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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; register struct proc *p1, *p2;
int flags; int flags;
{ {
struct user *up;
struct trapframe *p2tf;
if ((flags & RFPROC) == 0) if ((flags & RFPROC) == 0)
return; return;
@ -170,50 +173,41 @@ cpu_fork(p1, p2, flags)
#endif #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.
*/ */
{ p2->p_frame = (struct trapframe *)
struct user *up = p2->p_addr; ((char *)p2->p_addr + USPACE - sizeof(struct trapframe));
struct trapframe *p2tf; bcopy(p1->p_frame, p2->p_frame, sizeof(struct trapframe));
/* /*
* Pick a stack pointer, leaving room for a trapframe; * Set up return-value registers as fork() libc stub expects.
* copy trapframe from parent so return to user mode */
* will be to right address, with correct registers. p2tf = p2->p_frame;
*/ p2tf->tf_regs[FRAME_V0] = 0; /* child's pid (linux) */
p2tf = p2->p_frame = (struct trapframe *) p2tf->tf_regs[FRAME_A3] = 0; /* no error */
((char *)p2->p_addr + USPACE - sizeof(struct trapframe)); p2tf->tf_regs[FRAME_A4] = 1; /* is child (FreeBSD) */
bcopy(p1->p_frame, p2->p_frame, sizeof(struct trapframe));
/* /*
* Set up return-value registers as fork() libc stub expects. * Arrange for continuation at fork_return(), which
*/ * will return to exception_return(). Note that the child
p2tf->tf_regs[FRAME_V0] = 0; /* child's pid (linux) */ * process doesn't stay in the kernel for long!
p2tf->tf_regs[FRAME_A3] = 0; /* no error */ */
p2tf->tf_regs[FRAME_A4] = 1; /* is child (FreeBSD) */ 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 */
* Arrange for continuation at fork_return(), which up->u_pcb.pcb_context[1] = (u_int64_t)exception_return; /* s1: ra */
* will return to exception_return(). Note that the child up->u_pcb.pcb_context[2] = (u_long) p2; /* s2: a1 */
* process doesn't stay in the kernel for long! up->u_pcb.pcb_context[7] = (u_int64_t)fork_trampoline; /* ra: magic */
*
* 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 */
#ifdef SMP #ifdef SMP
/* /*
* We start off at a nesting level of 1 within the kernel. * We start off at a nesting level of 1 within the kernel.
*/ */
p2->p_md.md_kernnest = 1; p2->p_md.md_kernnest = 1;
#endif #endif
}
} }
/* /*