[PATCH v5 0/9] livepatch: Introduce replace set support

[PATCH v5 0/9] livepatch: Introduce replace set support

[Yafang Shao]

We previously proposed a BPF+livepatch method to enable rapid
experimentation with new kernel features without interrupting production
workloads:

  https://lore.kernel.org/live-patching/20260402092607.96430-1-laoar.shao@gmail.com/

In the resulting discussion, Song and Petr suggested adding a "replace set"
to support scenarios where specific livepatches can be selectively replaced
or skipped.

This patchset introduces a more flexible model using two new fields in
struct klp_patch:

- provides: an unsigned int id identifying the patch replace set.
  By default (provides=0), any livepatch replaces any other livepatch.

- obsoletes: an optional array of unsigned int ids specifying
  additional provides ids to be replaced. This allows a new patch
  to explicitly obsolete patches from different replace sets.

A new livepatch atomically replaces any existing livepatch whose
provides id matches either:
  1. The new patch provides id (same replace set), or
  2. Any id in the new patch obsoletes list

Additionally, this design deprecates the traditional non-atomic-replace
model. Previously, setting 'replace' to 0 was the only way to keep
certain livepatches persistent on the system, forcing developers to
disable atomic replacement entirely. With the introduction of replace set,
developers now have a selective option to keep specific livepatches
persistent while maintaining atomic replacement capabilities elsewhere.

At present, KLP state, shadow variables, and callbacks are not integrated
with the new replace_set mechanism in this patchset. Support for these
features is deferred until Petr's klp-state-transfer infrastructure is
completed and merged:

  https://github.com/pmladek/linux/tree/klp-state-transfer-v1-iter12

Future Work
===========

- Allow `provides` and `obsoletes` to be configured dynamically at
  module load time, rather than being fixed at build time.

Changes
=======

v4(RFC)->v5:
- Add selftests and Remove the RFC
- Fmprove klp_has_function_conflict() (Song)
- Fix a pre-exisiting bug
- Fix bugs reported by sashiko

v4 (RFC): https://lore.kernel.org/live-patching/20260804065010.44922-1-laoar.shao@gmail.com/

v3->v4(RFC):
- Allow a livepatch to replace livepatches with different provides IDs.
  Replace the single `replace_set` field with two separate fields,
  `provides` and `obsoletes`, for more flexible replacement semantics.
  (Petr, Joe)

v3: https://lore.kernel.org/live-patching/20260607131659.29281-1-laoar.shao@gmail.com/

v2->v3:
- Address the feedback from Sachiko AI
 - Fix the pre-existing NULL pointer dereference issue
 - Move klp_find_func into core.h
 - Don't deprecate stack_order completely

v2: https://lore.kernel.org/live-patching/20260529034542.68766-1-laoar.shao@gmail.com/

v1->v2:
- Incorporate feedback from Petr:
  - Initialize replace_set to 0 by default
  - Improve documentation
  - Enforce that livepatches in different replace_sets cannot use the same
    state->id.
  - Enforce that livepatches in different replace_sets cannot modify the
    same function.
  - Ensure consistent capitalization and naming usage of KLP_REPLACE_SET.
- Incorporate feedback from Sachiko AI:
  - Skip the klp_transition patch during klp_force_transition().

v1 (RFC): https://lore.kernel.org/live-patching/20260513143321.26185-1-laoar.shao@gmail.com/

Yafang Shao (9):
  livepatch: Fix wrong index in funcs cleanup error path
  livepatch: Make klp_find_func() non static
  livepatch: Call klp_init_patch_early() earlier
  livepatch: Implement replace set for scoped atomic replace
  livepatch: Deprecate stack_order
  selftests: livepatch: Adapt atomic replace tests to provides/obsoletes
  selftests: livepatch: Add provides/obsoletes test scenarios
  selftests: livepatch: Add test for state ID conflict across provides
  selftests: livepatch: Add test for function conflict across provides

 .../ABI/removed/sysfs-kernel-livepatch        |  16 +
 .../ABI/testing/sysfs-kernel-livepatch        |  27 +-
 .../livepatch/cumulative-patches.rst          |  93 ++--
 Documentation/livepatch/livepatch.rst         |  23 +-
 include/linux/livepatch.h                     |   7 +-
 kernel/livepatch/core.c                       | 114 +++--
 kernel/livepatch/core.h                       |   2 +
 kernel/livepatch/state.c                      |  57 ++-
 kernel/livepatch/transition.c                 |  11 +-
 scripts/livepatch/init.c                      |  71 +++-
 scripts/livepatch/klp-build                   |  77 +++-
 tools/testing/selftests/livepatch/Makefile    |   3 +-
 .../testing/selftests/livepatch/functions.sh  |  15 +
 .../selftests/livepatch/test-callbacks.sh     |   6 +
 .../selftests/livepatch/test-livepatch.sh     |   6 +
 .../livepatch/test-provides-obsoletes.sh      | 401 ++++++++++++++++++
 .../selftests/livepatch/test_modules/Makefile |  11 +
 .../test_modules/test_klp_atomic_replace.c    |  22 +
 .../test_modules/test_klp_callbacks_demo2.c   |  12 +
 .../test_modules/test_klp_livepatch.c         |   9 +
 .../test_modules/test_klp_provides.c          |  72 ++++
 .../livepatch/test_modules/test_klp_state.c   |  13 +
 .../livepatch/test_modules/test_klp_state2.c  |  23 +
 23 files changed, 968 insertions(+), 123 deletions(-)
 create mode 100644 Documentation/ABI/removed/sysfs-kernel-livepatch
 create mode 100755 tools/testing/selftests/livepatch/test-provides-obsoletes.sh
 create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_provides.c

-- 
2.52.0

[PATCH v5 1/9] livepatch: Fix wrong index in funcs cleanup error path

[Yafang Shao]

In the object allocation loop, when kzalloc() for funcs fails, the
cleanup loop uses `objs[i].funcs` instead of `objs[j].funcs`. Since
`objs[i].funcs` is still NULL at that point, it repeatedly calls
kfree(NULL) and leaks all previously allocated funcs arrays.
Fix by using the correct loop variable `j`.

Fixes: 59adee07b568 ("livepatch/klp-build: Add stub init code for livepatch modules")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 scripts/livepatch/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
index f14d8c8fb35f..16aff8f736eb 100644
--- a/scripts/livepatch/init.c
+++ b/scripts/livepatch/init.c
@@ -51,7 +51,7 @@ static int __init livepatch_mod_init(void)
 		if (!funcs) {
 			ret = -ENOMEM;
 			for (int j = 0; j < i; j++)
-				kfree(objs[i].funcs);
+				kfree(objs[j].funcs);
 			goto err_free_objs;
 		}
 
-- 
2.52.0

[PATCH v5 2/9] livepatch: Make klp_find_func() non static

[Yafang Shao]

Make klp_find_func() non static to allow its use in other source files
by an upcoming patch.

While at it, rename the parameter @old_func to @func to better reflect
its generic purpose.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 kernel/livepatch/core.c | 18 +++++++++---------
 kernel/livepatch/core.h |  1 +
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index a240d1144e89..c34306ecfb0b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -82,21 +82,21 @@ static bool klp_initialized(void)
 	return !!klp_root_kobj;
 }
 
-static struct klp_func *klp_find_func(struct klp_object *obj,
-				      struct klp_func *old_func)
+/* Check if @func is present in @obj. */
+struct klp_func *klp_find_func(struct klp_object *obj, struct klp_func *func)
 {
-	struct klp_func *func;
+	struct klp_func *obj_func;
 
-	klp_for_each_func(obj, func) {
+	klp_for_each_func(obj, obj_func) {
 		/*
 		 * Besides identical old_sympos, also consider old_sympos
 		 * of 0 and 1 are identical.
 		 */
-		if ((strcmp(old_func->old_name, func->old_name) == 0) &&
-		    ((old_func->old_sympos == func->old_sympos) ||
-		     (old_func->old_sympos == 0 && func->old_sympos == 1) ||
-		     (old_func->old_sympos == 1 && func->old_sympos == 0))) {
-			return func;
+		if ((strcmp(obj_func->old_name, func->old_name) == 0) &&
+		    ((obj_func->old_sympos == func->old_sympos) ||
+		     (obj_func->old_sympos == 0 && func->old_sympos == 1) ||
+		     (obj_func->old_sympos == 1 && func->old_sympos == 0))) {
+			return obj_func;
 		}
 	}
 
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 38209c7361b6..361a0917a03f 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -17,6 +17,7 @@ void klp_free_patch_async(struct klp_patch *patch);
 void klp_free_replaced_patches_async(struct klp_patch *new_patch);
 void klp_unpatch_replaced_patches(struct klp_patch *new_patch);
 void klp_discard_nops(struct klp_patch *new_patch);
+struct klp_func *klp_find_func(struct klp_object *obj, struct klp_func *func);
 
 static inline bool klp_is_object_loaded(struct klp_object *obj)
 {
-- 
2.52.0

[PATCH v5 3/9] livepatch: Call klp_init_patch_early() earlier

[Yafang Shao]

Invoke klp_init_patch_early() during early initialization to avoid
mixing for_each_() and for_each_*_static() variants later in the code.

No functional change. This prepares the code for an upcoming patch.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 kernel/livepatch/core.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index c34306ecfb0b..3de3940d34b2 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1145,13 +1145,6 @@ int klp_enable_patch(struct klp_patch *patch)
 
 	mutex_lock(&klp_mutex);
 
-	if (!klp_is_patch_compatible(patch)) {
-		pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
-			patch->mod->name);
-		mutex_unlock(&klp_mutex);
-		return -EINVAL;
-	}
-
 	if (!try_module_get(patch->mod)) {
 		mutex_unlock(&klp_mutex);
 		return -ENODEV;
@@ -1159,6 +1152,14 @@ int klp_enable_patch(struct klp_patch *patch)
 
 	klp_init_patch_early(patch);
 
+	if (!klp_is_patch_compatible(patch)) {
+		pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
+			patch->mod->name);
+		ret = -EINVAL;
+		goto err;
+	}
+
+
 	ret = klp_init_patch(patch);
 	if (ret)
 		goto err;
-- 
2.52.0

[PATCH v5 4/9] livepatch: Implement replace set for scoped atomic replace

[Yafang Shao]

The current bool replace flag is too coarse: it is either all or
nothing. A livepatch with .replace=true replaces ALL existing
livepatches, which is safe but inflexible. There is no way to have
multiple independent livepatch sets coexist on the same system.

Replace it with a more flexible model using two new fields in
struct klp_patch:

- provides: an unsigned int id identifying the patch replace set.
  By default (provides=0), any livepatch replaces any other livepatch.

- obsoletes: an optional array of unsigned int ids specifying
  additional provides ids to be replaced. This allows a new patch
  to explicitly obsolete patches from different replace sets.

A new livepatch atomically replaces any existing livepatch whose
provides id matches either:
  1. The new patch provides id (same replace set), or
  2. Any id in the new patch obsoletes list

The klp-build script is updated with -p/--provides and -r/--obsoletes
options. The obsoletes list automatically includes the provides id
and deduplicates entries. Input validation rejects malformed values
at build time.

Two helper functions are introduced:
- klp_patch_replaceable(): checks if an old patch should be replaced
  by a new patch.
- klp_has_function_conflict(): rejects loading a livepatch that would
  modify a function already patched by a livepatch with a different
  provides id.

Suggested-by: Song Liu <song@kernel.org>
Suggested-by: Joe Lawrence <joe.lawrence@redhat.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Co-developed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 .../ABI/testing/sysfs-kernel-livepatch        | 22 ++++-
 .../livepatch/cumulative-patches.rst          | 93 +++++++++++++------
 Documentation/livepatch/livepatch.rst         | 23 +++--
 include/linux/livepatch.h                     |  7 +-
 kernel/livepatch/core.c                       | 69 ++++++++++++--
 kernel/livepatch/core.h                       |  1 +
 kernel/livepatch/state.c                      | 57 ++++++++++--
 kernel/livepatch/transition.c                 | 11 ++-
 scripts/livepatch/init.c                      | 71 +++++++++++++-
 scripts/livepatch/klp-build                   | 77 +++++++++++++--
 10 files changed, 350 insertions(+), 81 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 3c3f36b32b57..2588f676deb1 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -47,13 +47,25 @@ 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
+What:		/sys/kernel/livepatch/<patch>/provides
+Date:		Jun 2026
+KernelVersion:	7.4.0
 Contact:	live-patching@vger.kernel.org
 Description:
-		An attribute which indicates whether the patch supports
-		atomic-replace.
+		An attribute to show the provides id of this livepatch.
+		Only one active livepatch per provides id is allowed.
+
+What:		/sys/kernel/livepatch/<patch>/obsoletes
+Date:		Jun 2026
+KernelVersion:	7.4.0
+Contact:	live-patching@vger.kernel.org
+Description:
+		An attribute to show the obsoletes ids of this livepatch.
+		The obsoletes ids are a comma-separated list of provides
+		ids that this patch obsoletes. When this livepatch is
+		loaded, any existing livepatch whose provides id matches
+		either this patch's provides id or any id in the obsoletes
+		list will be atomically replaced.
 
