mprotect system call exposed to the untrusted code.

src/untrusted/irt/irt.h

Index: src/untrusted/irt/irt.h
diff --git a/src/untrusted/irt/irt.h b/src/untrusted/irt/irt.h
index d417be8fe41ad4f9427beed790f6564a9f19bab8..f1b92dcc2c4e79811608b4700e480da7119808fb 100644
--- a/src/untrusted/irt/irt.h
+++ b/src/untrusted/irt/irt.h
@@ -193,6 +193,15 @@ struct nacl_irt_dev_exception_handling {
   int (*exception_clear_flag)(void);
 };
 
+/*
+ * NOTE: This is a 'dev' interface which is NOT stable.
+ * In the future, requests for this interface will fail.
+ */
+#define NACL_IRT_DEV_MPROTECT_v0_1 "nacl-irt-dev-mprotect-0.1"
+struct nacl_irt_dev_mprotect {
+  int (*mprotect)(void *addr, size_t len, int prot);
+};
+
 #if defined(__cplusplus)
 }
 #endif