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

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

5 files changed, 23 insertions, 72 deletions

diff --git a/arch/score/Kconfig b/arch/score/Kconfig
index 4f93a431a45a..a285e78fb9c5 100644
--- a/arch/score/Kconfig
+++ b/arch/score/Kconfig
@@ -13,6 +13,8 @@ config SCORE
        select GENERIC_CLOCKEVENTS
        select HAVE_MOD_ARCH_SPECIFIC
         select MODULES_USE_ELF_REL
+        select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 choice
         prompt "System type"
diff --git a/arch/score/include/asm/processor.h b/arch/score/include/asm/processor.h
index ab3aceb54209..d9a922d8711b 100644
--- a/arch/score/include/asm/processor.h
+++ b/arch/score/include/asm/processor.h
@@ -13,7 +13,6 @@ struct task_struct;
  */
 extern void (*cpu_wait)(void);
 
-extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern unsigned long thread_saved_pc(struct task_struct *tsk);
 extern void start_thread(struct pt_regs *regs,
                         unsigned long pc, unsigned long sp);
diff --git a/arch/score/kernel/entry.S b/arch/score/kernel/entry.S
index 83bb96079c43..74a5cc7f596e 100644
--- a/arch/score/kernel/entry.S
+++ b/arch/score/kernel/entry.S
@@ -278,6 +278,13 @@ need_resched:
         nop
 #endif
 
+ENTRY(ret_from_kernel_thread)
+        bl      schedule_tail                   # r4=struct task_struct *prev
+        nop
+        mv      r4, r13
+        brl     r12
+        j       syscall_exit
+
 ENTRY(ret_from_fork)
         bl      schedule_tail                   # r4=struct task_struct *prev
 
diff --git a/arch/score/kernel/process.c b/arch/score/kernel/process.c
index 637970cfd3f4..6f311cf64b99 100644
--- a/arch/score/kernel/process.c
+++ b/arch/score/kernel/process.c
@@ -60,6 +60,7 @@ void __noreturn cpu_idle(void)
 }
 
 void ret_from_fork(void);
+void ret_from_kernel_thread(void);
 
 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 {
@@ -86,29 +87,27 @@ void flush_thread(void) {}
  * set up the kernel stack and exception frames for a new process
  */
 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 thread_info *ti = task_thread_info(p);
         struct pt_regs *childregs = task_pt_regs(p);
 
-        p->set_child_tid = NULL;
-        p->clear_child_tid = NULL;
-
-        *childregs = *regs;
-        childregs->regs[7] = 0;         /* Clear error flag */
-        childregs->regs[4] = 0;         /* Child gets zero as return value */
-        regs->regs[4] = p->pid;
-
-        if (childregs->cp0_psr & 0x8) { /* test kernel fork or user fork */
-                childregs->regs[0] = usp;               /* user fork */
+        p->thread.reg0 = (unsigned long) childregs;
+        if (unlikely(!regs)) {
+                memset(childregs, 0, sizeof(struct pt_regs));
+                p->thread->reg12 = usp;
+                p->thread->reg13 = arg;
+                p->thread.reg3 = (unsigned long) ret_from_kernel_thread;
         } else {
-                childregs->regs[28] = (unsigned long) ti; /* kernel fork */
-                childregs->regs[0] = (unsigned long) childregs;
+                *childregs = *regs;
+                childregs->regs[7] = 0;         /* Clear error flag */
+                childregs->regs[4] = 0;         /* Child gets zero as return value */
+                childregs->regs[0] = usp;       /* user fork */
+                regs->regs[4] = p->pid;         /* WTF? */
+                p->thread.reg3 = (unsigned long) ret_from_fork;
         }
 
-        p->thread.reg0 = (unsigned long) childregs;
-        p->thread.reg3 = (unsigned long) ret_from_fork;
         p->thread.cp0_psr = 0;
 
         return 0;
@@ -120,32 +119,6 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
         return 1;
 }
 
-static void __noreturn
-kernel_thread_helper(void *unused0, int (*fn)(void *),
-                 void *arg, void *unused1)
-{
-        do_exit(fn(arg));
-}
-
-/*
- * Create a kernel thread.
- */
-long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.regs[6] = (unsigned long) arg;
-        regs.regs[5] = (unsigned long) fn;
-        regs.cp0_epc = (unsigned long) kernel_thread_helper;
-        regs.cp0_psr = (regs.cp0_psr & ~(0x1|0x4|0x8)) | \
-                        ((regs.cp0_psr & 0x3) << 2);
-
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, \
-                        0, &regs, 0, NULL, NULL);
-}
-
 unsigned long thread_saved_pc(struct task_struct *tsk)
 {
         return task_pt_regs(tsk)->cp0_epc;
diff --git a/arch/score/kernel/sys_score.c b/arch/score/kernel/sys_score.c
index d45cf00a3351..5a682fce1fdb 100644
--- a/arch/score/kernel/sys_score.c
+++ b/arch/score/kernel/sys_score.c
@@ -107,33 +107,3 @@ score_execve(struct pt_regs *regs)
         putname(filename);
         return error;
 }
-
-/*
- * Do a system call from kernel instead of calling sys_execve so we
- * end up with proper pt_regs.
- */
-asmlinkage
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        register unsigned long __r4 asm("r4") = (unsigned long) filename;
-        register unsigned long __r5 asm("r5") = (unsigned long) argv;
-        register unsigned long __r6 asm("r6") = (unsigned long) envp;
-        register unsigned long __r7 asm("r7");
-
-        __asm__ __volatile__ (" \n"
-                "ldi    r27, %5         \n"
-                "syscall                \n"
-                "mv     %0, r4          \n"
-                "mv     %1, r7          \n"
-                : "=&r" (__r4), "=r" (__r7)
-                : "r" (__r4), "r" (__r5), "r" (__r6), "i" (__NR_execve)
-                : "r8", "r9", "r10", "r11", "r22", "r23", "r24", "r25",
-                  "r26", "r27", "memory");
-
-        if (__r7 == 0)
-                return __r4;
-
-        return -__r4;
-}