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linux/arch/m68k/include/asm/bitops_mm.h
Geert Uytterhoeven f82a519f12 m68k: bitops - Never step beyond the end of the bitmap 
find_next bitops on m68k (find_next_zero_bit, find_next_bit, and
find_next_bit_le) may cause out of bounds memory access
when the bitmap size in bits % 32 != 0 and offset (the bitnumber
to start searching at) is very close to the bitmap size.

For example,

       unsigned long bitmap[2] = { 0, 0 };
       find_next_bit(bitmap, 63, 62);

1. find_next_bit() tries to find any set bits in bitmap[1],
   but no bits set.

2. Then find_first_bit(bimap + 2, -1)

3. Unfortunately find_first_bit() takes unsigned int as the size argument.

4. find_first_bit will access bitmap[2~] until it find any set bits.

Add missing tests for stepping beyond the end of the bitmap to all
find_{first,next}_*() functions, and make sure they never return a value
larger than the bitmap size.

Reported-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
2011-05-19 18:19:09 +02:00

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#ifndef _M68K_BITOPS_H
#define _M68K_BITOPS_H
/*
* Copyright 1992, Linus Torvalds.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive
* for more details.
*/
#ifndef _LINUX_BITOPS_H
#error only <linux/bitops.h> can be included directly
#endif
#include <linux/compiler.h>
/*
* Require 68020 or better.
*
* They use the standard big-endian m680x0 bit ordering.
*/
#define test_and_set_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_test_and_set_bit(nr, vaddr) : \
__generic_test_and_set_bit(nr, vaddr))
#define __test_and_set_bit(nr,vaddr) test_and_set_bit(nr,vaddr)
static inline int __constant_test_and_set_bit(int nr, unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
char retval;
__asm__ __volatile__ ("bset %2,%1; sne %0"
: "=d" (retval), "+m" (*p)
: "di" (nr & 7));
return retval;
}
static inline int __generic_test_and_set_bit(int nr, unsigned long *vaddr)
{
char retval;
__asm__ __volatile__ ("bfset %2{%1:#1}; sne %0"
: "=d" (retval) : "d" (nr^31), "o" (*vaddr) : "memory");
return retval;
}
#define set_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_set_bit(nr, vaddr) : \
__generic_set_bit(nr, vaddr))
#define __set_bit(nr,vaddr) set_bit(nr,vaddr)
static inline void __constant_set_bit(int nr, volatile unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
__asm__ __volatile__ ("bset %1,%0"
: "+m" (*p) : "di" (nr & 7));
}
static inline void __generic_set_bit(int nr, volatile unsigned long *vaddr)
{
__asm__ __volatile__ ("bfset %1{%0:#1}"
: : "d" (nr^31), "o" (*vaddr) : "memory");
}
#define test_and_clear_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_test_and_clear_bit(nr, vaddr) : \
__generic_test_and_clear_bit(nr, vaddr))
#define __test_and_clear_bit(nr,vaddr) test_and_clear_bit(nr,vaddr)
static inline int __constant_test_and_clear_bit(int nr, unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
char retval;
__asm__ __volatile__ ("bclr %2,%1; sne %0"
: "=d" (retval), "+m" (*p)
: "di" (nr & 7));
return retval;
}
static inline int __generic_test_and_clear_bit(int nr, unsigned long *vaddr)
{
char retval;
__asm__ __volatile__ ("bfclr %2{%1:#1}; sne %0"
: "=d" (retval) : "d" (nr^31), "o" (*vaddr) : "memory");
return retval;
}
/*
* clear_bit() doesn't provide any barrier for the compiler.
*/
#define smp_mb__before_clear_bit() barrier()
#define smp_mb__after_clear_bit() barrier()
#define clear_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_clear_bit(nr, vaddr) : \
__generic_clear_bit(nr, vaddr))
#define __clear_bit(nr,vaddr) clear_bit(nr,vaddr)
static inline void __constant_clear_bit(int nr, volatile unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
