h8300: generic kernel_thread()

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

arch/h8300/Kconfig

@@ -8,6 +8,7 @@ config H8300
 	select GENERIC_IRQ_SHOW
 	select GENERIC_CPU_DEVICES
 	select MODULES_USE_ELF_RELA
+	select GENERIC_KERNEL_THREAD
 
 config SYMBOL_PREFIX
 	string

arch/h8300/include/asm/processor.h

@@ -107,8 +107,6 @@ 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..
  */

arch/h8300/include/asm/ptrace.h

@@ -60,6 +60,8 @@ struct pt_regs {
 #define user_mode(regs) (!((regs)->ccr & PS_S))
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)
+#define current_pt_regs() ((struct pt_regs *) \
+	(THREAD_SIZE + (unsigned long)current_thread_info()) - 1)
 #endif /* __KERNEL__ */
 #endif /* __ASSEMBLY__ */
 #endif /* _H8300_PTRACE_H */

arch/h8300/kernel/entry.S

@@ -158,6 +158,7 @@ INTERRUPTS = 128
 .globl SYMBOL_NAME(system_call)
 .globl SYMBOL_NAME(ret_from_exception)
 .globl SYMBOL_NAME(ret_from_fork)
+.globl SYMBOL_NAME(ret_from_kernel_thread)
 .globl SYMBOL_NAME(ret_from_interrupt)
 .globl SYMBOL_NAME(interrupt_redirect_table)
 .globl SYMBOL_NAME(sw_ksp),SYMBOL_NAME(sw_usp)
@@ -330,6 +331,15 @@ SYMBOL_NAME_LABEL(ret_from_fork)
 	jsr	@SYMBOL_NAME(schedule_tail)
 	jmp	@SYMBOL_NAME(ret_from_exception)
 
+SYMBOL_NAME_LABEL(ret_from_kernel_thread)
+	mov.l	er2,er0
+	jsr	@SYMBOL_NAME(schedule_tail)
+	mov.l	@(LER4:16,sp),er0
+	mov.l	@(LER5:16,sp),er1
+	jsr	@er1
+	sub.l	@er0,@er0
+	jsr	@SYMBOL_NAME(sys_exit)
+
 SYMBOL_NAME_LABEL(resume)
 	/*
 	 * Beware - when entering resume, offset of tss is in d1,

arch/h8300/kernel/h8300_ksyms.c

@@ -33,7 +33,6 @@ EXPORT_SYMBOL(strncmp);
 
 EXPORT_SYMBOL(ip_fast_csum);
 
-EXPORT_SYMBOL(kernel_thread);
 EXPORT_SYMBOL(enable_irq);
 EXPORT_SYMBOL(disable_irq);
 

arch/h8300/kernel/process.c

@@ -47,6 +47,7 @@ void (*pm_power_off)(void) = NULL;
 EXPORT_SYMBOL(pm_power_off);
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 /*
  * The idle loop on an H8/300..
@@ -122,39 +123,6 @@ void show_regs(struct pt_regs * regs)
 		printk("\n");
 }
 
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-	long retval;
-	long clone_arg;
-	mm_segment_t fs;
-
-	fs = get_fs();
-	set_fs (KERNEL_DS);
-	clone_arg = flags | CLONE_VM;
-	__asm__("mov.l sp,er3\n\t"
-		"sub.l er2,er2\n\t"
-		"mov.l %2,er1\n\t"
-		"mov.l %1,er0\n\t"
-		"trapa #0\n\t"
-		"cmp.l sp,er3\n\t"
-		"beq 1f\n\t"
-		"mov.l %4,er0\n\t"
-		"mov.l %3,er1\n\t"
-		"jsr @er1\n\t"
-		"mov.l %5,er0\n\t"
-		"trapa #0\n"
-		"1:\n\t"
-		"mov.l er0,%0"
-		:"=r"(retval)
-		:"i"(__NR_clone),"g"(clone_arg),"g"(fn),"g"(arg),"i"(__NR_exit)
-		:"er0","er1","er2","er3");
-	set_fs (fs);
-	return retval;
-}
-
 void flush_thread(void)
 {
 }
@@ -198,6 +166,13 @@ int copy_thread(unsigned long clone_flags,
 
 	childregs = (struct pt_regs *) (THREAD_SIZE + task_stack_page(p)) - 1;
 
+	if (unlikely(p->flags & PF_KTHREAD)) {
+		memset(childregs, 0, sizeof(struct pt_regs));
+		childregs->retpc = (unsigned long) ret_from_kernel_thread;
+		childregs->er4 = topstk; /* arg */
+		childregs->er5 = usp; /* fn */
+		p->thread.ksp = (unsigned long)childregs;
+	}
 	*childregs = *regs;
 	childregs->retpc = (unsigned long) ret_from_fork;
 	childregs->er0 = 0;