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 weak _makecontext = makecontext 31 32 #include "lint.h" 33 #include <stdarg.h> 34 #include <ucontext.h> 35 #include <sys/stack.h> 36 #include <sys/regset.h> 37 38 /* 39 * The ucontext_t that the user passes in must have been primed with a 40 * call to getcontext(2), have the uc_stack member set to reflect the 41 * stack which this context will use, and have the uc_link member set 42 * to the context which should be resumed when this context returns. 43 * When makecontext() returns, the ucontext_t will be set to run the 44 * given function with the given parameters on the stack specified by 45 * uc_stack, and which will return to the ucontext_t specified by uc_link. 46 */ 47 48 static void resumecontext(void); 49 50 void 51 makecontext(ucontext_t *ucp, void (*func)(), int argc, ...) 52 { 53 long *sp; 54 long *tsp; 55 va_list ap; 56 size_t size; 57 int pusharg = (argc > 6 ? argc - 6 : 0); 58 greg_t tmp; 59 int i; 60 61 ucp->uc_mcontext.gregs[REG_PC] = (greg_t)func; 62 63 size = sizeof (long) * (pusharg + 1); 64 65 /* 66 * Calculate new value for %rsp. On entry to a function, 67 * %rsp must be STACK_ENTRY_ALIGNed but not STACK_ALIGNed. 68 * This is because the pushq %rbp will correct the alignment. 69 */ 70 71 sp = (long *)(((uintptr_t)ucp->uc_stack.ss_sp + 72 ucp->uc_stack.ss_size - size) & ~(STACK_ENTRY_ALIGN - 1)); 73 74 if (((uintptr_t)sp & (STACK_ALIGN - 1ul)) == 0) 75 sp -= STACK_ENTRY_ALIGN / sizeof (*sp); 76 77 tsp = sp + 1; 78 79 va_start(ap, argc); 80 81 for (i = 0; i < argc; i++) { 82 tmp = va_arg(ap, long); 83 switch (i) { 84 case 0: 85 ucp->uc_mcontext.gregs[REG_RDI] = tmp; 86 break; 87 case 1: 88 ucp->uc_mcontext.gregs[REG_RSI] = tmp; 89 break; 90 case 2: 91 ucp->uc_mcontext.gregs[REG_RDX] = tmp; 92 break; 93 case 3: 94 ucp->uc_mcontext.gregs[REG_RCX] = tmp; 95 break; 96 case 4: 97 ucp->uc_mcontext.gregs[REG_R8] = tmp; 98 break; 99 case 5: 100 ucp->uc_mcontext.gregs[REG_R9] = tmp; 101 break; 102 default: 103 *tsp++ = tmp; 104 break; 105 } 106 } 107 108 va_end(ap); 109 110 *sp = (long)resumecontext; /* return address */ 111 112 ucp->uc_mcontext.gregs[REG_SP] = (greg_t)sp; 113 } 114 115 116 static void 117 resumecontext(void) 118 { 119 ucontext_t uc; 120 121 (void) getcontext(&uc); 122 (void) setcontext(uc.uc_link); 123 } 124