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linux/include/asm-m68knommu/bitops.h
Greg Ungerer 3960f2faaf [PATCH] m68knommu: fix find_next_zero_bit in bitops.h 
We're starting a number of big applications (memory footprint app.
1MByte) on our Arcturus uC5272.  Therefore memory fragmentation is a
real pain for us.  We've switched to uClinux-2.4.27-uc1 and found that
page_alloc2 fragments the memory heavily.

Digging into it we found a bug in the find_next_zero_bit function in the
m68knommu/bitops.h file.  if the size isn't a multiple of 32 than the
upper bits of the last word to be searched should be masked.  But the
functions masks the lower bits of the last word because it uses a right
shift instead of a left shift operator.

Patch submitted by Sascha Smejkal <s.smejkal@centersystems.at>

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 09:31:27 -08:00

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#ifndef _M68KNOMMU_BITOPS_H
#define _M68KNOMMU_BITOPS_H
/*
* Copyright 1992, Linus Torvalds.
*/
#include <linux/config.h>
#include <linux/compiler.h>
#include <asm/byteorder.h> /* swab32 */
#include <asm/system.h> /* save_flags */
#ifdef __KERNEL__
/*
* Generic ffs().
*/
static inline int ffs(int x)
{
int r = 1;
if (!x)
return 0;
if (!(x & 0xffff)) {
x >>= 16;
r += 16;
}
if (!(x & 0xff)) {
x >>= 8;
r += 8;
}
if (!(x & 0xf)) {
x >>= 4;
r += 4;
}
if (!(x & 3)) {
x >>= 2;
r += 2;
}
if (!(x & 1)) {
x >>= 1;
r += 1;
}
return r;
}
/*
* Generic __ffs().
*/
static inline int __ffs(int x)
{
int r = 0;
if (!x)
return 0;
if (!(x & 0xffff)) {
x >>= 16;
r += 16;
}
if (!(x & 0xff)) {
x >>= 8;
r += 8;
}
if (!(x & 0xf)) {
x >>= 4;
r += 4;
}
if (!(x & 3)) {
x >>= 2;
r += 2;
}
if (!(x & 1)) {
x >>= 1;
r += 1;
}
return r;
}
/*
* Every architecture must define this function. It's the fastest
* way of searching a 140-bit bitmap where the first 100 bits are
* unlikely to be set. It's guaranteed that at least one of the 140
* bits is cleared.
*/
static inline int sched_find_first_bit(unsigned long *b)
{
if (unlikely(b[0]))
return __ffs(b[0]);
if (unlikely(b[1]))
return __ffs(b[1]) + 32;
if (unlikely(b[2]))
return __ffs(b[2]) + 64;
if (b[3])
return __ffs(b[3]) + 96;
return __ffs(b[4]) + 128;
}
/*
* ffz = Find First Zero in word. Undefined if no zero exists,
* so code should check against ~0UL first..
*/
static __inline__ unsigned long ffz(unsigned long word)
{
unsigned long result = 0;
while(word & 1) {
result++;
word >>= 1;
}
return result;
}
static __inline__ void set_bit(int nr, volatile unsigned long * addr)
{
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %0,%%a0; bset %1,(%%a0)"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0", "cc");
#else
__asm__ __volatile__ ("bset %1,%0"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
: "cc");
#endif
}
#define __set_bit(nr, addr) set_bit(nr, addr)
/*
* clear_bit() doesn't provide any barrier for the compiler.
