1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 static char sccsid[] = "@(#)crt0.c 5.4 (Berkeley) 07/16/92"; 10 #endif /* not lint */ 11 12 /* 13 * C start up routine. 14 * Robert Henry, UCB, 20 Oct 81 15 * 16 * We make the following (true) assumptions: 17 * 1) When the kernel calls start, it does a jump to location 2, 18 * and thus avoids the register save mask. We are NOT called 19 * with a calls! 20 * 2) The only register variable that we can trust is sp, 21 * which points to the base of the kernel calling frame. 22 */ 23 24 char **environ = (char **)0; 25 static int fd; 26 27 extern unsigned char etext; 28 extern unsigned char eprol asm ("eprol"); 29 extern start() asm("start"); 30 31 /* 32 * Some kluges: store sp at entry in environ, and 33 * install 16 bits of 0 at location 0 (a zero register save mask). 34 * These two hacks remove limits on the use of local 35 * and register variables in start(). 36 * The reason for using 'moval (sp),...' is that 'movl sp,...' generates 37 * a privileged instruction trap (argh). 38 * XXX 'addl3 $start,$2,r0; jmp (r0)' should be replaced with 39 * XXX 'jbr start+2' when we convert over to gas. 40 */ 41 asm(".text; .word 0; moval (sp),_environ; addl3 $start,$2,r0; jmp (r0)"); 42 43 start() 44 { 45 struct kframe { 46 int kargc; 47 char *kargv[1]; /* size depends on kargc */ 48 char kargstr[1]; /* size varies */ 49 char kenvstr[1]; /* size varies */ 50 }; 51 register struct kframe *kfp; 52 register char **targv; 53 register char **argv; 54 extern int errno; 55 56 kfp = (struct kframe *) environ; 57 for (argv = targv = &kfp->kargv[0]; *targv++; /* void */) 58 /* void */ ; 59 if (targv >= (char **)(*argv)) 60 --targv; 61 environ = targv; 62 asm("eprol:"); 63 64 #ifdef MCRT0 65 monstartup(&eprol, &etext); 66 #endif MCRT0 67 errno = 0; 68 exit(main(kfp->kargc, argv, environ)); 69 } 70 71 #ifdef MCRT0 72 /*ARGSUSED*/ 73 exit(code) 74 register int code; 75 { 76 _mcleanup(); 77 _cleanup(); 78 _exit(code); 79 } 80 #endif MCRT0 81 82 #ifdef CRT0 83 /* 84 * null moncontrol, just in case some routine is compiled for profiling 85 */ 86 moncontrol(val) 87 int val; 88 { 89 90 } 91 #endif CRT0 92