__asm__ __volatile__ ("bclr %1,%0"
: "+m" (*p) : "di" (nr & 7));
}
static inline void __generic_clear_bit(int nr, volatile unsigned long *vaddr)
{
__asm__ __volatile__ ("bfclr %1{%0:#1}"
: : "d" (nr^31), "o" (*vaddr) : "memory");
}
#define test_and_change_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_test_and_change_bit(nr, vaddr) : \
__generic_test_and_change_bit(nr, vaddr))
#define __test_and_change_bit(nr,vaddr) test_and_change_bit(nr,vaddr)
#define __change_bit(nr,vaddr) change_bit(nr,vaddr)
static inline int __constant_test_and_change_bit(int nr, unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
char retval;
__asm__ __volatile__ ("bchg %2,%1; sne %0"
: "=d" (retval), "+m" (*p)
: "di" (nr & 7));
return retval;
}
static inline int __generic_test_and_change_bit(int nr, unsigned long *vaddr)
{
char retval;
__asm__ __volatile__ ("bfchg %2{%1:#1}; sne %0"
: "=d" (retval) : "d" (nr^31), "o" (*vaddr) : "memory");
return retval;
}
#define change_bit(nr,vaddr) \
(__builtin_constant_p(nr) ? \
__constant_change_bit(nr, vaddr) : \
__generic_change_bit(nr, vaddr))
static inline void __constant_change_bit(int nr, unsigned long *vaddr)
{
char *p = (char *)vaddr + (nr ^ 31) / 8;
__asm__ __volatile__ ("bchg %1,%0"
: "+m" (*p) : "di" (nr & 7));
}
static inline void __generic_change_bit(int nr, unsigned long *vaddr)
{
__asm__ __volatile__ ("bfchg %1{%0:#1}"
: : "d" (nr^31), "o" (*vaddr) : "memory");
}
static inline int test_bit(int nr, const unsigned long *vaddr)
{
return (vaddr[nr >> 5] & (1UL << (nr & 31))) != 0;
}
static inline int find_first_zero_bit(const unsigned long *vaddr,
unsigned size)
{
const unsigned long *p = vaddr;
int res = 32;
unsigned int words;
unsigned long num;
if (!size)
return 0;
words = (size + 31) >> 5;
while (!(num = ~*p++)) {
if (!--words)
goto out;
}
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
res ^= 31;
out:
res += ((long)p - (long)vaddr - 4) * 8;
return res < size ? res : size;
}
static inline int find_next_zero_bit(const unsigned long *vaddr, int size,
int offset)
{
const unsigned long *p = vaddr + (offset >> 5);
int bit = offset & 31UL, res;
if (offset >= size)
return size;
if (bit) {
unsigned long num = ~*p++ & (~0UL << bit);
offset -= bit;
/* Look for zero in first longword */
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
if (res < 32) {
offset += res ^ 31;
return offset < size ? offset : size;
}
offset += 32;
if (offset >= size)
return size;
}
/* No zero yet, search remaining full bytes for a zero */
return offset + find_first_zero_bit(p, size - offset);
}
static inline int find_first_bit(const unsigned long *vaddr, unsigned size)
{
const unsigned long *p = vaddr;
int res = 32;
unsigned int words;
unsigned long num;
if (!size)
return 0;
words = (size + 31) >> 5;
while (!(num = *p++)) {
if (!--words)
goto out;
}
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
res ^= 31;
out:
res += ((long)p - (long)vaddr - 4) * 8;
return res < size ? res : size;
}
static inline int find_next_bit(const unsigned long *vaddr, int size,
int offset)
{
const unsigned long *p = vaddr + (offset >> 5);
int bit = offset & 31UL, res;
if (offset >= size)
return size;
if (bit) {
unsigned long num = *p++ & (~0UL << bit);
offset -= bit;
/* Look for one in first longword */
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
if (res < 32) {
offset += res ^ 31;
return offset < size ? offset : size;
}
offset += 32;
if (offset >= size)
return size;
}
/* No one yet, search remaining full bytes for a one */
return offset + find_first_bit(p, size - offset);
}
/*
* 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)
{
int res;
