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Tidy up cpu_fork() a little. This is mainly for changes I've been

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working on in the KSE area.
This commit is contained in:
Peter Wemm 2001-08-31 02:11:24 +00:00
parent 7bb862d793
commit 13fdaee622
1 changed files with 33 additions and 39 deletions
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72
sys/alpha/alpha/vm_machdep.c
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@ -122,6 +122,9 @@ cpu_fork(p1, p2, flags)
register struct proc *p1, *p2;
int flags;
{
struct user *up;
struct trapframe *p2tf;
if ((flags & RFPROC) == 0)
return;
@ -170,50 +173,41 @@ cpu_fork(p1, p2, flags)
#endif
/*
* create the child's kernel stack, from scratch.
* Create the child's kernel stack, from scratch.
*
* 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.
*/
{
struct user *up = p2->p_addr;
struct trapframe *p2tf;
p2->p_frame = (struct trapframe *)
((char *)p2->p_addr + USPACE - sizeof(struct trapframe));
bcopy(p1->p_frame, p2->p_frame, sizeof(struct trapframe));
/*
* 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.
*/
p2tf = p2->p_frame = (struct trapframe *)
((char *)p2->p_addr + USPACE - sizeof(struct trapframe));
bcopy(p1->p_frame, p2->p_frame, sizeof(struct trapframe));
/*
* Set up return-value registers as fork() libc stub expects.
*/
p2tf = p2->p_frame;
p2tf->tf_regs[FRAME_V0] = 0; /* child's pid (linux) */
p2tf->tf_regs[FRAME_A3] = 0; /* no error */
p2tf->tf_regs[FRAME_A4] = 1; /* is child (FreeBSD) */
/*
* Set up return-value registers as fork() libc stub expects.
*/
p2tf->tf_regs[FRAME_V0] = 0; /* child's pid (linux) */
p2tf->tf_regs[FRAME_A3] = 0; /* no error */
p2tf->tf_regs[FRAME_A4] = 1; /* is child (FreeBSD) */
/*
* Arrange for continuation at fork_return(), which
* will return to exception_return(). Note that the child
* process doesn't stay in the kernel for long!
*
* This is an inlined version of cpu_set_kpc.
*/
up->u_pcb.pcb_hw.apcb_ksp = (u_int64_t)p2tf;
up->u_pcb.pcb_context[0] =
(u_int64_t)fork_return; /* s0: a0 */
up->u_pcb.pcb_context[1] =
(u_int64_t)exception_return; /* s1: ra */
up->u_pcb.pcb_context[2] = (u_long) p2; /* s2: a1 */
up->u_pcb.pcb_context[7] =
(u_int64_t)fork_trampoline; /* ra: assembly magic */
/*
* Arrange for continuation at fork_return(), which
* will return to exception_return(). Note that the child
* process doesn't stay in the kernel for long!
*/
up = p2->p_addr;
up->u_pcb.pcb_hw.apcb_ksp = (u_int64_t)p2tf;
up->u_pcb.pcb_context[0] = (u_int64_t)fork_return; /* s0: a0 */
up->u_pcb.pcb_context[1] = (u_int64_t)exception_return; /* s1: ra */
up->u_pcb.pcb_context[2] = (u_long) p2; /* s2: a1 */
up->u_pcb.pcb_context[7] = (u_int64_t)fork_trampoline; /* ra: magic */
#ifdef SMP
/*
* We start off at a nesting level of 1 within the kernel.
*/
p2->p_md.md_kernnest = 1;
/*
* We start off at a nesting level of 1 within the kernel.
*/
p2->p_md.md_kernnest = 1;
#endif
}
}
/*