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/* $OpenBSD: crt0.c,v 1.8 2013/12/01 17:18:31 guenther Exp $ */
/* $NetBSD: crt0.c,v 1.1 1996/09/12 16:59:02 cgd Exp $ */
/*
* Copyright (c) 1995 Christopher G. Demetriou
* 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 Christopher G. Demetriou
* for the NetBSD Project.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include <sys/param.h>
#include <stdlib.h>
#include <sys/syscall.h>
char **environ;
char * __progname = "";
char __progname_storage[NAME_MAX+1];
#ifdef MCRT0
extern void monstartup(u_long, u_long);
extern void _mcleanup(void);
extern unsigned char _etext, _eprol;
#endif /* MCRT0 */
static inline char * _strrchr(const char *p, char ch);
#define STR(x) __STRING(x)
__asm(
" .text \n"
" .section \".text\" \n"
" .align 2 \n"
" .size __got_start, 0 \n"
" .type __got_start, @object \n"
" .size __got_end, 0 \n"
" .type __got_end, @object \n"
" .weak __got_start \n"
" .weak __got_end \n"
" .globl _start \n"
" .type _start, @function \n"
" .globl __start \n"
" .type __start, @function \n"
"_start: \n"
"__start: \n"
" # move argument registers to saved registers for startup flush \n"
" mr %r26, %r3 \n"
" mr %r25, %r4 \n"
" mr %r24, %r5 \n"
" mr %r23, %r6 \n"
" mr %r22, %r7 \n"
" mflr %r27 /* save off old link register */ \n"
" bl 1f \n"
" # this instruction never gets executed but can be used \n"
" # to find the virtual address where the page is loaded. \n"
" bl _GLOBAL_OFFSET_TABLE_@local-4 \n"
"1: \n"
" mflr %r6 # this stores where we are (+4) \n"
" lwz %r18, 0(%r6) # load the instruction at offset_sym \n"
" # it contains an offset to the location \n"
" # of the GOT. \n"
" \n"
" rlwinm %r18,%r18,0,8,30 # mask off the offset portion of the instr. \n"
" \n"
" /* \n"
" * these adds effectively calculate the value the \n"
" * bl _GLOBAL_OFFSET_TABLE_@local-4 \n"
" * operation that would be below would calculate. \n"
" */ \n"
" add %r28, %r18, %r6 \n"
" \n"
" addi %r3,%r28,4 # calculate the actual got addr \n"
" lwz %r0,__got_start@got(%r3) \n"
" cmpwi %r0,0 \n"
" beq 4f \n"
" cmpw %r0,%r28 \n"
" bne 4f \n"
" lwz %r4,__got_end@got(%r3) \n"
" cmpwi %r4,0 \n"
" beq 2f \n"
" \n"
" sub %r4, %r4, %r0 \n"
" b 3f \n"
"2: \n"
" li %r4, 4 \n"
"3: \n"
" \n"
" /* mprotect GOT to eliminate W+X regions in static binaries */ \n"
" li %r0, " STR(SYS_mprotect) " \n"
" mr %r3, %r28 \n"
" li %r5, 5 /* (PROT_READ|PROT_EXEC) */ \n"
" sc \n"
" \n"
"4: \n"
" li %r0, 0 \n"
" # flush the blrl instruction out of the data cache \n"
" dcbf %r6, %r18 \n"
" sync \n"
" isync \n"
" # make certain that the got table addr is not in the icache \n"
" icbi %r6, %r18 \n"
" sync \n"
" isync \n"
" mtlr %r27 \n"
" # move argument registers back from saved registers \n"
" mr %r3, %r26 \n"
" mr %r4, %r25 \n"
" mr %r5, %r24 \n"
" mr %r6, %r23 \n"
" mr %r7, %r22 \n"
" b ___start \n"
);
void
___start(int argc, char **argv, char **envp, void *aux, void (*cleanup)(void))
{
char *s;
environ = envp;
if ((__progname = argv[0]) != NULL) { /* NULL ptr if argc = 0 */
if ((__progname = _strrchr(__progname, '/')) == NULL)
__progname = argv[0];
else
__progname++;
for (s = __progname_storage; *__progname &&
s < &__progname_storage[sizeof __progname_storage - 1]; )
*s++ = *__progname++;
*s = '\0';
__progname = __progname_storage;
}
if (cleanup)
atexit(cleanup);
#ifdef MCRT0
atexit(_mcleanup);
monstartup((u_long)&_eprol, (u_long)&_etext);
#endif
__init();
exit(main(argc, argv, environ));
}
static inline char *
_strrchr(const char *p, char ch)
{
char *save;
for (save = NULL;; ++p) {
if (*p == ch)
save = (char *)p;
if (!*p)
return(save);
}
/* NOTREACHED */
}
asm (" .section \".text\" \n_eprol:");
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