cris: switch to generic kernel_thread()

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

2 files changed, 33 insertions, 60 deletions

diff --git a/arch/cris/arch-v10/kernel/entry.S b/arch/cris/arch-v10/kernel/entry.S
index 592fbe9dfb62..b8e39e00acb2 100644
--- a/arch/cris/arch-v10/kernel/entry.S
+++ b/arch/cris/arch-v10/kernel/entry.S
@@ -35,6 +35,7 @@
         .globl system_call
         .globl ret_from_intr
         .globl ret_from_fork
+        .globl ret_from_kernel_thread
         .globl resume
         .globl multiple_interrupt
         .globl hwbreakpoint
@@ -81,7 +82,14 @@ ret_from_fork:
         jsr schedule_tail
         ba  ret_from_sys_call
         nop
-                
+
+ret_from_kernel_thread:
+        jsr schedule_tail
+        move.d  $r2, $r10       ; argument is here
+        jsr     $r1             ; call the payload
+        moveq   0, $r10
+        jsr     sys_exit        ; never returns
+
 ret_from_intr:
         ;; check for resched if preemptive kernel or if we're going back to user-mode 
         ;; this test matches the user_regs(regs) macro
diff --git a/arch/cris/arch-v10/kernel/process.c b/arch/cris/arch-v10/kernel/process.c
index 15ac7150371f..8a673aa81cdd 100644
--- a/arch/cris/arch-v10/kernel/process.c
+++ b/arch/cris/arch-v10/kernel/process.c
@@ -17,6 +17,7 @@
 #include <arch/svinto.h>
 #include <linux/init.h>
 #include <arch/system.h>
+#include <asm/ptrace.h>
 
 #ifdef CONFIG_ETRAX_GPIO
 void etrax_gpio_wake_up_check(void); /* drivers/gpio.c */
@@ -81,31 +82,6 @@ unsigned long thread_saved_pc(struct task_struct *t)
         return task_pt_regs(t)->irp;
 }
 
-static void kernel_thread_helper(void* dummy, int (*fn)(void *), void * arg)
-{
-  fn(arg);
-  do_exit(-1); /* Should never be called, return bad exit value */
-}
-
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        /* Don't use r10 since that is set to 0 in copy_thread */
-        regs.r11 = (unsigned long)fn;
-        regs.r12 = (unsigned long)arg;
-        regs.irp = (unsigned long)kernel_thread_helper;
-        regs.dccr = 1 << I_DCCR_BITNR;
-
-        /* Ok, create the new process.. */
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-
 /* setup the child's kernel stack with a pt_regs and switch_stack on it.
  * it will be un-nested during _resume and _ret_from_sys_call when the
  * new thread is scheduled.
@@ -115,29 +91,35 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  *
  */
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-                unsigned long unused,
+                unsigned long arg,
                 struct task_struct *p, struct pt_regs *regs)
 {
-        struct pt_regs * childregs;
-        struct switch_stack *swstack;
+        struct pt_regs *childregs = task_pt_regs(p);
+        struct switch_stack *swstack = ((struct switch_stack *)childregs) - 1;
         
         /* put the pt_regs structure at the end of the new kernel stack page and fix it up
          * remember that the task_struct doubles as the kernel stack for the task
          */
 
-        childregs = task_pt_regs(p);
-        
+        if (unlikely(p->flags & PF_KTHREAD)) {
+                memset(swstack, 0,
+                        sizeof(struct switch_stack) + sizeof(struct pt_regs));
+                swstack->r1 = usp;
+                swstack->r2 = arg;
+                childregs->dccr = 1 << I_DCCR_BITNR;
+                swstack->return_ip = (unsigned long) ret_from_kernel_thread;
+                p->thread.ksp = (unsigned long) swstack;
+                p->thread.usp = 0;
+                return 0;
+        }
         *childregs = *regs;  /* struct copy of pt_regs */
-        
-        p->set_child_tid = p->clear_child_tid = NULL;
 
         childregs->r10 = 0;  /* child returns 0 after a fork/clone */
-        
-        /* put the switch stack right below the pt_regs */
 
-        swstack = ((struct switch_stack *)childregs) - 1;
+        /* put the switch stack right below the pt_regs */
 
         swstack->r9 = 0; /* parameter to ret_from_sys_call, 0 == dont restart the syscall */
 
@@ -147,7 +129,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         
         /* fix the user-mode stackpointer */
 
-        p->thread.usp = usp;    
+        p->thread.usp = usp;
 
         /* and the kernel-mode one */
 
@@ -161,45 +143,28 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         return 0;
 }
 
-/* 
- * Be aware of the "magic" 7th argument in the four system-calls below.
- * They need the latest stackframe, which is put as the 7th argument by
- * entry.S. The previous arguments are dummies or actually used, but need
- * to be defined to reach the 7th argument.
- *
- * N.B.: Another method to get the stackframe is to use current_regs(). But
- * it returns the latest stack-frame stacked when going from _user mode_ and
- * some of these (at least sys_clone) are called from kernel-mode sometimes
- * (for example during kernel_thread, above) and thus cannot use it. Thus,
- * to be sure not to get any surprises, we use the method for the other calls
- * as well.
- */
-
-asmlinkage int sys_fork(long r10, long r11, long r12, long r13, long mof, long srp,
-                        struct pt_regs *regs)
+asmlinkage int sys_fork(void)
 {
-        return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
+        return do_fork(SIGCHLD, rdusp(), current_pt_regs(), 0, NULL, NULL);
 }
 
 /* if newusp is 0, we just grab the old usp */
 /* FIXME: Is parent_tid/child_tid really third/fourth argument? Update lib? */
 asmlinkage int sys_clone(unsigned long newusp, unsigned long flags,
-                         int* parent_tid, int* child_tid, long mof, long srp,
-                         struct pt_regs *regs)
+                         int* parent_tid, int* child_tid)
 {
         if (!newusp)
                 newusp = rdusp();
-        return do_fork(flags, newusp, regs, 0, parent_tid, child_tid);
+        return do_fork(flags, newusp, current_pt_regs(), 0, parent_tid, child_tid);
 }
 
 /* vfork is a system call in i386 because of register-pressure - maybe
  * we can remove it and handle it in libc but we put it here until then.
  */
 
-asmlinkage int sys_vfork(long r10, long r11, long r12, long r13, long mof, long srp,
-                         struct pt_regs *regs)
+asmlinkage int sys_vfork(void)
 {
-        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL, NULL);
+        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), current_pt_regs(), 0, NULL, NULL);
 }
 
 /*