xref: /freebsd-11-stable/sys/amd64/include/asmacros.h

/*-
 * Copyright (c) 1993 The Regents of the University of California.
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	$Id: asmacros.h,v 1.5 1994/09/08 12:25:18 bde Exp $
 */

#ifndef _MACHINE_ASMACROS_H_
#define _MACHINE_ASMACROS_H_

#ifdef KERNEL

/* XXX too much duplication in various asm*.h's and gprof.h's */

#define ALIGN_DATA	.align	2	/* 4 byte alignment, zero filled */
#define ALIGN_TEXT	.align	2,0x90	/* 4-byte alignment, nop filled */
#define SUPERALIGN_TEXT	.align	4,0x90	/* 16-byte alignment (better for 486), nop filled */

#define GEN_ENTRY(name)		ALIGN_TEXT; .globl _/**/name; _/**/name:
#define NON_GPROF_ENTRY(name)	GEN_ENTRY(name)

#ifdef GPROF
/*
 * __mcount is like mcount except that doesn't require its caller to set
 * up a frame pointer.  It must be called before pushing anything onto the
 * stack.  gcc should eventually generate code to call __mcount in most
 * cases.  This would make -pg in combination with -fomit-frame-pointer
 * useful.  gcc has a configuration variable PROFILE_BEFORE_PROLOGUE to
 * allow profiling before setting up the frame pointer, but this is
 * inadequate for good handling of special cases, e.g., -fpic works best
 * with profiling after the prologue.
 *
 * Neither __mcount nor mcount requires %eax to point to 4 bytes of data,
 * so don't waste space allocating the data or time setting it up.  Changes
 * to avoid the wastage in gcc-2.4.5-compiled code are available.
 *
 * mexitcount is a new profiling feature to allow accurate timing of all
 * functions if an accurate clock is available.  Changes to gcc-2.4.5 to
 * support it are are available.  The changes currently don't allow not
 * generating mexitcounts for non-kernel code.  It is best to call
 * mexitcount right at the end of a function like the MEXITCOUNT macro
 * does, but the changes to gcc only implement calling it as the first
 * thing in the epilogue to avoid problems with -fpic.
 *
 * mcount and __mexitcount may clobber the call-used registers and %ef.
 * mexitcount may clobber %ecx and %ef.
 *
 * Cross-jumping makes accurate timing more difficult.  It is handled in
 * many cases by calling mexitcount before jumping.  It is not handled
 * for some conditional jumps (e.g., in bcopyx) or for some fault-handling
 * jumps.  It is handled for some fault-handling jumps by not sharing the
 * exit routine.
 *
 * ALTENTRY() must be before a corresponding ENTRY() so that it can jump to
 * the main entry point.  Note that alt entries are counted twice.  They
 * have to be counted as ordinary entries for gprof to get the call times
 * right for the ordinary entries.
 *
 * High local labels are used in macros to avoid clashes with local labels
 * in functions.
 *
 * "ret" is used instead of "RET" because there are a lot of "ret"s.
 * 0xc3 is the opcode for "ret" (#define ret ... ret fails because this
 * file is preprocessed in traditional mode).  "ret" clobbers eflags
 * but this doesn't matter.
 */
#define ALTENTRY(name)		GEN_ENTRY(name) ; MCOUNT ; MEXITCOUNT ; jmp 9f
#define ENTRY(name)		GEN_ENTRY(name) ; 9: ; MCOUNT
#define FAKE_MCOUNT(caller)	pushl caller ; call __mcount ; popl %ecx
#define MCOUNT			call __mcount
#define MCOUNT_LABEL(name)	GEN_ENTRY(name) ; nop ; ALIGN_TEXT
#define MEXITCOUNT		call mexitcount
#define ret			MEXITCOUNT ; .byte 0xc3
#else /* not GPROF */
/*
 * ALTENTRY() has to align because it is before a corresponding ENTRY().
 * ENTRY() has to align to because there may be no ALTENTRY() before it.
 * If there is a previous ALTENTRY() then the alignment code for ENTRY()
 * is empty.
 */
#define ALTENTRY(name)		GEN_ENTRY(name)
#define ENTRY(name)		GEN_ENTRY(name)
#define FAKE_MCOUNT(caller)
#define MCOUNT
#define MCOUNT_LABEL(name)
#define MEXITCOUNT
#endif /* GPROF */

/* XXX NOP and FASTER_NOP are misleadingly named */
#ifdef DUMMY_NOPS			/* this will break some older machines */
#define FASTER_NOP
#define NOP
#else
#define FASTER_NOP	pushl %eax ; inb $0x84,%al ; popl %eax
#define NOP		pushl %eax ; inb $0x84,%al ; inb $0x84,%al ; popl %eax
#endif

#else /* !KERNEL */

#include "/usr/src/lib/libc/i386/DEFS.h"	/* XXX blech */

#ifndef RCSID
#define RCSID(a)
#endif

#endif /* KERNEL */

#endif /* !_MACHINE_ASMACROS_H_ */