 What:		/sys/kernel/livepatch/<patch>/stack_order
 Date:		Jan 2025
diff --git a/Documentation/livepatch/cumulative-patches.rst b/Documentation/livepatch/cumulative-patches.rst
index 1931f318976a..04352ae3f0d0 100644
--- a/Documentation/livepatch/cumulative-patches.rst
+++ b/Documentation/livepatch/cumulative-patches.rst
@@ -2,33 +2,66 @@
 Atomic Replace & Cumulative Patches
 ===================================
 
-There might be dependencies between livepatches. If multiple patches need
-to do different changes to the same function(s) then we need to define
-an order in which the patches will be installed. And function implementations
-from any newer livepatch must be done on top of the older ones.
-
-This might become a maintenance nightmare. Especially when more patches
-modified the same function in different ways.
-
-An elegant solution comes with the feature called "Atomic Replace". It allows
-creation of so called "Cumulative Patches". They include all wanted changes
-from all older livepatches and completely replace them in one transition.
-
-Usage
------
-
-The atomic replace can be enabled by setting "replace" flag in struct klp_patch,
-for example::
-
-	static struct klp_patch patch = {
-		.mod = THIS_MODULE,
-		.objs = objs,
-		.replace = true,
-	};
-
-All processes are then migrated to use the code only from the new patch.
-Once the transition is finished, all older patches are automatically
-disabled.
+Livepatches are used to fix kernel bugs. New fixes need to be added over time.
+The fixes might be independent, but they might also depend on each other. This
+brings a challenge of how to keep the livepatched system safe and consistent.
+
+Part of the solution is the "Atomic Replace" feature, which allows the kernel to
+atomically replace an existing livepatch with another one. These newer
+livepatches are designed as "Cumulative Patches". They include all wanted
+changes from all older livepatches and completely replace them in one
+transition.
+
+The second part of the solution is the newly introduced ``provides`` and
+``obsoletes`` fields in ``struct klp_patch``, which allow the installation of
+multiple livepatches in parallel. A livepatch will atomically replace any
+already installed livepatch whose ``provides`` id matches either the new
+patch's ``provides`` id or any id in the new patch's ``obsoletes`` list.
+This might be used to fix independent problems separately, for example, the
+livepatches might be prepared by separate teams focusing on particular
+functionality or a subsystem.
+
+It should be emphasized that the preferred and most secure way is to always use
+the default ``provides = 0``. In this mode, any livepatch replaces any other
+livepatch, preventing any unexpected interactions between incompatible
+livepatches.
+
+Provides and Obsoletes
+-----------------------
+
+The ``provides`` field in ``struct klp_patch`` is an unsigned integer that
+identifies the livepatch's replace set. By default, it is 0.
+
+The ``obsoletes`` field is an optional array of unsigned integers that
+specifies additional ``provides`` ids to be replaced when this patch is
+loaded. By default, it includes the patch's own ``provides`` id, ensuring
+that a new patch always replaces any existing patch with the same
+``provides`` id.
+
+For example::
+
+        static struct klp_patch patch = {
+                .mod = THIS_MODULE,
+                .objs = objs,
+                .provides = 0,
+        };
+
+Any ``provides`` value might be associated with a set of livepatched symbols,
+callbacks, shadow variables, and state IDs. By definition, there can only ever
+be one active livepatch for a given ``provides`` id.
+
+On the contrary, livepatches with a different ``provides`` id must not
+modify the same function, or use the state with the same ID. Any attempt to
+load an incompatible livepatch will be rejected by the kernel.
+
+Atomic Replace
+--------------
+
+A livepatch with a given ``provides`` id is replaced by another livepatch
+with the same ``provides`` id, or whose ``obsoletes`` list includes that id.
+All processes are migrated to use the code only from the new patch. Once
+the transition is finished, the older patch is disabled. Patches with a
+different ``provides`` id are not affected and remain active.
 
 Ftrace handlers are transparently removed from functions that are no
 longer modified by the new cumulative patch.
@@ -64,7 +97,11 @@ Limitations:
   - Once the operation finishes, there is no straightforward way
     to reverse it and restore the replaced patches atomically.
 
-    A good practice is to set .replace flag in any released livepatch.
+    A good practice is to use only one (default) ``provides`` id. It
+    makes sure that there always will be only one enabled livepatch
+    on the system. The consistency model will ensure a safe update
+    between two versions. It prevents potential problems with installing
+    two livepatches doing incompatible functional changes.
     Then re-adding an older livepatch is equivalent to downgrading
     to that patch. This is safe as long as the livepatches do _not_ do
     extra modifications in (un)patching callbacks or in the module_init()
diff --git a/Documentation/livepatch/livepatch.rst b/Documentation/livepatch/livepatch.rst
index acb90164929e..73635f9ddd91 100644
--- a/Documentation/livepatch/livepatch.rst
+++ b/Documentation/livepatch/livepatch.rst
@@ -347,15 +347,20 @@ to '0'.
 5.3. Replacing
 --------------
 
-All enabled patches might get replaced by a cumulative patch that
-has the .replace flag set.
-
-Once the new patch is enabled and the 'transition' finishes then
-all the functions (struct klp_func) associated with the replaced
-patches are removed from the corresponding struct klp_ops. Also
-the ftrace handler is unregistered and the struct klp_ops is
-freed when the related function is not modified by the new patch
-and func_stack list becomes empty.
+There can be only one active livepatch for a given ``provides`` id.
+A new livepatch atomically replaces any existing livepatch whose
+``provides`` id matches either the new patch's ``provides`` id or
+any id in the new patch's ``obsoletes`` list.
+
+Once the transition is complete, all functions (``struct klp_func``)
+associated with the matching replaced patches are removed from the
+corresponding ``struct klp_ops``. If a function is no longer modified by
+the new patch and its ``func_stack`` list becomes empty, the ftrace
+handler is unregistered and the ``struct klp_ops`` is freed.
+
+Patches with a different ``provides`` id are not affected by this
+process and remain active. This allows for the independent management
+and stacking of multiple, non-conflicting livepatch sets.
 
 See Documentation/livepatch/cumulative-patches.rst for more details.
 
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index ba9e3988c07c..854ed6230b96 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -123,7 +123,8 @@ struct klp_state {
  * @mod:	reference to the live patch module
  * @objs:	object entries for kernel objects to be patched
  * @states:	system states that can get modified
- * @replace:	replace all actively used patches
+ * @provides:	only one active livepatch per id
+ * @obsoletes:	replace given livepatch id(s)
  * @list:	list node for global list of actively used patches
  * @kobj:	kobject for sysfs resources
  * @obj_list:	dynamic list of the object entries
@@ -137,7 +138,9 @@ struct klp_patch {
 	struct module *mod;
 	struct klp_object *objs;
 	struct klp_state *states;
-	bool replace;
+	unsigned int provides;
+	unsigned int *obsoletes;
+	unsigned int nr_obsoletes;
 
 	/* internal */
 	struct list_head list;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3de3940d34b2..922aa00a6329 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -350,7 +350,8 @@ 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>/provides
+ * /sys/kernel/livepatch/<patch>/obsoletes
  * /sys/kernel/livepatch/<patch>/stack_order
  * /sys/kernel/livepatch/<patch>/<object>
  * /sys/kernel/livepatch/<patch>/<object>/patched
@@ -448,13 +449,32 @@ static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
 	return count;
 }
 
-static ssize_t replace_show(struct kobject *kobj,
+static ssize_t provides_show(struct kobject *kobj,
 			    struct kobj_attribute *attr, char *buf)
 {
 	struct klp_patch *patch;
 
 	patch = container_of(kobj, struct klp_patch, kobj);
-	return sysfs_emit(buf, "%d\n", patch->replace);
+	return sysfs_emit(buf, "%u\n", patch->provides);
+}
+
+static ssize_t obsoletes_show(struct kobject *kobj,
+			      struct kobj_attribute *attr, char *buf)
+{
+	struct klp_patch *patch;
+	unsigned int i;
+	int len = 0;
+
+	patch = container_of(kobj, struct klp_patch, kobj);
+	if (!patch->obsoletes || !patch->nr_obsoletes)
+		return sysfs_emit(buf, "\n");
+
+	for (i = 0; i < patch->nr_obsoletes; i++)
+		len += sysfs_emit_at(buf, len, "%u%s", patch->obsoletes[i],
+				     i < patch->nr_obsoletes - 1 ? "," : "");
+
+	len += sysfs_emit_at(buf, len, "\n");
+	return len;
 }
 
 static ssize_t stack_order_show(struct kobject *kobj,
@@ -481,13 +501,15 @@ static ssize_t stack_order_show(struct kobject *kobj,
 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 provides_kobj_attr = __ATTR_RO(provides);
+static struct kobj_attribute obsoletes_kobj_attr = __ATTR_RO(obsoletes);
 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,
+	&provides_kobj_attr.attr,
+	&obsoletes_kobj_attr.attr,
 	&stack_order_kobj_attr.attr,
 	NULL
 };
@@ -520,6 +542,28 @@ static void klp_init_func_early(struct klp_object *obj,
 static void klp_init_object_early(struct klp_patch *patch,
 				  struct klp_object *obj);
 
+/*
+ * Check if old_patch should be replaced by new_patch:
+ * 1. Same provides ID
+ * 2. Old provides ID is in new patch's obsoletes list
+ */
+bool klp_patch_replaceable(struct klp_patch *old_patch, struct klp_patch *new_patch)
+{
+	unsigned int i;
+
+	if (old_patch->provides == new_patch->provides)
+		return true;
+
+	if (!new_patch->obsoletes)
+		return false;
+
+	for (i = 0; i < new_patch->nr_obsoletes; i++) {
+		if (new_patch->obsoletes[i] == old_patch->provides)
+			return true;
+	}
+	return false;
+}
+
 static struct klp_object *klp_alloc_object_dynamic(const char *name,
 						   struct klp_patch *patch)
 {
@@ -618,6 +662,9 @@ static int klp_add_nops(struct klp_patch *patch)
 	struct klp_object *old_obj;
 
 	klp_for_each_patch(old_patch) {
+		if (!klp_patch_replaceable(old_patch, patch))
+			continue;
+
 		klp_for_each_object(old_patch, old_obj) {
 			int err;
 
@@ -793,6 +840,8 @@ void klp_free_replaced_patches_async(struct klp_patch *new_patch)
 	klp_for_each_patch_safe(old_patch, tmp_patch) {
 		if (old_patch == new_patch)
 			return;
+		if (!klp_patch_replaceable(old_patch, new_patch))
+			continue;
 		klp_free_patch_async(old_patch);
 	}
 }
@@ -985,11 +1034,9 @@ static int klp_init_patch(struct klp_patch *patch)
 	if (ret)
 		return ret;
 
-	if (patch->replace) {
-		ret = klp_add_nops(patch);
-		if (ret)
-			return ret;
-	}
+	ret = klp_add_nops(patch);
+	if (ret)
+		return ret;
 
 	klp_for_each_object(patch, obj) {
 		ret = klp_init_object(patch, obj);
@@ -1205,6 +1252,8 @@ void klp_unpatch_replaced_patches(struct klp_patch *new_patch)
 	klp_for_each_patch(old_patch) {
 		if (old_patch == new_patch)
 			return;
+		if (!klp_patch_replaceable(old_patch, new_patch))
+			continue;
 
 		old_patch->enabled = false;
 		klp_unpatch_objects(old_patch);
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 361a0917a03f..558ce7b70754 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -18,6 +18,7 @@ void klp_free_replaced_patches_async(struct klp_patch *new_patch);
 void klp_unpatch_replaced_patches(struct klp_patch *new_patch);
 void klp_discard_nops(struct klp_patch *new_patch);
 struct klp_func *klp_find_func(struct klp_object *obj, struct klp_func *func);
+bool klp_patch_replaceable(struct klp_patch *old_patch, struct klp_patch *new_patch);
 
 static inline bool klp_is_object_loaded(struct klp_object *obj)
 {
diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c
index 2565d039ade0..c31746f47f71 100644
--- a/kernel/livepatch/state.c
+++ b/kernel/livepatch/state.c
@@ -85,24 +85,62 @@ EXPORT_SYMBOL_GPL(klp_get_prev_state);
 
 /* Check if the patch is able to deal with the existing system state. */
 static bool klp_is_state_compatible(struct klp_patch *patch,
+				    struct klp_patch *old_patch,
 				    struct klp_state *old_state)
 {
 	struct klp_state *state;
 
 	state = klp_get_state(patch, old_state->id);
+	if (klp_patch_replaceable(old_patch, patch)) {
+		/*
+		 * If the new livepatch will replace the old one, it must
+		 * handle all already modified states (cumulative patch).
+		 */
+		if (!state)
+			return false;
+		return state->version >= old_state->version;
 
-	/* A cumulative livepatch must handle all already modified states. */
-	if (!state)
-		return !patch->replace;
+	}
 
