1 files changed, 21 insertions, 14 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 8a6d20ce1978..16c6365e2b86 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -146,29 +146,18 @@ static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
-                unsigned long unused,
+                unsigned long arg,
         struct task_struct *p, struct pt_regs *regs)
 {
         int err;
         struct pt_regs *childregs;
         struct task_struct *me = current;
 
-        childregs = ((struct pt_regs *)
-                        (THREAD_SIZE + task_stack_page(p))) - 1;
-        *childregs = *regs;
-
-        childregs->ax = 0;
-        if (user_mode(regs))
-                childregs->sp = sp;
-        else
-                childregs->sp = (unsigned long)childregs;
-
+        p->thread.sp0 = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+        childregs = task_pt_regs(p);
         p->thread.sp = (unsigned long) childregs;
-        p->thread.sp0 = (unsigned long) (childregs+1);
         p->thread.usersp = me->thread.usersp;
-
         set_tsk_thread_flag(p, TIF_FORK);
-
         p->fpu_counter = 0;
         p->thread.io_bitmap_ptr = NULL;
 
@@ -178,6 +167,24 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
         p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
         savesegment(es, p->thread.es);
         savesegment(ds, p->thread.ds);
+        memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+
+        if (unlikely(!regs)) {
+                /* kernel thread */
+                memset(childregs, 0, sizeof(struct pt_regs));
+                childregs->sp = (unsigned long)childregs;
+                childregs->ss = __KERNEL_DS;
+                childregs->bx = sp; /* function */
+                childregs->bp = arg;
+                childregs->orig_ax = -1;
+                childregs->cs = __KERNEL_CS | get_kernel_rpl();
+                childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
+                return 0;
+        }
+        *childregs = *regs;
+
+        childregs->ax = 0;
+        childregs->sp = sp;
 
         err = -ENOMEM;
         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));