From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arm/include/asm/cmpxchg.h | 288 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 288 insertions(+) create mode 100644 arch/arm/include/asm/cmpxchg.h (limited to 'arch/arm/include/asm/cmpxchg.h') diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h new file mode 100644 index 000000000..abb2c3769 --- /dev/null +++ b/arch/arm/include/asm/cmpxchg.h @@ -0,0 +1,288 @@ +#ifndef __ASM_ARM_CMPXCHG_H +#define __ASM_ARM_CMPXCHG_H + +#include +#include +#include + +#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(); + prefetchw((const void *)ptr); + + 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 + +#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 +#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; + + prefetchw((const void *)ptr); + + 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; +} + +static inline unsigned long long __cmpxchg64(unsigned long long *ptr, + unsigned long long old, + unsigned long long new) +{ + unsigned long long oldval; + unsigned long res; + + prefetchw(ptr); + + __asm__ __volatile__( +"1: ldrexd %1, %H1, [%3]\n" +" teq %1, %4\n" +" teqeq %H1, %H4\n" +" bne 2f\n" +" strexd %0, %5, %H5, [%3]\n" +" teq %0, #0\n" +" bne 1b\n" +"2:" + : "=&r" (res), "=&r" (oldval), "+Qo" (*ptr) + : "r" (ptr), "r" (old), "r" (new) + : "cc"); + + return oldval; +} + +static inline unsigned long long __cmpxchg64_mb(unsigned long long *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 cmpxchg_local(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) + +#define cmpxchg64(ptr, o, n) \ + ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#define cmpxchg64_relaxed(ptr, o, n) \ + ((__typeof__(*(ptr)))__cmpxchg64((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#define cmpxchg64_local(ptr, o, n) cmpxchg64_relaxed((ptr), (o), (n)) + +#endif /* __LINUX_ARM_ARCH__ >= 6 */ + +#endif /* __ASM_ARM_CMPXCHG_H */ -- cgit v1.2.3-54-g00ecf