fb0be37ded
-fomit-frame-pointer is not used). This is mostly moot for -current because gcc-3 does the alignment (slightly incorrectly) in main(). This patch is intended for easy MFC'ing and should be backed out in -current soon since it causes compiler warnings and better fixes are possible in -current. The best fix is to do nothing here and wait for gcc to do stack alignment right. gcc-3 aligns the stack in main(), but does it too late for main()'s local variables and too late for anything called before main(). A misaligned stack is now more than an efficiency problem, since some SSE instructions in some or all (hardware) implementations trap on misaligned operands even if alignment checking is not enabled. PR: 41528: Submitted by: NIIMI Satoshi <sa2c@sa2c.net> (original version) MFC after: 3 days
146 lines
3.7 KiB
C
146 lines
3.7 KiB
C
/*-
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* Copyright 1996-1998 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef lint
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#ifndef __GNUC__
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#error "GCC is needed to compile this file"
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#endif
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#endif /* lint */
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#include <stdlib.h>
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#include "libc_private.h"
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#include "crtbrand.c"
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extern int _DYNAMIC;
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#pragma weak _DYNAMIC
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typedef void (*fptr)(void);
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extern void _fini(void);
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extern void _init(void);
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extern int main(int, char **, char **);
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extern void _start(char *, ...);
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#ifdef GCRT
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extern void _mcleanup(void);
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extern void monstartup(void *, void *);
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extern int eprol;
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extern int etext;
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#endif
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char **environ;
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const char *__progname = "";
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static __inline fptr
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get_rtld_cleanup(void)
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{
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fptr retval;
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#ifdef __GNUC__
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__asm__("movl %%edx,%0" : "=rm"(retval));
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#else
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retval = (fptr)0; /* XXXX Fix this for other compilers */
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#endif
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return(retval);
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}
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/* The entry function. */
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void
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_start(char *ap, ...)
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{
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fptr cleanup;
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int argc;
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char **argv;
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char **env;
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const char *s;
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cleanup = get_rtld_cleanup();
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argv = ≈
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argc = *(long *)(void *)(argv - 1);
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env = argv + argc + 1;
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environ = env;
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if (argc > 0 && argv[0] != NULL) {
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__progname = argv[0];
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for (s = __progname; *s != '\0'; s++)
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if (*s == '/')
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__progname = s + 1;
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}
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if (&_DYNAMIC != NULL)
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atexit(cleanup);
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#ifdef GCRT
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atexit(_mcleanup);
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#endif
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atexit(_fini);
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#ifdef GCRT
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monstartup(&eprol, &etext);
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#endif
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_init();
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#ifndef __GNUC__
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exit( main(argc, argv, env) );
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#else
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/*
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* Some versions of gcc-2 expect the stack frame to be aligned as
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* follows after it is set up in main():
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*
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* +--------------+ <--- aligned by PREFERRED_STACK_BOUNDARY
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* +%ebp (if any) +
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* +--------------+
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* |return address|
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* +--------------+
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* | arguments |
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* | : |
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* | : |
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* +--------------+
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*
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* We implement the above to fix just the usual case in FreeBSD-4.
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* Alignment for main() is too compiler-dependent to handle correctly
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* in all cases here (or in the kernel). E.g., a different alignment
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* is required for at least gcc-2.95.4 even for the small variation
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* of compiling main() with -fomit-frame-pointer.
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*/
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__asm__("
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andl $~0xf, %%esp # align stack to 16-byte boundary
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subl $12+12, %%esp # space for args and padding
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movl %0, 0(%%esp)
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movl %1, 4(%%esp)
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movl %2, 8(%%esp)
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call main
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movl %%eax, 0(%%esp)
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call exit
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" : : "r" (argc), "r" (argv), "r" (env) : "ax", "cx", "dx", "memory");
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#endif
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}
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#ifdef GCRT
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__asm__(".text");
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__asm__("eprol:");
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__asm__(".previous");
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#endif
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__asm__(".ident\t\"$FreeBSD$\"");
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