diff options
Diffstat (limited to 'kern/kmem.h')
| -rw-r--r-- | kern/kmem.h | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/kern/kmem.h b/kern/kmem.h new file mode 100644 index 00000000..dee4a857 --- /dev/null +++ b/kern/kmem.h @@ -0,0 +1,306 @@ +/* + * Copyright (c) 2010, 2011, 2012 Richard Braun. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * + * Object caching and general purpose memory allocator. + */ + +#ifndef _KERN_KMEM_H +#define _KERN_KMEM_H + +#include <kern/param.h> +#include <lib/list.h> +#include <lib/rbtree.h> +#include <lib/stddef.h> + +/* + * Per-processor cache of pre-constructed objects. + * + * The flags member is a read-only CPU-local copy of the parent cache flags. + */ +struct kmem_cpu_pool { + /* struct mutex mutex; */ + int flags; + int size; + int transfer_size; + int nr_objs; + void **array; +} __aligned(CPU_L1_SIZE); + +/* + * When a cache is created, its CPU pool type is determined from the buffer + * size. For small buffer sizes, many objects can be cached in a CPU pool. + * Conversely, for large buffer sizes, this would incur much overhead, so only + * a few objects are stored in a CPU pool. + */ +struct kmem_cpu_pool_type { + size_t buf_size; + int array_size; + size_t array_align; + struct kmem_cache *array_cache; +}; + +/* + * Buffer descriptor. + * + * For normal caches (i.e. without KMEM_CF_VERIFY), bufctls are located at the + * end of (but inside) each buffer. If KMEM_CF_VERIFY is set, bufctls are + * located after each buffer. + * + * When an object is allocated to a client, its bufctl isn't used. This memory + * is instead used for redzoning if cache debugging is in effect. + */ +union kmem_bufctl { + union kmem_bufctl *next; + unsigned long redzone; +}; + +/* + * Redzone guard word. + */ +#ifdef __LP64__ +#ifdef __BIG_ENDIAN__ +#define KMEM_REDZONE_WORD 0xfeedfacefeedfaceUL +#else /* __BIG_ENDIAN__ */ +#define KMEM_REDZONE_WORD 0xcefaedfecefaedfeUL +#endif /* __BIG_ENDIAN__ */ +#else /* __LP64__ */ +#ifdef __BIG_ENDIAN__ +#define KMEM_REDZONE_WORD 0xfeedfaceUL +#else /* __BIG_ENDIAN__ */ +#define KMEM_REDZONE_WORD 0xcefaedfeUL +#endif /* __BIG_ENDIAN__ */ +#endif /* __LP64__ */ + +/* + * Redzone byte for padding. + */ +#define KMEM_REDZONE_BYTE 0xbb + +/* + * Buffer tag. + * + * This structure is only used for KMEM_CF_VERIFY caches. It is located after + * the bufctl and includes information about the state of the buffer it + * describes (allocated or not). It should be thought of as a debugging + * extension of the bufctl. + */ +struct kmem_buftag { + unsigned long state; +}; + +/* + * Values the buftag state member can take. + */ +#ifdef __LP64__ +#ifdef __BIG_ENDIAN__ +#define KMEM_BUFTAG_ALLOC 0xa110c8eda110c8edUL +#define KMEM_BUFTAG_FREE 0xf4eeb10cf4eeb10cUL +#else /* __BIG_ENDIAN__ */ +#define KMEM_BUFTAG_ALLOC 0xedc810a1edc810a1UL +#define KMEM_BUFTAG_FREE 0x0cb1eef40cb1eef4UL +#endif /* __BIG_ENDIAN__ */ +#else /* __LP64__ */ +#ifdef __BIG_ENDIAN__ +#define KMEM_BUFTAG_ALLOC 0xa110c8edUL +#define KMEM_BUFTAG_FREE 0xf4eeb10cUL +#else /* __BIG_ENDIAN__ */ +#define KMEM_BUFTAG_ALLOC 0xedc810a1UL +#define KMEM_BUFTAG_FREE 0x0cb1eef4UL +#endif /* __BIG_ENDIAN__ */ +#endif /* __LP64__ */ + +/* + * Free and uninitialized patterns. + * + * These values are unconditionnally 64-bit wide since buffers are at least + * 8-byte aligned. + */ +#ifdef __BIG_ENDIAN__ +#define KMEM_FREE_PATTERN 0xdeadbeefdeadbeefULL +#define KMEM_UNINIT_PATTERN 0xbaddcafebaddcafeULL +#else /* __BIG_ENDIAN__ */ +#define KMEM_FREE_PATTERN 0xefbeaddeefbeaddeULL +#define KMEM_UNINIT_PATTERN 0xfecaddbafecaddbaULL +#endif /* __BIG_ENDIAN__ */ + +/* + * Page-aligned collection of unconstructed buffers. + * + * This structure is either allocated from the slab cache, or, when internal + * fragmentation allows it, or if forced by the cache creator, from the slab + * it describes. + */ +struct kmem_slab { + struct list list_node; + struct rbtree_node tree_node; + unsigned long nr_refs; + union kmem_bufctl *first_free; + void *addr; +}; + +/* + * Type for constructor functions. + * + * The pre-constructed state of an object is supposed to include only + * elements such as e.g. linked lists, locks, reference counters. Therefore + * constructors are expected to 1) never fail and 2) not need any + * user-provided