cpu_proc_fork: use pcb1 and pcb2, and thus make routine more readable.
Remove or update outdated comments, add new ones. Clean-up.
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rmind
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@ -1,4 +1,4 @@
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/* $NetBSD: vm_machdep.c,v 1.2 2009/10/21 21:12:04 rmind Exp $ */
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/* $NetBSD: vm_machdep.c,v 1.3 2009/10/27 03:48:59 rmind Exp $ */
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/*-
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* Copyright (c) 1982, 1986 The Regents of the University of California.
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@ -80,7 +80,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: vm_machdep.c,v 1.2 2009/10/21 21:12:04 rmind Exp $");
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__KERNEL_RCSID(0, "$NetBSD: vm_machdep.c,v 1.3 2009/10/27 03:48:59 rmind Exp $");
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#include "opt_mtrr.h"
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@ -115,8 +115,6 @@ __KERNEL_RCSID(0, "$NetBSD: vm_machdep.c,v 1.2 2009/10/21 21:12:04 rmind Exp $")
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#endif
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#endif
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static void setredzone(struct lwp *);
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void
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cpu_proc_fork(struct proc *p1, struct proc *p2)
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{
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@ -127,97 +125,103 @@ cpu_proc_fork(struct proc *p1, struct proc *p2)
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}
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/*
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* Finish a new thread operation, with LWP l2 nearly set up.
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* Copy and update the pcb and trap frame, making the child ready to run.
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* cpu_lwp_fork: finish a new LWP (l2) operation.
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*
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* Rig the child's kernel stack so that it will start out in
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* lwp_trampoline() and call child_return() with l2 as an
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* argument. This causes the newly-created child process to go
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* directly to user level with an apparent return value of 0 from
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* fork(), while the parent process returns normally.
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*
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* l1 is the thread being forked; if l1 == &lwp0, we are creating
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* a kernel thread, and the return path and argument are specified with
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* `func' and `arg'.
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* First LWP (l1) is the process being forked. If it is &lwp, then we
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* are creating a kthread, where return path and argument are specified
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* with `func' and `arg'.
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*
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* If an alternate user-level stack is requested (with non-zero values
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* in both the stack and stacksize args), set up the user stack pointer
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* accordingly.
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* in both the stack and stacksize arguments), then set up the user stack
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* pointer accordingly.
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*/
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void
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cpu_lwp_fork(struct lwp *l1, struct lwp *l2, void *stack, size_t stacksize,
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void (*func)(void *), void *arg)
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{
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struct pcb *pcb = &l2->l_addr->u_pcb;
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struct pcb *pcb1, *pcb2;
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struct trapframe *tf;
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pcb1 = &l1->l_addr->u_pcb;
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pcb2 = &l2->l_addr->u_pcb;
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/*
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* If fpuproc != p1, then the fpu h/w state is irrelevant and the
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* state had better already be in the pcb. This is true for forks
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* but not for dumps.
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*
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* If fpuproc == p1, then we have to save the fpu h/w state to
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* p1's pcb so that we can copy it.
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* If parent LWP was using FPU, then we have to save the FPU h/w
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* state to PCB so that we can copy it.
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*/
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if (l1->l_addr->u_pcb.pcb_fpcpu != NULL) {
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if (pcb1->pcb_fpcpu != NULL) {
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fpusave_lwp(l1, true);
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}
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l2->l_md.md_flags = l1->l_md.md_flags;
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/* Copy pcb from proc p1 to p2. */
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/*
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* Sync the PCB before we copy it.
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*/
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if (l1 == curlwp) {
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/* Sync the PCB before we copy it. */
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savectx(curpcb);
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KASSERT(pcb1 == curpcb);
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savectx(pcb1);
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} else {
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KASSERT(l1 == &lwp0);
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}
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*pcb = l1->l_addr->u_pcb;
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/* Copy the PCB from parent. */
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memcpy(pcb2, pcb1, sizeof(struct pcb));
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#if defined(XEN)
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pcb->pcb_iopl = SEL_KPL;
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#endif /* defined(XEN) */
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#ifdef __x86_64__
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/*
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* Note: pcb_ldt_sel is handled in the pmap_activate() call when
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* we run the new process.
