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218ac107c5
find_next_zero_bit() incorrectly handles cases when:
- total bitmap size < 32
- rest of bits to process
static inline int find_next_zero_bit(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)
[1]
goto found_first;
if (~tmp)
goto found_middle;
size -= 32;
result += 32;
}
while (size & ~31UL) {
tmp = *(p++);
if (~tmp)
goto found_middle;
result += 32;
size -= 32;
}
[2]
if (!size)
return result;
tmp = *p;
found_first:
[3] tmp |= ~0UL >> size;
^^^ algo can reach above line from from points:
[1] offset > 0 and size < 32, tmp[offset-1..0] bits set to 1
[2] size < 32 - rest of bits to process
in both cases bits to search are tmp[size-1..0], but line [3] will simply
set all tmp[31-size..0] bits to 1 and ffz(tmp) below will fail.
example: bitmap size = 16, offset = 0, bitmap is empty.
code will go through the point [2], tmp = 0x0
after line [3] => tmp = 0xFFFF and ffz(tmp) will return 16.
found_middle:
return result + ffz(tmp);
}
Fix it by correctly seting tmp[31..size] bits to 1 in the above case [3].
Fixes: 81e9fe5a29 ("arm: implement find_next_zero_bit function")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
198 lines
4.6 KiB
C
198 lines
4.6 KiB
C
/*
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* Copyright 1995, Russell King.
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* Various bits and pieces copyrights include:
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* Linus Torvalds (test_bit).
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*
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* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
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*
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* Please note that the code in this file should never be included
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* from user space. Many of these are not implemented in assembler
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* since they would be too costly. Also, they require priviledged
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* instructions (which are not available from user mode) to ensure
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* that they are atomic.
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*/
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#ifndef __ASM_ARM_BITOPS_H
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#define __ASM_ARM_BITOPS_H
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#ifdef __KERNEL__
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#include <asm/proc-armv/system.h>
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#define smp_mb__before_clear_bit() do { } while (0)
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#define smp_mb__after_clear_bit() do { } while (0)
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/*
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* Function prototypes to keep gcc -Wall happy.
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*/
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extern void set_bit(int nr, volatile void * addr);
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extern void clear_bit(int nr, volatile void * addr);
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extern void change_bit(int nr, volatile void * addr);
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static inline void __change_bit(int nr, volatile void *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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*p ^= mask;
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}
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static inline int __test_and_set_bit(int nr, volatile void *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old | mask;
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return (old & mask) != 0;
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}
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static inline int test_and_set_bit(int nr, volatile void * addr)
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{
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unsigned long flags = 0;
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int out;
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local_irq_save(flags);
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out = __test_and_set_bit(nr, addr);
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local_irq_restore(flags);
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return out;
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}
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static inline int __test_and_clear_bit(int nr, volatile void *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old & ~mask;
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return (old & mask) != 0;
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}
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static inline int test_and_clear_bit(int nr, volatile void * addr)
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{
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unsigned long flags = 0;
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int out;
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local_irq_save(flags);
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out = __test_and_clear_bit(nr, addr);
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local_irq_restore(flags);
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return out;
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}
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extern int test_and_change_bit(int nr, volatile void * addr);
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static inline int __test_and_change_bit(int nr, volatile void *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
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unsigned long old = *p;
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*p = old ^ mask;
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return (old & mask) != 0;
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}
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/*
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* This routine doesn't need to be atomic.
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*/
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static inline int test_bit(int nr, const void * addr)
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{
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return ((unsigned char *) addr)[nr >> 3] & (1U << (nr & 7));
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}
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static inline int __ilog2(unsigned int x)
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{
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return generic_fls(x) - 1;
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}
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/*
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* ffz = Find First Zero in word. Undefined if no zero exists,
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* so code should check against ~0UL first..
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*/
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static inline unsigned long ffz(unsigned long word)
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{
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int k;
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word = ~word;
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k = 31;
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if (word & 0x0000ffff) { k -= 16; word <<= 16; }
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if (word & 0x00ff0000) { k -= 8; word <<= 8; }
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if (word & 0x0f000000) { k -= 4; word <<= 4; }
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if (word & 0x30000000) { k -= 2; word <<= 2; }
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if (word & 0x40000000) { k -= 1; }
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return k;
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}
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static inline int find_next_zero_bit(void *addr, int size, int offset)
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{
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unsigned long *p = ((unsigned long *)addr) + (offset >> 5);
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unsigned long result = offset & ~31UL;
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset &= 31UL;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (32-offset);
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if (size < 32)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= 32;
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result += 32;
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}
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while (size & ~31UL) {
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tmp = *(p++);
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if (~tmp)
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goto found_middle;
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result += 32;
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size -= 32;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp |= ~0UL << size;
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found_middle:
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return result + ffz(tmp);
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}
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/*
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* hweightN: returns the hamming weight (i.e. the number
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* of bits set) of a N-bit word
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*/
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#define hweight32(x) generic_hweight32(x)
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#define hweight16(x) generic_hweight16(x)
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#define hweight8(x) generic_hweight8(x)
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#define find_first_zero_bit(addr, size) \
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find_next_zero_bit((addr), (size), 0)
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#define ext2_set_bit test_and_set_bit
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#define ext2_clear_bit test_and_clear_bit
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#define ext2_test_bit test_bit
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#define ext2_find_first_zero_bit find_first_zero_bit
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#define ext2_find_next_zero_bit find_next_zero_bit
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/* Bitmap functions for the minix filesystem. */
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#define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
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#define minix_set_bit(nr,addr) set_bit(nr,addr)
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#define minix_test_and_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
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#define minix_test_bit(nr,addr) test_bit(nr,addr)
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#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
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#endif /* __KERNEL__ */
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#include <asm-generic/bitops/__fls.h>
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#include <asm-generic/bitops/__ffs.h>
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#include <asm-generic/bitops/fls.h>
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#include <asm-generic/bitops/fls64.h>
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#endif /* _ARM_BITOPS_H */
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