_SYMBOL(find_first_zero_bit);
+#endif
+
+#ifndef find_last_bit
+unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+{
+	if (size) {
+		unsigned long val = BITMAP_LAST_WORD_MASK(size);
+		unsigned long idx = (size-1) / BITS_PER_LONG;
+
+		do {
+			val &= addr[idx];
+			if (val)
+				return idx * BITS_PER_LONG + __fls(val);
+
+			val = ~0ul;
+		} while (idx--);
+	}
+	return size;
+}
+EXPORT_SYMBOL(find_last_bit);
+#endif
+
+#ifdef __BIG_ENDIAN
+
+/* include/linux/byteorder does not support "unsigned long" type */
+static inline unsigned long ext2_swab(const unsigned long y)
+{
+#if BITS_PER_LONG == 64
+	return (unsigned long) __swab64((u64) y);
+#elif BITS_PER_LONG == 32
+	return (unsigned long) __swab32((u32) y);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+#if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
+static unsigned long _find_next_bit_le(const unsigned long *addr,
+		unsigned long nbits, unsigned long start, unsigned long invert)
+{
+	unsigned long tmp;
+
+	if (!nbits || start >= nbits)
+		return nbits;
+
+	tmp = addr[start / BITS_PER_LONG] ^ invert;
+
+	/* Handle 1st word. */
+	tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
+	start = round_down(start, BITS_PER_LONG);
+
+	while (!tmp) {
+		start += BITS_PER_LONG;
+		if (start >= nbits)
+			return nbits;
+
+		tmp = addr[start / BITS_PER_LONG] ^ invert;
+	}
+
+	return min(start + __ffs(ext2_swab(tmp)), nbits);
+}
+#endif
+
+#ifndef find_next_zero_bit_le
+unsigned long find_next_zero_bit_le(const void *addr, unsigned
+		long size, unsigned long offset)
+{
+	return _find_next_bit_le(addr, size, offset, ~0UL);
+}
+EXPORT_SYMBOL(find_next_zero_bit_le);
+#endif
+
+#ifndef find_next_bit_le
+unsigned long find_next_bit_le(const void *addr, unsigned
+		long size, unsigned long offset)
+{
+	return _find_next_bit_le(addr, size, offset, 0UL);
+}
+EXPORT_SYMBOL(find_next_bit_le);
+#endif
+
+#endif /* __BIG_ENDIAN */
diff --git a/lib/find_last_bit.c b/lib/find_last_bit.c
index 91ca09f..3e3be40 100644
--- a/lib/find_last_bit.c
+++ b/lib/find_last_bit.c
@@ -4,6 +4,9 @@
  * Written by Rusty Russell <rusty@rustcorp.com.au>
  * (Inspired by David Howell's find_next_bit implementation)
  *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
@@ -11,37 +14,26 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/bitmap.h>
 #include <linux/export.h>
-#include <asm/types.h>
-#include <asm/byteorder.h>
+#include <linux/kernel.h>
 
 #ifndef find_last_bit
 
 unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
 {
-	unsigned long words;
-	unsigned long tmp;
-
-	/* Start at final word. */
-	words = size / BITS_PER_LONG;
+	if (size) {
+		unsigned long val = BITMAP_LAST_WORD_MASK(size);
+		unsigned long idx = (size-1) / BITS_PER_LONG;
 
-	/* Partial final word? */
-	if (size & (BITS_PER_LONG-1)) {
-		tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
-					 - (size & (BITS_PER_LONG-1)))));
-		if (tmp)
-			goto found;
-	}
+		do {
+			val &= addr[idx];
+			if (val)
+				return idx * BITS_PER_LONG + __fls(val);
 
