alpha: introduce ret_from_kernel_execve(), switch to generic kernel_execve()

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

arch/alpha/include/asm/unistd.h

@@ -482,6 +482,7 @@
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_KERNEL_EXECVE
 
 /* "Conditional" syscalls.  What we want is
 

arch/alpha/kernel/entry.S

@@ -626,6 +626,19 @@ ret_from_kernel_thread:
 	jmp	$31, sys_exit
 .end ret_from_kernel_thread
 
+	.globl	ret_from_kernel_execve
+	.align	4
+	.ent	ret_from_kernel_execve
+ret_from_kernel_execve:
+	mov	$16, $sp
+	/* Avoid the HAE being gratuitously wrong, to avoid restoring it.  */
+	ldq	$2, alpha_mv+HAE_CACHE
+	stq	$2, 152($sp)		/* HAE */
+	mov	$31, $19		/* to disable syscall restarts */
+	br	$31, ret_to_user
+
+.end	ret_from_kernel_execve
+
 
 /*
  * Special system calls.  Most of these are special in that they either

arch/alpha/kernel/process.c

@@ -435,22 +435,3 @@ get_wchan(struct task_struct *p)
 	}
 	return pc;
 }
-
-int kernel_execve(const char *path, const char *const argv[], const char *const envp[])
-{
-	/* Avoid the HAE being gratuitously wrong, which would cause us
-	   to do the whole turn off interrupts thing and restore it.  */
-	struct pt_regs regs = {.hae = alpha_mv.hae_cache};
-	int err = do_execve(path, argv, envp, &regs);
-	if (!err) {
-		struct pt_regs *p = current_pt_regs();
-		/* copy regs to normal position and off to userland we go... */
-		*p = regs;
-		__asm__ __volatile__ (
-			"mov	%0, $sp;"
-			"br	$31, ret_from_sys_call"
-			: : "r"(p));
-	}
-	return err;
-}
-EXPORT_SYMBOL(kernel_execve);