frv: split ret_from_fork, simplify kernel_thread() a lot

Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 23 insertions, 21 deletions

diff --git a/arch/frv/kernel/process.c b/arch/frv/kernel/process.c
index ff95f50efea5..0f02dee25e26 100644
--- a/arch/frv/kernel/process.c
+++ b/arch/frv/kernel/process.c
@@ -37,6 +37,7 @@
 #include "local.h"
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 #include <asm/pgalloc.h>
 
@@ -172,29 +173,21 @@ int copy_thread(unsigned long clone_flags,
 		unsigned long usp, unsigned long topstk,
 		struct task_struct *p, struct pt_regs *regs)
 {
-	struct pt_regs *childregs0, *childregs, *regs0;
+	struct pt_regs *childregs;
 
-	regs0 = __kernel_frame0_ptr;
-	childregs0 = (struct pt_regs *)
+	childregs = (struct pt_regs *)
 		(task_stack_page(p) + THREAD_SIZE - FRV_FRAME0_SIZE);
-	childregs = childregs0;
 
 	/* set up the userspace frame (the only place that the USP is stored) */
-	*childregs0 = *regs0;
-
-	childregs0->gr8		= 0;
-	childregs0->sp		= usp;
-	childregs0->next_frame	= NULL;
-
-	/* set up the return kernel frame if called from kernel_thread() */
-	if (regs != regs0) {
-		childregs--;
-		*childregs = *regs;
-		childregs->sp = (unsigned long) childregs0;
-		childregs->next_frame = childregs0;
-		childregs->gr15 = (unsigned long) task_thread_info(p);
-		childregs->gr29 = (unsigned long) p;
-	}
+	*childregs = *regs;
+
+	childregs->sp		= usp;
+	childregs->next_frame	= NULL;
+
+	if (unlikely(!user_mode(regs)))
+		p->thread.pc = (unsigned long) ret_from_kernel_thread;
+	else
+		p->thread.pc = (unsigned long) ret_from_fork;
 
 	p->set_child_tid = p->clear_child_tid = NULL;
 
@@ -203,8 +196,7 @@ int copy_thread(unsigned long clone_flags,
 	p->thread.sp	 = (unsigned long) childregs;
 	p->thread.fp	 = 0;
 	p->thread.lr	 = 0;
-	p->thread.pc	 = (unsigned long) ret_from_fork;
-	p->thread.frame0 = childregs0;
+	p->thread.frame0 = childregs;
 
 	/* the new TLS pointer is passed in as arg #5 to sys_clone() */
 	if (clone_flags & CLONE_SETTLS)
@@ -347,3 +339,13 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 	       sizeof(current->thread.user->f));
 	return 1;
 }
+
+int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+{
+	struct pt_regs regs = {
+		.gr8 = (unsigned long)arg;
+		.gr9 = (unsigned long)fn;
+		.psr = PSR_S;
+	};
+	return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
+}