mn10300: switch to saner kernel_execve() semantics

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

arch/mn10300/Kconfig

@@ -9,6 +9,7 @@ config MN10300
 	select HAVE_NMI_WATCHDOG if MN10300_WD_TIMER
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_KERNEL_THREAD
+	select GENERIC_KERNEL_EXECVE
 	select MODULES_USE_ELF_RELA
 
 config AM33_2

arch/mn10300/include/asm/unistd.h

@@ -44,7 +44,6 @@
 #define __ARCH_WANT_SYS_RT_SIGACTION
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
-#define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls

arch/mn10300/kernel/entry.S

@@ -60,13 +60,8 @@ ENTRY(ret_from_kernel_thread)
 	mov	(REG_D0,fp),d0
 	mov	(REG_A0,fp),a0
 	calls	(a0)
-	jmp	sys_exit
-
-ENTRY(ret_from_kernel_execve)
-	add	-12,d0	/* pt_regs -> frame */
-	mov	d0,sp
-	GET_THREAD_INFO a2
 	clr	d0
+	mov	d0,(REG_D0,fp)
 	jmp	syscall_exit
 
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