-	return state->version >= old_state->version;
+	/*
+	 * Two livepatches with a different "provides" must _not_ use
+	 * the same "state->id.
+	 */
+	return !state;
 }
 
 /*
- * Check that the new livepatch will not break the existing system states.
- * Cumulative patches must handle all already modified states.
- * Non-cumulative patches can touch already modified states.
+ * Refuse loading a livepatch which would want to modify a function
+ * which is already livepatched by a patch that will not be replaced.
+ * A patch is replaced if it has the same provides id or if its
+ * provides id is in the new patch's obsoletes list.
  */
+static bool klp_has_function_conflict(struct klp_patch *patch,
+				      struct klp_patch *old_patch)
+{
+	struct klp_object *obj, *old_obj;
+	struct klp_func *func;
+
+	if (klp_patch_replaceable(old_patch, patch))
+		return false;
+
+	klp_for_each_object(patch, obj) {
+		klp_for_each_object(old_patch, old_obj) {
+			if (!!obj->name != !!old_obj->name)
+				continue;
+			if (obj->name && strcmp(obj->name, old_obj->name))
+				continue;
+
+			klp_for_each_func(obj, func) {
+				if (klp_find_func(old_obj, func))
+					return true;
+			}
+		}
+	}
+	return false;
+}
+
+/* Check that the new livepatch will not break the existing system states. */
 bool klp_is_patch_compatible(struct klp_patch *patch)
 {
 	struct klp_patch *old_patch;
@@ -110,9 +148,12 @@ bool klp_is_patch_compatible(struct klp_patch *patch)
 
 	klp_for_each_patch(old_patch) {
 		klp_for_each_state(old_patch, old_state) {
-			if (!klp_is_state_compatible(patch, old_state))
+			if (!klp_is_state_compatible(patch, old_patch, old_state))
 				return false;
 		}
+
+		if (klp_has_function_conflict(patch, old_patch))
+			return false;
 	}
 
 	return true;
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 2351a19ac2a9..15dbc13d0341 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -89,7 +89,7 @@ static void klp_complete_transition(void)
 		 klp_transition_patch->mod->name,
 		 klp_target_state == KLP_TRANSITION_PATCHED ? "patching" : "unpatching");
 
-	if (klp_transition_patch->replace && klp_target_state == KLP_TRANSITION_PATCHED) {
+	if (klp_target_state == KLP_TRANSITION_PATCHED) {
 		klp_unpatch_replaced_patches(klp_transition_patch);
 		klp_discard_nops(klp_transition_patch);
 	}
@@ -498,7 +498,7 @@ void klp_try_complete_transition(void)
 	 */
 	if (!patch->enabled)
 		klp_free_patch_async(patch);
-	else if (patch->replace)
+	else
 		klp_free_replaced_patches_async(patch);
 }
 
@@ -720,11 +720,12 @@ void klp_force_transition(void)
 		klp_update_patch_state(idle_task(cpu));
 
 	/* Set forced flag for patches being removed. */
-	if (klp_target_state == KLP_TRANSITION_UNPATCHED)
+	if (klp_target_state == KLP_TRANSITION_UNPATCHED) {
 		klp_transition_patch->forced = true;
-	else if (klp_transition_patch->replace) {
+	} else {
 		klp_for_each_patch(patch) {
-			if (patch != klp_transition_patch)
+			if (patch != klp_transition_patch &&
+			    klp_patch_replaceable(patch, klp_transition_patch))
 				patch->forced = true;
 		}
 	}
diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
index 16aff8f736eb..044263191652 100644
--- a/scripts/livepatch/init.c
+++ b/scripts/livepatch/init.c
@@ -8,6 +8,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/livepatch.h>
+#include <linux/string.h>
 
 static struct klp_patch *patch;
 
@@ -50,8 +51,6 @@ static int __init livepatch_mod_init(void)
 		funcs = kzalloc(sizeof(struct klp_func) * (nr_funcs + 1), GFP_KERNEL);
 		if (!funcs) {
 			ret = -ENOMEM;
-			for (int j = 0; j < i; j++)
-				kfree(objs[j].funcs);
 			goto err_free_objs;
 		}
 
@@ -72,15 +71,76 @@ static int __init livepatch_mod_init(void)
 
 	/* TODO patch->states */
 
-#ifdef KLP_NO_REPLACE
-	patch->replace = false;
+#ifdef KLP_PROVIDES
+	patch->provides = KLP_PROVIDES;
 #else
-	patch->replace = true;
+	patch->provides = 0;
+#endif
+
+#ifdef KLP_OBSOLETES
+	/*
+	 * Parse KLP_OBSOLETES string (format: "1,2,3") and convert to
+	 * unsigned int array for patch->obsoletes.
+	 *
+	 * Note: The provides ID is not included here; the kernel will
+	 * replace livepatch with the same provides ID.
+	 */
+	{
+		unsigned int *obs_array;
+		unsigned int count = 1;
+		char *obsoletes_str;
+		char *token, *str;
+		int i = 0;
+
+		for (str = (char *)KLP_OBSOLETES; *str; str++) {
+			if (*str == ',')
+				count++;
+		}
+
+		obsoletes_str = kstrdup(KLP_OBSOLETES, GFP_KERNEL);
+		if (!obsoletes_str) {
+			ret = -ENOMEM;
+			goto err_free_objs;
+		}
+
+		obs_array = kmalloc_array(count, sizeof(unsigned int), GFP_KERNEL);
+		if (!obs_array) {
+			kfree(obsoletes_str);
+			ret = -ENOMEM;
+			goto err_free_objs;
+		}
+
+		str = obsoletes_str;
+		while ((token = strsep(&str, ",")) != NULL) {
+			unsigned int val;
+
+			ret = kstrtouint(token, 10, &val);
+			if (ret) {
+				kfree(obsoletes_str);
+				kfree(obs_array);
+				goto err_free_objs;
+			}
+			obs_array[i++] = val;
+		}
+
+		patch->obsoletes = obs_array;
+		patch->nr_obsoletes = i;
+
+		if (i > 0)
+			pr_info("obsoletes patch ids: %s\n", KLP_OBSOLETES);
+
+		kfree(obsoletes_str);
+	}
+#else
+	patch->obsoletes = NULL;
+	patch->nr_obsoletes = 0;
 #endif
 
 	return klp_enable_patch(patch);
 
 err_free_objs:
+	for (int i = 0; i < nr_objs; i++)
+		kfree(objs[i].funcs);
 	kfree(objs);
 err_free_patch:
 	kfree(patch);
@@ -96,6 +156,7 @@ static void __exit livepatch_mod_exit(void)
 		kfree(obj->funcs);
 
 	kfree(patch->objs);
+	kfree(patch->obsoletes);
 	kfree(patch);
 }
 
diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index c4a7acf8edc3..3600f93d9c1c 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -21,7 +21,8 @@ shopt -s lastpipe
 
 unset DEBUG_CLONE DIFF_CHECKSUM SKIP_CLEANUP VERBOSE XTRACE
 
-REPLACE=1
+PROVIDES=0
+OBSOLETES=""
 SHORT_CIRCUIT=0
 JOBS="$(getconf _NPROCESSORS_ONLN)"
 shopt -o xtrace | grep -q 'on' && XTRACE=1
@@ -132,7 +133,8 @@ Options:
    -f, --show-first-changed	Show address of first changed instruction
    -j, --jobs=<jobs>		Build jobs to run simultaneously [default: $JOBS]
    -o, --output=<file.ko>	Output file [default: livepatch-<patch-name>.ko]
-       --no-replace		Disable livepatch atomic replace
+   -p, --provides=<id>		Set the provides id for this livepatch
+   -r, --obsoletes=<ids>	Set the obsoletes ids array (e.g., "[0,1,2]")
    -v, --verbose		Pass V=1 to kernel/module builds
 
 Advanced Options:
@@ -147,7 +149,6 @@ Advanced Options:
 
 EOF
 }
-
 usage() {
 	__usage >&2
 }
@@ -159,8 +160,8 @@ process_args() {
 	local args
 	local patch
 
-	short="hfj:o:vdS:T"
-	long="help,show-first-changed,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
+	short="hfj:o:p:r:vdS:T"
+	long="help,show-first-changed,jobs:,output:,provides:,obsoletes:,verbose,debug,short-circuit:,keep-tmp"
 
 	args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
 		echo; usage; exit
@@ -189,9 +190,26 @@ process_args() {
 				NAME="$(module_name_string "$NAME")"
 				shift 2
 				;;
-			--no-replace)
-				REPLACE=0
-				shift
+			-p | --provides)
+				PROVIDES="$2"
+				shift 2
+				;;
+			-r | --obsoletes)
+				OBSOLETES="$2"
+				local obs_val="$2"
+				[[ "$obs_val" != \[*\] ]] && die "obsoletes must be enclosed in brackets, e.g., '[0,1,2]'"
+				local obs_check="${obs_val//[\[\] ]/}"
+				[[ -z "$obs_check" ]] && shift 2 && continue
+				[[ "$obs_check" == ,* || "$obs_check" == *, || "$obs_check" == *,,* ]] && \
+					die "obsoletes has invalid comma usage: '$obs_val'"
+				local IFS=','
+				local obs_elem
+				for obs_elem in $obs_check; do
+					[[ ! "$obs_elem" =~ ^[0-9]+$ ]] && \
+						die "obsoletes contains invalid value '$obs_elem': only non-negative integers allowed"
+				done
+				unset IFS
+				shift 2
 				;;
 			-v | --verbose)
 				VERBOSE=1
@@ -235,6 +253,37 @@ process_args() {
 		exit 1
 	fi
 
+	# Remove duplicates from obsoletes (if specified)
+	# Note: provides ID is not added here; the kernel will replace
+	# livepatch with the same provides ID.
+	if [[ -n "$OBSOLETES" && "$OBSOLETES" != "[]" ]]; then
+		local obsoletes_clean="${OBSOLETES//[\[\] ]/}"
+		local IFS=','
+		local -a obs_array=()
+		local obs_id
+		local already_exists
+
+		for obs_id in $obsoletes_clean; do
+			if [[ -n "$obs_id" ]]; then
+				already_exists=0
+				for existing in "${obs_array[@]}"; do
+					if [[ "$existing" -eq "$obs_id" ]]; then
+						already_exists=1
+						break
+					fi
+				done
+
+				if [[ "$already_exists" -eq 0 ]]; then
+					obs_array+=("$obs_id")
+				fi
+			fi
+		done
+
+		local IFS=','
+		OBSOLETES="[${obs_array[*]}]"
+		unset IFS
+	fi
+
 	KEEP_TMP="$keep_tmp"
 	PATCHES=("$@")
 
@@ -847,7 +896,17 @@ build_patch_module() {
 
 	cflags=("-ffunction-sections")
 	cflags+=("-fdata-sections")
-	[[ $REPLACE -eq 0 ]] && cflags+=("-DKLP_NO_REPLACE")
+	cflags+=("-DKLP_PROVIDES=$PROVIDES")
+
+	# Process OBSOLETES: remove brackets and spaces, convert to comma-separated string
+	# Input: "[0, 1, 2]" or "[]" or "" -> Output: "0,1,2" or empty
+	if [[ -n "$OBSOLETES" && "$OBSOLETES" != "[]" ]]; then
+		# Remove '[', ']', and spaces, keep commas
+		local obsoletes_clean="${OBSOLETES//[\[\] ]/}"
+		# Escape quotes properly for C string macro
+		cflags+=("-DKLP_OBSOLETES=\\\"$obsoletes_clean\\\"")
+		[[ -v VERBOSE ]] && echo "  KLP_OBSOLETES=$obsoletes_clean (from OBSOLETES=$OBSOLETES, PROVIDES=$PROVIDES)" >&2
+	fi
 
 	cmd=("make")
 	if [[ -v VERBOSE ]]; then
-- 
2.52.0

[PATCH v5 5/9] livepatch: Deprecate stack_order

[Yafang Shao]

stack_order is no longer needed for atomic-replace livepatches, as a
single function can only be modified by a unique replace_set.
Since this livepatch sysfs interface is mainly intended for kernel
developers, backward compatibility does not need to be maintained.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Wardenjohn <zhangwarden@gmail.com>
---
 .../ABI/removed/sysfs-kernel-livepatch        | 16 +++++++++++++
 .../ABI/testing/sysfs-kernel-livepatch        |  9 -------
 kernel/livepatch/core.c                       | 24 -------------------
 3 files changed, 16 insertions(+), 33 deletions(-)
 create mode 100644 Documentation/ABI/removed/sysfs-kernel-livepatch

diff --git a/Documentation/ABI/removed/sysfs-kernel-livepatch b/Documentation/ABI/removed/sysfs-kernel-livepatch
new file mode 100644
index 000000000000..fb6ff9c3b43e
--- /dev/null
+++ b/Documentation/ABI/removed/sysfs-kernel-livepatch
@@ -0,0 +1,16 @@
+What:		/sys/kernel/livepatch/<patch>/replace
+Date:		Jun 2024
+KernelVersion:	6.11.0
+Contact:	live-patching@vger.kernel.org
+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.
diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 2588f676deb1..3564b3e4385f 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -67,15 +67,6 @@ Description:
 		either this patch's provides id or any id in the obsoletes
 		list will be atomically replaced.
 
