2 files changed, 388 insertions, 1 deletions

diff --git a/mm/Makefile b/mm/Makefile
index 74c85ddc9176..9aa03fa1dcc3 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -9,7 +9,7 @@ mmu-$(CONFIG_MMU)	:= fremap.o highmem.o madvise.o memory.o mincore.o \
 
 obj-y                   := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
                            page_alloc.o page-writeback.o pdflush.o \
-                           readahead.o slab.o swap.o truncate.o vmscan.o \
+                           readahead.o swap.o truncate.o vmscan.o \
                            prio_tree.o util.o $(mmu-y)
 
 obj-$(CONFIG_SWAP)      += page_io.o swap_state.o swapfile.o thrash.o
@@ -18,5 +18,7 @@ obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM) += sparse.o
 obj-$(CONFIG_SHMEM) += shmem.o
 obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
+obj-$(CONFIG_SLOB) += slob.o
+obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
diff --git a/mm/slob.c b/mm/slob.c
new file mode 100644
index 000000000000..1c240c4b71d9
--- /dev/null
+++ b/mm/slob.c
@@ -0,0 +1,385 @@
+/*
+ * SLOB Allocator: Simple List Of Blocks
+ *
+ * Matt Mackall <mpm@selenic.com> 12/30/03
+ *
+ * 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 8 bytes on x86, though it's perhaps possible to reduce
+ * this to 4 if it's deemed worth the effort. The slob heap is a
+ * singly-linked list of pages from __get_free_page, 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 8-byte aligned and prepended with a 8-byte header.
+ * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
+ * __get_free_pages directly so that it can return page-aligned blocks
+ * and keeps a linked list of such pages and their orders. These
+ * objects are detected in kfree() by their page alignment.
+ *
+ * SLAB is emulated on top of SLOB by simply calling constructors and
+ * destructors for every SLAB allocation. Objects are returned with
+ * the 8-byte alignment unless the SLAB_MUST_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 __get_free_pages. As SLAB objects know
+ * their size, no separate size bookkeeping is necessary and there is
+ * essentially no allocation space overhead.
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+
+struct slob_block {
+        int units;
+        struct slob_block *next;
+};
+typedef struct slob_block slob_t;
+
+#define SLOB_UNIT sizeof(slob_t)
+#define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)
+#define SLOB_ALIGN L1_CACHE_BYTES
+
+struct bigblock {
+        int order;
+        void *pages;
+        struct bigblock *next;
+};
+typedef struct bigblock bigblock_t;
+
+static slob_t arena = { .next = &arena, .units = 1 };
+static slob_t *slobfree = &arena;
+static bigblock_t *bigblocks;
+static DEFINE_SPINLOCK(slob_lock);
+static DEFINE_SPINLOCK(block_lock);
+
+static void slob_free(void *b, int size);
+
+static void *slob_alloc(size_t size, gfp_t gfp, int align)
+{
+        slob_t *prev, *cur, *aligned = 0;
+        int delta = 0, units = SLOB_UNITS(size);
+        unsigned long flags;
+
+        spin_lock_irqsave(&slob_lock, flags);
+        prev = slobfree;
+        for (cur = prev->next; ; prev = cur, cur = cur->next) {
+                if (align) {
+                        aligned = (slob_t *)ALIGN((unsigned long)cur, align);
+                        delta = aligned - cur;
+                }
+                if (cur->units >= units + delta) { /* room enough? */
+                        if (delta) { /* need to fragment head to align? */
+                                aligned->units = cur->units - delta;
+                                aligned->next = cur->next;
+                                cur->next = aligned;
+                                cur->units = delta;
+                                prev = cur;
+                                cur = aligned;
+                        }
+
+                        if (cur->units == units) /* exact fit? */
+                                prev->next = cur->next; /* unlink */
+                        else { /* fragment */
+                                prev->next = cur + units;
