3 files changed, 19 insertions, 0 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c4bd0e2c173c..772c784ba763 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -256,6 +256,7 @@
 	.rodata           : AT(ADDR(.rodata) - LOAD_OFFSET) {		\
 		VMLINUX_SYMBOL(__start_rodata) = .;			\
 		*(.rodata) *(.rodata.*)					\
+		*(.data..ro_after_init)	/* Read only after init */	\
 		*(__vermagic)		/* Kernel version magic */	\
 		. = ALIGN(8);						\
 		VMLINUX_SYMBOL(__start___tracepoints_ptrs) = .;		\
diff --git a/include/linux/cache.h b/include/linux/cache.h
index 17e7e82d2aa7..1be04f8c563a 100644
--- a/include/linux/cache.h
+++ b/include/linux/cache.h
@@ -12,10 +12,24 @@
 #define SMP_CACHE_BYTES L1_CACHE_BYTES
 #endif
 
+/*
+ * __read_mostly is used to keep rarely changing variables out of frequently
+ * updated cachelines. If an architecture doesn't support it, ignore the
+ * hint.
+ */
 #ifndef __read_mostly
 #define __read_mostly
 #endif
 
+/*
+ * __ro_after_init is used to mark things that are read-only after init (i.e.
+ * after mark_rodata_ro() has been called). These are effectively read-only,
+ * but may get written to during init, so can't live in .rodata (via "const").
+ */
+#ifndef __ro_after_init
+#define __ro_after_init __attribute__((__section__(".data..ro_after_init")))
+#endif
+
 #ifndef ____cacheline_aligned
 #define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
 #endif
diff --git a/include/linux/init.h b/include/linux/init.h
index b449f378f995..aedb254abc37 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -142,6 +142,10 @@ void prepare_namespace(void);
 void __init load_default_modules(void);
 int __init init_rootfs(void);
 
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void);
+#endif
+
 extern void (*late_time_init)(void);
 
 extern bool initcall_debug;