-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
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 922aa00a6329..171e689fdbcb 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -352,7 +352,6 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
  * /sys/kernel/livepatch/<patch>/force
  * /sys/kernel/livepatch/<patch>/provides
  * /sys/kernel/livepatch/<patch>/obsoletes
- * /sys/kernel/livepatch/<patch>/stack_order
  * /sys/kernel/livepatch/<patch>/<object>
  * /sys/kernel/livepatch/<patch>/<object>/patched
  * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
@@ -477,40 +476,17 @@ static ssize_t obsoletes_show(struct kobject *kobj,
 	return len;
 }
 
-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 provides_kobj_attr = __ATTR_RO(provides);
 static struct kobj_attribute obsoletes_kobj_attr = __ATTR_RO(obsoletes);
-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,
 	&provides_kobj_attr.attr,
 	&obsoletes_kobj_attr.attr,
-	&stack_order_kobj_attr.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(klp_patch);
-- 
2.52.0

[PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

[Yafang Shao]

The legacy "replace" field in struct klp_patch was replaced by the
provides/obsoletes mechanism. As a result, the atomic replace
selftests fail to build against kernels that only support
provides/obsoletes.

Adapt the selftests so that they build and run on both old and new
kernels:

- test_modules/Makefile detects whether the kernel header still
  declares the "replace" field. If so, it passes KLP_HAS_REPLACE to
  the modules via ccflags-y.

- test_klp_atomic_replace.c and other source files using .replace guard
  their replace module parameter and .replace assignment with
  #ifdef KLP_HAS_REPLACE. The #else branches are left as TODO
  placeholders for the upcoming provides/obsoletes based tests.

- functions.sh adds detect_replace_attr(), which loads a temporary
  livepatch and checks for the /sys/kernel/livepatch/<patch>/replace
  attribute, setting HAS_REPLACE_ATTR accordingly.

- test-livepatch.sh and test-callbacks.sh run the tests that depend
  on multiple livepatches coexisting or on the atomic replace
  behavior ("multiple livepatches" and "atomic replace") only when
  HAS_REPLACE_ATTR is set. These scenarios do not apply to the new
  kernel, where provides=0 replaces any other livepatch by default.

The provides/obsoletes based selftests will be added later.

Assisted-by: Comagic:DeepSeek-V4-Flash
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 tools/testing/selftests/livepatch/functions.sh   | 15 +++++++++++++++
 .../selftests/livepatch/test-callbacks.sh        |  6 ++++++
 .../selftests/livepatch/test-livepatch.sh        |  6 ++++++
 .../selftests/livepatch/test_modules/Makefile    | 10 ++++++++++
 .../test_modules/test_klp_atomic_replace.c       | 16 ++++++++++++++++
 .../test_modules/test_klp_callbacks_demo2.c      | 16 ++++++++++++++++
 .../livepatch/test_modules/test_klp_state.c      |  7 +++++++
 .../livepatch/test_modules/test_klp_state2.c     |  7 +++++++
 8 files changed, 83 insertions(+)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 30dc677b2f45..17810521d069 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -351,6 +351,21 @@ function does_sysfs_exist() {
 	[[ -f "$SYSFS_KLP_DIR/$mod/$attr" ]]
 }
 
+# detect_replace_attr() - detect whether the running kernel still exposes
+# the legacy "replace" sysfs attribute and set HAS_REPLACE_ATTR
+# accordingly. The atomic replace tests are only run when the attribute
+# is present. The provides/obsoletes based tests will be added later.
+function detect_replace_attr() {
+	HAS_REPLACE_ATTR=0
+
+	load_lp test_klp_livepatch
+	if does_sysfs_exist test_klp_livepatch "replace"; then
+		HAS_REPLACE_ATTR=1
+	fi
+	disable_lp test_klp_livepatch
+	unload_lp test_klp_livepatch
+}
+
 # check_sysfs_rights(modname, rel_path, expected_rights) - check sysfs
 # path permissions
 #	modname - livepatch module creating the sysfs interface
diff --git a/tools/testing/selftests/livepatch/test-callbacks.sh b/tools/testing/selftests/livepatch/test-callbacks.sh
index 2a03deb26a12..e9b2dc6ea099 100755
--- a/tools/testing/selftests/livepatch/test-callbacks.sh
+++ b/tools/testing/selftests/livepatch/test-callbacks.sh
@@ -11,6 +11,8 @@ MOD_TARGET_BUSY=test_klp_callbacks_busy
 
 setup_config
 
+detect_replace_attr
+
 
 # Test a combination of loading a kernel module and a livepatch that
 # patches a function in the first module.  Load the target module
@@ -451,6 +453,7 @@ $MOD_TARGET_BUSY: busymod_work_func exit
 $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_exit"
 
 
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
 # Test loading multiple livepatches.  This test-case is mainly for comparing
 # with the next test-case.
 #
@@ -499,8 +502,10 @@ $MOD_LIVEPATCH: post_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH2
 % rmmod $MOD_LIVEPATCH"
+fi
 
 
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
 # Load multiple livepatches, but the second as an 'atomic-replace'
 # patch.  When the latter loads, the original livepatch should be
 # disabled and *none* of its pre/post-unpatch callbacks executed.  On
@@ -548,6 +553,7 @@ $MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
 livepatch: '$MOD_LIVEPATCH2': unpatching complete
 % rmmod $MOD_LIVEPATCH2
 % rmmod $MOD_LIVEPATCH"
+fi
 
 
 exit 0
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index c44c5341a2f1..b3b7cd81e3d0 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -13,6 +13,8 @@ MOD_TARGET_PATCH=test_klp_mod_patch
 
 setup_config
 
+detect_replace_attr
+
 
 # - load a livepatch that modifies the output from /proc/cmdline and
 #   verify correct behavior
@@ -49,6 +51,7 @@ livepatch: '$MOD_LIVEPATCH1': unpatching complete
 % rmmod $MOD_LIVEPATCH1"
 
 
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
 # - load a livepatch that modifies the output from /proc/cmdline and
 #   verify correct behavior
 # - load another livepatch and verify that both livepatches are active
@@ -107,8 +110,10 @@ livepatch: '$MOD_LIVEPATCH1': starting unpatching transition
 livepatch: '$MOD_LIVEPATCH1': completing unpatching transition
 livepatch: '$MOD_LIVEPATCH1': unpatching complete
 % rmmod $MOD_LIVEPATCH1"
+fi
 
 
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
 # - load a livepatch that modifies the output from /proc/cmdline and
 #   verify correct behavior
 # - load two additional livepatches and check the number of livepatch modules
@@ -196,6 +201,7 @@ livepatch: '$MOD_REPLACE': starting unpatching transition
 livepatch: '$MOD_REPLACE': completing unpatching transition
 livepatch: '$MOD_REPLACE': unpatching complete
 % rmmod $MOD_REPLACE"
+fi
 
 
 # - load a target module that provides /proc/test_klp_mod_target with
diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
index a13d398585dc..29c55df36046 100644
--- a/tools/testing/selftests/livepatch/test_modules/Makefile
+++ b/tools/testing/selftests/livepatch/test_modules/Makefile
@@ -16,6 +16,16 @@ obj-m += test_klp_atomic_replace.o \
 	test_klp_state3.o \
 	test_klp_syscall.o
 
+# The legacy "replace" field was replaced by provides/obsoletes. When the
+# kernel (KDIR) still supports "replace", pass KLP_HAS_REPLACE to the
+# modules so that they can #ifdef the legacy "replace" code. Otherwise
+# the modules are built with the provides/obsoletes based code (to be
+# added later).
+KLP_HAS_REPLACE := $(shell grep -q 'bool replace' $(KDIR)/include/linux/livepatch.h 2>/dev/null && echo y)
+ifeq ($(KLP_HAS_REPLACE),y)
+ccflags-y += -DKLP_HAS_REPLACE
+endif
+
 # Ensure that KDIR exists, otherwise skip the compilation
 modules:
 ifneq ("$(wildcard $(KDIR))", "")
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
index 5af7093ca00c..4b3ed17886e7 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
@@ -7,9 +7,16 @@
 #include <linux/kernel.h>
 #include <linux/livepatch.h>
 
+#ifdef KLP_HAS_REPLACE
 static int replace;
 module_param(replace, int, 0644);
 MODULE_PARM_DESC(replace, "replace (default=0)");
+#else
+/*
+ * TODO: Add provides/obsoletes module parameters for the
+ * provides/obsoletes based tests (to be added later).
+ */
+#endif
 
 #include <linux/seq_file.h>
 static int livepatch_meminfo_proc_show(struct seq_file *m, void *v)
@@ -36,12 +43,21 @@ static struct klp_object objs[] = {
 static struct klp_patch patch = {
 	.mod = THIS_MODULE,
 	.objs = objs,
+#ifdef KLP_HAS_REPLACE
 	/* set .replace in the init function below for demo purposes */
+#endif
 };
 
 static int test_klp_atomic_replace_init(void)
 {
+#ifdef KLP_HAS_REPLACE
 	patch.replace = replace;
+#else
+	/*
+	 * TODO: Set provides/obsoletes from the module parameters
+	 * for the provides/obsoletes based tests (to be added later).
+	 */
+#endif
 	return klp_enable_patch(&patch);
 }
 
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
index 5417573e80af..135da6d4d882 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
@@ -7,9 +7,16 @@
 #include <linux/kernel.h>
 #include <linux/livepatch.h>
 
+#ifdef KLP_HAS_REPLACE
 static int replace;
 module_param(replace, int, 0644);
 MODULE_PARM_DESC(replace, "replace (default=0)");
+#else
+/*
+ * TODO: Add provides/obsoletes module parameters for the
+ * provides/obsoletes based tests (to be added later).
+ */
+#endif
 
 static const char *const module_state[] = {
 	[MODULE_STATE_LIVE]	= "[MODULE_STATE_LIVE] Normal state",
@@ -72,12 +79,21 @@ static struct klp_object objs[] = {
 static struct klp_patch patch = {
 	.mod = THIS_MODULE,
 	.objs = objs,
+#ifdef KLP_HAS_REPLACE
 	/* set .replace in the init function below for demo purposes */
+#endif
 };
 
 static int test_klp_callbacks_demo2_init(void)
 {
+#ifdef KLP_HAS_REPLACE
 	patch.replace = replace;
+#else
+	/*
+	 * TODO: Set provides/obsoletes from the module parameters
+	 * for the provides/obsoletes based tests (to be added later).
+	 */
+#endif
 	return klp_enable_patch(&patch);
 }
 
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
index 57a4253acb01..3492472e5d07 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
@@ -142,7 +142,14 @@ static struct klp_patch patch = {
 	.mod = THIS_MODULE,
 	.objs = objs,
 	.states = states,
+#ifdef KLP_HAS_REPLACE
 	.replace = true,
+#else
+/*
+ * TODO: Add provides/obsoletes module parameters for the
+ * provides/obsoletes based tests (to be added later).
+ */
+#endif
 };
 
 static int test_klp_callbacks_demo_init(void)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
index c978ea4d5e67..8160b565a659 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
@@ -171,7 +171,14 @@ static struct klp_patch patch = {
 	.mod = THIS_MODULE,
 	.objs = objs,
 	.states = states,
+#ifdef KLP_HAS_REPLACE
 	.replace = true,
+#else
+/*
+ * TODO: Add provides/obsoletes module parameters for the
+ * provides/obsoletes based tests (to be added later).
+ */
+#endif
 };
 
 static int test_klp_callbacks_demo_init(void)
-- 
2.52.0

[PATCH v5 7/9] selftests: livepatch: Add provides/obsoletes test scenarios

[Yafang Shao]

Now that the legacy "replace" field has been replaced by the
provides/obsoletes mechanism, add test scenarios to verify the new
behavior.

Fill in the #else branches of the test modules that were left as
TODO placeholders in the previous patch:

- test_klp_atomic_replace.c gains provides and obsoletes module
  parameters for the provides/obsoletes based tests.

- test_klp_callbacks_demo2.c gains a provides module parameter.

- test_klp_livepatch.c gains a provides module parameter so that it
  can be loaded with a specific provides id for coexistence tests.

- test_klp_state.c and test_klp_state2.c add a comment in the #else
  branch noting that provides=0 (the default) is equivalent to the
  previous .replace=true behavior.

Add test-provides.sh with four test scenarios:

1. provides=0 replaces provides=0: two livepatches with provides=0
   that modify different functions; the second replaces the first.

2. Same provides replaces: two livepatches with provides=1 that
   modify different functions; the second replaces the first.

3. Obsoletes replaces: a livepatch with provides=2 and obsoletes=[1]
   replaces a livepatch with provides=1. The provides/obsoletes sysfs
   values are verified.