-	while (words) {
-		tmp = addr[--words];
-		if (tmp) {
-found:
-			return words * BITS_PER_LONG + __fls(tmp);
-		}
+			val = ~0ul;
+		} while (idx--);
 	}
-
-	/* Not found */
 	return size;
 }
 EXPORT_SYMBOL(find_last_bit);
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
deleted file mode 100644
index 0cbfc0b..0000000
--- a/lib/find_next_bit.c
+++ /dev/null
@@ -1,285 +0,0 @@
-/* find_next_bit.c: fallback find next bit implementation
- *
- * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#include <linux/bitops.h>
-#include <linux/export.h>
-#include <asm/types.h>
-#include <asm/byteorder.h>
-
-#define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)
-
-#ifndef find_next_bit
-/*
- * Find the next set bit in a memory region.
- */
-unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
-			    unsigned long offset)
-{
-	const unsigned long *p = addr + BITOP_WORD(offset);
-	unsigned long result = offset & ~(BITS_PER_LONG-1);
-	unsigned long tmp;
-
-	if (offset >= size)
-		return size;
-	size -= result;
-	offset %= BITS_PER_LONG;
-	if (offset) {
-		tmp = *(p++);
-		tmp &= (~0UL << offset);
-		if (size < BITS_PER_LONG)
-			goto found_first;
-		if (tmp)
-			goto found_middle;
-		size -= BITS_PER_LONG;
-		result += BITS_PER_LONG;
-	}
-	while (size & ~(BITS_PER_LONG-1)) {
-		if ((tmp = *(p++)))
-			goto found_middle;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-	tmp = *p;
-
-found_first:
-	tmp &= (~0UL >> (BITS_PER_LONG - size));
-	if (tmp == 0UL)		/* Are any bits set? */
-		return result + size;	/* Nope. */
-found_middle:
-	return result + __ffs(tmp);
-}
-EXPORT_SYMBOL(find_next_bit);
-#endif
-
-#ifndef find_next_zero_bit
-/*
- * This implementation of find_{first,next}_zero_bit was stolen from
- * Linus' asm-alpha/bitops.h.
- */
-unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
-				 unsigned long offset)
-{
-	const unsigned long *p = addr + BITOP_WORD(offset);
-	unsigned long result = offset & ~(BITS_PER_LONG-1);
-	unsigned long tmp;
-
-	if (offset >= size)
-		return size;
-	size -= result;
-	offset %= BITS_PER_LONG;
-	if (offset) {
-		tmp = *(p++);
-		tmp |= ~0UL >> (BITS_PER_LONG - offset);
-		if (size < BITS_PER_LONG)
-			goto found_first;
-		if (~tmp)
-			goto found_middle;
-		size -= BITS_PER_LONG;
-		result += BITS_PER_LONG;
-	}
-	while (size & ~(BITS_PER_LONG-1)) {
-		if (~(tmp = *(p++)))
-			goto found_middle;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-	tmp = *p;
-
-found_first:
-	tmp |= ~0UL << size;
-	if (tmp == ~0UL)	/* Are any bits zero? */
-		return result + size;	/* Nope. */
-found_middle:
-	return result + ffz(tmp);
-}
-EXPORT_SYMBOL(find_next_zero_bit);
-#endif
-
-#ifndef find_first_bit
-/*
- * Find the first set bit in a memory region.
- */
-unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
-{
-	const unsigned long *p = addr;
-	unsigned long result = 0;
-	unsigned long tmp;
-
-	while (size & ~(BITS_PER_LONG-1)) {
-		if ((tmp = *(p++)))
-			goto found;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-
-	tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
-	if (tmp == 0UL)		/* Are any bits set? */
-		return result + size;	/* Nope. */
-found:
-	return result + __ffs(tmp);
-}
-EXPORT_SYMBOL(find_first_bit);
-#endif
-
-#ifndef find_first_zero_bit
-/*
- * Find the first cleared bit in a memory region.
- */
-unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
