blackfin: convert kernel_thread() and kernel_execve() to generic ones

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

1 files changed, 17 insertions, 38 deletions

diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index bb1cc721fcf7..9945b94c63d4 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -102,40 +102,6 @@ void cpu_idle(void)
 }
 
 /*
- * This gets run with P1 containing the
- * function to call, and R1 containing
- * the "args".  Note P0 is clobbered on the way here.
- */
-void kernel_thread_helper(void);
-__asm__(".section .text\n"
-        ".align 4\n"
-        "_kernel_thread_helper:\n\t"
-        "\tsp += -12;\n\t"
-        "\tr0 = r1;\n\t" "\tcall (p1);\n\t" "\tcall _do_exit;\n" ".previous");
-
-/*
- * Create a kernel thread.
- */
-pid_t kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.r1 = (unsigned long)arg;
-        regs.p1 = (unsigned long)fn;
-        regs.pc = (unsigned long)kernel_thread_helper;
-        regs.orig_p0 = -1;
-        /* Set bit 2 to tell ret_from_fork we should be returning to kernel
-           mode.  */
-        regs.ipend = 0x8002;
-        __asm__ __volatile__("%0 = syscfg;":"=da"(regs.syscfg):);
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
-                       NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
-/*
  * Do necessary setup to start up a newly executed thread.
  *
  * pass the data segment into user programs if it exists,
@@ -193,13 +159,26 @@ copy_thread(unsigned long clone_flags,
             struct task_struct *p, struct pt_regs *regs)
 {
         struct pt_regs *childregs;
+        unsigned long *v;
 
         childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
-        *childregs = *regs;
-        childregs->r0 = 0;
+        v = ((unsigned long *)childregs) - 2;
+        if (unlikely(!regs)) {
+                memset(childregs, 0, sizeof(struct pt_regs));
+                v[0] = usp;
+                v[1] = topstk;
+                childregs->orig_p0 = -1;
+                childregs->ipend = 0x8000;
+                __asm__ __volatile__("%0 = syscfg;":"=da"(childregs->syscfg):);
+                p->thread.usp = 0;
+        } else {
+                *childregs = *regs;
+                childregs->r0 = 0;
+                p->thread.usp = usp;
+                v[0] = v[1] = 0;
+        }
 
-        p->thread.usp = usp;
-        p->thread.ksp = (unsigned long)childregs;
+        p->thread.ksp = (unsigned long)v;
         p->thread.pc = (unsigned long)ret_from_fork;
 
         return 0;