Messages in this thread Patch in this message |  | | From | Jessica Yu <> | Subject | [PATCH] module: break nested ARCH_HAS_STRICT_MODULE_RWX and STRICT_MODULE_RWX #ifdefs | Date | Wed, 8 Apr 2020 17:43:23 +0200 |
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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 b88ec9cd2a7f..2b28f8bf2322 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 /* -- 2.16.4
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