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 .file "getcontext.s" 28 29#include <sys/asm_linkage.h> 30 31 ANSI_PRAGMA_WEAK(getcontext,function) 32 ANSI_PRAGMA_WEAK(swapcontext,function) 33 34#include "SYS.h" 35#include <../assym.h> 36 37/* 38 * getcontext() is written in assembler since it has to capture the correct 39 * machine state of the calle. 40 * 41 * As swapcontext() is actually equivalent to getcontext() + setcontext(), 42 * swapcontext() shares the most code with getcontext(). 43 */ 44 45#define GETCONTEXT_IMPL(offset) \ 46 pushq %rdi; /* preserve the ucontext_t pointer */ \ 47 call __getcontext; \ 48 /* call getcontext: syscall */ \ 49 popq %rdx; \ 50 andl %eax, %eax; /* if (error_return_from_syscall) */ \ 51 je 1f; \ 52 addq $offset, %rsp; \ 53 ret; /* then just return */ \ 541: \ 55 /* \ 56 * fix up %rsp and %rip \ 57 */ \ 58 addq $UC_MCONTEXT_GREGS, %rdx; \ 59 /* &ucp->uc_mcontext.gregs */ \ 60 movq offset+0(%rsp), %rax; \ 61 /* read return PC from stack */ \ 62 movq %rax, RIP_OFF (%rdx); \ 63 /* store ret PC in EIP of env var */ \ 64 leaq offset+8(%rsp), %rax; \ 65 /* get caller's sp at time of call */ \ 66 movq %rax, RSP_OFF (%rdx); \ 67 /* store the sp into UESP of env var */ \ 68 xorq %rax, %rax; /* return 0 */ \ 69 movq %rax, RAX_OFF (%rdx); \ 70 /* getcontext returns 0 after setcontext */ 71 72/* 73 * getcontext(ucontext_t *ucp) 74 */ 75 76 ENTRY(getcontext) 77 GETCONTEXT_IMPL(0) 78 ret 79 SET_SIZE(getcontext) 80 81/* 82 * swapcontext(ucontext_t *oucp, const ucontext_t *ucp) 83 */ 84 85 ENTRY(swapcontext) 86 pushq %rsi /* preserve the 2nd argument */ 87 88 GETCONTEXT_IMPL(8) 89 90 /* call setcontext */ 91 popq %rdi 92 call setcontext 93 ret 94 SET_SIZE(swapcontext) 95