parisc: switch to generic kernel_thread()

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

3 files changed, 18 insertions, 89 deletions

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 11def45b98c5..c779da7cd96b 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -22,6 +22,7 @@ config PARISC
         select GENERIC_STRNCPY_FROM_USER
         select HAVE_MOD_ARCH_SPECIFIC
         select MODULES_USE_ELF_RELA
+        select GENERIC_KERNEL_THREAD
 
         help
           The PA-RISC microprocessor is designed by Hewlett-Packard and used
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index 18670a078849..18d05e7373b5 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -708,59 +708,9 @@ ENTRY(end_fault_vector)
         .import         do_cpu_irq_mask,code
 
         /*
-         * r26 = function to be called
-         * r25 = argument to pass in
-         * r24 = flags for do_fork()
-         *
-         * Kernel threads don't ever return, so they don't need
-         * a true register context. We just save away the arguments
-         * for copy_thread/ret_ to properly set up the child.
-         */
-
-#define CLONE_VM 0x100  /* Must agree with <linux/sched.h> */
-#define CLONE_UNTRACED 0x00800000
-
-        .import do_fork
-ENTRY(__kernel_thread)
-        STREG   %r2, -RP_OFFSET(%r30)
-
-        copy    %r30, %r1
-        ldo     PT_SZ_ALGN(%r30),%r30
-#ifdef CONFIG_64BIT
-        /* Yo, function pointers in wide mode are little structs... -PB */
-        ldd     24(%r26), %r2
-        STREG   %r2, PT_GR27(%r1)       /* Store childs %dp */
-        ldd     16(%r26), %r26
-
-        STREG   %r22, PT_GR22(%r1)      /* save r22 (arg5) */
-        copy    %r0, %r22               /* user_tid */
-#endif
-        STREG   %r26, PT_GR26(%r1)  /* Store function & argument for child */
-        STREG   %r25, PT_GR25(%r1)
-        ldil    L%CLONE_UNTRACED, %r26
-        ldo     CLONE_VM(%r26), %r26   /* Force CLONE_VM since only init_mm */
-        or      %r26, %r24, %r26      /* will have kernel mappings.      */
-        ldi     1, %r25                 /* stack_start, signals kernel thread */
-        stw     %r0, -52(%r30)          /* user_tid */
-#ifdef CONFIG_64BIT
-        ldo     -16(%r30),%r29          /* Reference param save area */
-#endif
-        BL      do_fork, %r2
-        copy    %r1, %r24               /* pt_regs */
-
-        /* Parent Returns here */
-
-        LDREG   -PT_SZ_ALGN-RP_OFFSET(%r30), %r2
-        ldo     -PT_SZ_ALGN(%r30), %r30
-        bv      %r0(%r2)
-        nop
-ENDPROC(__kernel_thread)
-
-        /*
          * Child Returns here
          *
-         * copy_thread moved args from temp save area set up above
-         * into task save area.
+         * copy_thread moved args into task save area.
          */
 
 ENTRY(ret_from_kernel_thread)
@@ -773,7 +723,6 @@ ENTRY(ret_from_kernel_thread)
         LDREG   TASK_PT_GR25(%r1), %r26
 #ifdef CONFIG_64BIT
         LDREG   TASK_PT_GR27(%r1), %r27
-        LDREG   TASK_PT_GR22(%r1), %r22
 #endif
         LDREG   TASK_PT_GR26(%r1), %r1
         ble     0(%sr7, %r1)
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index cbc37216bf90..b7b4126774e0 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -165,23 +165,6 @@ void (*pm_power_off)(void) = machine_power_off;
 EXPORT_SYMBOL(pm_power_off);
 
 /*
- * Create a kernel thread
- */
-
-extern pid_t __kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-
-        /*
-         * FIXME: Once we are sure we don't need any debug here,
-         *        kernel_thread can become a #define.
-         */
-
-        return __kernel_thread(fn, arg, flags);
-}
-EXPORT_SYMBOL(kernel_thread);
-
-/*
  * Free current thread data structures etc..
  */
 void exit_thread(void)
@@ -256,8 +239,8 @@ sys_vfork(struct pt_regs *regs)
 
 int
 copy_thread(unsigned long clone_flags, unsigned long usp,
-            unsigned long unused,       /* in ia64 this is "user_stack_size" */
-            struct task_struct * p, struct pt_regs * pregs)
+            unsigned long arg,
+            struct task_struct *p, struct pt_regs *pregs)
 {
         struct pt_regs * cregs = &(p->thread.regs);
         void *stack = task_stack_page(p);
@@ -271,21 +254,8 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
         extern void * const hpux_child_return;
 #endif
 
-        *cregs = *pregs;
-
-        /* Set the return value for the child.  Note that this is not
-           actually restored by the syscall exit path, but we put it
-           here for consistency in case of signals. */
-        cregs->gr[28] = 0; /* child */
-
-        /*
-         * We need to differentiate between a user fork and a
-         * kernel fork. We can't use user_mode, because the
-         * the syscall path doesn't save iaoq. Right now
-         * We rely on the fact that kernel_thread passes
-         * in zero for usp.
-         */
-        if (usp == 1) {
+        if (unlikely((p->flags & PF_KTHREAD) && usp != 0)) {
+                memset(cregs, 0, sizeof(struct pt_regs));
                 /* kernel thread */
                 cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN;
                 /* Must exit via ret_from_kernel_thread in order
@@ -297,10 +267,12 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
                  * ret_from_kernel_thread.
                  */
 #ifdef CONFIG_64BIT
-                cregs->gr[27] = pregs->gr[27];
+                cregs->gr[27] = ((unsigned long *)usp)[3];
+                cregs->gr[26] = ((unsigned long *)usp)[2];
+#else
+                cregs->gr[26] = usp;
 #endif
-                cregs->gr[26] = pregs->gr[26];
-                cregs->gr[25] = pregs->gr[25];
+                cregs->gr[25] = arg;
         } else {
                 /* user thread */
                 /*
@@ -308,6 +280,13 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
                  * for setting gr[21].
                  */
 
+                *cregs = *pregs;
+
+                /* Set the return value for the child.  Note that this is not
+                   actually restored by the syscall exit path, but we put it
+                   here for consistency in case of signals. */
+                cregs->gr[28] = 0; /* child */
+
                 /* Use same stack depth as parent */
                 cregs->ksp = (unsigned long)stack
                         + (pregs->gr[21] & (THREAD_SIZE - 1));