Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * SLOB Allocator: Simple List Of Blocks

 *

 * Matt Mackall <mpm@selenic.com> 12/30/03

 *

 * NUMA support by Paul Mundt, 2007.

 *

 * How SLOB works:

 *

 * The core of SLOB is a traditional K&R style heap allocator, with

 * support for returning aligned objects. The granularity of this

 * allocator is as little as 2 bytes, however typically most architectures

 * will require 4 bytes on 32-bit and 8 bytes on 64-bit.

 *

 * The slob heap is a linked list of pages from alloc_pages(), and

 * within each page, there is a singly-linked list of free blocks (slob_t).

 * The heap is grown on demand and allocation from the heap is currently

 * first-fit.

 *

 * Above this is an implementation of kmalloc/kfree. Blocks returned

 * from kmalloc are prepended with a 4-byte header with the kmalloc size.

 * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls

 * alloc_pages() directly, allocating compound pages so the page order

 * does not have to be separately tracked, and also stores the exact

 * allocation size in page->private so that it can be used to accurately

 * provide ksize(). These objects are detected in kfree() because slob_page()

 * is false for them.

 *

 * SLAB is emulated on top of SLOB by simply calling constructors and

 * destructors for every SLAB allocation. Objects are returned with the

 * 4-byte alignment unless the SLAB_HWCACHE_ALIGN flag is set, in which

 * case the low-level allocator will fragment blocks to create the proper

 * alignment. Again, objects of page-size or greater are allocated by

 * calling alloc_pages(). As SLAB objects know their size, no separate

 * size bookkeeping is necessary and there is essentially no allocation

 * space overhead, and compound pages aren't needed for multi-page

 * allocations.

 *

 * NUMA support in SLOB is fairly simplistic, pushing most of the real

 * logic down to the page allocator, and simply doing the node accounting

 * on the upper levels. In the event that a node id is explicitly

 * provided, alloc_pages_node() with the specified node id is used

 * instead. The common case (or when the node id isn't explicitly provided)

 * will default to the current node, as per numa_node_id().

 *

 * Node aware pages are still inserted in to the global freelist, and

 * these are scanned for by matching against the node id encoded in the

 * page flags. As a result, block allocations that can be satisfied from

 * the freelist will only be done so on pages residing on the same node,

 * in order to prevent random node placement.

 */

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/mm.h>

#include <linux/cache.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/rcupdate.h>

#include <linux/list.h>

#include <asm/atomic.h>

/*

 * slob_block has a field 'units', which indicates size of block if +ve,

 * or offset of next block if -ve (in SLOB_UNITs).

 *

 * Free blocks of size 1 unit simply contain the offset of the next block.

 * Those with larger size contain their size in the first SLOB_UNIT of

 * memory, and the offset of the next free block in the second SLOB_UNIT.

 */

#if PAGE_SIZE <= (32767 * 2)

typedef s16 slobidx_t;

#else

typedef s32 slobidx_t;

#endif

struct slob_block {

        slobidx_t units;

};

typedef struct slob_block slob_t;

/*

 * We use struct page fields to manage some slob allocation aspects,

 * however to avoid the horrible mess in include/linux/mm_types.h, we'll

 * just define our own struct page type variant here.

 */

struct slob_page {

        union {

                struct {

                        unsigned long flags;    /* mandatory */

                        atomic_t _count;        /* mandatory */

                        slobidx_t units;        /* free units left in page */

                        unsigned long pad[2];

                        slob_t *free;           /* first free slob_t in page */

                        struct list_head list;  /* linked list of free pages */

                };

                struct page page;

        };

};

static inline void struct_slob_page_wrong_size(void)

{ BUILD_BUG_ON(sizeof(struct slob_page) != sizeof(struct page)); }

/*

 * free_slob_page: call before a slob_page is returned to the page allocator.

 */

static inline void free_slob_page(struct slob_page *sp)

{

        reset_page_mapcount(&sp->page);

        sp->page.mapping = NULL;

}

/*

 * All (partially) free slob pages go on this list.

 */

static LIST_HEAD(free_slob_pages);

/*

 * slob_page: True for all slob pages (false for bigblock pages)

 */

static inline int slob_page(struct slob_page *sp)

{

        return test_bit(PG_active, &sp->flags);

}

static inline void set_slob_page(struct slob_page *sp)

{

        __set_bit(PG_active, &sp->flags);

}

static inline void clear_slob_page(struct slob_page *sp)

{

        __clear_bit(PG_active, &sp->flags);

}

/*

 * slob_page_free: true for pages on free_slob_pages list.