-{
-	const unsigned long *p = addr;
-	unsigned long result = 0;
-	unsigned long tmp;
-
-	while (size & ~(BITS_PER_LONG-1)) {
-		if (~(tmp = *(p++)))
-			goto found;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-
-	tmp = (*p) | (~0UL << size);
-	if (tmp == ~0UL)	/* Are any bits zero? */
-		return result + size;	/* Nope. */
-found:
-	return result + ffz(tmp);
-}
-EXPORT_SYMBOL(find_first_zero_bit);
-#endif
-
-#ifdef __BIG_ENDIAN
-
-/* include/linux/byteorder does not support "unsigned long" type */
-static inline unsigned long ext2_swabp(const unsigned long * x)
-{
-#if BITS_PER_LONG == 64
-	return (unsigned long) __swab64p((u64 *) x);
-#elif BITS_PER_LONG == 32
-	return (unsigned long) __swab32p((u32 *) x);
-#else
-#error BITS_PER_LONG not defined
-#endif
-}
-
-/* include/linux/byteorder doesn't support "unsigned long" type */
-static inline unsigned long ext2_swab(const unsigned long y)
-{
-#if BITS_PER_LONG == 64
-	return (unsigned long) __swab64((u64) y);
-#elif BITS_PER_LONG == 32
-	return (unsigned long) __swab32((u32) y);
-#else
-#error BITS_PER_LONG not defined
-#endif
-}
-
-#ifndef find_next_zero_bit_le
-unsigned long find_next_zero_bit_le(const void *addr, unsigned
-		long size, unsigned long offset)
-{
-	const unsigned long *p = addr;
-	unsigned long result = offset & ~(BITS_PER_LONG - 1);
-	unsigned long tmp;
-
-	if (offset >= size)
-		return size;
-	p += BITOP_WORD(offset);
-	size -= result;
-	offset &= (BITS_PER_LONG - 1UL);
-	if (offset) {
-		tmp = ext2_swabp(p++);
-		tmp |= (~0UL >> (BITS_PER_LONG - offset));
-		if (size < BITS_PER_LONG)
-			goto found_first;
-		if (~tmp)
-			goto found_middle;
-		size -= BITS_PER_LONG;
-		result += BITS_PER_LONG;
-	}
-
-	while (size & ~(BITS_PER_LONG - 1)) {
-		if (~(tmp = *(p++)))
-			goto found_middle_swap;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-	tmp = ext2_swabp(p);
-found_first:
-	tmp |= ~0UL << size;
-	if (tmp == ~0UL)	/* Are any bits zero? */
-		return result + size; /* Nope. Skip ffz */
-found_middle:
-	return result + ffz(tmp);
-
-found_middle_swap:
-	return result + ffz(ext2_swab(tmp));
-}
-EXPORT_SYMBOL(find_next_zero_bit_le);
-#endif
-
-#ifndef find_next_bit_le
-unsigned long find_next_bit_le(const void *addr, unsigned
-		long size, unsigned long offset)
-{
-	const unsigned long *p = addr;
-	unsigned long result = offset & ~(BITS_PER_LONG - 1);
-	unsigned long tmp;
-
-	if (offset >= size)
-		return size;
-	p += BITOP_WORD(offset);
-	size -= result;
-	offset &= (BITS_PER_LONG - 1UL);
-	if (offset) {
-		tmp = ext2_swabp(p++);
-		tmp &= (~0UL << offset);
-		if (size < BITS_PER_LONG)
-			goto found_first;
-		if (tmp)
-			goto found_middle;
-		size -= BITS_PER_LONG;
-		result += BITS_PER_LONG;
-	}
-
-	while (size & ~(BITS_PER_LONG - 1)) {
-		tmp = *(p++);
-		if (tmp)
-			goto found_middle_swap;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-	tmp = ext2_swabp(p);
-found_first:
-	tmp &= (~0UL >> (BITS_PER_LONG - size));
-	if (tmp == 0UL)		/* Are any bits set? */
-		return result + size; /* Nope. */
-found_middle:
-	return result + __ffs(tmp);
-
-found_middle_swap:
-	return result + __ffs(ext2_swab(tmp));
-}
-EXPORT_SYMBOL(find_next_bit_le);
-#endif
-
-#endif /* __BIG_ENDIAN */
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3a1e084..da39c60 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -33,6 +33,7 @@
 