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*/
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pcb->pcb_rsp0 = (USER_TO_UAREA(l2->l_addr) + KSTACK_SIZE - 16) & ~0xf;
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pcb->pcb_fs = l1->l_addr->u_pcb.pcb_fs;
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pcb->pcb_gs = l1->l_addr->u_pcb.pcb_gs;
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#else
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pcb->pcb_esp0 = USER_TO_UAREA(l2->l_addr) + KSTACK_SIZE - 16;
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memcpy(&pcb->pcb_fsd, curpcb->pcb_fsd, sizeof(pcb->pcb_fsd));
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memcpy(&pcb->pcb_gsd, curpcb->pcb_gsd, sizeof(pcb->pcb_gsd));
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pcb->pcb_iomap = NULL;
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pcb2->pcb_iopl = SEL_KPL;
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#endif
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l2->l_md.md_astpending = 0;
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/*
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* Copy the trapframe.
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* Set the kernel stack address (from the address to uarea) and
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* trapframe address for child.
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*
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* Rig kernel stack so that it would start out in lwp_trampoline()
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* and call child_return() with l2 as an argument. This causes the
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* newly-created child process to go directly to user level with a
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* parent return value of 0 from fork(), while the parent process
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* returns normally.
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*
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* Also, copy PCB %fs/%gs base from parent.
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*/
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#ifdef __x86_64__
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tf = (struct trapframe *)pcb->pcb_rsp0 - 1;
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pcb2->pcb_rsp0 = (USER_TO_UAREA(l2->l_addr) + KSTACK_SIZE - 16) & ~0xf;
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tf = (struct trapframe *)pcb2->pcb_rsp0 - 1;
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pcb2->pcb_fs = pcb1->pcb_fs;
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pcb2->pcb_gs = pcb1->pcb_gs;
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#else
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tf = (struct trapframe *)pcb->pcb_esp0 - 1;
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pcb2->pcb_esp0 = (USER_TO_UAREA(l2->l_addr) + KSTACK_SIZE - 16);
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tf = (struct trapframe *)pcb2->pcb_esp0 - 1;
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memcpy(&pcb2->pcb_fsd, pcb1->pcb_fsd, sizeof(pcb2->pcb_fsd));
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memcpy(&pcb2->pcb_gsd, pcb1->pcb_gsd, sizeof(pcb2->pcb_gsd));
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pcb2->pcb_iomap = NULL;
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#endif
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l2->l_md.md_regs = tf;
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*tf = *l1->l_md.md_regs;
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/* Copy the trapframe from parent. */
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memcpy(tf, l1->l_md.md_regs, sizeof(struct trapframe));
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/* Child LWP might get aston() before returning to userspace. */
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tf->tf_trapno = T_ASTFLT;
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setredzone(l2);
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#ifdef DIAGNOSTIC
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/* Set a red zone in the kernel stack after the uarea. */
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pmap_kremove(USER_TO_UAREA(l2->l_addr), PAGE_SIZE);
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pmap_update(pmap_kernel());
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#endif
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/*
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* If specified, give the child a different stack.
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*/
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/* If specified, set a different user stack for a child. */
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if (stack != NULL) {
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#ifdef __x86_64__
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tf->tf_rsp = (uint64_t)stack + stacksize;
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#else
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tf->tf_esp = (u_int)stack + stacksize;
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tf->tf_esp = (uint32_t)stack + stacksize;
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#endif
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}
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l2->l_md.md_flags = l1->l_md.md_flags;
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l2->l_md.md_astpending = 0;
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cpu_setfunc(l2, func, arg);
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}
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@ -277,22 +281,6 @@ cpu_lwp_free2(struct lwp *l)
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/* nothing */
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}
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/*
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* Set a red zone in the kernel stack after the u. area.
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*/
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static void
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setredzone(struct lwp *l)
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{
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#ifdef DIAGNOSTIC
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vaddr_t addr;
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addr = USER_TO_UAREA(l->l_addr);
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pmap_kremove(addr, PAGE_SIZE);
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pmap_update(pmap_kernel());
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#endif
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}
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/*
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* Convert kernel VA to physical address
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*/
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