module: clean up RO/NX handling.

Modules have three sections: text, rodata and writable data.  The code
handled the case where these overlapped, however they never can:
debug_align() ensures they are always page-aligned.

This is why we got away with manually traversing the pages in
set_all_modules_text_rw() without rounding.

We create three helper functions: frob_text(), frob_rodata() and
frob_writable_data().  We then call these explicitly at every point,
so it's clear what we're doing.

We also expose module_enable_ro() and module_disable_ro() for
livepatch to use.

Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 6e68e8cf4d0d..4560d8f1545d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -762,9 +762,13 @@ extern int module_sysfs_initialized;
 #ifdef CONFIG_DEBUG_SET_MODULE_RONX
 extern void set_all_modules_text_rw(void);
 extern void set_all_modules_text_ro(void);
+extern void module_enable_ro(const struct module *mod);
+extern void module_disable_ro(const struct module *mod);
 #else
 static inline void set_all_modules_text_rw(void) { }
 static inline void set_all_modules_text_ro(void) { }
+static inline void module_enable_ro(const struct module *mod) { }
+static inline void module_disable_ro(const struct module *mod) { }
 #endif
 
 #ifdef CONFIG_GENERIC_BUG