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livepatch: Add stack_order sysfs attribute

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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: Petr Mladek <pmladek@suse.com>
Suggested-by: Miroslav Benes <mbenes@suse.cz>
Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Wardenjohn <zhangwarden@gmail.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Miroslav 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: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Wardenjohn 2024-10-08 09:48:56 +08:00 committed by Petr Mladek
parent aa44f41470
commit 3dae09de40
2 changed files with 33 additions and 0 deletions
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9
Documentation/ABI/testing/sysfs-kernel-livepatch
View File

@ -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

24
kernel/livepatch/core.c
View File

@ -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);