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