4. provides=0 coexists with provides=1: two livepatches with
   different provides ids that modify different functions coexist,
   verifying that provides=0 does not replace a patch with a
   different provides id.

The provides/obsoletes based tests only run on kernels that no longer
support the legacy "replace" attribute.

Assisted-by: Comagic:DeepSeek-V4-Flash
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 tools/testing/selftests/livepatch/Makefile    |   3 +-
 .../livepatch/test-provides-obsoletes.sh      | 195 ++++++++++++++++++
 .../test_modules/test_klp_atomic_replace.c    |  22 +-
 .../test_modules/test_klp_callbacks_demo2.c   |  12 +-
 .../test_modules/test_klp_livepatch.c         |   9 +
 .../livepatch/test_modules/test_klp_state.c   |   5 +-
 .../livepatch/test_modules/test_klp_state2.c  |   5 +-
 7 files changed, 226 insertions(+), 25 deletions(-)
 create mode 100755 tools/testing/selftests/livepatch/test-provides-obsoletes.sh

diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
index a080eb54a215..38f98594d883 100644
--- a/tools/testing/selftests/livepatch/Makefile
+++ b/tools/testing/selftests/livepatch/Makefile
@@ -11,7 +11,8 @@ TEST_PROGS := \
 	test-ftrace.sh \
 	test-sysfs.sh \
 	test-syscall.sh \
-	test-kprobe.sh
+	test-kprobe.sh \
+	test-provides-obsoletes.sh
 
 TEST_FILES := settings
 
diff --git a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
new file mode 100755
index 000000000000..c740d463f556
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
@@ -0,0 +1,195 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2026 Yafang Shao <laoar.shao@gmail.com>
+
+. $(dirname $0)/functions.sh
+
+MOD_ATOMIC=test_klp_atomic_replace
+MOD_LIVEPATCH=test_klp_livepatch
+
+setup_config
+
+detect_replace_attr
+
+# The provides/obsoletes based tests only run on kernels that no longer
+# support the legacy "replace" attribute.
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
+	echo "SKIP: kernel still supports the legacy replace attribute"
+	exit $ksft_skip
+fi
+
+
+# - load a livepatch with provides=0 (cmdline), then another with
+#   provides=0 (meminfo). The second replaces the first (same provides).
+# - unload the remaining livepatch
+
+start_test "provides 0 replaces provides 0"
+
+load_lp $MOD_LIVEPATCH provides=0
+load_lp $MOD_ATOMIC provides=0
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 1 ]]; then
+	die "Expecting one module listed, found $nmods"
+fi
+check_sysfs_value "$MOD_ATOMIC" "enabled" "1"
+
+disable_lp $MOD_ATOMIC
+unload_lp $MOD_ATOMIC
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko provides=0
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+% insmod test_modules/$MOD_ATOMIC.ko provides=0
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_ATOMIC/enabled
+livepatch: '$MOD_ATOMIC': initializing unpatching transition
+livepatch: '$MOD_ATOMIC': starting unpatching transition
+livepatch: '$MOD_ATOMIC': completing unpatching transition
+livepatch: '$MOD_ATOMIC': unpatching complete
+% rmmod $MOD_ATOMIC
+% rmmod $MOD_LIVEPATCH"
+
+
+# - load a livepatch with provides=1 (cmdline), then another with
+#   provides=1 (meminfo). The second replaces the first (same provides).
+# - unload the remaining livepatch
+
+start_test "same provides replaces"
+
+load_lp $MOD_LIVEPATCH provides=1
+load_lp $MOD_ATOMIC provides=1
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 1 ]]; then
+	die "Expecting one module listed, found $nmods"
+fi
+check_sysfs_value "$MOD_ATOMIC" "enabled" "1"
+
+disable_lp $MOD_ATOMIC
+unload_lp $MOD_ATOMIC
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko provides=1
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+% insmod test_modules/$MOD_ATOMIC.ko provides=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_ATOMIC/enabled
+livepatch: '$MOD_ATOMIC': initializing unpatching transition
+livepatch: '$MOD_ATOMIC': starting unpatching transition
+livepatch: '$MOD_ATOMIC': completing unpatching transition
+livepatch: '$MOD_ATOMIC': unpatching complete
+% rmmod $MOD_ATOMIC
+% rmmod $MOD_LIVEPATCH"
+
+
+# - load a livepatch with provides=1 (cmdline), then another with
+#   provides=2 and obsoletes=[1] (meminfo). The second replaces the
+#   first (obsoletes contains the first patch's provides id).
+# - verify the provides/obsoletes sysfs values
+# - unload the remaining livepatch
+
+start_test "obsoletes replaces"
+
+load_lp $MOD_LIVEPATCH provides=1
+load_lp $MOD_ATOMIC provides=2 obsoletes=1
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 1 ]]; then
+	die "Expecting one module listed, found $nmods"
+fi
+check_sysfs_value "$MOD_ATOMIC" "provides" "2"
+check_sysfs_value "$MOD_ATOMIC" "obsoletes" "1"
+
+disable_lp $MOD_ATOMIC
+unload_lp $MOD_ATOMIC
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko provides=1
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+% insmod test_modules/$MOD_ATOMIC.ko provides=2 obsoletes=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_ATOMIC/enabled
+livepatch: '$MOD_ATOMIC': initializing unpatching transition
+livepatch: '$MOD_ATOMIC': starting unpatching transition
+livepatch: '$MOD_ATOMIC': completing unpatching transition
+livepatch: '$MOD_ATOMIC': unpatching complete
+% rmmod $MOD_ATOMIC
+% rmmod $MOD_LIVEPATCH"
+
+
+# - load two livepatches with different provides ids that modify
+#   different functions and verify that they coexist
+# - in particular, verify that provides=0 does NOT replace a patch
+#   with a different provides id
+# - unload both livepatches
+
+start_test "provides 0 coexists with provides 1"
+
+load_lp $MOD_LIVEPATCH provides=0
+load_lp $MOD_ATOMIC provides=1
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 2 ]]; then
+	die "Expecting two modules listed, found $nmods"
+fi
+
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+disable_lp $MOD_ATOMIC
+unload_lp $MOD_ATOMIC
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko provides=0
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+% insmod test_modules/$MOD_ATOMIC.ko provides=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH
+% echo 0 > /sys/kernel/livepatch/$MOD_ATOMIC/enabled
+livepatch: '$MOD_ATOMIC': initializing unpatching transition
+livepatch: '$MOD_ATOMIC': starting unpatching transition
+livepatch: '$MOD_ATOMIC': completing unpatching transition
+livepatch: '$MOD_ATOMIC': unpatching complete
+% rmmod $MOD_ATOMIC"
+
+exit 0
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
index 4b3ed17886e7..b0ed924eeeed 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace.c
@@ -12,10 +12,15 @@ static int replace;
 module_param(replace, int, 0644);
 MODULE_PARM_DESC(replace, "replace (default=0)");
 #else
-/*
- * TODO: Add provides/obsoletes module parameters for the
- * provides/obsoletes based tests (to be added later).
- */
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
+
+#define KLP_MAX_OBSOLETES 16
+static unsigned int obsoletes[KLP_MAX_OBSOLETES];
+static int nr_obsoletes;
+module_param_array(obsoletes, uint, &nr_obsoletes, 0644);
+MODULE_PARM_DESC(obsoletes, "obsoletes provides ids");
 #endif
 
 #include <linux/seq_file.h>
@@ -53,10 +58,11 @@ static int test_klp_atomic_replace_init(void)
 #ifdef KLP_HAS_REPLACE
 	patch.replace = replace;
 #else
-	/*
-	 * TODO: Set provides/obsoletes from the module parameters
-	 * for the provides/obsoletes based tests (to be added later).
-	 */
+	patch.provides = provides;
+	if (nr_obsoletes > 0) {
+		patch.obsoletes = obsoletes;
+		patch.nr_obsoletes = nr_obsoletes;
+	}
 #endif
 	return klp_enable_patch(&patch);
 }
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
index 135da6d4d882..a0e7b7d1e198 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
@@ -12,10 +12,9 @@ static int replace;
 module_param(replace, int, 0644);
 MODULE_PARM_DESC(replace, "replace (default=0)");
 #else
-/*
- * TODO: Add provides/obsoletes module parameters for the
- * provides/obsoletes based tests (to be added later).
- */
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
 #endif
 
 static const char *const module_state[] = {
@@ -89,10 +88,7 @@ static int test_klp_callbacks_demo2_init(void)
 #ifdef KLP_HAS_REPLACE
 	patch.replace = replace;
 #else
-	/*
-	 * TODO: Set provides/obsoletes from the module parameters
-	 * for the provides/obsoletes based tests (to be added later).
-	 */
+	patch.provides = provides;
 #endif
 	return klp_enable_patch(&patch);
 }
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_livepatch.c b/tools/testing/selftests/livepatch/test_modules/test_klp_livepatch.c
index aff08199de71..fa2bc6ec921d 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_livepatch.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_livepatch.c
@@ -7,6 +7,12 @@
 #include <linux/kernel.h>
 #include <linux/livepatch.h>
 
+#ifndef KLP_HAS_REPLACE
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
+#endif
+
 #include <linux/seq_file.h>
 static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
 {
@@ -36,6 +42,9 @@ static struct klp_patch patch = {
 
 static int test_klp_livepatch_init(void)
 {
+#ifndef KLP_HAS_REPLACE
+	patch.provides = provides;
+#endif
 	return klp_enable_patch(&patch);
 }
 
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
index 3492472e5d07..313401a5506e 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
@@ -145,10 +145,7 @@ static struct klp_patch patch = {
 #ifdef KLP_HAS_REPLACE
 	.replace = true,
 #else
-/*
- * TODO: Add provides/obsoletes module parameters for the
- * provides/obsoletes based tests (to be added later).
- */
+	/* provides=0 by default, replaces all provides=0 patches */
 #endif
 };
 
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
index 8160b565a659..1afc2cabc39d 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
@@ -174,10 +174,7 @@ static struct klp_patch patch = {
 #ifdef KLP_HAS_REPLACE
 	.replace = true,
 #else
-/*
- * TODO: Add provides/obsoletes module parameters for the
- * provides/obsoletes based tests (to be added later).
- */
+	/* provides=0 by default, replaces all provides=0 patches */
 #endif
 };
 
-- 
2.52.0

[PATCH v5 8/9] selftests: livepatch: Add test for state ID conflict across provides

[Yafang Shao]

Livepatches with different provides ids must not share the same state
id. If a second livepatch attempts to reuse a state id already
registered by a livepatch with a different provides id, the loading
will fail. However, if the second livepatch's obsoletes list includes
the first livepatch's provides id, the second livepatch replaces the
first one and may reuse the same state id.

Add provides and obsoletes module parameters to test_klp_state.c and
test_klp_state2.c (guarded by #ifndef KLP_HAS_REPLACE) so that they
can be loaded with different provides ids and obsoletes ids.

Add a "state id conflict across provides" test scenario to
test-provides.sh:

  - Load test_klp_state with provides=1, which registers state ID 1.
  - Attempt to load test_klp_state2 with provides=2, which reuses the
    same state ID 1. The second livepatch is rejected because
    livepatches with different provides ids must not share the same
    state id.
  - Disable and unload the remaining livepatch.

Add a "taking over system state via obsoletes" test scenario to
test-state.sh:

  - Load test_klp_state with provides=10, which registers state ID 1.
  - Load test_klp_state2 with provides=20 obsoletes=10, which reuses the
    same state ID 1. Although the provides ids differ, the second livepatch
    replaces the first one because its obsoletes list includes the first
    livepatch's provides id (10). The state is taken over successfully.
  - Unload the replaced livepatch, then disable and unload the second
    livepatch.

