powerpc: split ret_from_fork

... and get rid of in-kernel syscalls in kernel_thread()

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

1 files changed, 21 insertions, 13 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1a1f2ddfb581..3b06898fa175 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -734,30 +734,39 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 extern unsigned long dscr_default; /* defined in arch/powerpc/kernel/sysfs.c */
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-                unsigned long unused, struct task_struct *p,
+                unsigned long arg, struct task_struct *p,
                 struct pt_regs *regs)
 {
         struct pt_regs *childregs, *kregs;
         extern void ret_from_fork(void);
+        extern void ret_from_kernel_thread(void);
+        void (*f)(void);
         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 
-        CHECK_FULL_REGS(regs);
         /* Copy registers */
         sp -= sizeof(struct pt_regs);
         childregs = (struct pt_regs *) sp;
-        *childregs = *regs;
-        if ((childregs->msr & MSR_PR) == 0) {
+        if (!regs) {
                 /* for kernel thread, set `current' and stackptr in new task */
+                memset(childregs, 0, sizeof(struct pt_regs));
                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
-#ifdef CONFIG_PPC32
-                childregs->gpr[2] = (unsigned long) p;
-#else
+#ifdef CONFIG_PPC64
+                childregs->gpr[14] = *(unsigned long *)usp;
+                childregs->gpr[2] = ((unsigned long *)usp)[1],
                 clear_tsk_thread_flag(p, TIF_32BIT);
+#else
+                childregs->gpr[14] = usp;       /* function */
+                childregs->gpr[2] = (unsigned long) p;
 #endif
+                childregs->gpr[15] = arg;
                 p->thread.regs = NULL;  /* no user register state */
+                f = ret_from_kernel_thread;
         } else {
+                CHECK_FULL_REGS(regs);
+                *childregs = *regs;
                 childregs->gpr[1] = usp;
                 p->thread.regs = childregs;
+                childregs->gpr[3] = 0;  /* Result from fork() */
                 if (clone_flags & CLONE_SETTLS) {
 #ifdef CONFIG_PPC64
                         if (!is_32bit_task())
@@ -766,8 +775,9 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 #endif
                                 childregs->gpr[2] = childregs->gpr[6];
                 }
+
+                f = ret_from_fork;
         }
-        childregs->gpr[3] = 0;  /* Result from fork() */
         sp -= STACK_FRAME_OVERHEAD;
 
         /*
@@ -806,19 +816,17 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
                 p->thread.dscr = current->thread.dscr;
         }
 #endif
-
         /*
          * The PPC64 ABI makes use of a TOC to contain function 
          * pointers.  The function (ret_from_except) is actually a pointer
          * to the TOC entry.  The first entry is a pointer to the actual
          * function.
-         */
+         */
 #ifdef CONFIG_PPC64
-        kregs->nip = *((unsigned long *)ret_from_fork);
+        kregs->nip = *((unsigned long *)f);
 #else
-        kregs->nip = (unsigned long)ret_from_fork;
+        kregs->nip = (unsigned long)f;
 #endif
-
         return 0;
 }