266 lines
6 KiB
C
266 lines
6 KiB
C
|
/*
|
||
|
|
* Generic barrier definitions.
|
||
|
|
*
|
||
|
|
* It should be possible to use these on really simple architectures,
|
||
|
|
* but it serves more as a starting point for new ports.
|
||
|
|
*
|
||
|
|
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
|
||
|
|
* Written by David Howells (dhowells@redhat.com)
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public Licence
|
||
|
|
* as published by the Free Software Foundation; either version
|
||
|
|
* 2 of the Licence, or (at your option) any later version.
|
||
|
|
*/
|
||
|
|
#ifndef __ASM_GENERIC_BARRIER_H
|
||
|
|
#define __ASM_GENERIC_BARRIER_H
|
||
|
|
|
||
|
|
#ifndef __ASSEMBLY__
|
||
|
|
|
||
|
|
#include <linux/compiler.h>
|
||
|
|
|
||
|
|
#ifndef nop
|
||
|
|
#define nop() asm volatile ("nop")
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Force strict CPU ordering. And yes, this is required on UP too when we're
|
||
|
|
* talking to devices.
|
||
|
|
*
|
||
|
|
* Fall back to compiler barriers if nothing better is provided.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef mb
|
||
|
|
#define mb() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef rmb
|
||
|
|
#define rmb() mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef wmb
|
||
|
|
#define wmb() mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef dma_rmb
|
||
|
|
#define dma_rmb() rmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef dma_wmb
|
||
|
|
#define dma_wmb() wmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef read_barrier_depends
|
||
|
|
#define read_barrier_depends() do { } while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_mb
|
||
|
|
#define __smp_mb() mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_rmb
|
||
|
|
#define __smp_rmb() rmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_wmb
|
||
|
|
#define __smp_wmb() wmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_read_barrier_depends
|
||
|
|
#define __smp_read_barrier_depends() read_barrier_depends()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifdef CONFIG_SMP
|
||
|
|
|
||
|
|
#ifndef smp_mb
|
||
|
|
#define smp_mb() __smp_mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_rmb
|
||
|
|
#define smp_rmb() __smp_rmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_wmb
|
||
|
|
#define smp_wmb() __smp_wmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_read_barrier_depends
|
||
|
|
#define smp_read_barrier_depends() __smp_read_barrier_depends()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#else /* !CONFIG_SMP */
|
||
|
|
|
||
|
|
#ifndef smp_mb
|
||
|
|
#define smp_mb() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_rmb
|
||
|
|
#define smp_rmb() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_wmb
|
||
|
|
#define smp_wmb() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_read_barrier_depends
|
||
|
|
#define smp_read_barrier_depends() do { } while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif /* CONFIG_SMP */
|
||
|
|
|
||
|
|
#ifndef __smp_store_mb
|
||
|
|
#define __smp_store_mb(var, value) do { WRITE_ONCE(var, value); __smp_mb(); } while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_mb__before_atomic
|
||
|
|
#define __smp_mb__before_atomic() __smp_mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_mb__after_atomic
|
||
|
|
#define __smp_mb__after_atomic() __smp_mb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_store_release
|
||
|
|
#define __smp_store_release(p, v) \
|
||
|
|
do { \
|
||
|
|
compiletime_assert_atomic_type(*p); \
|
||
|
|
__smp_mb(); \
|
||
|
|
WRITE_ONCE(*p, v); \
|
||
|
|
} while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef __smp_load_acquire
|
||
|
|
#define __smp_load_acquire(p) \
|
||
|
|
({ \
|
||
|
|
typeof(*p) ___p1 = READ_ONCE(*p); \
|
||
|
|
compiletime_assert_atomic_type(*p); \
|
||
|
|
__smp_mb(); \
|
||
|
|
___p1; \
|
||
|
|
})
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifdef CONFIG_SMP
|
||
|
|
|
||
|
|
#ifndef smp_store_mb
|
||
|
|
#define smp_store_mb(var, value) __smp_store_mb(var, value)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_mb__before_atomic
