microblaze: switch to generic kernel_execve()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/Kconfig

@@ -27,6 +27,7 @@ config MICROBLAZE
 	select GENERIC_CLOCKEVENTS
 	select MODULES_USE_ELF_RELA
 	select GENERIC_KERNEL_THREAD
+	select GENERIC_KERNEL_EXECVE
 
 config SWAP
 	def_bool n

arch/microblaze/kernel/entry-nommu.S

@@ -479,8 +479,8 @@ ENTRY(ret_from_kernel_thread)
 	addk	r5, r0, r3
 	brald	r15, r20
 	addk	r5, r0, r19
-	brid	sys_exit	/* won't be returning... */
-	addk	r5, r0, r0
+	brid	ret_to_user
+	addk	r3, r0, r0
 
 work_pending:
 	enable_irq

arch/microblaze/kernel/entry.S

@@ -293,24 +293,6 @@ C_ENTRY(_user_exception):
 	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
 	addi	r14, r14, 4	/* return address is 4 byte after call */
 
-	mfs	r1, rmsr
-	nop
-	andi	r1, r1, MSR_UMS
-	bnei	r1, 1f
-
-/* Kernel-mode state save - kernel execve */
-	lwi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
-	tophys(r1,r1);
-
-	addik	r1, r1, -PT_SIZE; /* Make room on the stack. */
-	SAVE_REGS
-
-	swi	r1, r1, PT_MODE; /* pt_regs -> kernel mode */
-	brid	2f;
-	nop;				/* Fill delay slot */
-
-/* User-mode state save.  */
-1:
 	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
 	tophys(r1,r1);
 	lwi	r1, r1, TS_THREAD_INFO;	/* get stack from task_struct */
@@ -490,8 +472,8 @@ C_ENTRY(ret_from_kernel_thread):
 				/* ( in the delay slot ) */
 	brald	r15, r20	/* fn was left in r20 */
 	addk	r5, r0, r19	/* ... and argument - in r19 */
-	brid	sys_exit	/* won't be returning... */
-	addk	r5, r0, r0
+	brid	ret_from_trap
+	add	r3, r0, r0
 
 C_ENTRY(sys_vfork):
 	brid	microblaze_vfork	/* Do real work (tail-call) */

arch/microblaze/kernel/process.c

@@ -215,6 +215,7 @@ void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 	regs->pt_mode = 0;
 #ifdef CONFIG_MMU
 	regs->msr |= MSR_UMS;
+	regs->msr &= ~MSR_VM;
 #endif
 }
 

arch/microblaze/kernel/sys_microblaze.c

@@ -75,24 +75,3 @@ asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
 
 	return sys_mmap_pgoff(addr, len, prot, flags, fd, pgoff >> PAGE_SHIFT);
 }
-
-/*
- * 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 const char *__a __asm__("r5") = filename;
-	register const void *__b __asm__("r6") = argv;
-	register const void *__c __asm__("r7") = envp;
-	register unsigned long __syscall __asm__("r12") = __NR_execve;
-	register unsigned long __ret __asm__("r3");
-	__asm__ __volatile__ ("brki r14, 0x8"
-			: "=r" (__ret), "=r" (__syscall)
-			: "1" (__syscall), "r" (__a), "r" (__b), "r" (__c)
-			: "r4", "r8", "r9",
-			"r10", "r11", "r14", "cc", "memory");
-	return __ret;
-}