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Cleanup in cpu_fork - remove use of curproc 

Startup code now ensures proc0pcb is valid.
This commit is contained in:
gwr 1995-05-26 17:20:30 +00:00
parent 851d298eea
commit 4dbca7a672
1 changed files with 13 additions and 33 deletions
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46
sys/arch/sun3/sun3/vm_machdep.c
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@ -1,4 +1,4 @@
/* $NetBSD: vm_machdep.c,v 1.28 1995/05/24 21:08:44 gwr Exp $ */
/* $NetBSD: vm_machdep.c,v 1.29 1995/05/26 17:20:30 gwr Exp $ */
/*
* Copyright (c) 1994 Gordon W. Ross
@ -63,9 +63,8 @@
#include <machine/pmap.h>
#include "cache.h"
/* XXX - Put these in some header file? */
/* XXX - Put this in some header file? */
void cpu_set_kpc __P((struct proc *p, u_long func));
void child_return __P((struct proc *p));
/*
@ -81,25 +80,13 @@ cpu_fork(p1, p2)
register struct pcb *pcb2 = &p2->p_addr->u_pcb;
register struct trapframe *p2tf;
register struct switchframe *p2sf;
extern void proc_do_uret();
extern void proc_do_uret(), child_return();
/* copy over the machdep part of struct proc */
p2->p_md.md_flags = p1->p_md.md_flags;
/*
* Copy pcb from proc p1 to p2.
* XXX - Note, if we have never called cpu_switch()
* then our own pcb will not have been initialized.
* Make sure it is valid or the child will die in
* cpu_switch() when it loads the new sr value.
* (Accidently clears the supervisor bit...)
*
* We can just save our context into p2, based on
* the assumption that p1 == curproc (verify that).
*/
if (p1 != curproc) /* XXX */
panic("cpu_fork: bad p1");
savectx(pcb2);
/* Copy pcb from proc p1 to p2. */
bcopy(&p1->p_addr->u_pcb, pcb2, sizeof(*pcb2));
/*
* Our cpu_switch MUST always call PMAP_ACTIVATE on a
@ -112,7 +99,8 @@ cpu_fork(p1, p2)
* Pick a stack pointer, leaving room for a trapframe;
* copy trapframe from parent so return to user mode
* will be to right address, with correct registers.
* Leave one word at the end just to be like proc0...
* Leave one word unused at the end of the kernel stack
* so the system stack pointer stays within its stack.
*/
p2tf = (struct trapframe *)((char*)p2->p_addr + USPACE-4) - 1;
p2->p_md.md_regs = (int *)p2tf;
@ -126,16 +114,13 @@ cpu_fork(p1, p2)
p2sf->sf_pc = (u_int)proc_do_uret;
pcb2->pcb_regs[11] = (int)p2sf; /* SSP */
#if 1 /* XXX - Which way is better? */
cpu_set_kpc(p2, (long)child_return);
#else
/*
* Set up return-value registers as fork() libc stub expects.
* This will "push a call" to an arbitrary kernel function
* onto the stack of p2, very much like signal delivery.
* When p2 runs, it will find itself in child_return().
*/
p2tf->tf_regs[D0] = 0;
p2tf->tf_sr &= ~PSL_C;
p2tf->tf_format = FMT0;
#endif
cpu_set_kpc(p2, (long)child_return);
return (0);
}
@ -149,7 +134,7 @@ cpu_fork(p1, p2)
* Note that it's assumed that when the named process returns,
* rei() should be invoked, to return to user mode. That is
* accomplished by having cpu_fork set the initial frame with a
* return address pointing to rei() which eventually does an rte.
* return address pointing to proc_do_uret() which does the rte.
*
* The design allows this function to be implemented as a general
* "kernel sendsig" utility, that can "push" a call to a kernel
@ -174,11 +159,6 @@ cpu_set_kpc(proc, func)
void *proc;
} *ksfp;
#ifdef DIAGNOSTIC
if (proc == curproc)
panic("cpu_set_kpc self");
#endif
pcbp = &proc->p_addr->u_pcb;
/* Push a ksig frame onto the kernel stack. */