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-rw-r--r--include/linux/slab.h231
1 files changed, 214 insertions, 17 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index eb2bf4629157..da3a546571e7 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -213,6 +213,12 @@ enum _slab_flag_bits {
#endif
/*
+ * freeptr_t represents a SLUB freelist pointer, which might be encoded
+ * and not dereferenceable if CONFIG_SLAB_FREELIST_HARDENED is enabled.
+ */
+typedef struct { unsigned long v; } freeptr_t;
+
+/*
* ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
*
* Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
@@ -234,14 +240,173 @@ struct mem_cgroup;
*/
bool slab_is_available(void);
-struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
- unsigned int align, slab_flags_t flags,
- void (*ctor)(void *));
-struct kmem_cache *kmem_cache_create_usercopy(const char *name,
- unsigned int size, unsigned int align,
- slab_flags_t flags,
- unsigned int useroffset, unsigned int usersize,
- void (*ctor)(void *));
+/**
+ * struct kmem_cache_args - Less common arguments for kmem_cache_create()
+ *
+ * Any uninitialized fields of the structure are interpreted as unused. The
+ * exception is @freeptr_offset where %0 is a valid value, so
+ * @use_freeptr_offset must be also set to %true in order to interpret the field
+ * as used. For @useroffset %0 is also valid, but only with non-%0
+ * @usersize.
+ *
+ * When %NULL args is passed to kmem_cache_create(), it is equivalent to all
+ * fields unused.
+ */
+struct kmem_cache_args {
+ /**
+ * @align: The required alignment for the objects.
+ *
+ * %0 means no specific alignment is requested.
+ */
+ unsigned int align;
+ /**
+ * @useroffset: Usercopy region offset.
+ *
+ * %0 is a valid offset, when @usersize is non-%0
+ */
+ unsigned int useroffset;
+ /**
+ * @usersize: Usercopy region size.
+ *
+ * %0 means no usercopy region is specified.
+ */
+ unsigned int usersize;
+ /**
+ * @freeptr_offset: Custom offset for the free pointer
+ * in &SLAB_TYPESAFE_BY_RCU caches
+ *
+ * By default &SLAB_TYPESAFE_BY_RCU caches place the free pointer
+ * outside of the object. This might cause the object to grow in size.
+ * Cache creators that have a reason to avoid this can specify a custom
+ * free pointer offset in their struct where the free pointer will be
+ * placed.
+ *
+ * Note that placing the free pointer inside the object requires the
+ * caller to ensure that no fields are invalidated that are required to
+ * guard against object recycling (See &SLAB_TYPESAFE_BY_RCU for
+ * details).
+ *
+ * Using %0 as a value for @freeptr_offset is valid. If @freeptr_offset
+ * is specified, %use_freeptr_offset must be set %true.
+ *
+ * Note that @ctor currently isn't supported with custom free pointers
+ * as a @ctor requires an external free pointer.
+ */
+ unsigned int freeptr_offset;
+ /**
+ * @use_freeptr_offset: Whether a @freeptr_offset is used.
+ */
+ bool use_freeptr_offset;
+ /**
+ * @ctor: A constructor for the objects.
+ *
+ * The constructor is invoked for each object in a newly allocated slab
+ * page. It is the cache user's responsibility to free object in the
+ * same state as after calling the constructor, or deal appropriately
+ * with any differences between a freshly constructed and a reallocated
+ * object.
+ *
+ * %NULL means no constructor.
+ */
+ void (*ctor)(void *);
+};
+
+struct kmem_cache *__kmem_cache_create_args(const char *name,
+ unsigned int object_size,
+ struct kmem_cache_args *args,
+ slab_flags_t flags);
+static inline struct kmem_cache *
+__kmem_cache_create(const char *name, unsigned int size, unsigned int align,
+ slab_flags_t flags, void (*ctor)(void *))
+{
+ struct kmem_cache_args kmem_args = {
+ .align = align,
+ .ctor = ctor,
+ };
+
+ return __kmem_cache_create_args(name, size, &kmem_args, flags);
+}
+
+/**
+ * kmem_cache_create_usercopy - Create a kmem cache with a region suitable
+ * for copying to userspace.
+ * @name: A string which is used in /proc/slabinfo to identify this cache.
+ * @size: The size of objects to be created in this cache.
+ * @align: The required alignment for the objects.
+ * @flags: SLAB flags
+ * @useroffset: Usercopy region offset
+ * @usersize: Usercopy region size
+ * @ctor: A constructor for the objects, or %NULL.
+ *
+ * This is a legacy wrapper, new code should use either KMEM_CACHE_USERCOPY()
+ * if whitelisting a single field is sufficient, or kmem_cache_create() with
+ * the necessary parameters passed via the args parameter (see
+ * &struct kmem_cache_args)
+ *
+ * Return: a pointer to the cache on success, NULL on failure.
