FreeBSD/Linux Kernel Cross Reference
sys/i386/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.
     *
     * $FreeBSD: src/sys/i386/include/asmacros.h,v 1.9.2.8 1999/09/05 08:11:38 peter Exp $
     */
    
    #ifndef _MACHINE_ASMACROS_H_
    #define _MACHINE_ASMACROS_H_
    
    #include <sys/cdefs.h>
    
    /* XXX too much duplication in various asm*.h's. */
    
    /*
     * CNAME and HIDENAME manage the relationship between symbol names in C
     * and the equivalent assembly language names.  CNAME is given a name as
     * it would be used in a C program.  It expands to the equivalent assembly
     * language name.  HIDENAME is given an assembly-language name, and expands
     * to a possibly-modified form that will be invisible to C programs.
     */
    #if defined(__ELF__)
    #define CNAME(csym)             csym
    #define HIDENAME(asmsym)        __CONCAT(.,asmsym)
    #else
    #define CNAME(csym)             __CONCAT(_,csym)
    #define HIDENAME(asmsym)        asmsym
    #endif
    
    #define ALIGN_DATA      .p2align 2      /* 4 byte alignment, zero filled */
    #ifdef GPROF
    #define ALIGN_TEXT      .p2align 4,0x90 /* 16-byte alignment, nop filled */
    #else
    #define ALIGN_TEXT      .p2align 2,0x90 /* 4-byte alignment, nop filled */
    #endif
    #define SUPERALIGN_TEXT .p2align 4,0x90 /* 16-byte alignment, nop filled */
    
    #define GEN_ENTRY(name)         ALIGN_TEXT; .globl CNAME(name); \
                                    CNAME(name):
    #define NON_GPROF_ENTRY(name)   GEN_ENTRY(name)
    #define NON_GPROF_RET           .byte 0xc3      /* opcode for `ret' */
    
    #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.
     *
     * mexitcount is a new function to support non-statistical profiling if an
     * accurate clock is available.  For C sources, calls to it are generated
     * by the FreeBSD extension `-mprofiler-epilogue' to gcc.  It is best to
     * call mexitcount at the end of a function like the MEXITCOUNT macro does,
     * but gcc currently generates calls to it at the start of 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 non-statistical profiling timing more complicated.
     * It is handled in many cases by calling mexitcount before jumping.  It is
     * handled for conditional jumps using CROSSJUMP() and CROSSJUMP_LABEL().
     * 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.
    *
    * Ordinary `ret' is used instead of a macro `RET' because there are a lot
    * of `ret's.  0xc3 is the opcode for `ret' (`#define ret ... ret' can't
    * be used because this file is sometimes preprocessed in traditional mode).
    * `ret' clobbers eflags but this doesn't matter.
    */
   #define ALTENTRY(name)          GEN_ENTRY(name) ; MCOUNT ; MEXITCOUNT ; jmp 9f
   #define CROSSJUMP(jtrue, label, jfalse) \
           jfalse 8f; MEXITCOUNT; jmp __CONCAT(to,label); 8:
   #define CROSSJUMPTARGET(label) \
           ALIGN_TEXT; __CONCAT(to,label): ; MCOUNT; jmp label
   #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 ; NON_GPROF_RET
   
   #else /* !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 CROSSJUMP(jtrue, label, jfalse) jtrue label
   #define CROSSJUMPTARGET(label)
   #define ENTRY(name)             GEN_ENTRY(name)
   #define FAKE_MCOUNT(caller)
   #define MCOUNT
   #define MCOUNT_LABEL(name)
   #define MEXITCOUNT
   #endif /* GPROF */
   
   #endif /* !_MACHINE_ASMACROS_H_ */

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