mips: switch to generic kernel_thread()

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

3 files changed, 29 insertions, 42 deletions

diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
index a6c133212003..aab6997b8f47 100644
--- a/arch/mips/kernel/entry.S
+++ b/arch/mips/kernel/entry.S
@@ -65,6 +65,13 @@ need_resched:
         b       need_resched
 #endif
 
+FEXPORT(ret_from_kernel_thread)
+        jal     schedule_tail           # a0 = struct task_struct *prev
+        move    a0, s1
+        jal     s0
+        li      a0, 0
+        j       sys_exit
+
 FEXPORT(ret_from_fork)
         jal     schedule_tail           # a0 = struct task_struct *prev
 
diff --git a/arch/mips/kernel/mips_ksyms.c b/arch/mips/kernel/mips_ksyms.c
index 3fc1691110dc..2d9304c2b54c 100644
--- a/arch/mips/kernel/mips_ksyms.c
+++ b/arch/mips/kernel/mips_ksyms.c
@@ -32,8 +32,6 @@ EXPORT_SYMBOL(memset);
 EXPORT_SYMBOL(memcpy);
 EXPORT_SYMBOL(memmove);
 
-EXPORT_SYMBOL(kernel_thread);
-
 /*
  * Functions that operate on entire pages.  Mostly used by memory management.
  */
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index e9a5fd7277f4..d13720ac656f 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -84,6 +84,7 @@ void __noreturn cpu_idle(void)
 }
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 {
@@ -113,7 +114,7 @@ void flush_thread(void)
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-        unsigned long unused, struct task_struct *p, struct pt_regs *regs)
+        unsigned long arg, struct task_struct *p, struct pt_regs *regs)
 {
         struct thread_info *ti = task_thread_info(p);
         struct pt_regs *childregs;
@@ -136,19 +137,30 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         childregs = (struct pt_regs *) childksp - 1;
         /*  Put the stack after the struct pt_regs.  */
         childksp = (unsigned long) childregs;
+        p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
+        if (unlikely(p->flags & PF_KTHREAD)) {
+                unsigned long status = p->thread.cp0_status;
+                memset(childregs, 0, sizeof(struct pt_regs));
+                ti->addr_limit = KERNEL_DS;
+                p->thread.reg16 = usp; /* fn */
+                p->thread.reg17 = arg;
+                p->thread.reg29 = childksp;
+                p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
+#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
+                status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
+                         ((status & (ST0_KUC | ST0_IEC)) << 2);
+#else
+                status |= ST0_EXL;
+#endif
+                childregs->cp0_status = status;
+                return 0;
+        }
         *childregs = *regs;
         childregs->regs[7] = 0; /* Clear error flag */
-
         childregs->regs[2] = 0; /* Child gets zero as return value */
+        childregs->regs[29] = usp;
+        ti->addr_limit = USER_DS;
 
-        if (childregs->cp0_status & ST0_CU0) {
-                childregs->regs[28] = (unsigned long) ti;
-                childregs->regs[29] = childksp;
-                ti->addr_limit = KERNEL_DS;
-        } else {
-                childregs->regs[29] = usp;
-                ti->addr_limit = USER_DS;
-        }
         p->thread.reg29 = (unsigned long) childregs;
         p->thread.reg31 = (unsigned long) ret_from_fork;
 
@@ -156,7 +168,6 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
          * New tasks lose permission to use the fpu. This accelerates context
          * switching for most programs since they don't use the fpu.
          */
-        p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 
 #ifdef CONFIG_MIPS_MT_SMTC
@@ -222,35 +233,6 @@ int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 }
 
 /*
- * Create a kernel thread
- */
-static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
-{
-        do_exit(fn(arg));
-}
-
-long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.regs[4] = (unsigned long) arg;
-        regs.regs[5] = (unsigned long) fn;
-        regs.cp0_epc = (unsigned long) kernel_thread_helper;
-        regs.cp0_status = read_c0_status();
-#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
-        regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
-                          ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2);
-#else
-        regs.cp0_status |= ST0_EXL;
-#endif
-
-        /* Ok, create the new process.. */
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-
-/*
  *
  */
 struct mips_frame_info {