diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/livepatch/shadow.c | 82 |
1 files changed, 53 insertions, 29 deletions
diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c index fdac27588d60..b10a0bbb7f84 100644 --- a/kernel/livepatch/shadow.c +++ b/kernel/livepatch/shadow.c @@ -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. + * 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. * - * 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. + * 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); @@ -197,25 +218,28 @@ 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); |