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Commit 444f9e99 authored by Chris J Arges's avatar Chris J Arges Committed by Jiri Kosina
Browse files

livepatch: function,sympos scheme in livepatch sysfs directory 

The following directory structure will allow for cases when the same
function name exists in a single object.
	/sys/kernel/livepatch/<patch>/<object>/<function,sympos>

The sympos number corresponds to the nth occurrence of the symbol name in
kallsyms for the patched object.

An example of patching multiple symbols can be found here:
	https://github.com/dynup/kpatch/issues/493



Signed-off-by: default avatarChris J Arges <chris.j.arges@canonical.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 064c89df

Documentation/ABI/testing/sysfs-kernel-livepatch

+5 −1
Original line number Diff line number Diff line
@@ -33,7 +33,7 @@ Description: 
		The object directory contains subdirectories for each function

		that is patched within the object.



What:		/sys/kernel/livepatch/<patch>/<object>/<function>

What:		/sys/kernel/livepatch/<patch>/<object>/<function,sympos>

Date:		Nov 2014

KernelVersion:	3.19.0

Contact:	live-patching@vger.kernel.org
@@ -41,4 +41,8 @@ Description: 
		The function directory contains attributes regarding the

		properties and state of the patched function.



		The directory name contains the patched function name and a

		sympos number corresponding to the nth occurrence of the symbol

		name in kallsyms for the patched object.



		There are currently no such attributes.

kernel/livepatch/core.c

+8 −2
Original line number Diff line number Diff line
@@ -535,7 +535,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch); 
 * /sys/kernel/livepatch/<patch>

 * /sys/kernel/livepatch/<patch>/enabled

 * /sys/kernel/livepatch/<patch>/<object>

 * /sys/kernel/livepatch/<patch>/<object>/<func>

 * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>

 */



static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
@@ -680,8 +680,14 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func) 
	INIT_LIST_HEAD(&func->stack_node);

	func->state = KLP_DISABLED;



	/* The format for the sysfs directory is <function,sympos> where sympos

	 * is the nth occurrence of this symbol in kallsyms for the patched

	 * object. If the user selects 0 for old_sympos, then 1 will be used

	 * since a unique symbol will be the first occurrence.

	 */

	return kobject_init_and_add(&func->kobj, &klp_ktype_func,

				    &obj->kobj, "%s", func->old_name);

				    &obj->kobj, "%s,%lu", func->old_name,

				    func->old_sympos ? func->old_sympos : 1);

}



/* parts of the initialization that is done only when the object is loaded */