m32r: switch to generic kernel_thread()/kernel_execve()

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

5 files changed, 27 insertions, 70 deletions

diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index f807721e19a5..5183f43a2cf7 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -15,6 +15,8 @@ config M32R
         select GENERIC_ATOMIC64
         select ARCH_USES_GETTIMEOFFSET
         select MODULES_USE_ELF_RELA
+        select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 config SBUS
         bool
diff --git a/arch/m32r/include/asm/processor.h b/arch/m32r/include/asm/processor.h
index da17253b5735..5767367550c6 100644
--- a/arch/m32r/include/asm/processor.h
+++ b/arch/m32r/include/asm/processor.h
@@ -118,11 +118,6 @@ struct mm_struct;
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/*
- * create a kernel thread without removing it from tasklists
- */
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
-
 /* Copy and release all segment info associated with a VM */
 extern void copy_segments(struct task_struct *p, struct mm_struct * mm);
 extern void release_segments(struct mm_struct * mm);
diff --git a/arch/m32r/kernel/entry.S b/arch/m32r/kernel/entry.S
index 225412bc227e..0c01543f10cd 100644
--- a/arch/m32r/kernel/entry.S
+++ b/arch/m32r/kernel/entry.S
@@ -125,6 +125,15 @@
         and     \reg, sp
         .endm
 
+ENTRY(ret_from_kernel_thread)
+        pop     r0
+        bl      schedule_tail
+        GET_THREAD_INFO(r8)
+        ld      r0, R0(r8)
+        ld      r1, R1(r8)
+        jl      r1
+        bra     syscall_exit
+
 ENTRY(ret_from_fork)
         pop     r0
         bl      schedule_tail
diff --git a/arch/m32r/kernel/process.c b/arch/m32r/kernel/process.c
index e7366276ef30..fa89f027c04a 100644
--- a/arch/m32r/kernel/process.c
+++ b/arch/m32r/kernel/process.c
@@ -165,41 +165,6 @@ void show_regs(struct pt_regs * regs)
 }
 
 /*
- * Create a kernel thread
- */
-
-/*
- * This is the mechanism for creating a new kernel thread.
- *
- * NOTE! Only a kernel-only process(ie the swapper or direct descendants
- * who haven't done an "execve()") should use this: it will work within
- * a system call from a "real" process, but the process memory space will
- * not be free'd until both the parent and the child have exited.
- */
-static void kernel_thread_helper(void *nouse, int (*fn)(void *), void *arg)
-{
-        fn(arg);
-        do_exit(-1);
-}
-
-int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof (regs));
-        regs.r1 = (unsigned long)fn;
-        regs.r2 = (unsigned long)arg;
-
-        regs.bpc = (unsigned long)kernel_thread_helper;
-
-        regs.psw = M32R_PSW_BIE;
-
-        /* Ok, create the new process. */
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
-                NULL);
-}
-
-/*
  * Free current thread data structures etc..
  */
 void exit_thread(void)
@@ -227,19 +192,26 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long spu,
-        unsigned long unused, struct task_struct *tsk, struct pt_regs *regs)
+        unsigned long arg, struct task_struct *tsk, struct pt_regs *regs)
 {
         struct pt_regs *childregs = task_pt_regs(tsk);
         extern void ret_from_fork(void);
-
-        /* Copy registers */
-        *childregs = *regs;
-
-        childregs->spu = spu;
-        childregs->r0 = 0;      /* Child gets zero as return value */
-        regs->r0 = tsk->pid;
+        extern void ret_from_kernel_thread(void);
+
+        if (unlikely(tsk->flags & PF_KTHREAD)) {
+                memset(childregs, 0, sizeof(struct pt_regs));
+                childregs->psw = M32R_PSW_BIE;
+                childregs->r1 = spu;    /* fn */
+                childregs->r0 = arg;
+                tsk->thread.lr = (unsigned long)ret_from_kernel_thread;
+        } else {
+                /* Copy registers */
+                *childregs = *regs;
+                childregs->spu = spu;
+                childregs->r0 = 0;      /* Child gets zero as return value */
+                tsk->thread.lr = (unsigned long)ret_from_fork;
+        }
         tsk->thread.sp = (unsigned long)childregs;
-        tsk->thread.lr = (unsigned long)ret_from_fork;
 
         return 0;
 }
diff --git a/arch/m32r/kernel/sys_m32r.c b/arch/m32r/kernel/sys_m32r.c
index d841fb6cc703..c3fdd632fba7 100644
--- a/arch/m32r/kernel/sys_m32r.c
+++ b/arch/m32r/kernel/sys_m32r.c
@@ -88,24 +88,3 @@ asmlinkage int sys_cachectl(char *addr, int nbytes, int op)
         /* Not implemented yet. */
         return -ENOSYS;
 }
-
-/*
- * Do a system call from kernel instead of calling sys_execve so we
- * end up with proper pt_regs.
- */
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        register long __scno __asm__ ("r7") = __NR_execve;
-        register long __arg3 __asm__ ("r2") = (long)(envp);
-        register long __arg2 __asm__ ("r1") = (long)(argv);
-        register long __res __asm__ ("r0") = (long)(filename);
-        __asm__ __volatile__ (
-                "trap #" SYSCALL_VECTOR "|| nop"
-                : "=r" (__res)
-                : "r" (__scno), "0" (__res), "r" (__arg2),
-                        "r" (__arg3)
-                : "memory");
-        return __res;
-}