[PATCH] arm26: new execve code

This pulls in the execve changes made in arm32.

Also, drops some old arm32 power management stuff thats no longer relevant
in process.c.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/arm26/kernel/process.c

@@ -67,42 +67,22 @@ static int __init hlt_setup(char *__unused)
 __setup("nohlt", nohlt_setup);
 __setup("hlt", hlt_setup);
 
-/*
- * The following aren't currently used.
- */
-void (*pm_idle)(void);
-void (*pm_power_off)(void);
-
 /*
  * This is our default idle handler.  We need to disable
  * interrupts here to ensure we don't miss a wakeup call.
  */
-void default_idle(void)
-{
-	local_irq_disable();
-	if (!need_resched() && !hlt_counter)
-	local_irq_enable();
-}
-
-/*
- * The idle thread.  We try to conserve power, while trying to keep
- * overall latency low.  The architecture specific idle is passed
- * a value to indicate the level of "idleness" of the system.
- */
 void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	preempt_disable();
 	while (1) {
-		void (*idle)(void) = pm_idle;
-		if (!idle)
-			idle = default_idle;
-		leds_event(led_idle_start);
-		while (!need_resched())
-			idle();
-		leds_event(led_idle_end);
-		schedule();
+		while (!need_resched()) {
+			local_irq_disable();
+			if (!need_resched() && !hlt_counter)
+				local_irq_enable();
 		}
+	}
+	schedule();
 }
 
 static char reboot_mode = 'h';
@@ -115,20 +95,15 @@ int __init reboot_setup(char *str)
 
 __setup("reboot=", reboot_setup);
 
+/* ARM26 cant do these but we still need to define them. */
 void machine_halt(void)
 {
-	leds_event(led_halted);
 }
-
-EXPORT_SYMBOL(machine_halt);
-
 void machine_power_off(void)
 {
-	leds_event(led_halted);
-	if (pm_power_off)
-		pm_power_off();
 }
 
+EXPORT_SYMBOL(machine_halt);
 EXPORT_SYMBOL(machine_power_off);
 
 void machine_restart(char * __unused)
@@ -306,7 +281,7 @@ void release_thread(struct task_struct *dead_task)
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 
 int
-copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
+copy_thread(int nr, unsigned long clone_flags, unsigned long stack_start,
 	    unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 {
 	struct thread_info *thread = p->thread_info;
@@ -315,7 +290,7 @@ copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
 	childregs = __get_user_regs(thread);
 	*childregs = *regs;
 	childregs->ARM_r0 = 0;
-	childregs->ARM_sp = esp;
+	childregs->ARM_sp = stack_start;
 
 	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 	thread->cpu_context.sp = (unsigned long)childregs;
@@ -367,35 +342,42 @@ void dump_thread(struct pt_regs * regs, struct user * dump)
 }
 
 /*
- * 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.
- * FIXME - taken from arm32
+ * Shuffle the argument into the correct register before calling the
+ * thread function.  r1 is the thread argument, r2 is the pointer to
+ * the thread function, and r3 points to the exit function.
+ * FIXME - make sure this is right - the older code used to zero fp
+ * and cause the parent to call sys_exit (do_exit in this version)
+ */
+extern void kernel_thread_helper(void);
+
+asm(    ".section .text\n"
+"       .align\n"
+"       .type   kernel_thread_helper, #function\n"
+"kernel_thread_helper:\n"
+"       mov     r0, r1\n"
+"       mov     lr, r3\n"
+"       mov     pc, r2\n"
+"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
+"       .previous");
+
+/*
+ * Create a kernel thread.
  */
 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 {
-        register unsigned int r0 asm("r0") = flags | CLONE_VM | CLONE_UNTRACED;
-        register unsigned int r1 asm("r1") = 0;
-        register pid_t __ret asm("r0");
-
-        __asm__ __volatile__(
-        __syscall(clone)"       @ kernel_thread sys_clone       \n\
-        movs    %0, r0          @ if we are the child           \n\
-        bne     1f                                              \n\
-        mov     fp, #0          @ ensure that fp is zero        \n\
-        mov     r0, %4                                          \n\
-        mov     lr, pc                                          \n\
-        mov     pc, %3                                          \n\
-        b       sys_exit                                        \n\
-1:      "
-        : "=r" (__ret)
-        : "0" (r0), "r" (r1), "r" (fn), "r" (arg)
-        : "lr");
-        return __ret;
+        struct pt_regs regs;
+
+        memset(&regs, 0, sizeof(regs));
+
+        regs.ARM_r1 = (unsigned long)arg;
+        regs.ARM_r2 = (unsigned long)fn;
+        regs.ARM_r3 = (unsigned long)do_exit;
+        regs.ARM_pc = (unsigned long)kernel_thread_helper | MODE_SVC26;
+
+        return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
+EXPORT_SYMBOL(kernel_thread);
+
 
 unsigned long get_wchan(struct task_struct *p)
 {

arch/arm26/kernel/sys_arm.c

@@ -13,6 +13,7 @@
  *  have a non-standard calling sequence on the Linux/arm
  *  platform.
  */
+#include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
@@ -281,3 +282,43 @@ asmlinkage int sys_execve(char *filenamei, char **argv, char **envp, struct pt_r
 out:
 	return error;
 }
+
+/* FIXME - see if this is correct for arm26 */
+long execve(const char *filename, char **argv, char **envp)
+{
+	struct pt_regs regs;
+        int ret;
+         memset(&regs, 0, sizeof(struct pt_regs));
+        ret = do_execve((char *)filename, (char __user * __user *)argv,                         (char __user * __user *)envp, &regs);
+        if (ret < 0)
+                goto out;
+
+        /*
+         * Save argc to the register structure for userspace.
+         */
+        regs.ARM_r0 = ret;
+
+        /*
+         * We were successful.  We won't be returning to our caller, but
+         * instead to user space by manipulating the kernel stack.
+         */
+        asm(    "add    r0, %0, %1\n\t"
+                "mov    r1, %2\n\t"
+                "mov    r2, %3\n\t"
+                "bl     memmove\n\t"    /* copy regs to top of stack */
+                "mov    r8, #0\n\t"     /* not a syscall */
+                "mov    r9, %0\n\t"     /* thread structure */
+                "mov    sp, r0\n\t"     /* reposition stack pointer */
+                "b      ret_to_user"
+                :
+                : "r" (current_thread_info()),
+                  "Ir" (THREAD_SIZE - 8 - sizeof(regs)),
+                  "r" (&regs),
+                  "Ir" (sizeof(regs))
+                : "r0", "r1", "r2", "r3", "ip", "memory");
+
+ out:
+        return ret;
+}
+
+EXPORT_SYMBOL(execve);