 #include <asm/page.h>		/* for PAGE_SIZE */
 #include <asm/sections.h>	/* for dereference_function_descriptor() */
+#include <asm/byteorder.h>	/* cpu_to_le16 */
 
 #include <linux/string_helpers.h>
 #include "kstrtox.h"
@@ -122,142 +123,145 @@ int skip_atoi(const char **s)
 	return i;
 }
 
-/* Decimal conversion is by far the most typical, and is used
- * for /proc and /sys data. This directly impacts e.g. top performance
- * with many processes running. We optimize it for speed
- * using ideas described at <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
- * (with permission from the author, Douglas W. Jones).
+/*
+ * Decimal conversion is by far the most typical, and is used for
+ * /proc and /sys data. This directly impacts e.g. top performance
+ * with many processes running. We optimize it for speed by emitting
+ * two characters at a time, using a 200 byte lookup table. This
+ * roughly halves the number of multiplications compared to computing
+ * the digits one at a time. Implementation strongly inspired by the
+ * previous version, which in turn used ideas described at
+ * <http://www.cs.uiowa.edu/~jones/bcd/divide.html> (with permission
+ * from the author, Douglas W. Jones).
+ *
+ * It turns out there is precisely one 26 bit fixed-point
+ * approximation a of 64/100 for which x/100 == (x * (u64)a) >> 32
+ * holds for all x in [0, 10^8-1], namely a = 0x28f5c29. The actual
+ * range happens to be somewhat larger (x <= 1073741898), but that's
+ * irrelevant for our purpose.
+ *
+ * For dividing a number in the range [10^4, 10^6-1] by 100, we still
+ * need a 32x32->64 bit multiply, so we simply use the same constant.
+ *
+ * For dividing a number in the range [100, 10^4-1] by 100, there are
+ * several options. The simplest is (x * 0x147b) >> 19, which is valid
+ * for all x <= 43698.
  */
 
-#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
-/* Formats correctly any integer in [0, 999999999] */
+static const u16 decpair[100] = {
+#define _(x) (__force u16) cpu_to_le16(((x % 10) | ((x / 10) << 8)) + 0x3030)
+	_( 0), _( 1), _( 2), _( 3), _( 4), _( 5), _( 6), _( 7), _( 8), _( 9),
+	_(10), _(11), _(12), _(13), _(14), _(15), _(16), _(17), _(18), _(19),
+	_(20), _(21), _(22), _(23), _(24), _(25), _(26), _(27), _(28), _(29),
+	_(30), _(31), _(32), _(33), _(34), _(35), _(36), _(37), _(38), _(39),
+	_(40), _(41), _(42), _(43), _(44), _(45), _(46), _(47), _(48), _(49),
+	_(50), _(51), _(52), _(53), _(54), _(55), _(56), _(57), _(58), _(59),
+	_(60), _(61), _(62), _(63), _(64), _(65), _(66), _(67), _(68), _(69),
+	_(70), _(71), _(72), _(73), _(74), _(75), _(76), _(77), _(78), _(79),
+	_(80), _(81), _(82), _(83), _(84), _(85), _(86), _(87), _(88), _(89),
+	_(90), _(91), _(92), _(93), _(94), _(95), _(96), _(97), _(98), _(99),
+#undef _
+};
+
+/*
+ * This will print a single '0' even if r == 0, since we would
+ * immediately jump to out_r where two 0s would be written but only
+ * one of them accounted for in buf. This is needed by ip4_string
+ * below. All other callers pass a non-zero value of r.
+*/
 static noinline_for_stack
-char *put_dec_full9(char *buf, unsigned q)
+char *put_dec_trunc8(char *buf, unsigned r)
 {
-	unsigned r;
+	unsigned q;
 