Assisted-by: Comagic:DeepSeek-V4-Flash
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 .../livepatch/test-provides-obsoletes.sh      | 86 +++++++++++++++++++
 .../livepatch/test_modules/test_klp_state.c   |  9 ++
 .../livepatch/test_modules/test_klp_state2.c  | 19 ++++
 3 files changed, 114 insertions(+)

diff --git a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
index c740d463f556..1b2c73bdd50b 100755
--- a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
+++ b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
@@ -6,6 +6,8 @@
 
 MOD_ATOMIC=test_klp_atomic_replace
 MOD_LIVEPATCH=test_klp_livepatch
+MOD_STATE=test_klp_state
+MOD_STATE2=test_klp_state2
 
 setup_config
 
@@ -192,4 +194,88 @@ livepatch: '$MOD_ATOMIC': completing unpatching transition
 livepatch: '$MOD_ATOMIC': unpatching complete
 % rmmod $MOD_ATOMIC"
 
+# - load a livepatch with provides=1 that registers state ID 1
+# - try to load another livepatch with provides=2 that reuses the same
+#   state ID. The second one must be rejected because livepatches with
+#   different provides ids must not share the same state id.
+# - disable and unload the remaining livepatch
+
+start_test "state id conflict across provides"
+
+load_lp $MOD_STATE provides=1
+load_failing_mod $MOD_STATE2 provides=2
+
+disable_lp $MOD_STATE
+unload_lp $MOD_STATE
+
+check_result "% insmod test_modules/$MOD_STATE.ko provides=1
+livepatch: enabling patch '$MOD_STATE'
+livepatch: '$MOD_STATE': initializing patching transition
+$MOD_STATE: pre_patch_callback: vmlinux
+$MOD_STATE: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_STATE': starting patching transition
+livepatch: '$MOD_STATE': completing patching transition
+$MOD_STATE: post_patch_callback: vmlinux
+$MOD_STATE: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_STATE': patching complete
+% insmod test_modules/$MOD_STATE2.ko provides=2
+livepatch: Livepatch patch ($MOD_STATE2) is not compatible with the already installed livepatches.
+insmod: ERROR: could not insert module test_modules/$MOD_STATE2.ko: Invalid parameters
+% echo 0 > $SYSFS_KLP_DIR/$MOD_STATE/enabled
+livepatch: '$MOD_STATE': initializing unpatching transition
+$MOD_STATE: pre_unpatch_callback: vmlinux
+$MOD_STATE: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_STATE': starting unpatching transition
+livepatch: '$MOD_STATE': completing unpatching transition
+$MOD_STATE: post_unpatch_callback: vmlinux
+$MOD_STATE: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_STATE': unpatching complete
+% rmmod $MOD_STATE"
+
+
+# Take over system state change by a patch that obsoletes the old one.
+# Although the provides IDs are different, the second patch's obsoletes
+# list includes the first patch's provides ID, so it can replace the
+# first patch and reuse the same state ID.
+
+start_test "taking over system state via obsoletes"
+
+load_lp $MOD_STATE provides=10
+load_lp $MOD_STATE2 provides=20 obsoletes=10
+unload_lp $MOD_STATE
+disable_lp $MOD_STATE2
+unload_lp $MOD_STATE2
+
+check_result "% insmod test_modules/$MOD_STATE.ko provides=10
+livepatch: enabling patch '$MOD_STATE'
+livepatch: '$MOD_STATE': initializing patching transition
+$MOD_STATE: pre_patch_callback: vmlinux
+$MOD_STATE: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_STATE': starting patching transition
+livepatch: '$MOD_STATE': completing patching transition
+$MOD_STATE: post_patch_callback: vmlinux
+$MOD_STATE: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_STATE': patching complete
+% insmod test_modules/$MOD_STATE2.ko provides=20 obsoletes=10
+livepatch: enabling patch '$MOD_STATE2'
+livepatch: '$MOD_STATE2': initializing patching transition
+$MOD_STATE2: pre_patch_callback: vmlinux
+$MOD_STATE2: allocate_loglevel_state: space to store console_loglevel already allocated
+livepatch: '$MOD_STATE2': starting patching transition
+livepatch: '$MOD_STATE2': completing patching transition
+$MOD_STATE2: post_patch_callback: vmlinux
+$MOD_STATE2: fix_console_loglevel: taking over the console_loglevel change
+livepatch: '$MOD_STATE2': patching complete
+% rmmod $MOD_STATE
+% echo 0 > $SYSFS_KLP_DIR/$MOD_STATE2/enabled
+livepatch: '$MOD_STATE2': initializing unpatching transition
+$MOD_STATE2: pre_unpatch_callback: vmlinux
+$MOD_STATE2: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_STATE2': starting unpatching transition
+livepatch: '$MOD_STATE2': completing unpatching transition
+$MOD_STATE2: post_unpatch_callback: vmlinux
+$MOD_STATE2: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_STATE2': unpatching complete
+% rmmod $MOD_STATE2"
+
 exit 0
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
index 313401a5506e..77a5511d9d69 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
@@ -9,6 +9,12 @@
 #include <linux/printk.h>
 #include <linux/livepatch.h>
 
+#ifndef KLP_HAS_REPLACE
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
+#endif
+
 #define CONSOLE_LOGLEVEL_STATE 1
 /* Version 1 does not support migration. */
 #define CONSOLE_LOGLEVEL_STATE_VERSION 1
@@ -151,6 +157,9 @@ static struct klp_patch patch = {
 
 static int test_klp_callbacks_demo_init(void)
 {
+#ifndef KLP_HAS_REPLACE
+	patch.provides = provides;
+#endif
 	return klp_enable_patch(&patch);
 }
 
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
index 1afc2cabc39d..53ff6e793952 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
@@ -9,6 +9,18 @@
 #include <linux/printk.h>
 #include <linux/livepatch.h>
 
+#ifndef KLP_HAS_REPLACE
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
+
+#define KLP_MAX_OBSOLETES 16
+static unsigned int obsoletes[KLP_MAX_OBSOLETES];
+static int nr_obsoletes;
+module_param_array(obsoletes, uint, &nr_obsoletes, 0644);
+MODULE_PARM_DESC(obsoletes, "obsoletes provides ids");
+#endif
+
 #define CONSOLE_LOGLEVEL_STATE 1
 /* Version 2 supports migration. */
 #define CONSOLE_LOGLEVEL_STATE_VERSION 2
@@ -180,6 +192,13 @@ static struct klp_patch patch = {
 
 static int test_klp_callbacks_demo_init(void)
 {
+#ifndef KLP_HAS_REPLACE
+	patch.provides = provides;
+	if (nr_obsoletes > 0) {
+		patch.obsoletes = obsoletes;
+		patch.nr_obsoletes = nr_obsoletes;
+	}
+#endif
 	return klp_enable_patch(&patch);
 }
 
-- 
2.52.0

[PATCH v5 9/9] selftests: livepatch: Add test for function conflict across provides

[Yafang Shao]

Livepatches with different provides ids must not modify the same
function. If a second livepatch attempts to modify a function that
has already been modified by a loaded livepatch with a different
provides id, the loading will fail. If the second livepatch shares
the same provides id, or if its obsoletes list contains the first
livepatch's provides id, it will load successfully and replace the
first one.

Add a new test module test_klp_provides.c that patches meminfo_proc_show
(the same function as test_klp_atomic_replace) so that the two modules
can be loaded with different provides ids to test the function conflict
detection.

Add three test scenarios to test-provides.sh:

1. Function conflict across provides: load test_klp_atomic_replace with
   provides=1, then attempt to load test_klp_provides with provides=2.
   The second livepatch is rejected because livepatches with different
   provides ids and no obsoletes must not modify the same function.

2. Function replace within same provides: load test_klp_atomic_replace
   with provides=1, then load test_klp_provides with provides=1. The
   second livepatch loads successfully and replaces the first one
   because they share the same provides id.

3. Function replace across provides with obsoletes: load
   test_klp_atomic_replace with provides=1, then load test_klp_provides
   with provides=2 and obsoletes=[1]. The second livepatch loads
   successfully and replaces the first one because the obsoletes list
   allows it to replace a livepatch with a different provides id.

Assisted-by: Comagic:DeepSeek-V4-Flash
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 .../livepatch/test-provides-obsoletes.sh      | 120 ++++++++++++++++++
 .../selftests/livepatch/test_modules/Makefile |   1 +
 .../test_modules/test_klp_provides.c          |  72 +++++++++++
 3 files changed, 193 insertions(+)
 create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_provides.c

diff --git a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
index 1b2c73bdd50b..32885625401d 100755
--- a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
+++ b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
@@ -8,6 +8,7 @@ MOD_ATOMIC=test_klp_atomic_replace
 MOD_LIVEPATCH=test_klp_livepatch
 MOD_STATE=test_klp_state
 MOD_STATE2=test_klp_state2
+MOD_PROVIDES=test_klp_provides
 
 setup_config
 
@@ -278,4 +279,123 @@ $MOD_STATE2: free_loglevel_state: freeing space for the stored console_loglevel
 livepatch: '$MOD_STATE2': unpatching complete
 % rmmod $MOD_STATE2"
 
+
+# - load a livepatch with provides=1 that modifies meminfo_proc_show
+# - try to load another livepatch with provides=2 that modifies the
+#   same function. The second one must be rejected because livepatches
+#   with different provides ids and no obsoletes must not modify
+#   the same function.
+# - disable and unload the remaining livepatch
+
+start_test "function conflict across provides"
+
+load_lp $MOD_ATOMIC provides=1
+load_failing_mod $MOD_PROVIDES provides=2
+
+disable_lp $MOD_ATOMIC
+unload_lp $MOD_ATOMIC
+
+check_result "% insmod test_modules/$MOD_ATOMIC.ko provides=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% insmod test_modules/$MOD_PROVIDES.ko provides=2
+livepatch: Livepatch patch ($MOD_PROVIDES) is not compatible with the already installed livepatches.
+insmod: ERROR: could not insert module test_modules/$MOD_PROVIDES.ko: Invalid parameters
+% echo 0 > $SYSFS_KLP_DIR/$MOD_ATOMIC/enabled
+livepatch: '$MOD_ATOMIC': initializing unpatching transition
+livepatch: '$MOD_ATOMIC': starting unpatching transition
+livepatch: '$MOD_ATOMIC': completing unpatching transition
+livepatch: '$MOD_ATOMIC': unpatching complete
+% rmmod $MOD_ATOMIC"
+
+
+# - load a livepatch with provides=1 that modifies meminfo_proc_show
+# - load another livepatch with provides=1 that modifies the same
+#   function. The second one loads successfully because livepatches
+#   with the same provides id replace each other.
+# - disable and unload the remaining livepatch
+
+start_test "function replace within same provides"
+
+load_lp $MOD_ATOMIC provides=1
+load_lp $MOD_PROVIDES provides=1
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 1 ]]; then
+	die "Expecting one module listed, found $nmods"
+fi
+check_sysfs_value "$MOD_PROVIDES" "enabled" "1"
+
+disable_lp $MOD_PROVIDES
+unload_lp $MOD_PROVIDES
+unload_lp $MOD_ATOMIC
+
+check_result "% insmod test_modules/$MOD_ATOMIC.ko provides=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% insmod test_modules/$MOD_PROVIDES.ko provides=1
+livepatch: enabling patch '$MOD_PROVIDES'
+livepatch: '$MOD_PROVIDES': initializing patching transition
+livepatch: '$MOD_PROVIDES': starting patching transition
+livepatch: '$MOD_PROVIDES': completing patching transition
+livepatch: '$MOD_PROVIDES': patching complete
+% echo 0 > $SYSFS_KLP_DIR/$MOD_PROVIDES/enabled
+livepatch: '$MOD_PROVIDES': initializing unpatching transition
+livepatch: '$MOD_PROVIDES': starting unpatching transition
+livepatch: '$MOD_PROVIDES': completing unpatching transition
+livepatch: '$MOD_PROVIDES': unpatching complete
+% rmmod $MOD_PROVIDES
+% rmmod $MOD_ATOMIC"
+
+
+# - load a livepatch with provides=1 that modifies meminfo_proc_show
+# - load another livepatch with provides=2 and obsoletes=[1] that
+#   modifies the same function. The second one loads successfully
+#   because the obsoletes list allows it to replace the first one
+#   even though they have different provides ids.
+# - disable and unload the remaining livepatch
+
+start_test "function replace across provides with obsoletes"
+
+load_lp $MOD_ATOMIC provides=1
+load_lp $MOD_PROVIDES provides=2 obsoletes=1
+
+mods=($SYSFS_KLP_DIR/*)
+nmods=${#mods[@]}
+if [[ "$nmods" -ne 1 ]]; then
+	die "Expecting one module listed, found $nmods"
+fi
+check_sysfs_value "$MOD_PROVIDES" "enabled" "1"
+
+disable_lp $MOD_PROVIDES
+unload_lp $MOD_PROVIDES
+unload_lp $MOD_ATOMIC
+
+check_result "% insmod test_modules/$MOD_ATOMIC.ko provides=1
+livepatch: enabling patch '$MOD_ATOMIC'
+livepatch: '$MOD_ATOMIC': initializing patching transition
+livepatch: '$MOD_ATOMIC': starting patching transition
+livepatch: '$MOD_ATOMIC': completing patching transition
+livepatch: '$MOD_ATOMIC': patching complete
+% insmod test_modules/$MOD_PROVIDES.ko provides=2 obsoletes=1
+livepatch: enabling patch '$MOD_PROVIDES'
+livepatch: '$MOD_PROVIDES': initializing patching transition
+livepatch: '$MOD_PROVIDES': starting patching transition
+livepatch: '$MOD_PROVIDES': completing patching transition
+livepatch: '$MOD_PROVIDES': patching complete
+% echo 0 > $SYSFS_KLP_DIR/$MOD_PROVIDES/enabled
+livepatch: '$MOD_PROVIDES': initializing unpatching transition
+livepatch: '$MOD_PROVIDES': starting unpatching transition
+livepatch: '$MOD_PROVIDES': completing unpatching transition
+livepatch: '$MOD_PROVIDES': unpatching complete
+% rmmod $MOD_PROVIDES
+% rmmod $MOD_ATOMIC"
+
 exit 0
diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
index 29c55df36046..9f5ea09c55f7 100644
--- a/tools/testing/selftests/livepatch/test_modules/Makefile
+++ b/tools/testing/selftests/livepatch/test_modules/Makefile
@@ -10,6 +10,7 @@ obj-m += test_klp_atomic_replace.o \
 	test_klp_livepatch.o \
 	test_klp_mod_patch.o \
 	test_klp_mod_target.o \
+	test_klp_provides.o \
 	test_klp_shadow_vars.o \
 	test_klp_state.o \
 	test_klp_state2.o \
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c b/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c
new file mode 100644
index 000000000000..9751a6f6c851
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+#ifdef KLP_HAS_REPLACE
+static int replace;
+module_param(replace, int, 0644);
+MODULE_PARM_DESC(replace, "replace (default=0)");
+#else
+static unsigned int provides;
+module_param(provides, uint, 0644);
+MODULE_PARM_DESC(provides, "provides id (default=0)");
+
+#define KLP_MAX_OBSOLETES 16
+static unsigned int obsoletes[KLP_MAX_OBSOLETES];
+static int nr_obsoletes;
+module_param_array(obsoletes, uint, &nr_obsoletes, 0644);
+MODULE_PARM_DESC(obsoletes, "obsoletes provides ids");
+#endif
+
+#include <linux/seq_file.h>
+static int livepatch_meminfo_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s: %s\n", THIS_MODULE->name,
+		   "this has been live patched");
+	return 0;
+}
+
+static struct klp_func funcs[] = {
+	{
+		.old_name = "meminfo_proc_show",
+		.new_func = livepatch_meminfo_proc_show,
+	}, {}
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	}, {}
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int test_klp_provides_init(void)
+{
+#ifdef KLP_HAS_REPLACE
+	patch.replace = replace;
+#else
+	patch.provides = provides;
+	if (nr_obsoletes > 0) {
+		patch.obsoletes = obsoletes;
+		patch.nr_obsoletes = nr_obsoletes;
+	}
+#endif
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_provides_exit(void)
+{
+}
+
+module_init(test_klp_provides_init);
+module_exit(test_klp_provides_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_DESCRIPTION("Livepatch test: provides conflict");
-- 
2.52.0