*/
#define smp_mb__before_clear_bit() barrier()
#define smp_mb__after_clear_bit() barrier()
static __inline__ void clear_bit(int nr, volatile unsigned long * addr)
{
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %0,%%a0; bclr %1,(%%a0)"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0", "cc");
#else
__asm__ __volatile__ ("bclr %1,%0"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
: "cc");
#endif
}
#define __clear_bit(nr, addr) clear_bit(nr, addr)
static __inline__ void change_bit(int nr, volatile unsigned long * addr)
{
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %0,%%a0; bchg %1,(%%a0)"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0", "cc");
#else
__asm__ __volatile__ ("bchg %1,%0"
: "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
: "cc");
#endif
}
#define __change_bit(nr, addr) change_bit(nr, addr)
static __inline__ int test_and_set_bit(int nr, volatile unsigned long * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0; bset %2,(%%a0); sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("bset %2,%1; sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
/* No clobber */);
#endif
return retval;
}
#define __test_and_set_bit(nr, addr) test_and_set_bit(nr, addr)
static __inline__ int test_and_clear_bit(int nr, volatile unsigned long * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0; bclr %2,(%%a0); sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("bclr %2,%1; sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
/* No clobber */);
#endif
return retval;
}
#define __test_and_clear_bit(nr, addr) test_and_clear_bit(nr, addr)
static __inline__ int test_and_change_bit(int nr, volatile unsigned long * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0\n\tbchg %2,(%%a0)\n\tsne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("bchg %2,%1; sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[(nr^31) >> 3])
: "di" (nr)
/* No clobber */);
#endif
return retval;
}
#define __test_and_change_bit(nr, addr) test_and_change_bit(nr, addr)
/*
* This routine doesn't need to be atomic.
*/
static __inline__ int __constant_test_bit(int nr, const volatile unsigned long * addr)
{
return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
}
static __inline__ int __test_bit(int nr, const volatile unsigned long * addr)
{
int * a = (int *) addr;
int mask;
a += nr >> 5;
mask = 1 << (nr & 0x1f);
return ((mask & *a) != 0);
}
#define test_bit(nr,addr) \
(__builtin_constant_p(nr) ? \
__constant_test_bit((nr),(addr)) : \
__test_bit((nr),(addr)))
#define find_first_zero_bit(addr, size) \
find_next_zero_bit((addr), (size), 0)
#define find_first_bit(addr, size) \
find_next_bit((addr), (size), 0)
static __inline__ int find_next_zero_bit (const void * addr, int size, int offset)
{
unsigned long *p = ((unsigned long *) addr) + (offset >> 5);
unsigned long result = offset & ~31UL;
unsigned long tmp;
if (offset >= size)
return size;
size -= result;
offset &= 31UL;
if (offset) {
tmp = *(p++);
tmp |= ~0UL >> (32-offset);
if (size < 32)
goto found_first;
if (~tmp)
goto found_middle;
size -= 32;
result += 32;
}
while (size & ~31UL) {
if (~(tmp = *(p++)))
goto found_middle;
result += 32;
size -= 32;
}
if (!size)
return result;
tmp = *p;
found_first:
tmp |= ~0UL << size;
found_middle:
return result + ffz(tmp);
}
/*
* Find next one bit in a bitmap reasonably efficiently.