-	/*
-	 * Possible ways to approx. divide by 10
-	 * (x * 0x1999999a) >> 32 x < 1073741829 (multiply must be 64-bit)
-	 * (x * 0xcccd) >> 19     x <      81920 (x < 262149 when 64-bit mul)
-	 * (x * 0x6667) >> 18     x <      43699
-	 * (x * 0x3334) >> 17     x <      16389
-	 * (x * 0x199a) >> 16     x <      16389
-	 * (x * 0x0ccd) >> 15     x <      16389
-	 * (x * 0x0667) >> 14     x <       2739
-	 * (x * 0x0334) >> 13     x <       1029
-	 * (x * 0x019a) >> 12     x <       1029
-	 * (x * 0x00cd) >> 11     x <       1029 shorter code than * 0x67 (on i386)
-	 * (x * 0x0067) >> 10     x <        179
-	 * (x * 0x0034) >>  9     x <         69 same
-	 * (x * 0x001a) >>  8     x <         69 same
-	 * (x * 0x000d) >>  7     x <         69 same, shortest code (on i386)
-	 * (x * 0x0007) >>  6     x <         19
-	 * See <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
-	 */
-	r      = (q * (uint64_t)0x1999999a) >> 32;
-	*buf++ = (q - 10 * r) + '0'; /* 1 */
-	q      = (r * (uint64_t)0x1999999a) >> 32;
-	*buf++ = (r - 10 * q) + '0'; /* 2 */
-	r      = (q * (uint64_t)0x1999999a) >> 32;
-	*buf++ = (q - 10 * r) + '0'; /* 3 */
-	q      = (r * (uint64_t)0x1999999a) >> 32;
-	*buf++ = (r - 10 * q) + '0'; /* 4 */
-	r      = (q * (uint64_t)0x1999999a) >> 32;
-	*buf++ = (q - 10 * r) + '0'; /* 5 */
-	/* Now value is under 10000, can avoid 64-bit multiply */
-	q      = (r * 0x199a) >> 16;
-	*buf++ = (r - 10 * q)  + '0'; /* 6 */
-	r      = (q * 0xcd) >> 11;
-	*buf++ = (q - 10 * r)  + '0'; /* 7 */
-	q      = (r * 0xcd) >> 11;
-	*buf++ = (r - 10 * q) + '0'; /* 8 */
-	*buf++ = q + '0'; /* 9 */
+	/* 1 <= r < 10^8 */
+	if (r < 100)
+		goto out_r;
+
+	/* 100 <= r < 10^8 */
+	q = (r * (u64)0x28f5c29) >> 32;
+	*((u16 *)buf) = decpair[r - 100*q];
+	buf += 2;
+
+	/* 1 <= q < 10^6 */
+	if (q < 100)
+		goto out_q;
+
+	/*  100 <= q < 10^6 */
+	r = (q * (u64)0x28f5c29) >> 32;
+	*((u16 *)buf) = decpair[q - 100*r];
+	buf += 2;
+
+	/* 1 <= r < 10^4 */
+	if (r < 100)
+		goto out_r;
+
+	/* 100 <= r < 10^4 */
+	q = (r * 0x147b) >> 19;
+	*((u16 *)buf) = decpair[r - 100*q];
+	buf += 2;
+out_q:
+	/* 1 <= q < 100 */
+	r = q;
+out_r:
+	/* 1 <= r < 100 */
+	*((u16 *)buf) = decpair[r];
+	buf += r < 10 ? 1 : 2;
 	return buf;
 }
-#endif
 
-/* Similar to above but do not pad with zeros.
- * Code can be easily arranged to print 9 digits too, but our callers
- * always call put_dec_full9() instead when the number has 9 decimal digits.
- */
+#if BITS_PER_LONG == 64 && BITS_PER_LONG_LONG == 64
 static noinline_for_stack
-char *put_dec_trunc8(char *buf, unsigned r)
+char *put_dec_full8(char *buf, unsigned r)
 {
 	unsigned q;
 
-	/* Copy of previous function's body with added early returns */
-	while (r >= 10000) {
-		q = r + '0';
-		r  = (r * (uint64_t)0x1999999a) >> 32;
-		*buf++ = q - 10*r;
-	}
+	/* 0 <= r < 10^8 */
+	q = (r * (u64)0x28f5c29) >> 32;
+	*((u16 *)buf) = decpair[r - 100*q];
+	buf += 2;
 
-	q      = (r * 0x199a) >> 16;	/* r <= 9999 */
-	*buf++ = (r - 10 * q)  + '0';
-	if (q == 0)
-		return buf;
-	r      = (q * 0xcd) >> 11;	/* q <= 999 */
-	*buf++ = (q - 10 * r)  + '0';
-	if (r == 0)
-		return buf;
-	q      = (r * 0xcd) >> 11;	/* r <= 99 */
-	*buf++ = (r - 10 * q) + '0';
-	if (q == 0)
-		return buf;
-	*buf++ = q + '0';		 /* q <= 9 */
-	return buf;
-}
+	/* 0 <= q < 10^6 */
+	r = (q * (u64)0x28f5c29) >> 32;
+	*((u16 *)buf) = decpair[q - 100*r];
+	buf += 2;
 
-/* There are two algorithms to print larger numbers.
- * One is generic: divide by 1000000000 and repeatedly print
- * groups of (up to) 9 digits. It's conceptually simple,
- * but requires a (unsigned long long) / 1000000000 division.
- *
- * Second algorithm splits 64-bit unsigned long long into 16-bit chunks,
- * manipulates them cleverly and generates groups of 4 decimal digits.
- * It so happens that it does NOT require long long division.
- *
- * If long is > 32 bits, division of 64-bit values is relatively easy,
- * and we will use the first algorithm.
- * If long long is > 64 bits (strange architecture with VERY large long long),
- * second algorithm can't be used, and we again use the first one.
- *
- * Else (if long is 32 bits and long long is 64 bits) we use second one.
- */
+	/* 0 <= r < 10^4 */
+	q = (r * 0x147b) >> 19;
+	*((u16 *)buf) = decpair[r - 100*q];
+	buf += 2;
 