 */

static inline int slob_page_free(struct slob_page *sp)

{

        return test_bit(PG_private, &sp->flags);

}

static inline void set_slob_page_free(struct slob_page *sp)

{

        list_add(&sp->list, &free_slob_pages);

        __set_bit(PG_private, &sp->flags);

}

static inline void clear_slob_page_free(struct slob_page *sp)

{

        list_del(&sp->list);

        __clear_bit(PG_private, &sp->flags);

}

#define SLOB_UNIT sizeof(slob_t)

#define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)

#define SLOB_ALIGN L1_CACHE_BYTES

/*

 * struct slob_rcu is inserted at the tail of allocated slob blocks, which

 * were created with a SLAB_DESTROY_BY_RCU slab. slob_rcu is used to free

 * the block using call_rcu.

 */

struct slob_rcu {

        struct rcu_head head;

        int size;

};

/*

 * slob_lock protects all slob allocator structures.

 */

static DEFINE_SPINLOCK(slob_lock);

/*

 * Encode the given size and next info into a free slob block s.

 */

static void set_slob(slob_t *s, slobidx_t size, slob_t *next)

{

        slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK);

        slobidx_t offset = next - base;

        if (size > 1) {

                s[0].units = size;

                s[1].units = offset;

        } else

                s[0].units = -offset;

}

/*

 * Return the size of a slob block.

 */

static slobidx_t slob_units(slob_t *s)

{

        if (s->units > 0)

                return s->units;

        return 1;

}

/*

 * Return the next free slob block pointer after this one.

 */

static slob_t *slob_next(slob_t *s)

{

        slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK);

        slobidx_t next;

        if (s[0].units < 0)

                next = -s[0].units;

        else

                next = s[1].units;

        return base+next;

}

/*

 * Returns true if s is the last free block in its page.

 */

static int slob_last(slob_t *s)

{

        return !((unsigned long)slob_next(s) & ~PAGE_MASK);

}

static void *slob_new_page(gfp_t gfp, int order, int node)

{

        void *page;

#ifdef CONFIG_NUMA

        if (node != -1)

                page = alloc_pages_node(node, gfp, order);

        else

#endif

                page = alloc_pages(gfp, order);

        if (!page)

                return NULL;

        return page_address(page);

}

/*

 * Allocate a slob block within a given slob_page sp.

 */

static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)

{

        slob_t *prev, *cur, *aligned = 0;

        int delta = 0, units = SLOB_UNITS(size);

        for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {

                slobidx_t avail = slob_units(cur);

                if (align) {

                        aligned = (slob_t *)ALIGN((unsigned long)cur, align);

                        delta = aligned - cur;

                }

                if (avail >= units + delta) { /* room enough? */

                        slob_t *next;

                        if (delta) { /* need to fragment head to align? */

                                next = slob_next(cur);

                                set_slob(aligned, avail - delta, next);

                                set_slob(cur, delta, aligned);

                                prev = cur;

                                cur = aligned;

                                avail = slob_units(cur);

                        }

                        next = slob_next(cur);

                        if (avail == units) { /* exact fit? unlink. */

                                if (prev)

                                        set_slob(prev, slob_units(prev), next);

                                else

                                        sp->free = next;

                        } else { /* fragment */

                                if (prev)

                                        set_slob(prev, slob_units(prev), cur + units);

                                else

                                        sp->free = cur + units;

                                set_slob(cur + units, avail - units, next);

                        }

                        sp->units -= units;

                        if (!sp->units)

                                clear_slob_page_free(sp);

                        return cur;

                }

                if (slob_last(cur))

                        return NULL;

        }

}

/*

 * slob_alloc: entry point into the slob allocator.

 */

static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)

{

        struct slob_page *sp;

        struct list_head *prev;

        slob_t *b = NULL;

        unsigned long flags;

        spin_lock_irqsave(&slob_lock, flags);

        /* Iterate through each partially free page, try to find room */

        list_for_each_entry(sp, &free_slob_pages, list) {

#ifdef CONFIG_NUMA

                /*

                 * If there's a node specification, search for a partial

                 * page with a matching node id in the freelist.

