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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

瀏覽代碼 
Pull livepatching fix from Jiri Kosina:
 "Shadow variable API list_head initialization fix from Petr Mladek"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: Allow to call a custom callback when freeing shadow variables
  livepatch: Initialize shadow variables safely by a custom callback
This commit is contained in:
Linus Torvalds
2018-04-20 08:51:55 -07:00
父節點 36e584de25 3b2c77d000
當前提交 41e3bef52e
共有 5 個文件被更改，包括 163 次插入 和 81 次删除
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108
kernel/livepatch/shadow.c
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@@ -113,8 +113,10 @@ void *klp_shadow_get(void *obj, unsigned long id)
}
EXPORT_SYMBOL_GPL(klp_shadow_get);
static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
size_t size, gfp_t gfp_flags, bool warn_on_exist)
static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id,
size_t size, gfp_t gfp_flags,
klp_shadow_ctor_t ctor, void *ctor_data,
bool warn_on_exist)
{
struct klp_shadow *new_shadow;
void *shadow_data;
@@ -125,18 +127,15 @@ static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
if (shadow_data)
goto exists;
/* Allocate a new shadow variable for use inside the lock below */
/*
* Allocate a new shadow variable. Fill it with zeroes by default.
* More complex setting can be done by @ctor function. But it is
* called only when the buffer is really used (under klp_shadow_lock).
*/
new_shadow = kzalloc(size + sizeof(*new_shadow), gfp_flags);
if (!new_shadow)
return NULL;
new_shadow->obj = obj;
new_shadow->id = id;
/* Initialize the shadow variable if data provided */
if (data)
memcpy(new_shadow->data, data, size);
/* Look for <obj, id> again under the lock */
spin_lock_irqsave(&klp_shadow_lock, flags);
shadow_data = klp_shadow_get(obj, id);
@@ -150,6 +149,22 @@ static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
goto exists;
}
new_shadow->obj = obj;
new_shadow->id = id;
if (ctor) {
int err;
err = ctor(obj, new_shadow->data, ctor_data);
if (err) {
spin_unlock_irqrestore(&klp_shadow_lock, flags);
kfree(new_shadow);
pr_err("Failed to construct shadow variable <%p, %lx> (%d)\n",
obj, id, err);
return NULL;
}
}
/* No <obj, id> found, so attach the newly allocated one */
hash_add_rcu(klp_shadow_hash, &new_shadow->node,
(unsigned long)new_shadow->obj);
@@ -170,26 +185,32 @@ exists:
* klp_shadow_alloc() - allocate and add a new shadow variable
* @obj: pointer to parent object
* @id: data identifier
* @data: pointer to data to attach to parent
* @size: size of attached data
* @gfp_flags: GFP mask for allocation
* @ctor: custom constructor to initialize the shadow data (optional)
* @ctor_data: pointer to any data needed by @ctor (optional)
*
* Allocates @size bytes for new shadow variable data using @gfp_flags
* and copies @size bytes from @data into the new shadow variable's own
* data space. If @data is NULL, @size bytes are still allocated, but
* no copy is performed. The new shadow variable is then added to the
* global hashtable.
* Allocates @size bytes for new shadow variable data using @gfp_flags.
* The data are zeroed by default. They are further initialized by @ctor
* function if it is not NULL. The new shadow variable is then added
* to the global hashtable.
*
* If an existing <obj, id> shadow variable can be found, this routine
* will issue a WARN, exit early and return NULL.
* If an existing <obj, id> shadow variable can be found, this routine will
* issue a WARN, exit early and return NULL.
*
* This function guarantees that the constructor function is called only when
* the variable did not exist before. The cost is that @ctor is called
* in atomic context under a spin lock.
*
* Return: the shadow variable data element, NULL on duplicate or
* failure.
