linux-stable/arch/mips/lib/bitops.c
David Daney 0c81157b46 MIPS: Fix logic errors in bitops.c
commit 92d11594f6 (MIPS: Remove irqflags.h dependency from bitops.h)
factored some of the bitops code out into a separate file
(arch/mips/lib/bitops.c).  Unfortunately the logic converting a bit
mask into a boolean result was lost in some of the functions.  We had:

   int res;
   unsigned long shifted_result_bit;
   .
   .
   .
   res = shifted_result_bit;
   return res;

Which truncates off the high 32 bits (thus yielding an incorrect
value) on 64-bit systems.

The manifestation of this is that a non-SMP 64-bit kernel will not
boot as the bitmap operations in bootmem.c are all screwed up.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc:  linux-mips@linux-mips.org
Cc: Jim Quinlan <jim2101024@gmail.com>
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/4965/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-03-12 18:57:47 +01:00

179 lines
4.3 KiB
C

/*
* 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.
*
* Copyright (c) 1994-1997, 99, 2000, 06, 07 Ralf Baechle (ralf@linux-mips.org)
* Copyright (c) 1999, 2000 Silicon Graphics, Inc.
*/
#include <linux/bitops.h>
#include <linux/irqflags.h>
#include <linux/export.h>
/**
* __mips_set_bit - Atomically set a bit in memory. This is called by
* set_bit() if it cannot find a faster solution.
* @nr: the bit to set
* @addr: the address to start counting from
*/
void __mips_set_bit(unsigned long nr, volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
*a |= mask;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL(__mips_set_bit);
/**
* __mips_clear_bit - Clears a bit in memory. This is called by clear_bit() if
* it cannot find a faster solution.
* @nr: Bit to clear
* @addr: Address to start counting from
*/
void __mips_clear_bit(unsigned long nr, volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
*a &= ~mask;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL(__mips_clear_bit);
/**
* __mips_change_bit - Toggle a bit in memory. This is called by change_bit()
* if it cannot find a faster solution.
* @nr: Bit to change
* @addr: Address to start counting from
*/
void __mips_change_bit(unsigned long nr, volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
*a ^= mask;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL(__mips_change_bit);
/**
* __mips_test_and_set_bit - Set a bit and return its old value. This is
* called by test_and_set_bit() if it cannot find a faster solution.
* @nr: Bit to set
* @addr: Address to count from
*/
int __mips_test_and_set_bit(unsigned long nr,
volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
int res;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
res = (mask & *a) != 0;
*a |= mask;
raw_local_irq_restore(flags);
return res;
}
EXPORT_SYMBOL(__mips_test_and_set_bit);
/**
* __mips_test_and_set_bit_lock - Set a bit and return its old value. This is
* called by test_and_set_bit_lock() if it cannot find a faster solution.
* @nr: Bit to set
* @addr: Address to count from
*/
int __mips_test_and_set_bit_lock(unsigned long nr,
volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
int res;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
res = (mask & *a) != 0;
*a |= mask;
raw_local_irq_restore(flags);
return res;
}
EXPORT_SYMBOL(__mips_test_and_set_bit_lock);
/**
* __mips_test_and_clear_bit - Clear a bit and return its old value. This is
* called by test_and_clear_bit() if it cannot find a faster solution.
* @nr: Bit to clear
* @addr: Address to count from
*/
int __mips_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
int res;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
res = (mask & *a) != 0;
*a &= ~mask;
raw_local_irq_restore(flags);
return res;
}
EXPORT_SYMBOL(__mips_test_and_clear_bit);
/**
* __mips_test_and_change_bit - Change a bit and return its old value. This is
* called by test_and_change_bit() if it cannot find a faster solution.
* @nr: Bit to change
* @addr: Address to count from
*/
int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr)
{
volatile unsigned long *a = addr;
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
int res;
a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
res = (mask & *a) != 0;
*a ^= mask;
raw_local_irq_restore(flags);
return res;
}
EXPORT_SYMBOL(__mips_test_and_change_bit);