+                                prev->next->units = cur->units - units;
+                                prev->next->next = cur->next;
+                                cur->units = units;
+                        }
+
+                        slobfree = prev;
+                        spin_unlock_irqrestore(&slob_lock, flags);
+                        return cur;
+                }
+                if (cur == slobfree) {
+                        spin_unlock_irqrestore(&slob_lock, flags);
+
+                        if (size == PAGE_SIZE) /* trying to shrink arena? */
+                                return 0;
+
+                        cur = (slob_t *)__get_free_page(gfp);
+                        if (!cur)
+                                return 0;
+
+                        slob_free(cur, PAGE_SIZE);
+                        spin_lock_irqsave(&slob_lock, flags);
+                        cur = slobfree;
+                }
+        }
+}
+
+static void slob_free(void *block, int size)
+{
+        slob_t *cur, *b = (slob_t *)block;
+        unsigned long flags;
+
+        if (!block)
+                return;
+
+        if (size)
+                b->units = SLOB_UNITS(size);
+
+        /* Find reinsertion point */
+        spin_lock_irqsave(&slob_lock, flags);
+        for (cur = slobfree; !(b > cur && b < cur->next); cur = cur->next)
+                if (cur >= cur->next && (b > cur || b < cur->next))
+                        break;
+
+        if (b + b->units == cur->next) {
+                b->units += cur->next->units;
+                b->next = cur->next->next;
+        } else
+                b->next = cur->next;
+
+        if (cur + cur->units == b) {
+                cur->units += b->units;
+                cur->next = b->next;
+        } else
+                cur->next = b;
+
+        slobfree = cur;
+
+        spin_unlock_irqrestore(&slob_lock, flags);
+}
+
+static int FASTCALL(find_order(int size));
+static int fastcall find_order(int size)
+{
+        int order = 0;
+        for ( ; size > 4096 ; size >>=1)
+                order++;
+        return order;
+}
+
+void *kmalloc(size_t size, gfp_t gfp)
+{
+        slob_t *m;
+        bigblock_t *bb;
+        unsigned long flags;
+
+        if (size < PAGE_SIZE - SLOB_UNIT) {
+                m = slob_alloc(size + SLOB_UNIT, gfp, 0);
+                return m ? (void *)(m + 1) : 0;
+        }
+
+        bb = slob_alloc(sizeof(bigblock_t), gfp, 0);
+        if (!bb)
+                return 0;
+
+        bb->order = find_order(size);
+        bb->pages = (void *)__get_free_pages(gfp, bb->order);
+
+        if (bb->pages) {
+                spin_lock_irqsave(&block_lock, flags);
+                bb->next = bigblocks;
+                bigblocks = bb;
+                spin_unlock_irqrestore(&block_lock, flags);
+                return bb->pages;
+        }
+
+        slob_free(bb, sizeof(bigblock_t));
+        return 0;
+}
+
+EXPORT_SYMBOL(kmalloc);
+
+void kfree(const void *block)
+{
+        bigblock_t *bb, **last = &bigblocks;
+        unsigned long flags;
+
+        if (!block)
+                return;
+
+        if (!((unsigned long)block & (PAGE_SIZE-1))) {
+                /* might be on the big block list */
+                spin_lock_irqsave(&block_lock, flags);
+                for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) {
+                        if (bb->pages == block) {
+                                *last = bb->next;
+                                spin_unlock_irqrestore(&block_lock, flags);
+                                free_pages((unsigned long)block, bb->order);
+                                slob_free(bb, sizeof(bigblock_t));
+                                return;
+                        }
+                }
+                spin_unlock_irqrestore(&block_lock, flags);
+        }
+
+        slob_free((slob_t *)block - 1, 0);
+        return;
+}
+
+EXPORT_SYMBOL(kfree);
+
+unsigned int ksize(const void *block)
+{
+        bigblock_t *bb;
+        unsigned long flags;
+
+        if (!block)
+                return 0;