*/
static __inline__ unsigned long find_next_bit(const unsigned long *addr,
unsigned long size, unsigned long offset)
{
unsigned int *p = ((unsigned int *) addr) + (offset >> 5);
unsigned int result = offset & ~31UL;
unsigned int tmp;
if (offset >= size)
return size;
size -= result;
offset &= 31UL;
if (offset) {
tmp = *p++;
tmp &= ~0UL << offset;
if (size < 32)
goto found_first;
if (tmp)
goto found_middle;
size -= 32;
result += 32;
}
while (size >= 32) {
if ((tmp = *p++) != 0)
goto found_middle;
result += 32;
size -= 32;
}
if (!size)
return result;
tmp = *p;
found_first:
tmp &= ~0UL >> (32 - size);
if (tmp == 0UL) /* Are any bits set? */
return result + size; /* Nope. */
found_middle:
return result + __ffs(tmp);
}
/*
* hweightN: returns the hamming weight (i.e. the number
* of bits set) of a N-bit word
*/
#define hweight32(x) generic_hweight32(x)
#define hweight16(x) generic_hweight16(x)
#define hweight8(x) generic_hweight8(x)
static __inline__ int ext2_set_bit(int nr, volatile void * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0; bset %2,(%%a0); sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[nr >> 3])
: "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("bset %2,%1; sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[nr >> 3])
: "di" (nr)
/* No clobber */);
#endif
return retval;
}
static __inline__ int ext2_clear_bit(int nr, volatile void * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0; bclr %2,(%%a0); sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[nr >> 3])
: "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("bclr %2,%1; sne %0"
: "=d" (retval), "+m" (((volatile char *)addr)[nr >> 3])
: "di" (nr)
/* No clobber */);
#endif
return retval;
}
#define ext2_set_bit_atomic(lock, nr, addr) \
({ \
int ret; \
spin_lock(lock); \
ret = ext2_set_bit((nr), (addr)); \
spin_unlock(lock); \
ret; \
})
#define ext2_clear_bit_atomic(lock, nr, addr) \
({ \
int ret; \
spin_lock(lock); \
ret = ext2_clear_bit((nr), (addr)); \
spin_unlock(lock); \
ret; \
})
static __inline__ int ext2_test_bit(int nr, const volatile void * addr)
{
char retval;
#ifdef CONFIG_COLDFIRE
__asm__ __volatile__ ("lea %1,%%a0; btst %2,(%%a0); sne %0"
: "=d" (retval)
: "m" (((const volatile char *)addr)[nr >> 3]), "d" (nr)
: "%a0");
#else
__asm__ __volatile__ ("btst %2,%1; sne %0"
: "=d" (retval)
: "m" (((const volatile char *)addr)[nr >> 3]), "di" (nr)
/* No clobber */);
#endif
return retval;
}
#define ext2_find_first_zero_bit(addr, size) \
ext2_find_next_zero_bit((addr), (size), 0)
static __inline__ unsigned long ext2_find_next_zero_bit(void *addr, unsigned long size, unsigned long offset)
{
unsigned long *p = ((unsigned long *) addr) + (offset >> 5);
unsigned long result = offset & ~31UL;
unsigned long tmp;
if (offset >= size)
return size;
size -= result;
offset &= 31UL;
if(offset) {
/* We hold the little endian value in tmp, but then the
* shift is illegal. So we could keep a big endian value
* in tmp, like this:
*
* tmp = __swab32(*(p++));
* tmp |= ~0UL >> (32-offset);
*
* but this would decrease preformance, so we change the
* shift:
*/
tmp = *(p++);
tmp |= __swab32(~0UL >> (32-offset));
if(size < 32)
goto found_first;
if(~tmp)
goto found_middle;
size -= 32;
result += 32;
}
while(size & ~31UL) {
if(~(tmp = *(p++)))
goto found_middle;
result += 32;
size -= 32;
}
if(!size)
return result;
tmp = *p;
found_first:
/* tmp is little endian, so we would have to swab the shift,
* see above. But then we have to swab tmp below for ffz, so
* we might as well do this here.
*/
return result + ffz(__swab32(tmp) | (~0UL << size));
found_middle:
return result + ffz(__swab32(tmp));
}
/* Bitmap functions for the minix filesystem. */
#define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
#define minix_set_bit(nr,addr) set_bit(nr,addr)
#define minix_test_and_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
#define minix_test_bit(nr,addr) test_bit(nr,addr)
#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
/**
* hweightN - returns the hamming weight of a N-bit word
* @x: the word to weigh
*
* The Hamming Weight of a number is the total number of bits set in it.
*/
#define hweight32(x) generic_hweight32(x)
#define hweight16(x) generic_hweight16(x)
#define hweight8(x) generic_hweight8(x)
#endif /* __KERNEL__ */
/*
* fls: find last bit set.
*/
#define fls(x) generic_fls(x)
#define fls64(x) generic_fls64(x)
#endif /* _M68KNOMMU_BITOPS_H */
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