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (~word & -~word));
return res ^ 31;
}
#ifdef __KERNEL__
/*
* ffs: find first bit set. This is defined the same way as
* the libc and compiler builtin ffs routines, therefore
* differs in spirit from the above ffz (man ffs).
*/
static inline int ffs(int x)
{
int cnt;
asm ("bfffo %1{#0:#0},%0" : "=d" (cnt) : "dm" (x & -x));
return 32 - cnt;
}
#define __ffs(x) (ffs(x) - 1)
/*
* fls: find last bit set.
*/
static inline int fls(int x)
{
int cnt;
asm ("bfffo %1{#0,#0},%0" : "=d" (cnt) : "dm" (x));
return 32 - cnt;
}
static inline int __fls(int x)
{
return fls(x) - 1;
}
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/lock.h>
/* Bitmap functions for the little endian bitmap. */
static inline void __set_bit_le(int nr, void *addr)
{
__set_bit(nr ^ 24, addr);
}
static inline void __clear_bit_le(int nr, void *addr)
{
__clear_bit(nr ^ 24, addr);
}
static inline int __test_and_set_bit_le(int nr, void *addr)
{
return __test_and_set_bit(nr ^ 24, addr);
}
static inline int test_and_set_bit_le(int nr, void *addr)
{
return test_and_set_bit(nr ^ 24, addr);
}
static inline int __test_and_clear_bit_le(int nr, void *addr)
{
return __test_and_clear_bit(nr ^ 24, addr);
}
static inline int test_and_clear_bit_le(int nr, void *addr)
{
return test_and_clear_bit(nr ^ 24, addr);
}
static inline int test_bit_le(int nr, const void *vaddr)
{
const unsigned char *p = vaddr;
return (p[nr >> 3] & (1U << (nr & 7))) != 0;
}
static inline int find_first_zero_bit_le(const void *vaddr, unsigned size)
{
const unsigned long *p = vaddr, *addr = vaddr;
int res = 0;
unsigned int words;
if (!size)
return 0;
words = (size >> 5) + ((size & 31) > 0);
while (*p++ == ~0UL) {
if (--words == 0)
goto out;
}
--p;
for (res = 0; res < 32; res++)
if (!test_bit_le(res, p))
break;
out:
res += (p - addr) * 32;
return res < size ? res : size;
}
static inline unsigned long find_next_zero_bit_le(const void *addr,
unsigned long size, unsigned long offset)
{
const unsigned long *p = addr;
int bit = offset & 31UL, res;
if (offset >= size)
return size;
p += offset >> 5;
if (bit) {
offset -= bit;
/* Look for zero in first longword */
for (res = bit; res < 32; res++)
if (!test_bit_le(res, p)) {
offset += res;
return offset < size ? offset : size;
}
p++;
offset += 32;
if (offset >= size)
return size;
}
/* No zero yet, search remaining full bytes for a zero */
return offset + find_first_zero_bit_le(p, size - offset);
}
static inline int find_first_bit_le(const void *vaddr, unsigned size)
{
const unsigned long *p = vaddr, *addr = vaddr;
int res = 0;
unsigned int words;
if (!size)
return 0;
words = (size >> 5) + ((size & 31) > 0);
while (*p++ == 0UL) {
if (--words == 0)
goto out;
}
--p;
for (res = 0; res < 32; res++)
if (test_bit_le(res, p))
break;
out:
res += (p - addr) * 32;
return res < size ? res : size;
}
static inline unsigned long find_next_bit_le(const void *addr,
unsigned long size, unsigned long offset)
{
const unsigned long *p = addr;
int bit = offset & 31UL, res;
if (offset >= size)
return size;
p += offset >> 5;
if (bit) {
offset -= bit;
/* Look for one in first longword */
for (res = bit; res < 32; res++)
if (test_bit_le(res, p)) {
offset += res;
return offset < size ? offset : size;
}
p++;
offset += 32;
if (offset >= size)
return size;
}
/* No set bit yet, search remaining full bytes for a set bit */
return offset + find_first_bit_le(p, size - offset);
}
/* Bitmap functions for the ext2 filesystem. */
#define ext2_set_bit_atomic(lock, nr, addr) \
test_and_set_bit_le(nr, addr)
#define ext2_clear_bit_atomic(lock, nr, addr) \
test_and_clear_bit_le(nr, addr)
#endif /* __KERNEL__ */
#endif /* _M68K_BITOPS_H */
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