alpha: simplify fork and friends
* no need to restore everything from switch_stack when we only need $26
* no need to pass current_pt_regs() manually, we can just as easily
calculate it in alpha_clone/alpha_vfork ($8 + constant)
* interpretation of zero usp as "use the parent's" is simpler in copy_thread();
let fork and vfork just pass 0.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index a760783..cc6d34e 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -617,7 +617,6 @@
.ent sys_fork
sys_fork:
.prologue 0
- mov $sp, $21
bsr $1, do_switch_stack
bis $31, SIGCHLD, $16
mov $31, $17
@@ -625,7 +624,9 @@
mov $31, $19
mov $31, $20
jsr $26, alpha_clone
- bsr $1, undo_switch_stack
+fork_out:
+ ldq $26, 56($sp)
+ lda $sp, SWITCH_STACK_SIZE($sp)
ret
.end sys_fork
@@ -634,12 +635,10 @@
.ent sys_clone
sys_clone:
.prologue 0
- mov $sp, $21
bsr $1, do_switch_stack
/* $16, $17, $18, $19, $20 come from the user. */
- jsr $26, alpha_clone
- bsr $1, undo_switch_stack
- ret
+ lda $26, fork_out
+ jsr $31, alpha_clone
.end sys_clone
.align 4
@@ -647,11 +646,9 @@
.ent sys_vfork
sys_vfork:
.prologue 0
- mov $sp, $16
bsr $1, do_switch_stack
- jsr $26, alpha_vfork
- bsr $1, undo_switch_stack
- ret
+ lda $26, fork_out
+ jsr $31, alpha_vfork
.end sys_vfork
.align 4
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 51987dc..ad86c09 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -246,19 +246,17 @@
int
alpha_clone(unsigned long clone_flags, unsigned long usp,
int __user *parent_tid, int __user *child_tid,
- unsigned long tls_value, struct pt_regs *regs)
+ unsigned long tls_value)
{
- if (!usp)
- usp = rdusp();
-
- return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
+ return do_fork(clone_flags, usp, current_pt_regs(), 0,
+ parent_tid, child_tid);
}
int
-alpha_vfork(struct pt_regs *regs)
+alpha_vfork(void)
{
- return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
- regs, 0, NULL, NULL);
+ return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
+ current_pt_regs(), 0, NULL, NULL);
}
/*
@@ -301,7 +299,7 @@
stack = ((struct switch_stack *) regs) - 1;
*childstack = *stack;
childstack->r26 = (unsigned long) ret_from_fork;
- childti->pcb.usp = usp;
+ childti->pcb.usp = usp ?: rdusp();
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */