x86, 64-bit: Move kernel_thread to C

Prepare for merging with 32-bit.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-2-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 29 insertions, 2 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 83019f94b83d..92484c2130c6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -59,8 +59,6 @@ asmlinkage extern void ret_from_fork(void);
 DEFINE_PER_CPU(unsigned long, old_rsp);
 static DEFINE_PER_CPU(unsigned char, is_idle);
 
-unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
-
 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
 
 void idle_notifier_register(struct notifier_block *n)
@@ -231,6 +229,35 @@ void show_regs(struct pt_regs *regs)
         show_trace(NULL, regs, (void *)(regs + 1), regs->bp);
 }
 
+/*
+ * This gets run with %si containing the
+ * function to call, and %di containing
+ * the "args".
+ */
+extern void kernel_thread_helper(void);
+
+/*
+ * Create a kernel thread
+ */
+int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+{
+        struct pt_regs regs;
+
+        memset(&regs, 0, sizeof(regs));
+
+        regs.si = (unsigned long) fn;
+        regs.di = (unsigned long) arg;
+
+        regs.orig_ax = -1;
+        regs.ip = (unsigned long) kernel_thread_helper;
+        regs.cs = __KERNEL_CS;
+        regs.flags = X86_EFLAGS_IF;
+
+        /* Ok, create the new process.. */
+        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, ~0UL, &regs, 0, NULL, NULL);
+}
+EXPORT_SYMBOL(kernel_thread);
+
 void release_thread(struct task_struct *dead_task)
 {
         if (dead_task->mm) {