*/
void *klp_shadow_alloc(void *obj, unsigned long id, void *data,
size_t size, gfp_t gfp_flags)
void *klp_shadow_alloc(void *obj, unsigned long id,
size_t size, gfp_t gfp_flags,
klp_shadow_ctor_t ctor, void *ctor_data)
{
return __klp_shadow_get_or_alloc(obj, id, data, size, gfp_flags, true);
return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
ctor, ctor_data, true);
}
EXPORT_SYMBOL_GPL(klp_shadow_alloc);
@@ -197,37 +218,51 @@ EXPORT_SYMBOL_GPL(klp_shadow_alloc);
* klp_shadow_get_or_alloc() - get existing or allocate a new shadow variable
* @obj: pointer to parent object
* @id: data identifier
* @data: pointer to data to attach to parent
* @size: size of attached data
* @gfp_flags: GFP mask for allocation
* @ctor: custom constructor to initialize the shadow data (optional)
* @ctor_data: pointer to any data needed by @ctor (optional)
*
* Returns a pointer to existing shadow data if an <obj, id> shadow
* variable is already present. Otherwise, it creates a new shadow
* variable like klp_shadow_alloc().
*
* This function guarantees that only one shadow variable exists with
* the given @id for the given @obj. It also guarantees that the shadow
* variable will be initialized by the given @data only when it did not
* exist before.
* This function guarantees that only one shadow variable exists with the given
* @id for the given @obj. It also guarantees that the constructor function
* will be called only when the variable did not exist before. The cost is
* that @ctor is called in atomic context under a spin lock.
*
* Return: the shadow variable data element, NULL on failure.
*/
void *klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
size_t size, gfp_t gfp_flags)
void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
size_t size, gfp_t gfp_flags,
klp_shadow_ctor_t ctor, void *ctor_data)
{
return __klp_shadow_get_or_alloc(obj, id, data, size, gfp_flags, false);
return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
ctor, ctor_data, false);
}
EXPORT_SYMBOL_GPL(klp_shadow_get_or_alloc);
static void klp_shadow_free_struct(struct klp_shadow *shadow,
klp_shadow_dtor_t dtor)
{
hash_del_rcu(&shadow->node);
if (dtor)
dtor(shadow->obj, shadow->data);
kfree_rcu(shadow, rcu_head);
}
/**
* klp_shadow_free() - detach and free a <obj, id> shadow variable
* @obj: pointer to parent object
* @id: data identifier
* @dtor: custom callback that can be used to unregister the variable
* and/or free data that the shadow variable points to (optional)
*
* This function releases the memory for this <obj, id> shadow variable
* instance, callers should stop referencing it accordingly.
*/
void klp_shadow_free(void *obj, unsigned long id)
void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
{
struct klp_shadow *shadow;
unsigned long flags;
@@ -239,8 +274,7 @@ void klp_shadow_free(void *obj, unsigned long id)
(unsigned long)obj) {
if (klp_shadow_match(shadow, obj, id)) {
hash_del_rcu(&shadow->node);
kfree_rcu(shadow, rcu_head);
klp_shadow_free_struct(shadow, dtor);
break;
}
}
@@ -252,11 +286,13 @@ EXPORT_SYMBOL_GPL(klp_shadow_free);
/**
* klp_shadow_free_all() - detach and free all <*, id> shadow variables
* @id: data identifier
* @dtor: custom callback that can be used to unregister the variable
* and/or free data that the shadow variable points to (optional)
*
* This function releases the memory for all <*, id> shadow variable
* instances, callers should stop referencing them accordingly.
*/
void klp_shadow_free_all(unsigned long id)
void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
{
struct klp_shadow *shadow;
unsigned long flags;
@@ -266,10 +302,8 @@ void klp_shadow_free_all(unsigned long id)
/* Delete all <*, id> from hash */
hash_for_each(klp_shadow_hash, i, shadow, node) {
if (klp_shadow_match(shadow, shadow->obj, id)) {
hash_del_rcu(&shadow->node);
kfree_rcu(shadow, rcu_head);
}
if (klp_shadow_match(shadow, shadow->obj, id))
klp_shadow_free_struct(shadow, dtor);
}
spin_unlock_irqrestore(&klp_shadow_lock, flags);