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author | David Howells <dhowells@redhat.com> | 2012-03-28 18:30:01 +0100 |
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committer | David Howells <dhowells@redhat.com> | 2012-03-28 18:30:01 +0100 |
commit | 9f97da78bf018206fb623cd351d454af2f105fe0 (patch) | |
tree | 509971bf0d93f56d7ad182bdad3c89886f7ce675 /arch/arm/include/asm/cmpxchg.h | |
parent | 15d07dc9c59eae51219c40253bdf920f62bb10f2 (diff) | |
download | op-kernel-dev-9f97da78bf018206fb623cd351d454af2f105fe0.zip op-kernel-dev-9f97da78bf018206fb623cd351d454af2f105fe0.tar.gz |
Disintegrate asm/system.h for ARM
Disintegrate asm/system.h for ARM.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org
Diffstat (limited to 'arch/arm/include/asm/cmpxchg.h')
-rw-r--r-- | arch/arm/include/asm/cmpxchg.h | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h new file mode 100644 index 0000000..d41d7cb --- /dev/null +++ b/arch/arm/include/asm/cmpxchg.h @@ -0,0 +1,295 @@ +#ifndef __ASM_ARM_CMPXCHG_H +#define __ASM_ARM_CMPXCHG_H + +#include <linux/irqflags.h> +#include <asm/barrier.h> + +#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) +/* + * On the StrongARM, "swp" is terminally broken since it bypasses the + * cache totally. This means that the cache becomes inconsistent, and, + * since we use normal loads/stores as well, this is really bad. + * Typically, this causes oopsen in filp_close, but could have other, + * more disastrous effects. There are two work-arounds: + * 1. Disable interrupts and emulate the atomic swap + * 2. Clean the cache, perform atomic swap, flush the cache + * + * We choose (1) since its the "easiest" to achieve here and is not + * dependent on the processor type. + * + * NOTE that this solution won't work on an SMP system, so explcitly + * forbid it here. + */ +#define swp_is_buggy +#endif + +static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size) +{ + extern void __bad_xchg(volatile void *, int); + unsigned long ret; +#ifdef swp_is_buggy + unsigned long flags; +#endif +#if __LINUX_ARM_ARCH__ >= 6 + unsigned int tmp; +#endif + + smp_mb(); + + switch (size) { +#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: + raw_local_irq_save(flags); + ret = *(volatile unsigned char *)ptr; + *(volatile unsigned char *)ptr = x; + raw_local_irq_restore(flags); + break; + + case 4: + raw_local_irq_save(flags); + ret = *(volatile unsigned long *)ptr; + *(volatile unsigned long *)ptr = x; + raw_local_irq_restore(flags); + break; +#else + case 1: + asm volatile("@ __xchg1\n" + " swpb %0, %1, [%2]" + : "=&r" (ret) + : "r" (x), "r" (ptr) + : "memory", "cc"); + break; + case 4: + asm volatile("@ __xchg4\n" + " swp %0, %1, [%2]" + : "=&r" (ret) + : "r" (x), "r" (ptr) + : "memory", "cc"); + break; +#endif + default: + __bad_xchg(ptr, size), ret = 0; + break; + } + smp_mb(); + + return ret; +} + +#define xchg(ptr,x) \ + ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) + +#include <asm-generic/cmpxchg-local.h> + +#if __LINUX_ARM_ARCH__ < 6 +/* min ARCH < ARMv6 */ + +#ifdef CONFIG_SMP +#error "SMP is not supported on this platform" +#endif + +/* + * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make + * them available. + */ +#define cmpxchg_local(ptr, o, n) \ + ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ + (unsigned long)(n), sizeof(*(ptr)))) +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) + +#ifndef CONFIG_SMP +#include <asm-generic/cmpxchg.h> +#endif + +#else /* min ARCH >= ARMv6 */ + +extern void __bad_cmpxchg(volatile void *ptr, int size); + +/* + * cmpxchg only support 32-bits operands on ARMv6. + */ + +static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + unsigned long oldval, res; + + switch (size) { +#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ + case 1: + do { + asm volatile("@ __cmpxchg1\n" + " ldrexb %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexbeq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; + case 2: + do { + asm volatile("@ __cmpxchg1\n" + " ldrexh %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexheq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; +#endif + case 4: + do { + asm volatile("@ __cmpxchg4\n" + " ldrex %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexeq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; + default: + __bad_cmpxchg(ptr, size); + oldval = 0; + } + + return oldval; +} + +static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + unsigned long ret; + + smp_mb(); + ret = __cmpxchg(ptr, old, new, size); + smp_mb(); + + return ret; +} + +#define cmpxchg(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) + +static inline unsigned long __cmpxchg_local(volatile void *ptr, + unsigned long old, + unsigned long new, int size) +{ + unsigned long ret; + + switch (size) { +#ifdef CONFIG_CPU_V6 /* min ARCH == ARMv6 */ + case 1: + case 2: + ret = __cmpxchg_local_generic(ptr, old, new, size); + break; +#endif + default: + ret = __cmpxchg(ptr, old, new, size); + } + + return ret; +} + +#define cmpxchg_local(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) + +#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ + +/* + * Note : ARMv7-M (currently unsupported by Linux) does not support + * ldrexd/strexd. If ARMv7-M is ever supported by the Linux kernel, it should + * not be allowed to use __cmpxchg64. + */ +static inline unsigned long long __cmpxchg64(volatile void *ptr, + unsigned long long old, + unsigned long long new) +{ + register unsigned long long oldval asm("r0"); + register unsigned long long __old asm("r2") = old; + register unsigned long long __new asm("r4") = new; + unsigned long res; + + do { + asm volatile( + " @ __cmpxchg8\n" + " ldrexd %1, %H1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " teqeq %H1, %H3\n" + " strexdeq %0, %4, %H4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (__old), "r" (__new) + : "memory", "cc"); + } while (res); + + return oldval; +} + +static inline unsigned long long __cmpxchg64_mb(volatile void *ptr, + unsigned long long old, + unsigned long long new) +{ + unsigned long long ret; + + smp_mb(); + ret = __cmpxchg64(ptr, old, new); + smp_mb(); + + return ret; +} + +#define cmpxchg64(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#define cmpxchg64_local(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg64((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#else /* min ARCH = ARMv6 */ + +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) + +#endif + +#endif /* __LINUX_ARM_ARCH__ >= 6 */ + +#endif /* __ASM_ARM_CMPXCHG_H */ |