From 439e7271dc2b63de379e37971dc2f64d71e24f8a Mon Sep 17 00:00:00 2001 From: Joe Lawrence Date: Thu, 31 Aug 2017 16:37:41 -0400 Subject: livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence Acked-by: Josh Poimboeuf Acked-by: Miroslav Benes Signed-off-by: Jiri Kosina --- include/linux/livepatch.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/livepatch.h') diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h index 194991ef9347..d08eddc00497 100644 --- a/include/linux/livepatch.h +++ b/include/linux/livepatch.h @@ -164,6 +164,14 @@ static inline bool klp_have_reliable_stack(void) IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); } +void *klp_shadow_get(void *obj, unsigned long id); +void *klp_shadow_alloc(void *obj, unsigned long id, void *data, + size_t size, gfp_t gfp_flags); +void *klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data, + size_t size, gfp_t gfp_flags); +void klp_shadow_free(void *obj, unsigned long id); +void klp_shadow_free_all(unsigned long id); + #else /* !CONFIG_LIVEPATCH */ static inline int klp_module_coming(struct module *mod) { return 0; } -- cgit v1.2.3 From 93862e385ded7c60351e09fcd2a541d273650905 Mon Sep 17 00:00:00 2001 From: Joe Lawrence Date: Fri, 13 Oct 2017 15:08:41 -0400 Subject: livepatch: add (un)patch callbacks Provide livepatch modules a klp_object (un)patching notification mechanism. Pre and post-(un)patch callbacks allow livepatch modules to setup or synchronize changes that would be difficult to support in only patched-or-unpatched code contexts. Callbacks can be registered for target module or vmlinux klp_objects, but each implementation is klp_object specific. - Pre-(un)patch callbacks run before any (un)patching transition starts. - Post-(un)patch callbacks run once an object has been (un)patched and the klp_patch fully transitioned to its target state. Example use cases include modification of global data and registration of newly available services/handlers. See Documentation/livepatch/callbacks.txt for details and samples/livepatch/ for examples. Signed-off-by: Joe Lawrence Acked-by: Josh Poimboeuf Acked-by: Miroslav Benes Signed-off-by: Jiri Kosina --- include/linux/livepatch.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include/linux/livepatch.h') diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h index d08eddc00497..fc5c1be3f6f4 100644 --- a/include/linux/livepatch.h +++ b/include/linux/livepatch.h @@ -87,10 +87,35 @@ struct klp_func { bool transition; }; +struct klp_object; + +/** + * struct klp_callbacks - pre/post live-(un)patch callback structure + * @pre_patch: executed before code patching + * @post_patch: executed after code patching + * @pre_unpatch: executed before code unpatching + * @post_unpatch: executed after code unpatching + * @post_unpatch_enabled: flag indicating if post-unpatch callback + * should run + * + * All callbacks are optional. Only the pre-patch callback, if provided, + * will be unconditionally executed. If the parent klp_object fails to + * patch for any reason, including a non-zero error status returned from + * the pre-patch callback, no further callbacks will be executed. + */ +struct klp_callbacks { + int (*pre_patch)(struct klp_object *obj); + void (*post_patch)(struct klp_object *obj); + void (*pre_unpatch)(struct klp_object *obj); + void (*post_unpatch)(struct klp_object *obj); + bool post_unpatch_enabled; +}; + /** * struct klp_object - kernel object structure for live patching * @name: module name (or NULL for vmlinux) * @funcs: function entries for functions to be patched in the object + * @callbacks: functions to be executed pre/post (un)patching * @kobj: kobject for sysfs resources * @mod: kernel module associated with the patched object * (NULL for vmlinux) @@ -100,6 +125,7 @@ struct klp_object { /* external */ const char *name; struct klp_func *funcs; + struct klp_callbacks callbacks; /* internal */ struct kobject kobj; -- cgit v1.2.3