commit 7147e215480323bb2617fcebf585c447188ff760
author Al Viro <viro@zeniv.linux.org.uk> Sun Oct 14 01:41:42 2012 -0400
committer Al Viro <viro@zeniv.linux.org.uk> Mon Oct 22 22:31:01 2012 -0400
tree fb5d92e4f9e2f4d5d5c8e4449c4ef43e05275826
parent ddffeb8c4d0331609ef2581d84de4d763607bd37

sh: switch to generic kernel_thread()/kernel_execve()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/sh/kernel/process_64.c

diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 98a709f..fd338b0 100644
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -285,39 +285,6 @@
 }
 
 /*
- * Create a kernel thread
- */
-__noreturn void kernel_thread_helper(void *arg, int (*fn)(void *))
-{
-	do_exit(fn(arg));
-}
-
-/*
- * This is the mechanism for creating a new kernel thread.
- *
- * NOTE! Only a kernel-only process(ie the swapper or direct descendants
- * who haven't done an "execve()") should use this: it will work within
- * a system call from a "real" process, but the process memory space will
- * not be freed until both the parent and the child have exited.
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-	struct pt_regs regs;
-
-	memset(&regs, 0, sizeof(regs));
-	regs.regs[2] = (unsigned long)arg;
-	regs.regs[3] = (unsigned long)fn;
-
-	regs.pc = (unsigned long)kernel_thread_helper;
-	regs.sr = (1 << 30);
-
-	/* Ok, create the new process.. */
-	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
-		      &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
-/*
  * Free current thread data structures etc..
  */
 void exit_thread(void)
@@ -401,15 +368,17 @@
 EXPORT_SYMBOL(dump_fpu);
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-		unsigned long unused,
+		unsigned long arg,
 		struct task_struct *p, struct pt_regs *regs)
 {
 	struct pt_regs *childregs;
 
 #ifdef CONFIG_SH_FPU
-	if(last_task_used_math == current) {
+	/* can't happen for a kernel thread */
+	if (last_task_used_math == current) {
 		enable_fpu();
 		save_fpu(current);
 		disable_fpu();
@@ -419,7 +388,17 @@
 #endif
 	/* Copy from sh version */
 	childregs = (struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1;
+	p->thread.sp = (unsigned long) childregs;
 
+	if (unlikely(p->flags & PF_KTHREAD)) {
+		memset(childregs, 0, sizeof(struct pt_regs));
+		childregs->regs[2] = (unsigned long)arg;
+		childregs->regs[3] = (unsigned long)fn;
+		childregs->sr = (1 << 30); /* not user_mode */
+		childregs->sr |= SR_FD; /* Invalidate FPU flag */
+		p->thread.pc = (unsigned long) ret_from_kernel_thread;
+		return 0;
+	}
 	*childregs = *regs;
 
 	/*
@@ -428,19 +407,12 @@
 	 * 32-bit wide and context switch must take care
 	 * of NEFF sign extension.
 	 */
-	if (user_mode(regs)) {
-		childregs->regs[15] = neff_sign_extend(usp);
-		p->thread.uregs = childregs;
-	} else {
-		childregs->regs[15] =
-			neff_sign_extend((unsigned long)task_stack_page(p) +
-					 THREAD_SIZE);
-	}
+	childregs->regs[15] = neff_sign_extend(usp);
+	p->thread.uregs = childregs;
 
 	childregs->regs[9] = 0; /* Set return value for child */
 	childregs->sr |= SR_FD; /* Invalidate FPU flag */
 
-	p->thread.sp = (unsigned long) childregs;
 	p->thread.pc = (unsigned long) ret_from_fork;
 
 	return 0;