data. The first constraint implies that object construction + * never performs dynamic resource allocation, which also means there is no + * need for destructors. + */ +typedef void (*kmem_cache_ctor_t)(void *); + +/* + * Types for slab allocation/free functions. + * + * All addresses and sizes must be page-aligned. + */ +typedef unsigned long (*kmem_slab_alloc_fn_t)(size_t); +typedef void (*kmem_slab_free_fn_t)(unsigned long, size_t); + +/* + * Cache name buffer size. + */ +#define KMEM_NAME_SIZE 32 + +/* + * Cache flags. + * + * The flags don't change once set and can be tested without locking. + */ +#define KMEM_CF_NO_CPU_POOL 0x01 /* CPU pool layer disabled */ +#define KMEM_CF_SLAB_EXTERNAL 0x02 /* Slab data is off slab */ +#define KMEM_CF_NO_RECLAIM 0x04 /* Slabs are not reclaimable */ +#define KMEM_CF_VERIFY 0x08 /* Debugging facilities enabled */ +#define KMEM_CF_DIRECT 0x10 /* No buf-to-slab tree lookup */ + +/* + * Cache of objects. + * + * Locking order : cpu_pool -> cache. CPU pools locking is ordered by CPU ID. + * + * The partial slabs list is sorted by slab references. Slabs with a high + * number of references are placed first on the list to reduce fragmentation. + * Sorting occurs at insertion/removal of buffers in a slab. As the list + * is maintained sorted, and the number of references only changes by one, + * this is a very cheap operation in the average case and the worst (linear) + * case is very unlikely. + */ +struct kmem_cache { + /* CPU pool layer */ + struct kmem_cpu_pool cpu_pools[MAX_CPUS]; + struct kmem_cpu_pool_type *cpu_pool_type; + + /* Slab layer */ + /* struct mutex mutex; */ + struct list node; /* Cache list linkage */ + struct list partial_slabs; + struct list free_slabs; + struct rbtree active_slabs; + int flags; + size_t obj_size; /* User-provided size */ + size_t align; + size_t buf_size; /* Aligned object size */ + size_t bufctl_dist; /* Distance from buffer to bufctl */ + size_t slab_size; + size_t color; + size_t color_max; + unsigned long bufs_per_slab; + unsigned long nr_objs; /* Number of allocated objects */ + unsigned long nr_bufs; /* Total number of buffers */ + unsigned long nr_slabs; + unsigned long nr_free_slabs; + kmem_cache_ctor_t ctor; + kmem_slab_alloc_fn_t slab_alloc_fn; + kmem_slab_free_fn_t slab_free_fn; + char name[KMEM_NAME_SIZE]; + size_t buftag_dist; /* Distance from buffer to buftag */ + size_t redzone_pad; /* Bytes from end of object to redzone word */ +}; + +/* + * Cache creation flags. + */ +#define KMEM_CACHE_NOCPUPOOL 0x1 /* Don't use the per-cpu pools */ +#define KMEM_CACHE_NOOFFSLAB 0x2 /* Don't allocate external slab data */ +#define KMEM_CACHE_NORECLAIM 0x4 /* Never give slabs back to their source, + implies KMEM_CACHE_NOOFFSLAB */ +#define KMEM_CACHE_VERIFY 0x8 /* Use debugging facilities */ + +/* + * Initialize a cache. + * + * If a slab allocation/free function pointer is NULL, the default backend + * (vm_kmem on the kmem map) is used for the allocation/free action. + */ +void kmem_cache_init(struct kmem_cache *cache, const char *name, + size_t obj_size, size_t align, kmem_cache_ctor_t ctor, + kmem_slab_alloc_fn_t slab_alloc_fn, + kmem_slab_free_fn_t slab_free_fn, int flags); + +/* + * Allocate an object from a cache. + */ +void * kmem_cache_alloc(struct kmem_cache *cache); + +/* + * Release an object to its cache. + */ +void kmem_cache_free(struct kmem_cache *cache, void *obj); + +/* + * Display internal cache information. + * + * If cache is NULL, this function displays all managed caches. + */ +void kmem_cache_info(struct kmem_cache *cache); + +/* + * Early initialization of the kernel memory allocator. + * + * Once this function returns, caches can be initialized. + */ +void kmem_bootstrap(void); + +/* + * Set up the kernel memory allocator module. + */ +void kmem_setup(void); + +/* + * Allocate size bytes of uninitialized memory. + */ +void * kmem_alloc(size_t size); + +/* + * Allocate size bytes of zeroed memory. + */ +void * kmem_zalloc(size_t size); + +/* + * Release memory obtained with kmem_alloc() or kmem_zalloc(). + * + * The size argument must strictly match the value given at allocation time. + */ +void kmem_free(void *ptr, size_t size); + +/* + * Display global kernel memory information. + */ +void kmem_info(void); + +#endif /* _KERN_KMEM_H */ |