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/* 28 * Copyright 2023 Oxide Computer Company 29 */ 30 31 .file "getcontext.s" 32 33#include <sys/asm_linkage.h> 34 35 ANSI_PRAGMA_WEAK(getcontext,function) 36 ANSI_PRAGMA_WEAK(swapcontext,function) 37 38#include "SYS.h" 39#include <../assym.h> 40 41/* 42 * getcontext() is written in assembler since it has to capture the correct 43 * machine state of the calle. 44 * 45 * As swapcontext() is actually equivalent to getcontext() + setcontext(), 46 * swapcontext() shares the most code with getcontext(). 47 */ 48 49#define GETCONTEXT_IMPL(offset, func) \ 50 pushq %rdi; /* preserve the ucontext_t pointer */ \ 51 call func; /* call syscall */ \ 52 popq %rdx; \ 53 andl %eax, %eax; /* if (error_return_from_syscall) */ \ 54 je 1f; \ 55 addq $offset, %rsp; \ 56 ret; /* then just return */ \ 571: \ 58 /* \ 59 * fix up %rsp and %rip \ 60 */ \ 61 addq $UC_MCONTEXT_GREGS, %rdx; \ 62 /* &ucp->uc_mcontext.gregs */ \ 63 movq offset+0(%rsp), %rax; \ 64 /* read return PC from stack */ \ 65 movq %rax, RIP_OFF (%rdx); \ 66 /* store ret PC in EIP of env var */ \ 67 leaq offset+8(%rsp), %rax; \ 68 /* get caller's sp at time of call */ \ 69 movq %rax, RSP_OFF (%rdx); \ 70 /* store the sp into UESP of env var */ \ 71 xorq %rax, %rax; /* return 0 */ \ 72 movq %rax, RAX_OFF (%rdx); \ 73 /* getcontext returns 0 after setcontext */ 74 75/* 76 * int getcontext(ucontext_t *ucp) 77 */ 78 79 ENTRY(getcontext) 80 GETCONTEXT_IMPL(0, __getcontext) 81 ret 82 SET_SIZE(getcontext) 83 84/* 85 * int swapcontext(ucontext_t *oucp, const ucontext_t *ucp) 86 */ 87 88 ENTRY(swapcontext) 89 pushq %rsi /* preserve the 2nd argument */ 90 91 GETCONTEXT_IMPL(8, __getcontext) 92 93 /* call setcontext */ 94 popq %rdi 95 call setcontext 96 ret 97 SET_SIZE(swapcontext) 98 99/* 100 * int getcontext_extd(ucontext_t *ctx, uint32_t flags) 101 */ 102 ENTRY(getcontext_extd) 103 cmpl $0, %esi 104 jne 2f 105 GETCONTEXT_IMPL(0, __getcontext_extd) 106 ret 1072: 108 movl $EINVAL, %eax /* errno = EINVAL */ 109 jmp __cerror /* return (-1) */ 110 SET_SIZE(getcontext_extd) 111 112/* 113 * int swapcontext_extd(ucontext_t *oucp, uint32_t flags, const ucontext_t *ucp) 114 */ 115 ENTRY(swapcontext_extd) 116 cmpl $0, %esi 117 jne 2f 118 pushq %rdx /* preserve the 3rd argument */ 119 120 GETCONTEXT_IMPL(8, __getcontext_extd) 121 122 /* call setcontext */ 123 popq %rdi 124 call setcontext 125 ret 1262: 127 movl $EINVAL, %eax /* errno = EINVAL */ 128 jmp __cerror /* return (-1) */ 129 SET_SIZE(swapcontext_extd) 130