Commit 77b9bd9c authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar

x86: generic versions of find_first_(zero_)bit, convert i386

Generic versions of __find_first_bit and __find_first_zero_bit
are introduced as simplified versions of __find_next_bit and
__find_next_zero_bit. Their compilation and use are guarded by
a new config variable GENERIC_FIND_FIRST_BIT.

The generic versions of find_first_bit and find_first_zero_bit
are implemented in terms of the newly introduced __find_first_bit
and __find_first_zero_bit.

This patch does not remove the i386-specific implementation,
but it does switch i386 to use the generic functions by setting
GENERIC_FIND_FIRST_BIT=y for X86_32.
Signed-off-by: 's avatarAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: 's avatarIngo Molnar <mingo@elte.hu>
parent d57594c2
......@@ -77,6 +77,9 @@ config GENERIC_BUG
def_bool y
depends on BUG
config GENERIC_FIND_FIRST_BIT
def_bool X86_32
config GENERIC_FIND_NEXT_BIT
def_bool y
......
......@@ -5,6 +5,7 @@
* Copyright 1992, Linus Torvalds.
*/
#ifndef CONFIG_GENERIC_FIND_FIRST_BIT
/**
* find_first_zero_bit - find the first zero bit in a memory region
* @addr: The address to start the search at
......@@ -59,6 +60,7 @@ static inline unsigned find_first_bit(const unsigned long *addr, unsigned size)
}
return x;
}
#endif
#ifdef __KERNEL__
......
......@@ -113,6 +113,40 @@ static inline unsigned fls_long(unsigned long l)
}
#ifdef __KERNEL__
#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
extern unsigned long __find_first_bit(const unsigned long *addr,
unsigned long size);
/**
* find_first_bit - find the first set bit in a memory region
* @addr: The address to start the search at
* @size: The maximum size to search
*
* Returns the bit number of the first set bit.
*/
static __always_inline unsigned long
find_first_bit(const unsigned long *addr, unsigned long size)
{
return __find_first_bit(addr, size);
}
extern unsigned long __find_first_zero_bit(const unsigned long *addr,
unsigned long size);
/**
* find_first_zero_bit - find the first cleared bit in a memory region
* @addr: The address to start the search at
* @size: The maximum size to search
*
* Returns the bit number of the first cleared bit.
*/
static __always_inline unsigned long
find_first_zero_bit(const unsigned long *addr, unsigned long size)
{
return __find_first_zero_bit(addr, size);
}
#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
extern unsigned long __find_next_bit(const unsigned long *addr,
unsigned long size, unsigned long offset);
......
......@@ -29,6 +29,7 @@ obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o
obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
lib-$(CONFIG_GENERIC_FIND_FIRST_BIT) += find_next_bit.o
lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o
......
......@@ -16,6 +16,7 @@
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
/*
* Find the next set bit in a memory region.
*/
......@@ -102,6 +103,63 @@ unsigned long __find_next_zero_bit(const unsigned long *addr,
return result + ffz(tmp);
}
EXPORT_SYMBOL(__find_next_zero_bit);
#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
#ifdef CONFIG_GENERIC_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);
/*
* 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 /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifdef __BIG_ENDIAN
......
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