                 */

                if (node != -1 && page_to_nid(&sp->page) != node)

                        continue;

#endif

                /* Enough room on this page? */

                if (sp->units < SLOB_UNITS(size))

                        continue;

                /* Attempt to alloc */

                prev = sp->list.prev;

                b = slob_page_alloc(sp, size, align);

                if (!b)

                        continue;

                /* Improve fragment distribution and reduce our average

                 * search time by starting our next search here. (see

                 * Knuth vol 1, sec 2.5, pg 449) */

                if (prev != free_slob_pages.prev &&

                                free_slob_pages.next != prev->next)

                        list_move_tail(&free_slob_pages, prev->next);

                break;

        }

        spin_unlock_irqrestore(&slob_lock, flags);

        /* Not enough space: must allocate a new page */

        if (!b) {

                b = slob_new_page(gfp & ~__GFP_ZERO, 0, node);

                if (!b)

                        return 0;

                sp = (struct slob_page *)virt_to_page(b);

                set_slob_page(sp);

                spin_lock_irqsave(&slob_lock, flags);

                sp->units = SLOB_UNITS(PAGE_SIZE);

                sp->free = b;

                INIT_LIST_HEAD(&sp->list);

                set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));

                set_slob_page_free(sp);

                b = slob_page_alloc(sp, size, align);

                BUG_ON(!b);

                spin_unlock_irqrestore(&slob_lock, flags);

        }

        if (unlikely((gfp & __GFP_ZERO) && b))

                memset(b, 0, size);

        return b;

}

/*

 * slob_free: entry point into the slob allocator.

 */

static void slob_free(void *block, int size)

{

        struct slob_page *sp;

        slob_t *prev, *next, *b = (slob_t *)block;

        slobidx_t units;

        unsigned long flags;

        if (unlikely(ZERO_OR_NULL_PTR(block)))

                return;

        BUG_ON(!size);

        sp = (struct slob_page *)virt_to_page(block);

        units = SLOB_UNITS(size);

        spin_lock_irqsave(&slob_lock, flags);

        if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) {

                /* Go directly to page allocator. Do not pass slob allocator */

                if (slob_page_free(sp))

                        clear_slob_page_free(sp);

                clear_slob_page(sp);

                free_slob_page(sp);

                free_page((unsigned long)b);

                goto out;

        }

        if (!slob_page_free(sp)) {

                /* This slob page is about to become partially free. Easy! */

                sp->units = units;

                sp->free = b;

                set_slob(b, units,

                        (void *)((unsigned long)(b +

                                        SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));

                set_slob_page_free(sp);

                goto out;

        }

        /*

         * Otherwise the page is already partially free, so find reinsertion

         * point.

         */

        sp->units += units;

        if (b < sp->free) {

                set_slob(b, units, sp->free);

                sp->free = b;

        } else {

                prev = sp->free;

                next = slob_next(prev);

                while (b > next) {

                        prev = next;

                        next = slob_next(prev);

                }

                if (!slob_last(prev) && b + units == next) {

                        units += slob_units(next);

                        set_slob(b, units, slob_next(next));

                } else

                        set_slob(b, units, next);

                if (prev + slob_units(prev) == b) {

                        units = slob_units(b) + slob_units(prev);

                        set_slob(prev, units, slob_next(b));

                } else

                        set_slob(prev, slob_units(prev), b);

        }

out:

        spin_unlock_irqrestore(&slob_lock, flags);

}

/*

 * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend.

 */

#ifndef ARCH_KMALLOC_MINALIGN

#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long)

#endif

#ifndef ARCH_SLAB_MINALIGN

#define ARCH_SLAB_MINALIGN __alignof__(unsigned long)

#endif

void *__kmalloc_node(size_t size, gfp_t gfp, int node)

{

        unsigned int *m;

        int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);

        if (size < PAGE_SIZE - align) {

                if (!size)

                        return ZERO_SIZE_PTR;

                m = slob_alloc(size + align, gfp, align, node);

                if (m)

                        *m = size;

                return (void *)m + align;

        } else {

                void *ret;

                ret = slob_new_page(gfp | __GFP_COMP, get_order(size), node);

                if (ret) {

                        struct page *page;

                        page = virt_to_page(ret);

                        page->private = size;

                }

                return ret;

        }

}

EXPORT_SYMBOL(__kmalloc_node);

void kfree(const void *block)

