1/*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: src/sys/i386/i386/exception.s,v 1.65.2.3 2001/08/15 01:23:49 peter Exp $ 34 * $DragonFly: src/sys/platform/vkernel/i386/fork_tramp.s,v 1.3 2007/01/22 19:37:04 corecode Exp $ 35 */ 36 37#include <machine/asmacros.h> 38#include <machine/segments.h> 39#include <machine/lock.h> 40#include <machine/psl.h> 41#include <machine/trap.h> 42 43#include "assym.s" 44 45 .text 46 47/* 48 * This function is what cpu_heavy_restore jumps to after a new process 49 * is created. The LWKT subsystem switches while holding a critical 50 * section and we maintain that abstraction here (e.g. because 51 * cpu_heavy_restore needs it due to PCB_*() manipulation), then get out of 52 * it before calling the initial function (typically fork_return()) and/or 53 * returning to user mode. 54 * 55 * The MP lock is held on entry, but for processes fork_return(esi) 56 * releases it. 'doreti' always runs without the MP lock. 57 */ 58ENTRY(fork_trampoline) 59 movq PCPU(curthread),%rax 60 subl $TDPRI_CRIT,TD_PRI(%rax) 61 62 /* 63 * cpu_set_fork_handler intercepts this function call to 64 * have this call a non-return function to stay in kernel mode. 65 * 66 * initproc has its own fork handler, start_init(), which DOES 67 * return. 68 * 69 * %rbx - chaining function (typically fork_return) 70 * %r12 -> %rdi (argument) 71 * frame-> %rsi (trap frame) 72 * 73 * void (func:rbx)(arg:rdi, trapframe:rsi) 74 */ 75 movq %rsp, %rsi /* pass trapframe by reference */ 76 movq %r12, %rdi /* arg1 */ 77 call *%rbx /* function */ 78 79 /* cut from syscall */ 80 81 call splz 82 83#if defined(INVARIANTS) && defined(SMP) 84 movq PCPU(curthread),%rax 85 cmpl $0,TD_MPCOUNT(%rax) 86 je 1f 87 movq $pmsg4, %rdi 88 movl TD_MPCOUNT(%rax), %esi 89 movq %rbx, %rdx 90 xorl %eax, %eax 91 call panic 92pmsg4: .asciz "fork_trampoline mpcount %d after calling %p" 93 /* JG what's the purpose of this alignment and is it enough on amd64? */ 94 .p2align 2 951: 96#endif 97 /* 98 * Return via doreti to handle ASTs. 99 * 100 * trapframe is at the top of the stack. 101 */ 102 MEXITCOUNT 103 pushq $0 /* if_vec */ 104 movq %rsp,%rdi /* pass by reference */ 105 call go_user 106 /* NOT REACHED */ 107