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Diffstat (limited to '')
| -rw-r--r-- | arch/mips/include/asm/cmpxchg.h | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h new file mode 100644 index 000000000..520ca166c --- /dev/null +++ b/arch/mips/include/asm/cmpxchg.h @@ -0,0 +1,215 @@ +/* + * 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) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org) + */ +#ifndef __ASM_CMPXCHG_H +#define __ASM_CMPXCHG_H + +#include <linux/bug.h> +#include <linux/irqflags.h> +#include <asm/compiler.h> +#include <asm/war.h> + +/* + * Using a branch-likely instruction to check the result of an sc instruction + * works around a bug present in R10000 CPUs prior to revision 3.0 that could + * cause ll-sc sequences to execute non-atomically. + */ +#if R10000_LLSC_WAR +# define __scbeqz "beqzl" +#else +# define __scbeqz "beqz" +#endif + +/* + * These functions doesn't exist, so if they are called you'll either: + * + * - Get an error at compile-time due to __compiletime_error, if supported by + * your compiler. + * + * or: + * + * - Get an error at link-time due to the call to the missing function. + */ +extern unsigned long __cmpxchg_called_with_bad_pointer(void) + __compiletime_error("Bad argument size for cmpxchg"); +extern unsigned long __xchg_called_with_bad_pointer(void) + __compiletime_error("Bad argument size for xchg"); + +#define __xchg_asm(ld, st, m, val) \ +({ \ + __typeof(*(m)) __ret; \ + \ + if (kernel_uses_llsc) { \ + __asm__ __volatile__( \ + " .set push \n" \ + " .set noat \n" \ + " .set " MIPS_ISA_ARCH_LEVEL " \n" \ + "1: " ld " %0, %2 # __xchg_asm \n" \ + " .set mips0 \n" \ + " move $1, %z3 \n" \ + " .set " MIPS_ISA_ARCH_LEVEL " \n" \ + " " st " $1, %1 \n" \ + "\t" __scbeqz " $1, 1b \n" \ + " .set pop \n" \ + : "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \ + : GCC_OFF_SMALL_ASM() (*m), "Jr" (val) \ + : "memory"); \ + } else { \ + unsigned long __flags; \ + \ + raw_local_irq_save(__flags); \ + __ret = *m; \ + *m = val; \ + raw_local_irq_restore(__flags); \ + } \ + \ + __ret; \ +}) + +extern unsigned long __xchg_small(volatile void *ptr, unsigned long val, + unsigned int size); + +static __always_inline +unsigned long __xchg(volatile void *ptr, unsigned long x, int size) +{ + switch (size) { + case 1: + case 2: + return __xchg_small(ptr, x, size); + + case 4: + return __xchg_asm("ll", "sc", (volatile u32 *)ptr, x); + + case 8: + if (!IS_ENABLED(CONFIG_64BIT)) + return __xchg_called_with_bad_pointer(); + + return __xchg_asm("lld", "scd", (volatile u64 *)ptr, x); + + default: + return __xchg_called_with_bad_pointer(); + } +} + +#define xchg(ptr, x) \ +({ \ + __typeof__(*(ptr)) __res; \ + \ + smp_mb__before_llsc(); \ + \ + __res = (__typeof__(*(ptr))) \ + __xchg((ptr), (unsigned long)(x), sizeof(*(ptr))); \ + \ + smp_llsc_mb(); \ + \ + __res; \ +}) + +#define __cmpxchg_asm(ld, st, m, old, new) \ +({ \ + __typeof(*(m)) __ret; \ + \ + if (kernel_uses_llsc) { \ + __asm__ __volatile__( \ + " .set push \n" \ + " .set noat \n" \ + " .set "MIPS_ISA_ARCH_LEVEL" \n" \ + "1: " ld " %0, %2 # __cmpxchg_asm \n" \ + " bne %0, %z3, 2f \n" \ + " .set mips0 \n" \ + " move $1, %z4 \n" \ + " .set "MIPS_ISA_ARCH_LEVEL" \n" \ + " " st " $1, %1 \n" \ + "\t" __scbeqz " $1, 1b \n" \ + " .set pop \n" \ + "2: \n" \ + : "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \ + : GCC_OFF_SMALL_ASM() (*m), "Jr" (old), "Jr" (new) \ + : "memory"); \ + } else { \ + unsigned long __flags; \ + \ + raw_local_irq_save(__flags); \ + __ret = *m; \ + if (__ret == old) \ + *m = new; \ + raw_local_irq_restore(__flags); \ + } \ + \ + __ret; \ +}) + +extern unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old, + unsigned long new, unsigned int size); + +static __always_inline +unsigned long __cmpxchg(volatile void *ptr, unsigned long old, + unsigned long new, unsigned int size) +{ + switch (size) { + case 1: + case 2: + return __cmpxchg_small(ptr, old, new, size); + + case 4: + return __cmpxchg_asm("ll", "sc", (volatile u32 *)ptr, + (u32)old, new); + + case 8: + /* lld/scd are only available for MIPS64 */ + if (!IS_ENABLED(CONFIG_64BIT)) + return __cmpxchg_called_with_bad_pointer(); + + return __cmpxchg_asm("lld", "scd", (volatile u64 *)ptr, + (u64)old, new); + + default: + return __cmpxchg_called_with_bad_pointer(); + } +} + +#define cmpxchg_local(ptr, old, new) \ + ((__typeof__(*(ptr))) \ + __cmpxchg((ptr), \ + (unsigned long)(__typeof__(*(ptr)))(old), \ + (unsigned long)(__typeof__(*(ptr)))(new), \ + sizeof(*(ptr)))) + +#define cmpxchg(ptr, old, new) \ +({ \ + __typeof__(*(ptr)) __res; \ + \ + smp_mb__before_llsc(); \ + __res = cmpxchg_local((ptr), (old), (new)); \ + smp_llsc_mb(); \ + \ + __res; \ +}) + +#ifdef CONFIG_64BIT +#define cmpxchg64_local(ptr, o, n) \ + ({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + cmpxchg_local((ptr), (o), (n)); \ + }) + +#define cmpxchg64(ptr, o, n) \ + ({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + cmpxchg((ptr), (o), (n)); \ + }) +#else +#include <asm-generic/cmpxchg-local.h> +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) +#ifndef CONFIG_SMP +#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n)) +#endif +#endif + +#undef __scbeqz + +#endif /* __ASM_CMPXCHG_H */ |