1 files changed, 385 insertions, 0 deletions
diff --git a/mm/slob.c b/mm/slob.c
new file mode 100644
index 0000000..1c240c4
--- /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