Commit 3dae09de authored by Wardenjohn's avatar Wardenjohn Committed by Petr Mladek
Browse files

livepatch: Add stack_order sysfs attribute 



Add "stack_order" sysfs attribute which holds the order in which a live
patch module was loaded into the system. A user can then determine an
active live patched version of a function.

cat /sys/kernel/livepatch/livepatch_1/stack_order -> 1

means that livepatch_1 is the first live patch applied

cat /sys/kernel/livepatch/livepatch_module/stack_order -> N

means that livepatch_module is the Nth live patch applied

Suggested-by: default avatarPetr Mladek <pmladek@suse.com>
Suggested-by: default avatarMiroslav Benes <mbenes@suse.cz>
Suggested-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarWardenjohn <zhangwarden@gmail.com>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarPetr Mladek <pmladek@suse.com>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20241008014856.3729-2-zhangwarden@gmail.com


[pmladek@suse.com: Updated kernel version and date in the ABI documentation.]
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent aa44f414

Documentation/ABI/testing/sysfs-kernel-livepatch

+9 −0
Original line number Diff line number Diff line
@@ -55,6 +55,15 @@ Description: 
		An attribute which indicates whether the patch supports

		atomic-replace.



What:		/sys/kernel/livepatch/<patch>/stack_order

Date:		Jan 2025

KernelVersion:	6.14.0

Description:

		This attribute specifies the sequence in which live patch modules

		are applied to the system. If multiple live patches modify the same

		function, the implementation with the biggest 'stack_order' number

		is used, unless a transition is currently in progress.



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

Date:		Nov 2014

KernelVersion:	3.19.0

kernel/livepatch/core.c

+24 −0
Original line number Diff line number Diff line
@@ -347,6 +347,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, 
 * /sys/kernel/livepatch/<patch>/transition

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

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

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

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

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

 * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
@@ -452,15 +453,38 @@ static ssize_t replace_show(struct kobject *kobj, 
	return sysfs_emit(buf, "%d\n", patch->replace);

}



static ssize_t stack_order_show(struct kobject *kobj,

				struct kobj_attribute *attr, char *buf)

{

	struct klp_patch *patch, *this_patch;

	int stack_order = 0;



	this_patch = container_of(kobj, struct klp_patch, kobj);



	mutex_lock(&klp_mutex);



	klp_for_each_patch(patch) {

		stack_order++;

		if (patch == this_patch)

			break;

	}



	mutex_unlock(&klp_mutex);



	return sysfs_emit(buf, "%d\n", stack_order);

}



static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);

static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition);

static struct kobj_attribute force_kobj_attr = __ATTR_WO(force);

static struct kobj_attribute replace_kobj_attr = __ATTR_RO(replace);

static struct kobj_attribute stack_order_kobj_attr = __ATTR_RO(stack_order);

static struct attribute *klp_patch_attrs[] = {

	&enabled_kobj_attr.attr,

	&transition_kobj_attr.attr,

	&force_kobj_attr.attr,

	&replace_kobj_attr.attr,

	&stack_order_kobj_attr.attr,

	NULL

};

ATTRIBUTE_GROUPS(klp_patch);