|
||
|
|
#define smp_mb__before_atomic() __smp_mb__before_atomic()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_mb__after_atomic
|
||
|
|
#define smp_mb__after_atomic() __smp_mb__after_atomic()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_store_release
|
||
|
|
#define smp_store_release(p, v) __smp_store_release(p, v)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_load_acquire
|
||
|
|
#define smp_load_acquire(p) __smp_load_acquire(p)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#else /* !CONFIG_SMP */
|
||
|
|
|
||
|
|
#ifndef smp_store_mb
|
||
|
|
#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_mb__before_atomic
|
||
|
|
#define smp_mb__before_atomic() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_mb__after_atomic
|
||
|
|
#define smp_mb__after_atomic() barrier()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_store_release
|
||
|
|
#define smp_store_release(p, v) \
|
||
|
|
do { \
|
||
|
|
compiletime_assert_atomic_type(*p); \
|
||
|
|
barrier(); \
|
||
|
|
WRITE_ONCE(*p, v); \
|
||
|
|
} while (0)
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifndef smp_load_acquire
|
||
|
|
#define smp_load_acquire(p) \
|
||
|
|
({ \
|
||
|
|
typeof(*p) ___p1 = READ_ONCE(*p); \
|
||
|
|
compiletime_assert_atomic_type(*p); \
|
||
|
|
barrier(); \
|
||
|
|
___p1; \
|
||
|
|
})
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif /* CONFIG_SMP */
|
||
|
|
|
||
|
|
/* Barriers for virtual machine guests when talking to an SMP host */
|
||
|
|
#define virt_mb() __smp_mb()
|
||
|
|
#define virt_rmb() __smp_rmb()
|
||
|
|
#define virt_wmb() __smp_wmb()
|
||
|
|
#define virt_read_barrier_depends() __smp_read_barrier_depends()
|
||
|
|
#define virt_store_mb(var, value) __smp_store_mb(var, value)
|
||
|
|
#define virt_mb__before_atomic() __smp_mb__before_atomic()
|
||
|
|
#define virt_mb__after_atomic() __smp_mb__after_atomic()
|
||
|
|
#define virt_store_release(p, v) __smp_store_release(p, v)
|
||
|
|
#define virt_load_acquire(p) __smp_load_acquire(p)
|
||
|
|
|
||
|
|
/**
|
||
|
|
* smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency
|
||
|
|
*
|
||
|
|
* A control dependency provides a LOAD->STORE order, the additional RMB
|
||
|
|
* provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
|
||
|
|
* aka. (load)-ACQUIRE.
|
||
|
|
*
|
||
|
|
* Architectures that do not do load speculation can have this be barrier().
|
||
|
|
*/
|
||
|
|
#ifndef smp_acquire__after_ctrl_dep
|
||
|
|
#define smp_acquire__after_ctrl_dep() smp_rmb()
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/**
|
||
|
|
* smp_cond_load_relaxed() - (Spin) wait for cond with no ordering guarantees
|
||
|
|
* @ptr: pointer to the variable to wait on
|
||
|
|
* @cond: boolean expression to wait for
|
||
|
|
*
|
||
|
|
* Equivalent to using READ_ONCE() on the condition variable.
|
||
|
|
*
|
||
|
|
* Due to C lacking lambda expressions we load the value of *ptr into a
|
||
|
|
* pre-named variable @VAL to be used in @cond.
|
||
|
|
*/
|
||
|
|
#ifndef smp_cond_load_relaxed
|
||
|
|
#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
|
||
|
|
typeof(ptr) __PTR = (ptr); \
|
||
|
|
typeof(*ptr) VAL; \
|
||
|
|
for (;;) { \
|
||
|
|
VAL = READ_ONCE(*__PTR); \
|
||
|
|
if (cond_expr) \
|
||
|
|
break; \
|
||
|
|
cpu_relax(); \
|
||
|
|
} \
|
||
|
|
VAL; \
|
||
|
|
})
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/**
|
||
|
|
* smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering
|
||
|
|
* @ptr: pointer to the variable to wait on
|
||
|
|
* @cond: boolean expression to wait for
|
||
|
|
*
|
||
|
|
* Equivalent to using smp_load_acquire() on the condition variable but employs
|
||
|
|
* the control dependency of the wait to reduce the barrier on many platforms.
|
||
|
|
*/
|
||
|
|
#ifndef smp_cond_load_acquire
|
||
|
|
#define smp_cond_load_acquire(ptr, cond_expr) ({ \
|
||
|
|
typeof(*ptr) _val; \
|
||
|
|
_val = smp_cond_load_relaxed(ptr, cond_expr); \
|
||
|
|
smp_acquire__after_ctrl_dep(); \
|
||
|
|
_val; \
|
||
|
|
})
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif /* !__ASSEMBLY__ */
|
||
|
|
#endif /* __ASM_GENERIC_BARRIER_H */
|