[RFC PATCH 1/3] module: Split module_enable_rodata_ro()

[Christophe Leroy]

module_enable_rodata_ro() is called twice, once before module init
to set rodata sections readonly and once after module init to set
rodata_after_init section readonly.

The second time, only the rodata_after_init section needs to be
set to read-only, no need to re-apply it to already set rodata.

Split module_enable_rodata_ro() in two.

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
 kernel/module/internal.h   |  3 ++-
 kernel/module/main.c       |  4 ++--
 kernel/module/strict_rwx.c | 13 +++++++++----
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 2ebece8a789f..994f35a779dc 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -322,7 +322,8 @@ static inline struct module *mod_find(unsigned long addr, 
struct mod_tree_root *
 }
 #endif /* CONFIG_MODULES_TREE_LOOKUP */
 
-int module_enable_rodata_ro(const struct module *mod, bool after_init);
+int module_enable_rodata_ro(const struct module *mod);
+int module_enable_rodata_ro_after_init(const struct module *mod);
 int module_enable_data_nx(const struct module *mod);
 int module_enable_text_rox(const struct module *mod);
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 49b9bca9de12..2de4ad7af335 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2581,7 +2581,7 @@ static noinline int do_init_module(struct module *mod)
        /* Switch to core kallsyms now init is done: kallsyms may be walking! */
        rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms);
 #endif
-       ret = module_enable_rodata_ro(mod, true);
+       ret = module_enable_rodata_ro_after_init(mod);
        if (ret)
                goto fail_mutex_unlock;
        mod_tree_remove_init(mod);
@@ -2751,7 +2751,7 @@ static int complete_formation(struct module *mod, struct 
load_info *info)
        module_bug_finalize(info->hdr, info->sechdrs, mod);
        module_cfi_finalize(info->hdr, info->sechdrs, mod);
 
-       err = module_enable_rodata_ro(mod, false);
+       err = module_enable_rodata_ro(mod);
        if (err)
                goto out_strict_rwx;
        err = module_enable_data_nx(mod);
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index c45caa4690e5..f68c59974ae2 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -44,7 +44,7 @@ int module_enable_text_rox(const struct module *mod)
        return 0;
 }
 
-int module_enable_rodata_ro(const struct module *mod, bool after_init)
+int module_enable_rodata_ro(const struct module *mod)
 {
        int ret;
 
@@ -58,12 +58,17 @@ int module_enable_rodata_ro(const struct module *mod, bool 
after_init)
        if (ret)
                return ret;
 
-       if (after_init)
-               return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
-
        return 0;
 }
 
+int module_enable_rodata_ro_after_init(const struct module *mod)
+{
+       if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
+               return 0;
+
+       return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
+}
+
 int module_enable_data_nx(const struct module *mod)
 {
        if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
-- 
2.44.0