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/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#ifndef _ASM_TILE_PERCPU_H
#define _ASM_TILE_PERCPU_H
register unsigned long my_cpu_offset_reg asm("tp");
#ifdef CONFIG_PREEMPT
/*
* For full preemption, we can't just use the register variable
* directly, since we need barrier() to hazard against it, causing the
* compiler to reload anything computed from a previous "tp" value.
* But we also don't want to use volatile asm, since we'd like the
* compiler to be able to cache the value across multiple percpu reads.
* So we use a fake stack read as a hazard against barrier().
* The 'U' constraint is like 'm' but disallows postincrement.
*/
static inline unsigned long __my_cpu_offset(void)
{
unsigned long tp;
register unsigned long *sp asm("sp");
asm("move %0, tp" : "=r" (tp) : "U" (*sp));
return tp;
}
#define __my_cpu_offset __my_cpu_offset()
#else
/*
* We don't need to hazard against barrier() since "tp" doesn't ever
* change with PREEMPT_NONE, and with PREEMPT_VOLUNTARY it only
* changes at function call points, at which we are already re-reading
* the value of "tp" due to "my_cpu_offset_reg" being a global variable.
*/
#define __my_cpu_offset my_cpu_offset_reg
#endif
#define set_my_cpu_offset(tp) (my_cpu_offset_reg = (tp))
#include <asm-generic/percpu.h>
#endif /* _ASM_TILE_PERCPU_H */
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