linux-stable/include/linux/bitops.h
Josh Poimboeuf f80ac98a64 bitops: always inline sign extension helpers
With CONFIG_CC_OPTIMIZE_FOR_SIZE, objtool reports:

  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: i915_gem_execbuffer2_ioctl()+0x5b7: call to gen8_canonical_addr() with UACCESS enabled

This means i915_gem_execbuffer2_ioctl() is calling gen8_canonical_addr()
from the user_access_begin/end critical region (i.e, with SMAP disabled).

While it's probably harmless in this case, in general we like to avoid
extra function calls in SMAP-disabled regions because it can open up
inadvertent security holes.

Fix the warning by changing the sign extension helpers to __always_inline.
This convinces GCC to inline gen8_canonical_addr().

The sign extension functions are trivial anyway, so it makes sense to
always inline them.  With my test optimize-for-size-based config, this
actually shrinks the text size of i915_gem_execbuffer.o by 45 bytes -- and
no change for vmlinux.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://lkml.kernel.org/r/740179324b2b18b750b16295c48357f00b5fa9ed.1582982020.git.jpoimboe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:42 -07:00

304 lines
7.6 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_BITOPS_H
#define _LINUX_BITOPS_H
#include <asm/types.h>
#include <linux/bits.h>
/* Set bits in the first 'n' bytes when loaded from memory */
#ifdef __LITTLE_ENDIAN
# define aligned_byte_mask(n) ((1UL << 8*(n))-1)
#else
# define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n)))
#endif
#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
#define BITS_TO_U64(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
#define BITS_TO_U32(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
#define BITS_TO_BYTES(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
extern unsigned int __sw_hweight8(unsigned int w);
extern unsigned int __sw_hweight16(unsigned int w);
extern unsigned int __sw_hweight32(unsigned int w);
extern unsigned long __sw_hweight64(__u64 w);
/*
* Include this here because some architectures need generic_ffs/fls in
* scope
*/
#include <asm/bitops.h>
#define for_each_set_bit(bit, addr, size) \
for ((bit) = find_first_bit((addr), (size)); \
(bit) < (size); \
(bit) = find_next_bit((addr), (size), (bit) + 1))
/* same as for_each_set_bit() but use bit as value to start with */
#define for_each_set_bit_from(bit, addr, size) \
for ((bit) = find_next_bit((addr), (size), (bit)); \
(bit) < (size); \
(bit) = find_next_bit((addr), (size), (bit) + 1))
#define for_each_clear_bit(bit, addr, size) \
for ((bit) = find_first_zero_bit((addr), (size)); \
(bit) < (size); \
(bit) = find_next_zero_bit((addr), (size), (bit) + 1))
/* same as for_each_clear_bit() but use bit as value to start with */
#define for_each_clear_bit_from(bit, addr, size) \
for ((bit) = find_next_zero_bit((addr), (size), (bit)); \
(bit) < (size); \
(bit) = find_next_zero_bit((addr), (size), (bit) + 1))
/**
* for_each_set_clump8 - iterate over bitmap for each 8-bit clump with set bits
* @start: bit offset to start search and to store the current iteration offset
* @clump: location to store copy of current 8-bit clump
* @bits: bitmap address to base the search on
* @size: bitmap size in number of bits
*/
#define for_each_set_clump8(start, clump, bits, size) \
for ((start) = find_first_clump8(&(clump), (bits), (size)); \
(start) < (size); \
(start) = find_next_clump8(&(clump), (bits), (size), (start) + 8))
static inline int get_bitmask_order(unsigned int count)
{
int order;
order = fls(count);
return order; /* We could be slightly more clever with -1 here... */
}
static __always_inline unsigned long hweight_long(unsigned long w)
{
return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
}
/**
* rol64 - rotate a 64-bit value left
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u64 rol64(__u64 word, unsigned int shift)
{
return (word << (shift & 63)) | (word >> ((-shift) & 63));
}
/**
* ror64 - rotate a 64-bit value right
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u64 ror64(__u64 word, unsigned int shift)
{
return (word >> (shift & 63)) | (word << ((-shift) & 63));
}
/**
* rol32 - rotate a 32-bit value left
