Currently we have multiple kmem_cache_create*() variants that take up to
seven separate parameters with one of the functions having to grow an
eigth parameter in the future to handle both usercopy and a custom
freelist pointer.
Add a struct kmem_cache_args structure and move less common parameters
into it. Core parameters such as name, object size, and flags continue
to be passed separately.
Add a new function __kmem_cache_create_args() that takes a struct
kmem_cache_args pointer and port do_kmem_cache_create_usercopy() over to
it.
In follow-up patches we will port the other kmem_cache_create*()
variants over to it as well.
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
Reviewed-by: Jens Axboe <axboe@xxxxxxxxx>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
include/linux/slab.h | 21 ++++++++++++++++
mm/slab_common.c | 67 +++++++++++++++++++++++++++++++++++++++-------------
2 files changed, 72 insertions(+), 16 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5b2da2cf31a8..79d8c8bca4a4 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -240,6 +240,27 @@ struct mem_cgroup;
*/
bool slab_is_available(void);
+/**
+ * @align: The required alignment for the objects.
+ * @useroffset: Usercopy region offset
+ * @usersize: Usercopy region size
+ * @freeptr_offset: Custom offset for the free pointer in RCU caches
+ * @use_freeptr_offset: Whether a @freeptr_offset is used
+ * @ctor: A constructor for the objects.
+ */
+struct kmem_cache_args {
+ unsigned int align;
+ unsigned int useroffset;
+ unsigned int usersize;
+ unsigned int freeptr_offset;
+ bool use_freeptr_offset;
+ 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);
struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
unsigned int align, slab_flags_t flags,
void (*ctor)(void *));
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 91e0e36e4379..0f13c045b8d1 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -248,14 +248,24 @@ static struct kmem_cache *create_cache(const char *name,
return ERR_PTR(err);
}
-static struct kmem_cache *
-do_kmem_cache_create_usercopy(const char *name,
- unsigned int size, unsigned int freeptr_offset,
- unsigned int align, slab_flags_t flags,
- unsigned int useroffset, unsigned int usersize,
- void (*ctor)(void *))
+/**
+ * __kmem_cache_create_args - 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: Arguments for the cache creation (see struct kmem_cache_args).
+ * @flags: See %SLAB_* flags for an explanation of individual @flags.
+ *
+ * Cannot be called within a interrupt, but can be interrupted.
+ *
+ * Return: a pointer to the cache on success, NULL on failure.
+ */
+struct kmem_cache *__kmem_cache_create_args(const char *name,
+ unsigned int object_size,
+ struct kmem_cache_args *args,
+ slab_flags_t flags)
{
struct kmem_cache *s = NULL;
+ unsigned int freeptr_offset = UINT_MAX;
const char *cache_name;
int err;
@@ -275,7 +285,7 @@ do_kmem_cache_create_usercopy(const char *name,
mutex_lock(&slab_mutex);
- err = kmem_cache_sanity_check(name, size);
+ err = kmem_cache_sanity_check(name, object_size);
if (err) {
goto out_unlock;
}
@@ -296,12 +306,14 @@ do_kmem_cache_create_usercopy(const char *name,
/* Fail closed on bad usersize of useroffset values. */
if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
- WARN_ON(!usersize && useroffset) ||
- WARN_ON(size < usersize || size - usersize < useroffset))
- usersize = useroffset = 0;
-
- if (!usersize)
- s = __kmem_cache_alias(name, size, align, flags, ctor);
+ WARN_ON(!args->usersize && args->useroffset) ||
+ WARN_ON(object_size < args->usersize ||
+ object_size - args->usersize < args->useroffset))
+ args->usersize = args->useroffset = 0;
+
+ if (!args->usersize)
+ s = __kmem_cache_alias(name, object_size, args->align, flags,
+ args->ctor);
if (s)
goto out_unlock;
@@ -311,9 +323,11 @@ do_kmem_cache_create_usercopy(const char *name,
goto out_unlock;
}
- s = create_cache(cache_name, size, freeptr_offset,
- calculate_alignment(flags, align, size),
- flags, useroffset, usersize, ctor);
+ if (args->use_freeptr_offset)
+ freeptr_offset = args->freeptr_offset;
+ s = create_cache(cache_name, object_size, freeptr_offset,
+ calculate_alignment(flags, args->align, object_size),
+ flags, args->useroffset, args->usersize, args->ctor);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree_const(cache_name);
@@ -335,6 +349,27 @@ do_kmem_cache_create_usercopy(const char *name,
}
return s;
}
+EXPORT_SYMBOL(__kmem_cache_create_args);
+
+static struct kmem_cache *
+do_kmem_cache_create_usercopy(const char *name,
+ unsigned int size, unsigned int freeptr_offset,
+ unsigned int align, slab_flags_t flags,
+ unsigned int useroffset, unsigned int usersize,
+ void (*ctor)(void *))
+{
+ struct kmem_cache_args kmem_args = {
+ .align = align,
+ .use_freeptr_offset = freeptr_offset != UINT_MAX,
+ .freeptr_offset = freeptr_offset,
+ .useroffset = useroffset,
+ .usersize = usersize,
+ .ctor = ctor,
+ };
+
+ return __kmem_cache_create_args(name, size, &kmem_args, flags);
+}
+
/**
* kmem_cache_create_usercopy - Create a cache with a region suitable
--
2.45.2
