1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1988 AT&T */ 28 /* All Rights Reserved */ 29 30 #pragma ident "%Z%%M% %I% %E% SMI" 31 32 #pragma weak _makecontext = makecontext 33 34 #include "lint.h" 35 #include <stdarg.h> 36 #include <ucontext.h> 37 #include <sys/stack.h> 38 39 /* 40 * The ucontext_t that the user passes in must have been primed with a 41 * call to getcontext(2), have the uc_stack member set to reflect the 42 * stack which this context will use, and have the uc_link member set 43 * to the context which should be resumed when this context returns. 44 * When makecontext() returns, the ucontext_t will be set to run the 45 * given function with the given parameters on the stack specified by 46 * uc_stack, and which will return to the ucontext_t specified by uc_link. 47 */ 48 49 static void resumecontext(void); 50 51 void 52 makecontext(ucontext_t *ucp, void (*func)(), int argc, ...) 53 { 54 long *sp; 55 long *tsp; 56 va_list ap; 57 size_t size; 58 int pusharg = (argc > 6 ? argc - 6 : 0); 59 greg_t tmp; 60 int i; 61 62 ucp->uc_mcontext.gregs[REG_PC] = (greg_t)func; 63 64 size = sizeof (long) * (pusharg + 1); 65 66 /* 67 * Calculate new value for %rsp. On entry to a function, 68 * %rsp must be STACK_ENTRY_ALIGNed but not STACK_ALIGNed. 69 * This is because the pushq %rbp will correct the alignment. 70 */ 71 72 sp = (long *)(((uintptr_t)ucp->uc_stack.ss_sp + 73 ucp->uc_stack.ss_size - size) & ~(STACK_ENTRY_ALIGN - 1)); 74 75 if (((uintptr_t)sp & (STACK_ALIGN - 1ul)) == 0) 76 sp -= STACK_ENTRY_ALIGN / sizeof (*sp); 77 78 tsp = sp + 1; 79 80 va_start(ap, argc); 81 82 for (i = 0; i < argc; i++) { 83 tmp = va_arg(ap, long); 84 switch (i) { 85 case 0: 86 ucp->uc_mcontext.gregs[REG_RDI] = tmp; 87 break; 88 case 1: 89 ucp->uc_mcontext.gregs[REG_RSI] = tmp; 90 break; 91 case 2: 92 ucp->uc_mcontext.gregs[REG_RDX] = tmp; 93 break; 94 case 3: 95 ucp->uc_mcontext.gregs[REG_RCX] = tmp; 96 break; 97 case 4: 98 ucp->uc_mcontext.gregs[REG_R8] = tmp; 99 break; 100 case 5: 101 ucp->uc_mcontext.gregs[REG_R9] = tmp; 102 break; 103 default: 104 *tsp++ = tmp; 105 break; 106 } 107 } 108 109 va_end(ap); 110 111 *sp = (long)resumecontext; /* return address */ 112 113 ucp->uc_mcontext.gregs[REG_SP] = (greg_t)sp; 114 } 115 116 117 static void 118 resumecontext(void) 119 { 120 ucontext_t uc; 121 122 (void) getcontext(&uc); 123 (void) setcontext(uc.uc_link); 124 } 125