[PATCH] x86, vsyscall: Fix build warning in vsyscall_64.c

[Rakib Mullick <rakib.mullick@gmail.com>]

Due to commit 5cec93c216db77 (x86-64: Emulate legacy vsyscalls), we get the following warning:

   arch/x86/kernel/vsyscall_64.c: In function ‘do_emulate_vsyscall’:
   arch/x86/kernel/vsyscall_64.c:111:7: warning: ‘ret’ may be used uninitialized in this function

The uninitialized value of 'ret' maybe gets assigned to regs->ax. So, initialize it with -EINVAL.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
---

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 10cd8ac..180c56d 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -108,7 +108,7 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
 	struct task_struct *tsk;
 	unsigned long caller;
 	int vsyscall_nr;
-	long ret;
+	long ret = -EINVAL;
 
 	/* Kernel code must never get here. */
 	BUG_ON(!user_mode(regs));
@@ -163,7 +163,7 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
 		BUG();
 	}
 
-	if (ret == -EFAULT) {
+	if (ret == -EFAULT || ret == -EINVAL) {
 		/*
 		 * Bad news -- userspace fed a bad pointer to a vsyscall.
 		 *