Re: [PATCH v5 1/9] livepatch: Fix wrong index in funcs cleanup error path

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The patch introduces a double free vulnerability on the `funcs` allocation error path.
--

--- Patch [1]: [PATCH v5 1/9] livepatch: Fix wrong index in funcs cleanup error path ---
commit c03811c85b7c79e0d681d9978c346e4424c48a99
Author: Yafang Shao <laoar.shao@gmail.com>

livepatch: Fix wrong index in funcs cleanup error path

This commit modifies the cleanup loop in livepatch_mod_init() to use the
index j instead of i when kzalloc() fails for a function array. This
attempts to prevent leaking previously allocated function arrays.

> diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
> index f14d8c8fb35fa..16aff8f736eb6 100644
> --- a/scripts/livepatch/init.c
> +++ b/scripts/livepatch/init.c
> @@ -51,7 +51,7 @@ static int __init livepatch_mod_init(void)
>  		if (!funcs) {
>  			ret = -ENOMEM;
>  			for (int j = 0; j < i; j++)
> -				kfree(objs[i].funcs);
> +				kfree(objs[j].funcs);

[Severity: High]
Does this introduce a double free in livepatch_mod_init()?

When the inner loop here frees objs[j].funcs, it leaves the dangling pointer
in the objs array. The code then jumps to err_free_objs, which iterates over
all objects and frees the arrays again:

err_free_objs:
	for (int i = 0; i < nr_objs; i++)
		kfree(objs[i].funcs);

Since the pointers weren't set to NULL in the inner loop, won't the
err_free_objs cleanup loop free the identical memory allocations a
second time?

>  			goto err_free_objs;
>  		}
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=1

Re: [PATCH v5 7/9] selftests: livepatch: Add provides/obsoletes test scenarios

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Race condition in test-provides-obsoletes.sh leading to flaky test failures.
--

--- Patch [7]: [PATCH v5 7/9] selftests: livepatch: Add provides/obsoletes test scenarios ---
commit b45263c641deb4b2b48bbe22a1f0bf862b20a22f
Author: Yafang Shao <laoar.shao@gmail.com>

selftests: livepatch: Add provides/obsoletes test scenarios

This commit adds test scenarios for the new provides/obsoletes mechanism in
livepatching. It introduces test-provides-obsoletes.sh to verify replacement,
coexistence, and obsolete features.

> diff --git a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
> new file mode 100755
> index 0000000000000..c740d463f556d
> --- /dev/null
> +++ b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
[ ... ]
> +start_test "provides 0 replaces provides 0"
> +
> +load_lp $MOD_LIVEPATCH provides=0
> +load_lp $MOD_ATOMIC provides=0
> +
> +mods=($SYSFS_KLP_DIR/*)
> +nmods=${#mods[@]}
> +if [[ "$nmods" -ne 1 ]]; then
> +	die "Expecting one module listed, found $nmods"
> +fi

[Severity: Medium]
Could this directory check race with the asynchronous sysfs cleanup of the
replaced patch?

When load_lp returns, it polls until the new patch's sysfs transition file
reads '0'. However, in the kernel, klp_try_complete_transition() clears
klp_transition_patch before scheduling the asynchronous work to free replaced
patches (klp_free_replaced_patches_async).

If the test checks the directory count immediately, couldn't it sporadically
see the old patch before the async cleanup completes, causing the test to
flake with "Expecting one module listed, found 2"?

This same pattern appears in the "same provides replaces" and "obsoletes
replaces" test cases later in this script.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=7

Re: [PATCH v5 2/9] livepatch: Make klp_find_func() non static

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] A malformed livepatch module with a missing `old_name` triggers a NULL pointer dereference in `klp_find_func()`.
--

--- Patch [2]: [PATCH v5 2/9] livepatch: Make klp_find_func() non static ---
commit c50e76ff358d6d9f27c1c156d6d6f492f2cdd3b1
Author: Yafang Shao <laoar.shao@gmail.com>

livepatch: Make klp_find_func() non static

This commit makes klp_find_func() non-static to allow its use in other
source files by an upcoming patch. It also renames the parameter @old_func
to @func.

> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 28d15ba58a26d..5d05d6fcbf57c 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c

[ ... ]

> @@ -82,21 +82,21 @@ static bool klp_initialized(void)
>  	return !!klp_root_kobj;
>  }
>  
> -static struct klp_func *klp_find_func(struct klp_object *obj,
> -				      struct klp_func *old_func)
> +/* Check if @func is present in @obj. */
> +struct klp_func *klp_find_func(struct klp_object *obj, struct klp_func *func)
>  {
> -	struct klp_func *func;
> +	struct klp_func *obj_func;
>  
> -	klp_for_each_func(obj, func) {
> +	klp_for_each_func(obj, obj_func) {
>  		/*
>  		 * Besides identical old_sympos, also consider old_sympos
>  		 * of 0 and 1 are identical.
>  		 */
> -		if ((strcmp(old_func->old_name, func->old_name) == 0) &&
> -		    ((old_func->old_sympos == func->old_sympos) ||
> -		     (old_func->old_sympos == 0 && func->old_sympos == 1) ||
> -		     (old_func->old_sympos == 1 && func->old_sympos == 0))) {
> -			return func;
> +		if ((strcmp(obj_func->old_name, func->old_name) == 0) &&

[Severity: High]
This is a pre-existing issue, but could this strcmp() trigger a null pointer
dereference if a malformed livepatch module has a missing old_name field?

When loading a livepatch module where patch->replace is true, if a
struct klp_func element has .new_func defined but .old_name set to null,
klp_init_patch_early() adds this unvalidated function to obj->func_list.

Subsequently, klp_add_object_nops() calls klp_find_func() on the unvalidated
new patch object before klp_init_object() performs the expected null check:

kernel/livepatch/core.c:klp_add_object_nops() {
    ...
		func = klp_find_func(obj, old_func);
    ...
}

This unconditionally passes the unvalidated, null obj_func->old_name to
strcmp().

Does this allow a malformed module to bypass validation and crash the
system instead of being gracefully rejected?

> +		    ((obj_func->old_sympos == func->old_sympos) ||
> +		     (obj_func->old_sympos == 0 && func->old_sympos == 1) ||
> +		     (obj_func->old_sympos == 1 && func->old_sympos == 0))) {
> +			return obj_func;
>  		}
>  	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=2

Re: [PATCH v5 4/9] livepatch: Implement replace set for scoped atomic replace

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `--provides` argument in `klp-build` lacks input validation, allowing shell command injection during the kernel module build process.
--

--- Patch [4]: [PATCH v5 4/9] livepatch: Implement replace set for scoped atomic replace ---
commit 1fb78be5e32d18ecfd4bbeb7fa484d70bf6b9401
Author: Yafang Shao <laoar.shao@gmail.com>

livepatch: Implement replace set for scoped atomic replace

This commit introduces a more flexible model for livepatch replacement by
adding provides and obsoletes fields, allowing multiple independent 
livepatch sets to coexist on the same system.

> diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
> index c4a7acf8edc3f..3600f93d9c1c3 100755
> --- a/scripts/livepatch/klp-build
> +++ b/scripts/livepatch/klp-build

[ ... ]

> @@ -189,9 +190,26 @@ process_args() {
>  				NAME="$(module_name_string "$NAME")"
>  				shift 2
>  				;;
> -			--no-replace)
> -				REPLACE=0
> -				shift
> +			-p | --provides)
> +				PROVIDES="$2"

[Severity: Medium]
Is there a missing validation check for the provides argument here?

The obsoletes argument below checks for valid integers, but it appears this
assignment accepts any unvalidated string.

> +				shift 2
> +				;;
> +			-r | --obsoletes)
> +				OBSOLETES="$2"
> +				local obs_val="$2"
> +				[[ "$obs_val" != \[*\] ]] && die "obsoletes must be enclosed in brackets, e.g., '[0,1,2]'"

[ ... ]

> @@ -847,7 +896,17 @@ build_patch_module() {
>  
>  	cflags=("-ffunction-sections")
>  	cflags+=("-fdata-sections")
> -	[[ $REPLACE -eq 0 ]] && cflags+=("-DKLP_NO_REPLACE")
> +	cflags+=("-DKLP_PROVIDES=$PROVIDES")

[Severity: Medium]
Because the provides argument lacks validation in process_args(), could
this assignment allow shell command injection during the build process if 
un-escaped metacharacters are passed to the script?

> +
> +	# Process OBSOLETES: remove brackets and spaces, convert to comma-separated string
> +	# Input: "[0, 1, 2]" or "[]" or "" -> Output: "0,1,2" or empty
> +	if [[ -n "$OBSOLETES" && "$OBSOLETES" != "[]" ]]; then

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=4

Re: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The 'replace' feature detection in test_modules/Makefile fails for out-of-tree (O=) kernel builds, breaking tests on older kernels.
--

--- Patch [6]: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes ---
commit e4d15e9f2792340ea543b405f9d074e729665c9b
Author: Yafang Shao <laoar.shao@gmail.com>

selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

The legacy "replace" field in struct klp_patch was replaced by the
provides/obsoletes mechanism. This commit adapts selftests to build and
run on both old and new kernels by detecting the presence of the
"replace" field.

> diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
> index a13d398585dcb..29c55df360467 100644
> --- a/tools/testing/selftests/livepatch/test_modules/Makefile
> +++ b/tools/testing/selftests/livepatch/test_modules/Makefile
> @@ -16,6 +16,16 @@ obj-m += test_klp_atomic_replace.o \
>  	test_klp_state3.o \
>  	test_klp_syscall.o
>  
> +# The legacy "replace" field was replaced by provides/obsoletes. When the
> +# kernel (KDIR) still supports "replace", pass KLP_HAS_REPLACE to the
> +# modules so that they can #ifdef the legacy "replace" code. Otherwise
> +# the modules are built with the provides/obsoletes based code (to be
> +# added later).
> +KLP_HAS_REPLACE := $(shell grep -q 'bool replace' $(KDIR)/include/linux/livepatch.h 2>/dev/null && echo y)

[Severity: Medium]
Will this grep fail for out-of-tree (O=...) kernel builds?

If $(KDIR) points to the build directory rather than the source directory,
$(KDIR)/include/linux/livepatch.h might not exist.

When tests are run, detect_replace_attr() will still correctly identify the
replace sysfs attribute on the running kernel and set HAS_REPLACE_ATTR=1.

