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Commit 9560782f authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[PATCH] ARM SMP: Use exclusive load/store for __xchg 



Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 6b6a93c6

include/asm-arm/system.h

+58 −29
Original line number Original line Diff line number Diff line
@@ -323,12 +323,8 @@ do { \ 
 * NOTE that this solution won't work on an SMP system, so explcitly

 * NOTE that this solution won't work on an SMP system, so explcitly

 * forbid it here.

 * forbid it here.

 */

 */

#ifdef CONFIG_SMP

#error SMP is not supported on SA1100/SA110

#else

#define swp_is_buggy

#define swp_is_buggy

#endif

#endif

#endif





static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)

static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)

{

{
@@ -337,9 +333,36 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size 
#ifdef swp_is_buggy

#ifdef swp_is_buggy

	unsigned long flags;

	unsigned long flags;

#endif

#endif

#if __LINUX_ARM_ARCH__ >= 6

	unsigned int tmp;

#endif





	switch (size) {

	switch (size) {

#ifdef swp_is_buggy

#if __LINUX_ARM_ARCH__ >= 6

	case 1:

		asm volatile("@	__xchg1\n"

		"1:	ldrexb	%0, [%3]\n"

		"	strexb	%1, %2, [%3]\n"

		"	teq	%1, #0\n"

		"	bne	1b"

			: "=&r" (ret), "=&r" (tmp)

			: "r" (x), "r" (ptr)

			: "memory", "cc");

		break;

	case 4:

		asm volatile("@	__xchg4\n"

		"1:	ldrex	%0, [%3]\n"

		"	strex	%1, %2, [%3]\n"

		"	teq	%1, #0\n"

		"	bne	1b"

			: "=&r" (ret), "=&r" (tmp)

			: "r" (x), "r" (ptr)

			: "memory", "cc");

		break;

#elif defined(swp_is_buggy)

#ifdef CONFIG_SMP

#error SMP is not supported on this platform

#endif

	case 1:

	case 1:

		local_irq_save(flags);

		local_irq_save(flags);

		ret = *(volatile unsigned char *)ptr;

		ret = *(volatile unsigned char *)ptr;
@@ -354,18 +377,24 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size 
		local_irq_restore(flags);

		local_irq_restore(flags);

		break;

		break;

#else

#else

		case 1:	__asm__ __volatile__ ("swpb %0, %1, [%2]"

	case 1:

		asm volatile("@	__xchg1\n"

		"	swpb	%0, %1, [%2]"

			: "=&r" (ret)

			: "=&r" (ret)

			: "r" (x), "r" (ptr)

			: "r" (x), "r" (ptr)

			: "memory", "cc");

			: "memory", "cc");

		break;

		break;

		case 4:	__asm__ __volatile__ ("swp %0, %1, [%2]"

	case 4:

		asm volatile("@	__xchg4\n"

		"	swp	%0, %1, [%2]"

			: "=&r" (ret)

			: "=&r" (ret)

			: "r" (x), "r" (ptr)

			: "r" (x), "r" (ptr)

			: "memory", "cc");

			: "memory", "cc");

		break;

		break;

#endif

#endif

		default: __bad_xchg(ptr, size), ret = 0;

	default:

		__bad_xchg(ptr, size), ret = 0;

		break;

	}

	}





	return ret;

	return ret;