[PATCH] MIPS: Fix syscall_trace_enter compilation error

[Tony Wu <tung7970@gmail.com>]

Commit cf6ce084 (MIPS: Fix syscall_get_nr for the syscall exit
tracing.) broke 3.13 and 3.14 stable tree due to the missing syscall
argument. So, get the syscall from regs[2] before it's trashed.

This patch should go to the 3.13 and 3.14 stable tree.

Signed-off-by: Tony Wu <tung7970@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Lars Persson <larper@axis.com>
Cc: linux-mips@linux-mips.org

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 64e18f9..01f1413 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -799,7 +799,7 @@ asmlinkage void syscall_trace_enter(struct pt_regs *regs)
 	long ret = 0;
 	user_exit();
 
-	current_thread_info()->syscall = syscall;
+	current_thread_info()->syscall = regs->regs[2];
 
 	/* do the secure computing check first */
 	secure_computing_strict(regs->regs[2]);