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linux-next/include/asm-generic/irq_regs.h
Christoph Lameter 909ea96468 core: Replace __get_cpu_var with __this_cpu_read if not used for an address.
__get_cpu_var() can be replaced with this_cpu_read and will then use a
single read instruction with implied address calculation to access the
correct per cpu instance.

However, the address of a per cpu variable passed to __this_cpu_read()
cannot be determined (since it's an implied address conversion through
segment prefixes).  Therefore apply this only to uses of __get_cpu_var
where the address of the variable is not used.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-12-17 15:07:19 +01:00

38 lines
980 B
C

/* Fallback per-CPU frame pointer holder
*
* Copyright (C) 2006 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 License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_GENERIC_IRQ_REGS_H
#define _ASM_GENERIC_IRQ_REGS_H
#include <linux/percpu.h>
/*
* Per-cpu current frame pointer - the location of the last exception frame on
* the stack
*/
DECLARE_PER_CPU(struct pt_regs *, __irq_regs);
static inline struct pt_regs *get_irq_regs(void)
{
return __this_cpu_read(__irq_regs);
}
static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs)
{
struct pt_regs *old_regs;
old_regs = __this_cpu_read(__irq_regs);
__this_cpu_write(__irq_regs, new_regs);
return old_regs;
}
#endif /* _ASM_GENERIC_IRQ_REGS_H */