1 /* 2 * Copyright (c) 2004 Suleiman Souhlal 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/param.h> 31 32 #include <stdarg.h> 33 #include <stdlib.h> 34 #include <unistd.h> 35 #include <stdio.h> 36 #include <ucontext.h> 37 38 __weak_reference(__makecontext, makecontext); 39 40 void _ctx_done(ucontext_t *ucp); 41 void _ctx_start(void); 42 43 void 44 _ctx_done(ucontext_t *ucp) 45 { 46 if (ucp->uc_link == NULL) 47 exit(0); 48 else { 49 /* invalidate context */ 50 ucp->uc_mcontext.mc_len = 0; 51 52 setcontext((const ucontext_t *)ucp->uc_link); 53 54 abort(); /* should never return from above call */ 55 } 56 } 57 58 void 59 __makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...) 60 { 61 mcontext_t *mc; 62 char *sp; 63 va_list ap; 64 int i, regargs, stackargs; 65 66 /* Sanity checks */ 67 if ((ucp == NULL) || (argc < 0) || (argc > NCARGS) 68 || (ucp->uc_stack.ss_sp == NULL) 69 || (ucp->uc_stack.ss_size < MINSIGSTKSZ)) { 70 /* invalidate context */ 71 ucp->uc_mcontext.mc_len = 0; 72 return; 73 } 74 75 /* 76 * The stack must have space for the frame pointer, saved 77 * link register, overflow arguments, and be 16-byte 78 * aligned. 79 */ 80 stackargs = (argc > 8) ? argc - 8 : 0; 81 sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size 82 - sizeof(uint32_t)*(stackargs + 2); 83 sp = (char *)((uint32_t)sp & ~0x1f); 84 85 mc = &ucp->uc_mcontext; 86 87 /* 88 * Up to 8 register args. Assumes all args are 32-bit and 89 * integer only. Not sure how to cater for floating point, 90 * although 64-bit args will work if aligned correctly 91 * in the arg list. 92 */ 93 regargs = (argc > 8) ? 8 : argc; 94 va_start(ap, argc); 95 for (i = 0; i < regargs; i++) 96 mc->mc_gpr[3 + i] = va_arg(ap, uint32_t); 97 98 /* 99 * Overflow args go onto the stack 100 */ 101 if (argc > 8) { 102 uint32_t *argp; 103 104 /* Skip past frame pointer and saved LR */ 105 argp = (uint32_t *)sp + 2; 106 107 for (i = 0; i < stackargs; i++) 108 *argp++ = va_arg(ap, uint32_t); 109 } 110 va_end(ap); 111 112 /* 113 * Use caller-saved regs 14/15 to hold params that _ctx_start 114 * will use to invoke the user-supplied func 115 */ 116 mc->mc_srr0 = (uint32_t) _ctx_start; 117 mc->mc_gpr[1] = (uint32_t) sp; /* new stack pointer */ 118 mc->mc_gpr[14] = (uint32_t) start; /* r14 <- start */ 119 mc->mc_gpr[15] = (uint32_t) ucp; /* r15 <- ucp */ 120 } 121