[PATCH] x86: Revert new unwind kernel stack termination

Jan convinced me that it was unnecessary because the assembly stubs do
this already on the stack.

Cc: jbeulich@novell.com

Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/kernel/process.c

@@ -336,7 +336,6 @@ extern void kernel_thread_helper(void);
 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 {
 	struct pt_regs regs;
-	int err;
 
 	memset(&regs, 0, sizeof(regs));
 
@@ -351,10 +350,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 	regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
 
 	/* Ok, create the new process.. */
-	err = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-	if (err == 0) /* terminate kernel stack */
-		task_pt_regs(current)->eip = 0;
-	return err;
+	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
 EXPORT_SYMBOL(kernel_thread);
 

arch/x86_64/kernel/entry.S

@@ -980,11 +980,6 @@ ENTRY(kernel_thread)
 	call do_fork
 	movq %rax,RAX(%rsp)
 	xorl %edi,%edi
-	test %rax,%rax
-	jnz  1f
-	/* terminate stack in child */
-	movq %rdi,RIP(%rsp)
-1:
 
 	/*
 	 * It isn't worth to check for reschedule here,