vmlinux.lds.h: allow arch specific handling of ro_after_init data section
commit c74ba8b3480d ("arch: Introduce post-init read-only memory")
introduced the __ro_after_init attribute which allows to add variables
to the ro_after_init data section.
This new section was added to rodata, even though it contains writable
data. This in turn causes problems on architectures which mark the
page table entries read-only that point to rodata very early.
This patch allows architectures to implement an own handling of the
.data..ro_after_init section.
Usually that would be:
- mark the rodata section read-only very early
- mark the ro_after_init section read-only within mark_rodata_ro
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 6a67ab9..c4436d0 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -250,6 +250,14 @@
VMLINUX_SYMBOL(__end_init_task) = .;
/*
+ * Allow architectures to handle ro_after_init data on their
+ * own by defining an empty RO_AFTER_INIT_DATA.
+ */
+#ifndef RO_AFTER_INIT_DATA
+#define RO_AFTER_INIT_DATA *(.data..ro_after_init)
+#endif
+
+/*
* Read only Data
*/
#define RO_DATA_SECTION(align) \
@@ -257,7 +265,7 @@
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_rodata) = .; \
*(.rodata) *(.rodata.*) \
- *(.data..ro_after_init) /* Read only after init */ \
+ RO_AFTER_INIT_DATA /* Read only after init */ \
*(__vermagic) /* Kernel version magic */ \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___tracepoints_ptrs) = .; \