-#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
-
-/* First algorithm: generic */
+	/* 0 <= q < 100 */
+	*((u16 *)buf) = decpair[q];
+	buf += 2;
+	return buf;
+}
 
-static
+static noinline_for_stack
 char *put_dec(char *buf, unsigned long long n)
 {
-	if (n >= 100*1000*1000) {
-		while (n >= 1000*1000*1000)
-			buf = put_dec_full9(buf, do_div(n, 1000*1000*1000));
-		if (n >= 100*1000*1000)
-			return put_dec_full9(buf, n);
-	}
+	if (n >= 100*1000*1000)
+		buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
+	/* 1 <= n <= 1.6e11 */
+	if (n >= 100*1000*1000)
+		buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
+	/* 1 <= n < 1e8 */
 	return put_dec_trunc8(buf, n);
 }
 
-#else
+#elif BITS_PER_LONG == 32 && BITS_PER_LONG_LONG == 64
 
-/* Second algorithm: valid only for 64-bit long longs */
-
-/* See comment in put_dec_full9 for choice of constants */
-static noinline_for_stack
-void put_dec_full4(char *buf, unsigned q)
+static void
+put_dec_full4(char *buf, unsigned r)
 {
-	unsigned r;
-	r      = (q * 0xccd) >> 15;
-	buf[0] = (q - 10 * r) + '0';
-	q      = (r * 0xcd) >> 11;
-	buf[1] = (r - 10 * q)  + '0';
-	r      = (q * 0xcd) >> 11;
-	buf[2] = (q - 10 * r)  + '0';
-	buf[3] = r + '0';
+	unsigned q;
+
+	/* 0 <= r < 10^4 */
+	q = (r * 0x147b) >> 19;
+	*((u16 *)buf) = decpair[r - 100*q];
+	buf += 2;
+	/* 0 <= q < 100 */
+	*((u16 *)buf) = decpair[q];
 }
 
 /*
@@ -265,9 +269,9 @@ void put_dec_full4(char *buf, unsigned q)
  * The approximation x/10000 == (x * 0x346DC5D7) >> 43
  * holds for all x < 1,128,869,999.  The largest value this
  * helper will ever be asked to convert is 1,125,520,955.
- * (d1 in the put_dec code, assuming n is all-ones).
+ * (second call in the put_dec code, assuming n is all-ones).
  */
-static
+static noinline_for_stack
 unsigned put_dec_helper4(char *buf, unsigned x)
 {
         uint32_t q = (x * (uint64_t)0x346DC5D7) >> 43;
@@ -294,6 +298,8 @@ char *put_dec(char *buf, unsigned long long n)
 	d2  = (h      ) & 0xffff;
 	d3  = (h >> 16); /* implicit "& 0xffff" */
 
+	/* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
+	     = 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
 	q   = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
 	q = put_dec_helper4(buf, q);
 
@@ -323,7 +329,8 @@ char *put_dec(char *buf, unsigned long long n)
  */
 int num_to_str(char *buf, int size, unsigned long long num)
 {
-	char tmp[sizeof(num) * 3];
+	/* put_dec requires 2-byte alignment of the buffer. */
+	char tmp[sizeof(num) * 3] __aligned(2);
 	int idx, len;
 
 	/* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
@@ -384,7 +391,8 @@ static noinline_for_stack
 char *number(char *buf, char *end, unsigned long long num,
 	     struct printf_spec spec)
 {
-	char tmp[3 * sizeof(num)];
+	/* put_dec requires 2-byte alignment of the buffer. */
+	char tmp[3 * sizeof(num)] __aligned(2);
 	char sign;
 	char locase;
 	int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
@@ -944,7 +952,7 @@ char *ip4_string(char *p, const u8 *addr, const char *fmt)
 		break;
 	}
 	for (i = 0; i < 4; i++) {
-		char temp[3];	/* hold each IP quad in reverse order */
+		char temp[4] __aligned(2);	/* hold each IP quad in reverse order */
 		int digits = put_dec_trunc8(temp, addr[index]) - temp;
 		if (leading_zeros) {
 			if (digits < 3)