+ */
+static inline struct kmem_cache *
+kmem_cache_create_usercopy(const char *name, unsigned int size,
+ unsigned int align, slab_flags_t flags,
+ unsigned int useroffset, unsigned int usersize,
+ void (*ctor)(void *))
+{
+ struct kmem_cache_args kmem_args = {
+ .align = align,
+ .ctor = ctor,
+ .useroffset = useroffset,
+ .usersize = usersize,
+ };
+
+ return __kmem_cache_create_args(name, size, &kmem_args, flags);
+}
+
+/* If NULL is passed for @args, use this variant with default arguments. */
+static inline struct kmem_cache *
+__kmem_cache_default_args(const char *name, unsigned int size,
+ struct kmem_cache_args *args,
+ slab_flags_t flags)
+{
+ struct kmem_cache_args kmem_default_args = {};
+
+ /* Make sure we don't get passed garbage. */
+ if (WARN_ON_ONCE(args))
+ return ERR_PTR(-EINVAL);
+
+ return __kmem_cache_create_args(name, size, &kmem_default_args, flags);
+}
+
+/**
+ * kmem_cache_create - Create a kmem cache.
+ * @__name: A string which is used in /proc/slabinfo to identify this cache.
+ * @__object_size: The size of objects to be created in this cache.
+ * @__args: Optional arguments, see &struct kmem_cache_args. Passing %NULL
+ * means defaults will be used for all the arguments.
+ *
+ * This is currently implemented as a macro using ``_Generic()`` to call
+ * either the new variant of the function, or a legacy one.
+ *
+ * The new variant has 4 parameters:
+ * ``kmem_cache_create(name, object_size, args, flags)``
+ *
+ * See __kmem_cache_create_args() which implements this.
+ *
+ * The legacy variant has 5 parameters:
+ * ``kmem_cache_create(name, object_size, align, flags, ctor)``
+ *
+ * The align and ctor parameters map to the respective fields of
+ * &struct kmem_cache_args
+ *
+ * Context: Cannot be called within a interrupt, but can be interrupted.
+ *
+ * Return: a pointer to the cache on success, NULL on failure.
+ */
+#define kmem_cache_create(__name, __object_size, __args, ...) \
+ _Generic((__args), \
+ struct kmem_cache_args *: __kmem_cache_create_args, \
+ void *: __kmem_cache_default_args, \
+ default: __kmem_cache_create)(__name, __object_size, __args, __VA_ARGS__)
+
void kmem_cache_destroy(struct kmem_cache *s);
int kmem_cache_shrink(struct kmem_cache *s);
@@ -253,20 +418,23 @@ int kmem_cache_shrink(struct kmem_cache *s);
* f.e. add ____cacheline_aligned_in_smp to the struct declaration
* then the objects will be properly aligned in SMP configurations.
*/
-#define KMEM_CACHE(__struct, __flags) \
- kmem_cache_create(#__struct, sizeof(struct __struct), \
- __alignof__(struct __struct), (__flags), NULL)
+#define KMEM_CACHE(__struct, __flags) \
+ __kmem_cache_create_args(#__struct, sizeof(struct __struct), \
+ &(struct kmem_cache_args) { \
+ .align = __alignof__(struct __struct), \
+ }, (__flags))
/*
* To whitelist a single field for copying to/from usercopy, use this
* macro instead for KMEM_CACHE() above.
*/
-#define KMEM_CACHE_USERCOPY(__struct, __flags, __field) \
- kmem_cache_create_usercopy(#__struct, \
- sizeof(struct __struct), \
- __alignof__(struct __struct), (__flags), \
- offsetof(struct __struct, __field), \
- sizeof_field(struct __struct, __field), NULL)
+#define KMEM_CACHE_USERCOPY(__struct, __flags, __field) \
+ __kmem_cache_create_args(#__struct, sizeof(struct __struct), \
+ &(struct kmem_cache_args) { \
+ .align = __alignof__(struct __struct), \
+ .useroffset = offsetof(struct __struct, __field), \
+ .usersize = sizeof_field(struct __struct, __field), \
+ }, (__flags))
/*
* Common kmalloc functions provided by all allocators
@@ -547,6 +715,35 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru,
gfp_t gfpflags) __assume_slab_alignment __malloc;
#define kmem_cache_alloc_lru(...) alloc_hooks(kmem_cache_alloc_lru_noprof(__VA_ARGS__))
+/**
+ * kmem_cache_charge - memcg charge an already allocated slab memory
+ * @objp: address of the slab object to memcg charge
+ * @gfpflags: describe the allocation context
+ *
+ * kmem_cache_charge allows charging a slab object to the current memcg,
+ * primarily in cases where charging at allocation time might not be possible
+ * because the target memcg is not known (i.e. softirq context)
+ *
+ * The objp should be pointer returned by the slab allocator functions like
+ * kmalloc (with __GFP_ACCOUNT in flags) or kmem_cache_alloc. The memcg charge
+ * behavior can be controlled through gfpflags parameter, which affects how the
+ * necessary internal metadata can be allocated. Including __GFP_NOFAIL denotes
+ * that overcharging is requested instead of failure, but is not applied for the
+ * internal metadata allocation.
+ *
+ * There are several cases where it will return true even if the charging was
+ * not done:
+ * More specifically:
+ *
+ * 1. For !CONFIG_MEMCG or cgroup_disable=memory systems.
+ * 2. Already charged slab objects.
+ * 3. For slab objects from KMALLOC_NORMAL caches - allocated by kmalloc()
+ * without __GFP_ACCOUNT
+ * 4. Allocating internal metadata has failed
+ *
+ * Return: true if charge was successful otherwise false.
+ */
+bool kmem_cache_charge(void *objp, gfp_t gfpflags);
void kmem_cache_free(struct kmem_cache *s, void *objp);
kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags,