Commit 0c81157b authored by David Daney's avatar David Daney Committed by Ralf Baechle
Browse files

MIPS: Fix logic errors in bitops.c 



commit 92d11594 (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: default avatarDavid 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent e744109f

arch/mips/lib/bitops.c

+8 −8
Original line number Diff line number Diff line
@@ -90,12 +90,12 @@ int __mips_test_and_set_bit(unsigned long nr, 
	unsigned bit = nr & SZLONG_MASK;

	unsigned long mask;

	unsigned long flags;

	unsigned long res;

	int res;



	a += nr >> SZLONG_LOG;

	mask = 1UL << bit;

	raw_local_irq_save(flags);

	res = (mask & *a);

	res = (mask & *a) != 0;

	*a |= mask;

	raw_local_irq_restore(flags);

	return res;
@@ -116,12 +116,12 @@ int __mips_test_and_set_bit_lock(unsigned long nr, 
	unsigned bit = nr & SZLONG_MASK;

	unsigned long mask;

	unsigned long flags;

	unsigned long res;

	int res;



	a += nr >> SZLONG_LOG;

	mask = 1UL << bit;

	raw_local_irq_save(flags);

	res = (mask & *a);

	res = (mask & *a) != 0;

	*a |= mask;

	raw_local_irq_restore(flags);

	return res;
@@ -141,12 +141,12 @@ int __mips_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) 
	unsigned bit = nr & SZLONG_MASK;

	unsigned long mask;

	unsigned long flags;

	unsigned long res;

	int res;



	a += nr >> SZLONG_LOG;

	mask = 1UL << bit;

	raw_local_irq_save(flags);

	res = (mask & *a);

	res = (mask & *a) != 0;

	*a &= ~mask;

	raw_local_irq_restore(flags);

	return res;
@@ -166,12 +166,12 @@ int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr) 
	unsigned bit = nr & SZLONG_MASK;

	unsigned long mask;

	unsigned long flags;

	unsigned long res;

	int res;



	a += nr >> SZLONG_LOG;

	mask = 1UL << bit;

	raw_local_irq_save(flags);

	res = (mask & *a);

	res = (mask & *a) != 0;

	*a ^= mask;

	raw_local_irq_restore(flags);

	return res;

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