cris: switch to generic kernel_thread()

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

2 files changed, 35 insertions, 52 deletions

diff --git a/arch/cris/arch-v32/kernel/entry.S b/arch/cris/arch-v32/kernel/entry.S
index c3ea4694fbaf..a9bcbc419278 100644
--- a/arch/cris/arch-v32/kernel/entry.S
+++ b/arch/cris/arch-v32/kernel/entry.S
@@ -31,6 +31,7 @@
         .globl system_call
         .globl ret_from_intr
         .globl ret_from_fork
+        .globl ret_from_kernel_thread
         .globl resume
         .globl multiple_interrupt
         .globl nmi_interrupt
@@ -84,6 +85,18 @@ ret_from_fork:
         nop
         .size   ret_from_fork, . - ret_from_fork
 
+        .type   ret_from_kernel_thread,@function
+ret_from_kernel_thread:
+        jsr schedule_tail
+        nop
+        move.d  $r2, $r10
+        jsr     $r1
+        nop
+        moveq   0, $r10
+        jsr     sys_exit
+        nop
+        .size   ret_from_kernel_thread, . - ret_from_kernel_thread
+
         .type   ret_from_intr,@function
 ret_from_intr:
         ;; Check for resched if preemptive kernel, or if we're going back to
diff --git a/arch/cris/arch-v32/kernel/process.c b/arch/cris/arch-v32/kernel/process.c
index 4e9992246359..3edbdb88110e 100644
--- a/arch/cris/arch-v32/kernel/process.c
+++ b/arch/cris/arch-v32/kernel/process.c
@@ -16,6 +16,7 @@
 #include <hwregs/reg_map.h>
 #include <hwregs/timer_defs.h>
 #include <hwregs/intr_vect_defs.h>
+#include <asm/ptrace.h>
 
 extern void stop_watchdog(void);
 
@@ -94,31 +95,6 @@ unsigned long thread_saved_pc(struct task_struct *t)
         return task_pt_regs(t)->erp;
 }
 
-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.erp = (unsigned long) kernel_thread_helper;
-        regs.ccs = 1 << (I_CCS_BITNR + CCS_SHIFT);
-
-        /* 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 call switch_stack() on it.
  * It will be unnested during _resume and _ret_from_sys_call when the new thread
@@ -129,23 +105,33 @@ kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  */
 
 extern asmlinkage void ret_from_fork(void);
+extern 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. Note: 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->ccs = 1 << (I_CCS_BITNR + CCS_SHIFT);
+                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. */
 
         /* Set a new TLS ?
@@ -156,7 +142,6 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
         }
 
         /* Put the switch stack right below the pt_regs. */
-        swstack = ((struct switch_stack *) childregs) - 1;
 
         /* Parameter to ret_from_sys_call. 0 is don't restart the syscall. */
         swstack->r9 = 0;
@@ -174,35 +159,21 @@ 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)
+sys_fork(void)
 {
-        return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
+        return do_fork(SIGCHLD, rdusp(), current_pt_regs(), 0, NULL, NULL);
 }
 
 /* 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,
-        unsigned long tls, long srp, struct pt_regs *regs)
+        unsigned long tls)
 {
         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);
 }
 
 /*
@@ -210,10 +181,9 @@ sys_clone(unsigned long newusp, unsigned long flags, int *parent_tid, int *child
  * 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)
+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);
 }
 
 /* sys_execve() executes a new program. */