Created student weenix repository

1 files changed, 96 insertions, 0 deletions

diff --git a/kernel/include/mm/slab.h b/kernel/include/mm/slab.h
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+++ b/kernel/include/mm/slab.h
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+#pragma once
+
+#include <types.h>
+
+/* Define SLAB_REDZONE to add top and bottom redzones to every object. */
+#define SLAB_REDZONE 0xdeadbeefdeadbeef
+
+/* Define SLAB_CHECK_FREE to add extra book keeping to make sure there
+ * are no double frees. */
+#define SLAB_CHECK_FREE
+
+/*
+ * The slab allocator. A "cache" is a store of objects; you create one by
+ * specifying a constructor, destructor, and the size of an object. The
+ * "alloc" function allocates one object, and the "free" function returns
+ * it to the free list *without calling the destructor*. This lets you save
+ * on destruction/construction calls; the idea is that every free object in
+ * the cache is in a known state.
+ */
+typedef struct slab_allocator slab_allocator_t;
+
+/* Initializes the slab allocator subsystem. This should be done
+ * only after the page subsystem has been initialized. Slab allocators
+ * and kmalloc will not work until this function has been called. */
+void slab_init();
+
+/*
+ * Example Usage
+ * See the below example for how to use a slab allocator to allocate objects 
+ * of a given size. Note that you usually don't need to destroy most allocators,
+ * as they should last as long as the system is running (e.g. the process allocator).
+ * 
+ * ```
+ * typedef struct { 
+ *     int x; 
+ *     int y; 
+ * } point_t;
+ *
+ * // Create a new allocator for objects of type point_t. This only needs to 
+ * // happen once, usually in an initialization routine.
+ * slab_allocator_t *point_allocator = slab_allocator_create("point", sizeof(point_t));
+ * 
+ * // Allocate a new point_t from the slab allocator
+ * point_t *p = (point_t *)slab_obj_alloc(point_allocator);
+ * 
+ * // ... Use p here ...
+ * 
+ * // Deallocate the point_t
+ * slab_obj_free(point_allocator, p);
+ * ``` 
+ */
+
+/**
+ * Creates a slab allocator for allocating objects of a given size.
+ * 
+ * @param name The name of the allocator (for debugging)
+ * @param size The size (bytes) of objects that will be allocated from this allocator
+ * @return slab_allocator_t* An allocator, or NULL on failure
+ */
+slab_allocator_t *slab_allocator_create(const char *name, size_t size);
+
+/**
+ * Destroys a slab allocator.
+ * 
+ * @param allocator The allocator to destroy
+ */
+void slab_allocator_destroy(struct slab_allocator *allocator);
+
+/**
+ * Allocates an object from the given slab allocator. The object is a chunk of 
+ * memory as big as the size that slab allocator was created with. 
+ * 
+ * @param allocator The allocator to allocate from
+ * @return void* A chunk of memory of the appropriate object size, or NULL
+ *  on failure
+ */
+void *slab_obj_alloc(slab_allocator_t *allocator);
+
+/**
+ * Frees a given object that was allocated by a given slab allocator.
+ * 
+ * @param allocator The allocator that allocated this object
+ * @param obj The object to be freed
+ */
+void slab_obj_free(slab_allocator_t *allocator, void *obj);
+
+/**
+ * Reclaims memory from unused slabs. 
+ * 
+ * NOTE: This is not currently implemented.
+ * 
+ * @param target Target number of pages to reclaim. If negative, reclaim as many
+ *  as possible
+ * @return long Number of pages freed
+ */
+long slab_allocators_reclaim(long target);
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