+
+        if (!((unsigned long)block & (PAGE_SIZE-1))) {
+                spin_lock_irqsave(&block_lock, flags);
+                for (bb = bigblocks; bb; bb = bb->next)
+                        if (bb->pages == block) {
+                                spin_unlock_irqrestore(&slob_lock, flags);
+                                return PAGE_SIZE << bb->order;
+                        }
+                spin_unlock_irqrestore(&block_lock, flags);
+        }
+
+        return ((slob_t *)block - 1)->units * SLOB_UNIT;
+}
+
+struct kmem_cache {
+        unsigned int size, align;
+        const char *name;
+        void (*ctor)(void *, struct kmem_cache *, unsigned long);
+        void (*dtor)(void *, struct kmem_cache *, unsigned long);
+};
+
+struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+        size_t align, unsigned long flags,
+        void (*ctor)(void*, struct kmem_cache *, unsigned long),
+        void (*dtor)(void*, struct kmem_cache *, unsigned long))
+{
+        struct kmem_cache *c;
+
+        c = slob_alloc(sizeof(struct kmem_cache), flags, 0);
+
+        if (c) {
+                c->name = name;
+                c->size = size;
+                c->ctor = ctor;
+                c->dtor = dtor;
+                /* ignore alignment unless it's forced */
+                c->align = (flags & SLAB_MUST_HWCACHE_ALIGN) ? SLOB_ALIGN : 0;
+                if (c->align < align)
+                        c->align = align;
+        }
+
+        return c;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
+int kmem_cache_destroy(struct kmem_cache *c)
+{
+        slob_free(c, sizeof(struct kmem_cache));
+        return 0;
+}
+EXPORT_SYMBOL(kmem_cache_destroy);
+
+void *kmem_cache_alloc(struct kmem_cache *c, gfp_t flags)
+{
+        void *b;
+
+        if (c->size < PAGE_SIZE)
+                b = slob_alloc(c->size, flags, c->align);
+        else
+                b = (void *)__get_free_pages(flags, find_order(c->size));
+
+        if (c->ctor)
+                c->ctor(b, c, SLAB_CTOR_CONSTRUCTOR);
+
+        return b;
+}
+EXPORT_SYMBOL(kmem_cache_alloc);
+
+void kmem_cache_free(struct kmem_cache *c, void *b)
+{
+        if (c->dtor)
+                c->dtor(b, c, 0);
+
+        if (c->size < PAGE_SIZE)
+                slob_free(b, c->size);
+        else
+                free_pages((unsigned long)b, find_order(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);
+
+static struct timer_list slob_timer = TIMER_INITIALIZER(
+        (void (*)(unsigned long))kmem_cache_init, 0, 0);
+
+void kmem_cache_init(void)
+{
+        void *p = slob_alloc(PAGE_SIZE, 0, PAGE_SIZE-1);
+
+        if (p)
+                free_page((unsigned long)p);
+
+        mod_timer(&slob_timer, jiffies + HZ);
+}
+
+atomic_t slab_reclaim_pages = ATOMIC_INIT(0);
+EXPORT_SYMBOL(slab_reclaim_pages);
+
+#ifdef CONFIG_SMP
+
+void *__alloc_percpu(size_t size, size_t align)
+{
+        int i;
+        struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL);
+
+        if (!pdata)
+                return NULL;
+
+        for (i = 0; i < NR_CPUS; i++) {
+                if (!cpu_possible(i))
+                        continue;
+                pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
+                if (!pdata->ptrs[i])
+                        goto unwind_oom;
+                memset(pdata->ptrs[i], 0, size);
+        }
+
+        /* Catch derefs w/o wrappers */
+        return (void *) (~(unsigned long) pdata);
+
+unwind_oom:
+        while (--i >= 0) {
+                if (!cpu_possible(i))
+                        continue;
+                kfree(pdata->ptrs[i]);
+        }
+        kfree(pdata);
+        return NULL;
+}
+EXPORT_SYMBOL(__alloc_percpu);
+
+void
+free_percpu(const void *objp)
+{
+        int i;
+        struct percpu_data *p = (struct percpu_data *) (~(unsigned long) objp);
+
+        for (i = 0; i < NR_CPUS; i++) {
+                if (!cpu_possible(i))
+                        continue;
+                kfree(p->ptrs[i]);
+        }
+        kfree(p);
+}
+EXPORT_SYMBOL(free_percpu);
+
+#endif