MIPS: Don't corrupt page tables on vmalloc fault.

The code after the vmalloc_fault: label in do_page_fault() modifies
user page tables, this is not correct for 64-bit kernels.

For 64-bit kernels we should go straight to the no_context handler
skipping vmalloc_fault.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/fault.c

@@ -58,11 +58,17 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 */
+#ifdef CONFIG_64BIT
+# define VMALLOC_FAULT_TARGET no_context
+#else
+# define VMALLOC_FAULT_TARGET vmalloc_fault
+#endif
+
 	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
-		goto vmalloc_fault;
+		goto VMALLOC_FAULT_TARGET;
 #ifdef MODULE_START
 	if (unlikely(address >= MODULE_START && address < MODULE_END))
-		goto vmalloc_fault;
+		goto VMALLOC_FAULT_TARGET;
 #endif
 
 	/*
@@ -203,6 +209,7 @@ do_sigbus:
 	force_sig_info(SIGBUS, &info, tsk);
 
 	return;
+#ifndef CONFIG_64BIT
 vmalloc_fault:
 	{
 		/*
@@ -241,4 +248,5 @@ vmalloc_fault:
 			goto no_context;
 		return;
 	}
+#endif
 }