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alpha: reorganize copy_process(), prepare to saner fork_idle()

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-10-21 15:52:04 -04:00
parent b960f30344
commit 25906730ec
1 changed files with 14 additions and 21 deletions
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35
arch/alpha/kernel/process.c
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@ -266,18 +266,22 @@ alpha_vfork(void)
int
copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg,
struct task_struct * p, struct pt_regs * regs)
struct task_struct *p, struct pt_regs *wontuse)
{
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);
struct thread_info *childti = task_thread_info(p);
struct pt_regs *childregs = task_pt_regs(p);
struct pt_regs *regs = current_pt_regs();
struct switch_stack *childstack, *stack;
unsigned long settls;
childstack = ((struct switch_stack *) childregs) - 1;
if (unlikely(!regs)) {
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
@ -286,12 +290,17 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
childstack->r10 = arg;
childregs->hae = alpha_mv.hae_cache,
childti->pcb.usp = 0;
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */
return 0;
}
/* Note: if CLONE_SETTLS is not set, then we must inherit the
value from the parent, which will have been set by the block
copy in dup_task_struct. This is non-intuitive, but is
required for proper operation in the case of a threaded
application calling fork. */
if (clone_flags & CLONE_SETTLS)
childti->pcb.unique = regs->r20;
childti->pcb.usp = usp ?: rdusp();
*childregs = *regs;
settls = regs->r20;
childregs->r0 = 0;
childregs->r19 = 0;
childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
@ -299,22 +308,6 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
stack = ((struct switch_stack *) regs) - 1;
*childstack = *stack;
childstack->r26 = (unsigned long) ret_from_fork;
childti->pcb.usp = usp ?: rdusp();
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */
/* Set a new TLS for the child thread? Peek back into the
syscall arguments that we saved on syscall entry. Oops,
except we'd have clobbered it with the parent/child set
of r20. Read the saved copy. */
/* Note: if CLONE_SETTLS is not set, then we must inherit the
value from the parent, which will have been set by the block
copy in dup_task_struct. This is non-intuitive, but is
required for proper operation in the case of a threaded
application calling fork. */
if (clone_flags & CLONE_SETTLS)
childti->pcb.unique = settls;
return 0;
}