From db991af02f11053558431467102ee5832894d7a4 Mon Sep 17 00:00:00 2001
From: Jessica Yu <jeyu@kernel.org>
Date: Wed, 8 Apr 2020 16:31:06 +0200
Subject: [PATCH] module: break nested ARCH_HAS_STRICT_MODULE_RWX and
STRICT_MODULE_RWX #ifdefs
Various frob_* and module_{enable,disable}_* functions are defined in a
CONFIG_ARCH_HAS_STRICT_MODULE_RWX ifdef block which also has a nested
CONFIG_STRICT_MODULE_RWX ifdef block within it. This is unecessary and
makes things hard to read. Not only that, this construction requires
redundant empty stubs for module_enable_nx(). I suspect this was
originally done for cosmetic reasons - to keep all the frob_* functions
in the same place, and all the module_{enable,disable}_* functions right
after, but as a result it made the code harder to read.
Make this more readable by unnesting the ifdef blocks and getting rid of
the redundant empty stubs.
Signed-off-by: Jessica Yu <jeyu@kernel.org>
---
kernel/module.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 646f1e2330d2b..01d01a4897789 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1943,7 +1943,6 @@ static void mod_sysfs_teardown(struct module *mod)
mod_sysfs_fini(mod);
}
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
/*
* LKM RO/NX protection: protect module's text/ro-data
* from modification and any data from execution.
@@ -1957,6 +1956,14 @@ static void mod_sysfs_teardown(struct module *mod)
*
* These values are always page-aligned (as is base)
*/
+
+/*
+ * Since some arches are moving towards PAGE_KERNEL module allocations instead
+ * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
+ * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
+ * whether we are strict.
+ */
+#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
static void frob_text(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
{
@@ -1966,6 +1973,15 @@ static void frob_text(const struct module_layout *layout,
layout->text_size >> PAGE_SHIFT);
}
+static void module_enable_x(const struct module *mod)
+{
+ frob_text(&mod->core_layout, set_memory_x);
+ frob_text(&mod->init_layout, set_memory_x);
+}
+#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+static void module_enable_x(const struct module *mod) { }
+#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+
#ifdef CONFIG_STRICT_MODULE_RWX
static void frob_rodata(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
@@ -2037,18 +2053,9 @@ static void module_enable_nx(const struct module *mod)
}
#else /* !CONFIG_STRICT_MODULE_RWX */
+/* module_{enable,disable}_ro() stubs are in module.h */
static void module_enable_nx(const struct module *mod) { }
#endif /* CONFIG_STRICT_MODULE_RWX */
-static void module_enable_x(const struct module *mod)
-{
- frob_text(&mod->core_layout, set_memory_x);
- frob_text(&mod->init_layout, set_memory_x);
-}
-#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
-static void module_enable_nx(const struct module *mod) { }
-static void module_enable_x(const struct module *mod) { }
-#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
-
#ifdef CONFIG_LIVEPATCH
/*