freebsd-skq/sys/i386/include/globals.h
jake b2dd5fbcb8 Implement optimized PCPU accessors. These are necessary to support a
pre-emptable kernel.  For variables of size 4 bytes or less they compile
to a single instruction, which does not allow a process to migrate cpus
in the middle, and get the value for the "wrong" cpu.
2001-01-21 03:11:03 +00:00

140 lines
4.3 KiB
C

/*-
* Copyright (c) 1999 Luoqi Chen <luoqi@freebsd.org>
* All rights reserved.
* Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _MACHINE_GLOBALS_H_
#define _MACHINE_GLOBALS_H_
#ifdef _KERNEL
#include <machine/globaldata.h>
#ifndef __GNUC__
#error gcc is required to use this file
#endif
/*
* Evaluates to the byte offset of the per-cpu variable name.
*/
#define __pcpu_offset(name) \
__offsetof(struct globaldata, name)
/*
* Evaluates to the type of the per-cpu variable name.
*/
#define __pcpu_type(name) \
__typeof(((struct globaldata *)0)->name)
/*
* Evaluates to the address of the per-cpu variable name.
*/
#define __PCPU_PTR(name) ({ \
__pcpu_type(name) *__p; \
\
__asm __volatile("movl %%fs:%1,%0; addl %2,%0" \
: "=r" (__p) \
: "m" (*(struct globaldata *)(__pcpu_offset(gd_prvspace))), \
"i" (__pcpu_offset(name))); \
\
__p; \
})
/*
* Evaluates to the value of the per-cpu variable name.
*/
#define __PCPU_GET(name) ({ \
__pcpu_type(name) __result; \
\
if (sizeof(__result) == 1) { \
u_char __b; \
__asm __volatile("movb %%fs:%1,%0" \
: "=r" (__b) \
: "m" (*(u_char *)(__pcpu_offset(name)))); \
__result = *(__pcpu_type(name) *)&__b; \
} else if (sizeof(__result) == 2) { \
u_short __w; \
__asm __volatile("movw %%fs:%1,%0" \
: "=r" (__w) \
: "m" (*(u_short *)(__pcpu_offset(name)))); \
__result = *(__pcpu_type(name) *)&__w; \
} else if (sizeof(__result) == 4) { \
u_int __i; \
__asm __volatile("movl %%fs:%1,%0" \
: "=r" (__i) \
: "m" (*(u_int *)(__pcpu_offset(name)))); \
__result = *(__pcpu_type(name) *)&__i; \
} else { \
__result = *__PCPU_PTR(name); \
} \
\
__result; \
})
/*
* Sets the value of the per-cpu variable name to value val.
*/
#define __PCPU_SET(name, val) ({ \
__pcpu_type(name) __val = (val); \
\
if (sizeof(__val) == 1) { \
u_char __b; \
__b = *(u_char *)&__val; \
__asm __volatile("movb %1,%%fs:%0" \
: "=m" (*(u_char *)(__pcpu_offset(name))) \
: "r" (__b)); \
} else if (sizeof(__val) == 2) { \
u_short __w; \
__w = *(u_short *)&__val; \
__asm __volatile("movw %1,%%fs:%0" \
: "=m" (*(u_short *)(__pcpu_offset(name))) \
: "r" (__w)); \
} else if (sizeof(__val) == 4) { \
u_int __i; \
__i = *(u_int *)&__val; \
__asm __volatile("movl %1,%%fs:%0" \
: "=m" (*(u_int *)(__pcpu_offset(name))) \
: "r" (__i)); \
} else { \
*__PCPU_PTR(name) = __val; \
} \
})
#define PCPU_GET(member) __PCPU_GET(gd_ ## member)
#define PCPU_PTR(member) __PCPU_PTR(gd_ ## member)
#define PCPU_SET(member, val) __PCPU_SET(gd_ ## member, val)
#define CURPROC PCPU_GET(curproc)
#define CURTHD PCPU_GET(curproc)
#define GLOBALDATA PCPU_GET(prvspace)
#define curproc PCPU_GET(curproc)
#endif /* _KERNEL */
#endif /* !_MACHINE_GLOBALS_H_ */