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Message-Id: <20240828022350.71456-2-zhangwarden@gmail.com>
Date: Wed, 28 Aug 2024 10:23:49 +0800
From: Wardenjohn <zhangwarden@...il.com>
To: jpoimboe@...nel.org,
mbenes@...e.cz,
jikos@...nel.org,
pmladek@...e.com,
joe.lawrence@...hat.com
Cc: live-patching@...r.kernel.org,
linux-kernel@...r.kernel.org,
Wardenjohn <zhangwarden@...il.com>
Subject: [PATCH v4 1/2] Introduce klp_ops into klp_func structure
Before introduce feature "using". Klp transition will need an
easier way to get klp_ops from klp_func.
This patch make changes as follows:
1. Move klp_ops into klp_func structure.
Rewrite the logic of klp_find_ops and
other logic to get klp_ops of a function.
2. Move definition of struct klp_ops into
include/linux/livepatch.h
With this changes, we can get klp_ops of a klp_func easily.
klp_find_ops can also be simple and straightforward. And we
do not need to maintain one global list for now.
Signed-off-by: Wardenjohn <zhangwarden@...il.com>
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 51a258c24ff5..d874aecc817b 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -22,6 +22,25 @@
#define KLP_TRANSITION_UNPATCHED 0
#define KLP_TRANSITION_PATCHED 1
+/**
+ * struct klp_ops - structure for tracking registered ftrace ops structs
+ *
+ * A single ftrace_ops is shared between all enabled replacement functions
+ * (klp_func structs) which have the same old_func. This allows the switch
+ * between function versions to happen instantaneously by updating the klp_ops
+ * struct's func_stack list. The winner is the klp_func at the top of the
+ * func_stack (front of the list).
+ *
+ * @node: node for the global klp_ops list
+ * @func_stack: list head for the stack of klp_func's (active func is on top)
+ * @fops: registered ftrace ops struct
+ */
+struct klp_ops {
+ struct list_head node;
+ struct list_head func_stack;
+ struct ftrace_ops fops;
+};
+
/**
* struct klp_func - function structure for live patching
* @old_name: name of the function to be patched
@@ -32,6 +51,7 @@
* @kobj: kobject for sysfs resources
* @node: list node for klp_object func_list
* @stack_node: list node for klp_ops func_stack list
+ * @ops: pointer to klp_ops struct for this function
* @old_size: size of the old function
* @new_size: size of the new function
* @nop: temporary patch to use the original code again; dyn. allocated
@@ -71,6 +91,7 @@ struct klp_func {
struct kobject kobj;
struct list_head node;
struct list_head stack_node;
+ struct klp_ops *ops;
unsigned long old_size, new_size;
bool nop;
bool patched;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 52426665eecc..e4572bf34316 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -760,6 +760,8 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
if (!func->old_name)
return -EINVAL;
+ func->ops = NULL;
+
/*
* NOPs get the address later. The patched module must be loaded,
* see klp_init_object_loaded().
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 90408500e5a3..8ab9c35570f4 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -20,18 +20,25 @@
#include "patch.h"
#include "transition.h"
-static LIST_HEAD(klp_ops);
struct klp_ops *klp_find_ops(void *old_func)
{
- struct klp_ops *ops;
+ struct klp_patch *patch;
+ struct klp_object *obj;
struct klp_func *func;
- list_for_each_entry(ops, &klp_ops, node) {
- func = list_first_entry(&ops->func_stack, struct klp_func,
- stack_node);
- if (func->old_func == old_func)
- return ops;
+ klp_for_each_patch(patch) {
+ klp_for_each_object(patch, obj) {
+ klp_for_each_func(obj, func) {
+ /*
+ * Ignore entry where func->ops has not been
+ * assigned yet. It is most likely the one
+ * which is about to be created/added.
+ */
+ if (func->old_func == old_func && func->ops)
+ return func->ops;
+ }
+ }
}
return NULL;
@@ -133,7 +140,7 @@ static void klp_unpatch_func(struct klp_func *func)
if (WARN_ON(!func->old_func))
return;
- ops = klp_find_ops(func->old_func);
+ ops = func->ops;
if (WARN_ON(!ops))
return;
@@ -149,6 +156,7 @@ static void klp_unpatch_func(struct klp_func *func)
list_del_rcu(&func->stack_node);
list_del(&ops->node);
+ func->ops = NULL;
kfree(ops);
} else {
list_del_rcu(&func->stack_node);
@@ -168,7 +176,7 @@ static int klp_patch_func(struct klp_func *func)
if (WARN_ON(func->patched))
return -EINVAL;
- ops = klp_find_ops(func->old_func);
+ ops = func->ops;
if (!ops) {
unsigned long ftrace_loc;
@@ -191,8 +199,6 @@ static int klp_patch_func(struct klp_func *func)
FTRACE_OPS_FL_IPMODIFY |
FTRACE_OPS_FL_PERMANENT;
- list_add(&ops->node, &klp_ops);
-
INIT_LIST_HEAD(&ops->func_stack);
list_add_rcu(&func->stack_node, &ops->func_stack);
@@ -211,7 +217,7 @@ static int klp_patch_func(struct klp_func *func)
goto err;
}
-
+ func->ops = ops;
} else {
list_add_rcu(&func->stack_node, &ops->func_stack);
}
@@ -224,6 +230,7 @@ static int klp_patch_func(struct klp_func *func)
list_del_rcu(&func->stack_node);
list_del(&ops->node);
kfree(ops);
+ func->ops = NULL;
return ret;
}
diff --git a/kernel/livepatch/patch.h b/kernel/livepatch/patch.h
index d5f2fbe373e0..21d0d20b7189 100644
--- a/kernel/livepatch/patch.h
+++ b/kernel/livepatch/patch.h
@@ -6,25 +6,6 @@
#include <linux/list.h>
#include <linux/ftrace.h>
-/**
- * struct klp_ops - structure for tracking registered ftrace ops structs
- *
- * A single ftrace_ops is shared between all enabled replacement functions
- * (klp_func structs) which have the same old_func. This allows the switch
- * between function versions to happen instantaneously by updating the klp_ops
- * struct's func_stack list. The winner is the klp_func at the top of the
- * func_stack (front of the list).
- *
- * @node: node for the global klp_ops list
- * @func_stack: list head for the stack of klp_func's (active func is on top)
- * @fops: registered ftrace ops struct
- */
-struct klp_ops {
- struct list_head node;
- struct list_head func_stack;
- struct ftrace_ops fops;
-};
-
struct klp_ops *klp_find_ops(void *old_func);
int klp_patch_object(struct klp_object *obj);
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index ba069459c101..d9a3f9c7a93b 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -230,7 +230,7 @@ static int klp_check_stack_func(struct klp_func *func, unsigned long *entries,
* Check for the to-be-patched function
* (the previous func).
*/
- ops = klp_find_ops(func->old_func);
+ ops = func->ops;
if (list_is_singular(&ops->func_stack)) {
/* original function */
--
2.18.2
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