linux-kernel - [PATCH] [16/19] x86: Revert new unwind kernel stack termination

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Date:	Sat, 21 Oct 2006 18:51:36 +0200 (CEST)
From:	Andi Kleen <ak@...e.de>
To:	jbeulich@...ell.com, patches@...-64.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] [16/19] 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@...ell.com

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

---
 arch/i386/kernel/process.c |    6 +-----
 arch/x86_64/kernel/entry.S |    5 -----
 2 files changed, 1 insertion(+), 10 deletions(-)

Index: linux/arch/i386/kernel/process.c
===================================================================
--- linux.orig/arch/i386/kernel/process.c
+++ linux/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 *), voi
 	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);
 
Index: linux/arch/x86_64/kernel/entry.S
===================================================================
--- linux.orig/arch/x86_64/kernel/entry.S
+++ linux/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,
-
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