Commit db991af0 authored by Jessica Yu's avatar Jessica Yu
Browse files

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: default avatarJessica Yu <jeyu@kernel.org>
parent 8f3d9f35

kernel/module.c

+18 −11
Original line number Diff line number Diff line
@@ -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

/*

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