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() and swapcontext() are written in assembler since it has to 39 * capture the correct machine state of the caller, including 40 * the registers: %edi, %esi and %ebx. 41 * 42 * As swapcontext() is actually equivalent to getcontext() + setcontext(), 43 * swapcontext() shares the most code with getcontext(). 44 */ 45 46 47#define GETCONTEXT_IMPL \ 48 movl 4(%esp), %eax; /* %eax <-- first arg: ucp */ \ 49 pushl %eax; /* push ucp for system call */ \ 50 call __getcontext; /* call getcontext: syscall */ \ 51 addl $4, %esp; /* pop arg */ \ 52 andl %eax, %eax; /* if (err_ret_from_syscall) */ \ 53 je 1f; \ 54 ret; /* then return */ \ 551: \ 56 movl 4(%esp), %eax; /* recompute first arg */ \ 57 /* \ 58 * fix up %esp and %eip \ 59 */ \ 60 leal UC_MCONTEXT_GREGS (%eax), %edx; \ 61 /* %edx <-- &ucp->uc_mcontext.gregs */ \ 62 movl 0(%esp), %eax; /* read return PC from stack */ \ 63 movl %eax, EIP_OFF (%edx); \ 64 /* store ret PC in EIP of env var */ \ 65 leal 4(%esp), %eax; /* get caller's sp at time of call */ \ 66 movl %eax, UESP_OFF (%edx); \ 67 /* store the sp into UESP of env var */ \ 68 xorl %eax, %eax; /* return 0 */ \ 69 movl %eax, EAX_OFF (%edx); \ 70 /* getcontext returns 0 after a setcontext */ 71 72/* 73 * getcontext(ucontext_t *ucp) 74 */ 75 ENTRY(getcontext) 76 GETCONTEXT_IMPL 77 ret 78 SET_SIZE(getcontext) 79 80 81/* 82 * swapcontext(ucontext_t *oucp, const ucontext_t *ucp) 83 */ 84 ENTRY(swapcontext) 85 GETCONTEXT_IMPL 86 / call setcontext 87 movl 8(%esp), %eax /* %eax <-- second arg: ucp */ 88 pushl %eax /* push ucp for setcontext */ 89 call setcontext 90 addl $4, %esp /* pop arg: just in case */ 91 ret 92 SET_SIZE(swapcontext) 93