However, since the module would be compiled without KLP_HAS_REPLACE, it lacks
the replace module parameter. When the test scripts attempt to load the module
with replace=1, insmod will fail, causing the test suite to abort.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=6

Re: [PATCH v5 1/9] livepatch: Fix wrong index in funcs cleanup error path

[Yafang Shao]

On Sun, Aug 9, 2026 at 5:28 PM <sashiko-bot@kernel.org> wrote:
>
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] The patch introduces a double free vulnerability on the `funcs` allocation error path.
> --
>
> --- Patch [1]: [PATCH v5 1/9] livepatch: Fix wrong index in funcs cleanup error path ---
> commit c03811c85b7c79e0d681d9978c346e4424c48a99
> Author: Yafang Shao <laoar.shao@gmail.com>
>
> livepatch: Fix wrong index in funcs cleanup error path
>
> This commit modifies the cleanup loop in livepatch_mod_init() to use the
> index j instead of i when kzalloc() fails for a function array. This
> attempts to prevent leaking previously allocated function arrays.
>
> > diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
> > index f14d8c8fb35fa..16aff8f736eb6 100644
> > --- a/scripts/livepatch/init.c
> > +++ b/scripts/livepatch/init.c
> > @@ -51,7 +51,7 @@ static int __init livepatch_mod_init(void)
> >               if (!funcs) {
> >                       ret = -ENOMEM;
> >                       for (int j = 0; j < i; j++)
> > -                             kfree(objs[i].funcs);
> > +                             kfree(objs[j].funcs);
>
> [Severity: High]
> Does this introduce a double free in livepatch_mod_init()?
>
> When the inner loop here frees objs[j].funcs, it leaves the dangling pointer
> in the objs array. The code then jumps to err_free_objs, which iterates over
> all objects and frees the arrays again:
>
> err_free_objs:
>         for (int i = 0; i < nr_objs; i++)
>                 kfree(objs[i].funcs);
>
> Since the pointers weren't set to NULL in the inner loop, won't the
> err_free_objs cleanup loop free the identical memory allocations a
> second time?

This is an invalid review issue. Since kfree(objs[i].funcs) is not
added to err_free_objs in the current state, and it is moved from its
current place to err_free_objs in patch #4.

-- 
Regards
Yafang

Re: [PATCH v5 2/9] livepatch: Make klp_find_func() non static

[Yafang Shao]

On Sun, Aug 9, 2026 at 5:32 PM <sashiko-bot@kernel.org> wrote:
>
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>
> Pre-existing issues:
> - [High] A malformed livepatch module with a missing `old_name` triggers a NULL pointer dereference in `klp_find_func()`.

Invalid review issue.
This issue was already resolved by commit:

  livepatch: Fix NULL pointer dereference in klp_find_func()

https://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching.git/commit/?h=for-7.3/trivial&id=1a38fd13c31ed8e7c7b598cc975ecc0f41fca468

-- 
Regards
Yafang

Re: [PATCH v5 3/9] livepatch: Call klp_init_patch_early() earlier

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] When CONFIG_DEBUG_KOBJECT_RELEASE is enabled, an error during patch initialization causes a Use-After-Free during module unload due to delayed kobject release.
--

--- Patch [3]: [PATCH v5 3/9] livepatch: Call klp_init_patch_early() earlier ---
commit ebdb1e39e8d2124754d0f852abe91968ee2bb0d7
Author: Yafang Shao <laoar.shao@gmail.com>

livepatch: Call klp_init_patch_early() earlier

This patch moves klp_init_patch_early() to an earlier stage during patch
initialization. This is intended to avoid mixing for_each_() and
for_each_*_static() variants later in the code.

> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 5d05d6fcbf57c..1908ebedf8734 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
[ ... ]
> @@ -1149,6 +1142,14 @@ int klp_enable_patch(struct klp_patch *patch)
>  
>  	klp_init_patch_early(patch);
>  
> +	if (!klp_is_patch_compatible(patch)) {
> +		pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
> +			patch->mod->name);
> +		ret = -EINVAL;
> +		goto err;
> +	}

[Severity: High]
This is a pre-existing issue, but does moving klp_init_patch_early() before
klp_is_patch_compatible() make a delayed kobject release crash easier to hit
if the patch is incompatible?

When klp_init_patch_early() completes, it has called kobject_init() on the
patch->kobj, as well as all obj->kobj and func->kobj. If klp_is_patch_compatible()
fails and jumps to the err label, klp_free_patch_start() and klp_free_patch_finish()
are called.

klp_free_patch_start() drops the object and function kobject references:

kernel/livepatch/core.c:__klp_free_funcs() {
    ...
    kobject_put(&func->kobj);
    ...
}

kernel/livepatch/core.c:__klp_free_objects() {
    ...
    kobject_put(&obj->kobj);
    ...
}

However, klp_free_patch_finish() only waits for the patch kobject completion:

kernel/livepatch/core.c:klp_free_patch_finish() {
    ...
    wait_for_completion(&patch->finish);
    ...
}

When CONFIG_DEBUG_KOBJECT_RELEASE is enabled, the kobject_put() on the
un-added objects queues a delayed work up to 4 seconds later to free the
kobjects. Because klp_free_patch_finish() doesn't wait for the child
kobjects, klp_enable_patch() can return and allow the module to unload,
freeing the klp_object and klp_func arrays before the delayed work accesses
them.

Can this result in a Use-After-Free during module unload?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=3

Re: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes

[Yafang Shao]

On Sun, Aug 9, 2026 at 5:33 PM <sashiko-bot@kernel.org> wrote:
>
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The 'replace' feature detection in test_modules/Makefile fails for out-of-tree (O=) kernel builds, breaking tests on older kernels.
> --
>
> --- Patch [6]: [PATCH v5 6/9] selftests: livepatch: Adapt atomic replace tests to provides/obsoletes ---
> commit e4d15e9f2792340ea543b405f9d074e729665c9b
> Author: Yafang Shao <laoar.shao@gmail.com>
>
> selftests: livepatch: Adapt atomic replace tests to provides/obsoletes
>
> The legacy "replace" field in struct klp_patch was replaced by the
> provides/obsoletes mechanism. This commit adapts selftests to build and
> run on both old and new kernels by detecting the presence of the
> "replace" field.
>
> > diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
> > index a13d398585dcb..29c55df360467 100644
> > --- a/tools/testing/selftests/livepatch/test_modules/Makefile
> > +++ b/tools/testing/selftests/livepatch/test_modules/Makefile
> > @@ -16,6 +16,16 @@ obj-m += test_klp_atomic_replace.o \
> >       test_klp_state3.o \
> >       test_klp_syscall.o
> >
> > +# The legacy "replace" field was replaced by provides/obsoletes. When the
> > +# kernel (KDIR) still supports "replace", pass KLP_HAS_REPLACE to the
> > +# modules so that they can #ifdef the legacy "replace" code. Otherwise
> > +# the modules are built with the provides/obsoletes based code (to be
> > +# added later).
> > +KLP_HAS_REPLACE := $(shell grep -q 'bool replace' $(KDIR)/include/linux/livepatch.h 2>/dev/null && echo y)
>
> [Severity: Medium]
> Will this grep fail for out-of-tree (O=...) kernel builds?
>
> If $(KDIR) points to the build directory rather than the source directory,
> $(KDIR)/include/linux/livepatch.h might not exist.
>
> When tests are run, detect_replace_attr() will still correctly identify the
> replace sysfs attribute on the running kernel and set HAS_REPLACE_ATTR=1.
>
> However, since the module would be compiled without KLP_HAS_REPLACE, it lacks
> the replace module parameter. When the test scripts attempt to load the module
> with replace=1, insmod will fail, causing the test suite to abort.

I believe this case is invalid. We always run `make run_tests` to
execute the full livepatch selftests, which ensures all kernel modules
are rebuilt against the running kernel.

-- 
Regards
Yafang

Re: [PATCH v5 9/9] selftests: livepatch: Add test for function conflict across provides

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

New issues:
- [High] Malformed livepatch module missing `old_name` causes a kernel panic on load.

Pre-existing issues:
- [Medium] Race condition in sysfs polling causes flaky selftests.
--

--- Patch [9]: [PATCH v5 9/9] selftests: livepatch: Add test for function conflict across provides ---
commit eaca609db12a6842c4e94debcf9d9ef5049826db
Author: Yafang Shao <laoar.shao@gmail.com>

selftests: livepatch: Add test for function conflict across provides
    
This commit adds a new test module test_klp_provides.c and three new test
scenarios to test-provides-obsoletes.sh. These tests verify the behavior
of livepatch function conflicts and replacement when using different
provides IDs with and without obsoletes.

> diff --git a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
> index 1b2c73bdd50b0..32885625401d1 100755
> --- a/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
> +++ b/tools/testing/selftests/livepatch/test-provides-obsoletes.sh
[ ... ]
> @@ -278,4 +279,123 @@ $MOD_STATE2: free_loglevel_state: freeing space for the stored console_loglevel
>  livepatch: '$MOD_STATE2': unpatching complete
>  % rmmod $MOD_STATE2"
>  
> +
> +# - load a livepatch with provides=1 that modifies meminfo_proc_show
> +# - try to load another livepatch with provides=2 that modifies the
> +#   same function. The second one must be rejected because livepatches
> +#   with different provides ids and no obsoletes must not modify
> +#   the same function.
> +# - disable and unload the remaining livepatch
> +
> +start_test "function conflict across provides"
> +
> +load_lp $MOD_ATOMIC provides=1
> +load_failing_mod $MOD_PROVIDES provides=2
> +
> +disable_lp $MOD_ATOMIC
> +unload_lp $MOD_ATOMIC
> +
> +check_result "% insmod test_modules/$MOD_ATOMIC.ko provides=1
> +livepatch: enabling patch '$MOD_ATOMIC'
> +livepatch: '$MOD_ATOMIC': initializing patching transition
> +livepatch: '$MOD_ATOMIC': starting patching transition
> +livepatch: '$MOD_ATOMIC': completing patching transition
> +livepatch: '$MOD_ATOMIC': patching complete
> +% insmod test_modules/$MOD_PROVIDES.ko provides=2
> +livepatch: Livepatch patch ($MOD_PROVIDES) is not compatible with the already installed livepatches.
> +insmod: ERROR: could not insert module test_modules/$MOD_PROVIDES.ko: Invalid parameters
> +% echo 0 > $SYSFS_KLP_DIR/$MOD_ATOMIC/enabled
> +livepatch: '$MOD_ATOMIC': initializing unpatching transition
> +livepatch: '$MOD_ATOMIC': starting unpatching transition
> +livepatch: '$MOD_ATOMIC': completing unpatching transition
> +livepatch: '$MOD_ATOMIC': unpatching complete
> +% rmmod $MOD_ATOMIC"
> +
> +
> +# - load a livepatch with provides=1 that modifies meminfo_proc_show
> +# - load another livepatch with provides=1 that modifies the same
> +#   function. The second one loads successfully because livepatches
> +#   with the same provides id replace each other.
> +# - disable and unload the remaining livepatch
> +
> +start_test "function replace within same provides"
> +
> +load_lp $MOD_ATOMIC provides=1
> +load_lp $MOD_PROVIDES provides=1
> +
> +mods=($SYSFS_KLP_DIR/*)
> +nmods=${#mods[@]}
> +if [[ "$nmods" -ne 1 ]]; then

[Severity: Medium]
This is a pre-existing issue, but does this pattern cause a regression in the
form of flaky selftests?

The script synchronously counts the directories in the sysfs path immediately
after a transition. However, the old patch's sysfs directory removal is
deferred to an asynchronous workqueue:

kernel/livepatch/core.c:klp_free_replaced_patches_async()

Because of this, the script may momentarily see 2 directories instead of 1
before the asynchronous cleanup completes.

> +	die "Expecting one module listed, found $nmods"
> +fi

[ ... ]

> diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c b/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c
> new file mode 100644
> index 0000000000000..9751a6f6c8518
> --- /dev/null
> +++ b/tools/testing/selftests/livepatch/test_modules/test_klp_provides.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
[ ... ]
> +static int test_klp_provides_init(void)
> +{
> +#ifdef KLP_HAS_REPLACE
> +	patch.replace = replace;
> +#else
> +	patch.provides = provides;
> +	if (nr_obsoletes > 0) {
> +		patch.obsoletes = obsoletes;
> +		patch.nr_obsoletes = nr_obsoletes;
> +	}
> +#endif
> +	return klp_enable_patch(&patch);

[Severity: High]
Does klp_enable_patch() introduce a regression where a malformed livepatch
module missing old_name causes a kernel panic on load?

If a livepatch module defines a klp_func with .old_name = NULL but provides
.new_func, it bypasses the klp_for_each_func_static loop termination
condition.

Since klp_is_patch_compatible() executes before klp_init_patch():

kernel/livepatch/core.c:klp_enable_patch() {
    ...
    if (!klp_is_patch_compatible(patch)) {
    ...
    ret = klp_init_patch(patch);
    ...
}

klp_has_function_conflict() iterates over this malformed function, which then
passes the malformed func to klp_find_func():

kernel/livepatch/state.c:klp_has_function_conflict() {
    ...
    if (klp_find_func(old_obj, func))
    ...
}

This then passes func->old_name to strcmp():

kernel/livepatch/core.c:klp_find_func() {
    ...
    if ((strcmp(obj_func->old_name, func->old_name) == 0) &&
    ...
}

resulting in an immediate null pointer dereference.

> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809091954.22930-1-laoar.shao@gmail.com?part=9