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u32 rol32(__u32 word, unsigned int shift)
{
return (word << (shift & 31)) | (word >> ((-shift) & 31));
}
/**
* ror32 - rotate a 32-bit value right
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u32 ror32(__u32 word, unsigned int shift)
{
return (word >> (shift & 31)) | (word << ((-shift) & 31));
}
/**
* rol16 - rotate a 16-bit value left
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u16 rol16(__u16 word, unsigned int shift)
{
return (word << (shift & 15)) | (word >> ((-shift) & 15));
}
/**
* ror16 - rotate a 16-bit value right
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u16 ror16(__u16 word, unsigned int shift)
{
return (word >> (shift & 15)) | (word << ((-shift) & 15));
}
/**
* rol8 - rotate an 8-bit value left
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u8 rol8(__u8 word, unsigned int shift)
{
return (word << (shift & 7)) | (word >> ((-shift) & 7));
}
/**
* ror8 - rotate an 8-bit value right
* @word: value to rotate
* @shift: bits to roll
*/
static inline __u8 ror8(__u8 word, unsigned int shift)
{
return (word >> (shift & 7)) | (word << ((-shift) & 7));
}
/**
* sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
* @value: value to sign extend
* @index: 0 based bit index (0<=index<32) to sign bit
*
* This is safe to use for 16- and 8-bit types as well.
*/
static __always_inline __s32 sign_extend32(__u32 value, int index)
{
__u8 shift = 31 - index;
return (__s32)(value << shift) >> shift;
}
/**
* sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
* @value: value to sign extend
* @index: 0 based bit index (0<=index<64) to sign bit
*/
static __always_inline __s64 sign_extend64(__u64 value, int index)
{
__u8 shift = 63 - index;
return (__s64)(value << shift) >> shift;
}
static inline unsigned fls_long(unsigned long l)
{
if (sizeof(l) == 4)
return fls(l);
return fls64(l);
}
static inline int get_count_order(unsigned int count)
{
int order;
order = fls(count) - 1;
if (count & (count - 1))
order++;
return order;
}
/**
* get_count_order_long - get order after rounding @l up to power of 2
* @l: parameter
*
* it is same as get_count_order() but with long type parameter
*/
static inline int get_count_order_long(unsigned long l)
{
if (l == 0UL)
return -1;
else if (l & (l - 1UL))
return (int)fls_long(l);
else
return (int)fls_long(l) - 1;
}
/**
* __ffs64 - find first set bit in a 64 bit word
* @word: The 64 bit word
*
* On 64 bit arches this is a synomyn for __ffs
* The result is not defined if no bits are set, so check that @word
* is non-zero before calling this.
*/
static inline unsigned long __ffs64(u64 word)
{
#if BITS_PER_LONG == 32
if (((u32)word) == 0UL)
return __ffs((u32)(word >> 32)) + 32;
#elif BITS_PER_LONG != 64
#error BITS_PER_LONG not 32 or 64
#endif
return __ffs((unsigned long)word);
}
/**
* assign_bit - Assign value to a bit in memory
* @nr: the bit to set
* @addr: the address to start counting from
* @value: the value to assign
*/
static __always_inline void assign_bit(long nr, volatile unsigned long *addr,
bool value)
{
if (value)
set_bit(nr, addr);
else
clear_bit(nr, addr);
}
static __always_inline void __assign_bit(long nr, volatile unsigned long *addr,
bool value)
{
if (value)
__set_bit(nr, addr);
else
__clear_bit(nr, addr);
}
#ifdef __KERNEL__
#ifndef set_mask_bits
#define set_mask_bits(ptr, mask, bits) \
({ \
const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
typeof(*(ptr)) old__, new__; \
\
do { \
old__ = READ_ONCE(*(ptr)); \
new__ = (old__ & ~mask__) | bits__; \
} while (cmpxchg(ptr, old__, new__) != old__); \
\
old__; \
})
#endif
#ifndef bit_clear_unless
#define bit_clear_unless(ptr, clear, test) \
({ \
const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
typeof(*(ptr)) old__, new__; \
\
do { \
old__ = READ_ONCE(*(ptr)); \
new__ = old__ & ~clear__; \
} while (!(old__ & test__) && \
cmpxchg(ptr, old__, new__) != old__); \
\
!(old__ & test__); \
})
#endif
#ifndef find_last_bit
/**
* find_last_bit - find the last set bit in a memory region
* @addr: The address to start the search at
* @size: The number of bits to search
*
* Returns the bit number of the last set bit, or size.
*/
extern unsigned long find_last_bit(const unsigned long *addr,
unsigned long size);
#endif
#endif /* __KERNEL__ */
#endif