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Diffstat (limited to 'arch/x86/include/asm/local.h')
| -rw-r--r-- | arch/x86/include/asm/local.h | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h new file mode 100644 index 000000000000..ae91994fd6c9 --- /dev/null +++ b/arch/x86/include/asm/local.h @@ -0,0 +1,235 @@ +#ifndef ASM_X86__LOCAL_H +#define ASM_X86__LOCAL_H + +#include <linux/percpu.h> + +#include <asm/system.h> +#include <asm/atomic.h> +#include <asm/asm.h> + +typedef struct { + atomic_long_t a; +} local_t; + +#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) } + +#define local_read(l) atomic_long_read(&(l)->a) +#define local_set(l, i) atomic_long_set(&(l)->a, (i)) + +static inline void local_inc(local_t *l) +{ + asm volatile(_ASM_INC "%0" + : "+m" (l->a.counter)); +} + +static inline void local_dec(local_t *l) +{ + asm volatile(_ASM_DEC "%0" + : "+m" (l->a.counter)); +} + +static inline void local_add(long i, local_t *l) +{ + asm volatile(_ASM_ADD "%1,%0" + : "+m" (l->a.counter) + : "ir" (i)); +} + +static inline void local_sub(long i, local_t *l) +{ + asm volatile(_ASM_SUB "%1,%0" + : "+m" (l->a.counter) + : "ir" (i)); +} + +/** + * local_sub_and_test - subtract value from variable and test result + * @i: integer value to subtract + * @l: pointer to type local_t + * + * Atomically subtracts @i from @l and returns + * true if the result is zero, or false for all + * other cases. + */ +static inline int local_sub_and_test(long i, local_t *l) +{ + unsigned char c; + + asm volatile(_ASM_SUB "%2,%0; sete %1" + : "+m" (l->a.counter), "=qm" (c) + : "ir" (i) : "memory"); + return c; +} + +/** + * local_dec_and_test - decrement and test + * @l: pointer to type local_t + * + * Atomically decrements @l by 1 and + * returns true if the result is 0, or false for all other + * cases. + */ +static inline int local_dec_and_test(local_t *l) +{ + unsigned char c; + + asm volatile(_ASM_DEC "%0; sete %1" + : "+m" (l->a.counter), "=qm" (c) + : : "memory"); + return c != 0; +} + +/** + * local_inc_and_test - increment and test + * @l: pointer to type local_t + * + * Atomically increments @l by 1 + * and returns true if the result is zero, or false for all + * other cases. + */ +static inline int local_inc_and_test(local_t *l) +{ + unsigned char c; + + asm volatile(_ASM_INC "%0; sete %1" + : "+m" (l->a.counter), "=qm" (c) + : : "memory"); + return c != 0; +} + +/** + * local_add_negative - add and test if negative + * @i: integer value to add + * @l: pointer to type local_t + * + * Atomically adds @i to @l and returns true + * if the result is negative, or false when + * result is greater than or equal to zero. + */ +static inline int local_add_negative(long i, local_t *l) +{ + unsigned char c; + + asm volatile(_ASM_ADD "%2,%0; sets %1" + : "+m" (l->a.counter), "=qm" (c) + : "ir" (i) : "memory"); + return c; +} + +/** + * local_add_return - add and return + * @i: integer value to add + * @l: pointer to type local_t + * + * Atomically adds @i to @l and returns @i + @l + */ +static inline long local_add_return(long i, local_t *l) +{ + long __i; +#ifdef CONFIG_M386 + unsigned long flags; + if (unlikely(boot_cpu_data.x86 <= 3)) + goto no_xadd; +#endif + /* Modern 486+ processor */ + __i = i; + asm volatile(_ASM_XADD "%0, %1;" + : "+r" (i), "+m" (l->a.counter) + : : "memory"); + return i + __i; + +#ifdef CONFIG_M386 +no_xadd: /* Legacy 386 processor */ + local_irq_save(flags); + __i = local_read(l); + local_set(l, i + __i); + local_irq_restore(flags); + return i + __i; +#endif +} + +static inline long local_sub_return(long i, local_t *l) +{ + return local_add_return(-i, l); +} + +#define local_inc_return(l) (local_add_return(1, l)) +#define local_dec_return(l) (local_sub_return(1, l)) + +#define local_cmpxchg(l, o, n) \ + (cmpxchg_local(&((l)->a.counter), (o), (n))) +/* Always has a lock prefix */ +#define local_xchg(l, n) (xchg(&((l)->a.counter), (n))) + +/** + * local_add_unless - add unless the number is a given value + * @l: pointer of type local_t + * @a: the amount to add to l... + * @u: ...unless l is equal to u. + * + * Atomically adds @a to @l, so long as it was not @u. + * Returns non-zero if @l was not @u, and zero otherwise. + */ +#define local_add_unless(l, a, u) \ +({ \ + long c, old; \ + c = local_read((l)); \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = local_cmpxchg((l), c, c + (a)); \ + if (likely(old == c)) \ + break; \ + c = old; \ + } \ + c != (u); \ +}) +#define local_inc_not_zero(l) local_add_unless((l), 1, 0) + +/* On x86_32, these are no better than the atomic variants. + * On x86-64 these are better than the atomic variants on SMP kernels + * because they dont use a lock prefix. + */ +#define __local_inc(l) local_inc(l) +#define __local_dec(l) local_dec(l) +#define __local_add(i, l) local_add((i), (l)) +#define __local_sub(i, l) local_sub((i), (l)) + +/* Use these for per-cpu local_t variables: on some archs they are + * much more efficient than these naive implementations. Note they take + * a variable, not an address. + * + * X86_64: This could be done better if we moved the per cpu data directly + * after GS. + */ + +/* Need to disable preemption for the cpu local counters otherwise we could + still access a variable of a previous CPU in a non atomic way. */ +#define cpu_local_wrap_v(l) \ +({ \ + local_t res__; \ + preempt_disable(); \ + res__ = (l); \ + preempt_enable(); \ + res__; \ +}) +#define cpu_local_wrap(l) \ +({ \ + preempt_disable(); \ + (l); \ + preempt_enable(); \ +}) \ + +#define cpu_local_read(l) cpu_local_wrap_v(local_read(&__get_cpu_var((l)))) +#define cpu_local_set(l, i) cpu_local_wrap(local_set(&__get_cpu_var((l)), (i))) +#define cpu_local_inc(l) cpu_local_wrap(local_inc(&__get_cpu_var((l)))) +#define cpu_local_dec(l) cpu_local_wrap(local_dec(&__get_cpu_var((l)))) +#define cpu_local_add(i, l) cpu_local_wrap(local_add((i), &__get_cpu_var((l)))) +#define cpu_local_sub(i, l) cpu_local_wrap(local_sub((i), &__get_cpu_var((l)))) + +#define __cpu_local_inc(l) cpu_local_inc((l)) +#define __cpu_local_dec(l) cpu_local_dec((l)) +#define __cpu_local_add(i, l) cpu_local_add((i), (l)) +#define __cpu_local_sub(i, l) cpu_local_sub((i), (l)) + +#endif /* ASM_X86__LOCAL_H */ |