When building a livepatch, a user can set it to be either an atomic-replace livepatch or a non-atomic-replace livepatch. However, it is not easy to identify whether a livepatch is atomic-replace or not until it actually replaces some old livepatches. This can lead to mistakes in a mixed atomic-replace and non-atomic-replace environment, especially when transitioning all livepatches from non-atomic-replace to atomic-replace in a large fleet of servers.
To address this issue, a new sysfs interface called 'replace' is introduced in this patch. The result after this change is as follows: $ cat /sys/kernel/livepatch/livepatch-non_replace/replace 0 $ cat /sys/kernel/livepatch/livepatch-replace/replace 1 Signed-off-by: Yafang Shao <[email protected]> --- Documentation/ABI/testing/sysfs-kernel-livepatch | 8 ++++++++ kernel/livepatch/core.c | 12 ++++++++++++ 2 files changed, 20 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch index a5df9b4910dc..3735d868013d 100644 --- a/Documentation/ABI/testing/sysfs-kernel-livepatch +++ b/Documentation/ABI/testing/sysfs-kernel-livepatch @@ -47,6 +47,14 @@ Description: disabled when the feature is used. See Documentation/livepatch/livepatch.rst for more information. +What: /sys/kernel/livepatch/<patch>/replace +Date: Jun 2024 +KernelVersion: 6.11.0 +Contact: [email protected] +Description: + An attribute which indicates whether the patch supports + atomic-replace. + What: /sys/kernel/livepatch/<patch>/<object> Date: Nov 2014 KernelVersion: 3.19.0 diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 52426665eecc..0e9832f146f1 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -346,6 +346,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, * /sys/kernel/livepatch/<patch>/enabled * /sys/kernel/livepatch/<patch>/transition * /sys/kernel/livepatch/<patch>/force + * /sys/kernel/livepatch/<patch>/replace * /sys/kernel/livepatch/<patch>/<object> * /sys/kernel/livepatch/<patch>/<object>/patched * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> @@ -443,13 +444,24 @@ static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, return count; } +static ssize_t replace_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct klp_patch *patch; + + patch = container_of(kobj, struct klp_patch, kobj); + return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->replace); +} + 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 attribute *klp_patch_attrs[] = { &enabled_kobj_attr.attr, &transition_kobj_attr.attr, &force_kobj_attr.attr, + &replace_kobj_attr.attr, NULL }; ATTRIBUTE_GROUPS(klp_patch); -- 2.39.1
