MIPS: Switch over to generic sys_execve and kernel_execve.

This version contains a few updates by David Daney, in particular it's
now using __builtin_frame_address() instead of asm() which depending
on personal taste, is slightly more appealing.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
index 4f5da94..cec5e12 100644
--- a/arch/mips/include/asm/ptrace.h
+++ b/arch/mips/include/asm/ptrace.h
@@ -61,4 +61,10 @@
 		die(str, regs);
 }
 
+#define current_pt_regs()						\
+({									\
+	unsigned long sp = (unsigned long)__builtin_frame_address(0);	\
+	(struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1 - 32) - 1;	\
+})
+
 #endif /* _ASM_PTRACE_H */