m68k: split ret_from_fork(), simplify kernel_thread()
Al Viro [Sun, 16 Sep 2012 16:05:09 +0000 (12:05 -0400)]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/m68k/Kconfig
arch/m68k/include/asm/processor.h
arch/m68k/kernel/entry.S
arch/m68k/kernel/process.c

index b22df94..ccda007 100644 (file)
@@ -13,6 +13,7 @@ config M68K
        select FPU if MMU
        select ARCH_WANT_IPC_PARSE_VERSION
        select ARCH_USES_GETTIMEOFFSET if MMU && !COLDFIRE
+       select GENERIC_KERNEL_THREAD
 
 config RWSEM_GENERIC_SPINLOCK
        bool
index 9b4c82c..ae700f4 100644 (file)
@@ -154,8 +154,6 @@ static inline void release_thread(struct task_struct *dead_task)
 {
 }
 
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
-
 /*
  * Free current thread data structures etc..
  */
index 165ee9f..8a01f58 100644 (file)
@@ -111,6 +111,17 @@ ENTRY(ret_from_fork)
        addql   #4,%sp
        jra     ret_from_exception
 
+ENTRY(ret_from_kernel_thread)
+       | a3 contains the kernel thread payload, d7 - its argument
+       movel   %d1,%sp@-
+       jsr     schedule_tail
+       GET_CURRENT(%d0)
+       movel   %d7,(%sp)
+       jsr     %a3@
+       addql   #4,%sp
+       movel   %d0,(%sp)
+       jra     sys_exit
+
 #if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
 
 #ifdef TRAP_DBG_INTERRUPT
index c488e3c..b3d4760 100644 (file)
@@ -34,6 +34,7 @@
 
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 
 /*
@@ -120,51 +121,6 @@ void show_regs(struct pt_regs * regs)
                printk("USP: %08lx\n", rdusp());
 }
 
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-       int pid;
-       mm_segment_t fs;
-
-       fs = get_fs();
-       set_fs (KERNEL_DS);
-
-       {
-       register long retval __asm__ ("d0");
-       register long clone_arg __asm__ ("d1") = flags | CLONE_VM | CLONE_UNTRACED;
-
-       retval = __NR_clone;
-       __asm__ __volatile__
-         ("clrl %%d2\n\t"
-          "trap #0\n\t"                /* Linux/m68k system call */
-          "tstl %0\n\t"                /* child or parent */
-          "jne 1f\n\t"                 /* parent - jump */
-#ifdef CONFIG_MMU
-          "lea %%sp@(%c7),%6\n\t"      /* reload current */
-          "movel %6@,%6\n\t"
-#endif
-          "movel %3,%%sp@-\n\t"        /* push argument */
-          "jsr %4@\n\t"                /* call fn */
-          "movel %0,%%d1\n\t"          /* pass exit value */
-          "movel %2,%%d0\n\t"          /* exit */
-          "trap #0\n"
-          "1:"
-          : "+d" (retval)
-          : "i" (__NR_clone), "i" (__NR_exit),
-            "r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
-            "i" (-THREAD_SIZE)
-          : "d2");
-
-       pid = retval;
-       }
-
-       set_fs (fs);
-       return pid;
-}
-EXPORT_SYMBOL(kernel_thread);
-
 void flush_thread(void)
 {
        current->thread.fs = __USER_DS;
@@ -216,30 +172,18 @@ asmlinkage int m68k_clone(struct pt_regs *regs)
 }
 
 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 * childstack, *stack;
-       unsigned long *retp;
+       struct switch_stack *childstack;
 
        childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
-
-       *childregs = *regs;
-       childregs->d0 = 0;
-
-       retp = ((unsigned long *) regs);
-       stack = ((struct switch_stack *) retp) - 1;
-
        childstack = ((struct switch_stack *) childregs) - 1;
-       *childstack = *stack;
-       childstack->retpc = (unsigned long)ret_from_fork;
 
        p->thread.usp = usp;
        p->thread.ksp = (unsigned long)childstack;
-
-       if (clone_flags & CLONE_SETTLS)
-               task_thread_info(p)->tp_value = regs->d5;
+       p->thread.esp0 = (unsigned long)childregs;
 
        /*
         * Must save the current SFC/DFC value, NOT the value when
@@ -247,6 +191,26 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         */
        p->thread.fs = get_fs().seg;
 
+       if (unlikely(!regs)) {
+               /* kernel thread */
+               memset(childstack, 0,
+                       sizeof(struct switch_stack) + sizeof(struct pt_regs));
+               childregs->sr = PS_S;
+               childstack->a3 = usp; /* function */
+               childstack->d7 = arg;
+               childstack->retpc = (unsigned long)ret_from_kernel_thread;
+               p->thread.usp = 0;
+               return 0;
+       }
+       *childregs = *regs;
+       childregs->d0 = 0;
+
+       *childstack = ((struct switch_stack *) regs)[-1];
+       childstack->retpc = (unsigned long)ret_from_fork;
+
+       if (clone_flags & CLONE_SETTLS)
+               task_thread_info(p)->tp_value = regs->d5;
+
 #ifdef CONFIG_FPU
        if (!FPU_IS_EMU) {
                /* Copy the current fpu state */