{

        struct slob_page *sp;

        if (unlikely(ZERO_OR_NULL_PTR(block)))

                return;

        sp = (struct slob_page *)virt_to_page(block);

        if (slob_page(sp)) {

                int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);

                unsigned int *m = (unsigned int *)(block - align);

                slob_free(m, *m + align);

        } else

                put_page(&sp->page);

}

EXPORT_SYMBOL(kfree);

/* can't use ksize for kmem_cache_alloc memory, only kmalloc */

size_t ksize(const void *block)

{

        struct slob_page *sp;

        BUG_ON(!block);

        if (unlikely(block == ZERO_SIZE_PTR))

                return 0;

        sp = (struct slob_page *)virt_to_page(block);

        if (slob_page(sp))

                return ((slob_t *)block - 1)->units + SLOB_UNIT;

        else

                return sp->page.private;

}

EXPORT_SYMBOL(ksize);

struct kmem_cache {

        unsigned int size, align;

        unsigned long flags;

        const char *name;

        void (*ctor)(struct kmem_cache *, void *);

};

struct kmem_cache *kmem_cache_create(const char *name, size_t size,

        size_t align, unsigned long flags,

        void (*ctor)(struct kmem_cache *, void *))

{

        struct kmem_cache *c;

        c = slob_alloc(sizeof(struct kmem_cache), flags, 0, -1);

        if (c) {

                c->name = name;

                c->size = size;

                if (flags & SLAB_DESTROY_BY_RCU) {

                        /* leave room for rcu footer at the end of object */

                        c->size += sizeof(struct slob_rcu);

                }

                c->flags = flags;

                c->ctor = ctor;

                /* ignore alignment unless it's forced */

                c->align = (flags & SLAB_HWCACHE_ALIGN) ? SLOB_ALIGN : 0;

                if (c->align < ARCH_SLAB_MINALIGN)

                        c->align = ARCH_SLAB_MINALIGN;

                if (c->align < align)

                        c->align = align;

        } else if (flags & SLAB_PANIC)

                panic("Cannot create slab cache %s\n", name);

        return c;

}

EXPORT_SYMBOL(kmem_cache_create);

void kmem_cache_destroy(struct kmem_cache *c)

{

        slob_free(c, sizeof(struct kmem_cache));

}

EXPORT_SYMBOL(kmem_cache_destroy);

void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)

{

        void *b;

        if (c->size < PAGE_SIZE)

                b = slob_alloc(c->size, flags, c->align, node);

        else

                b = slob_new_page(flags, get_order(c->size), node);

        if (c->ctor)

                c->ctor(c, b);

        return b;

}

EXPORT_SYMBOL(kmem_cache_alloc_node);

static void __kmem_cache_free(void *b, int size)

{

        if (size < PAGE_SIZE)

                slob_free(b, size);

        else

                free_pages((unsigned long)b, get_order(size));

}

static void kmem_rcu_free(struct rcu_head *head)

{

        struct slob_rcu *slob_rcu = (struct slob_rcu *)head;

        void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu));

        __kmem_cache_free(b, slob_rcu->size);

}

void kmem_cache_free(struct kmem_cache *c, void *b)

{

        if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {

                struct slob_rcu *slob_rcu;

                slob_rcu = b + (c->size - sizeof(struct slob_rcu));

                INIT_RCU_HEAD(&slob_rcu->head);

                slob_rcu->size = c->size;

                call_rcu(&slob_rcu->head, kmem_rcu_free);

        } else {

                __kmem_cache_free(b, c->size);

        }

}

EXPORT_SYMBOL(kmem_cache_free);

unsigned int kmem_cache_size(struct kmem_cache *c)

{

        return c->size;

}

EXPORT_SYMBOL(kmem_cache_size);

const char *kmem_cache_name(struct kmem_cache *c)

{

        return c->name;

}

EXPORT_SYMBOL(kmem_cache_name);

int kmem_cache_shrink(struct kmem_cache *d)

{

        return 0;

}

EXPORT_SYMBOL(kmem_cache_shrink);

int kmem_ptr_validate(struct kmem_cache *a, const void *b)

{

        return 0;

}

static unsigned int slob_ready __read_mostly;

int slab_is_available(void)

{

        return slob_ready;

}

void __init kmem_cache_init(void)

{

        slob_ready = 1;

}