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305 rindas
6.8 KiB
305 rindas
6.8 KiB
#include <defs.h>
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#include <list.h>
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#include <memlayout.h>
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#include <assert.h>
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#include <kmalloc.h>
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#include <sync.h>
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#include <pmm.h>
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#include <stdio.h>
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/*
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* SLOB Allocator: Simple List Of Blocks
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*
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* Matt Mackall <mpm@selenic.com> 12/30/03
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*
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* How SLOB works:
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*
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* The core of SLOB is a traditional K&R style heap allocator, with
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* support for returning aligned objects. The granularity of this
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* allocator is 8 bytes on x86, though it's perhaps possible to reduce
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* this to 4 if it's deemed worth the effort. The slob heap is a
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* singly-linked list of pages from __get_free_page, grown on demand
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* and allocation from the heap is currently first-fit.
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*
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* Above this is an implementation of kmalloc/kfree. Blocks returned
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* from kmalloc are 8-byte aligned and prepended with a 8-byte header.
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* If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
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* __get_free_pages directly so that it can return page-aligned blocks
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* and keeps a linked list of such pages and their orders. These
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* objects are detected in kfree() by their page alignment.
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*
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* SLAB is emulated on top of SLOB by simply calling constructors and
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* destructors for every SLAB allocation. Objects are returned with
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* the 8-byte alignment unless the SLAB_MUST_HWCACHE_ALIGN flag is
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* set, in which case the low-level allocator will fragment blocks to
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* create the proper alignment. Again, objects of page-size or greater
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* are allocated by calling __get_free_pages. As SLAB objects know
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* their size, no separate size bookkeeping is necessary and there is
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* essentially no allocation space overhead.
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*/
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//some helper
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#define spin_lock_irqsave(l, f) local_intr_save(f)
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#define spin_unlock_irqrestore(l, f) local_intr_restore(f)
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typedef unsigned int gfp_t;
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#ifndef PAGE_SIZE
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#define PAGE_SIZE PGSIZE
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#endif
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#ifndef L1_CACHE_BYTES
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#define L1_CACHE_BYTES 64
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#endif
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#ifndef ALIGN
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#define ALIGN(addr,size) (((addr)+(size)-1)&(~((size)-1)))
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#endif
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struct slob_block {
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int units;
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struct slob_block *next;
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};
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typedef struct slob_block slob_t;
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#define SLOB_UNIT sizeof(slob_t)
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#define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)
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#define SLOB_ALIGN L1_CACHE_BYTES
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struct bigblock {
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int order;
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void *pages;
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struct bigblock *next;
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};
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typedef struct bigblock bigblock_t;
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static slob_t arena = { .next = &arena, .units = 1 };
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static slob_t *slobfree = &arena;
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static bigblock_t *bigblocks;
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static void* __slob_get_free_pages(gfp_t gfp, int order)
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{
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struct Page * page = alloc_pages(1 << order);
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if(!page)
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return NULL;
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return page2kva(page);
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}
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#define __slob_get_free_page(gfp) __slob_get_free_pages(gfp, 0)
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static inline void __slob_free_pages(unsigned long kva, int order)
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{
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free_pages(kva2page(kva), 1 << order);
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}
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static void slob_free(void *b, int size);
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static void *slob_alloc(size_t size, gfp_t gfp, int align)
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{
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assert( (size + SLOB_UNIT) < PAGE_SIZE );
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slob_t *prev, *cur, *aligned = 0;
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int delta = 0, units = SLOB_UNITS(size);
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unsigned long flags;
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spin_lock_irqsave(&slob_lock, flags);
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prev = slobfree;
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for (cur = prev->next; ; prev = cur, cur = cur->next) {
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if (align) {
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aligned = (slob_t *)ALIGN((unsigned long)cur, align);
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delta = aligned - cur;
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}
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if (cur->units >= units + delta) { /* room enough? */
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if (delta) { /* need to fragment head to align? */
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aligned->units = cur->units - delta;
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aligned->next = cur->next;
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cur->next = aligned;
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cur->units = delta;
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prev = cur;
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cur = aligned;
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}
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if (cur->units == units) /* exact fit? */
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prev->next = cur->next; /* unlink */
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else { /* fragment */
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prev->next = cur + units;
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prev->next->units = cur->units - units;
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prev->next->next = cur->next;
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cur->units = units;
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}
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slobfree = prev;
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spin_unlock_irqrestore(&slob_lock, flags);
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return cur;
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}
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if (cur == slobfree) {
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spin_unlock_irqrestore(&slob_lock, flags);
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if (size == PAGE_SIZE) /* trying to shrink arena? */
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return 0;
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cur = (slob_t *)__slob_get_free_page(gfp);
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if (!cur)
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return 0;
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slob_free(cur, PAGE_SIZE);
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spin_lock_irqsave(&slob_lock, flags);
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cur = slobfree;
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}
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}
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}
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static void slob_free(void *block, int size)
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{
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slob_t *cur, *b = (slob_t *)block;
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unsigned long flags;
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if (!block)
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return;
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if (size)
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b->units = SLOB_UNITS(size);
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/* Find reinsertion point */
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spin_lock_irqsave(&slob_lock, flags);
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for (cur = slobfree; !(b > cur && b < cur->next); cur = cur->next)
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if (cur >= cur->next && (b > cur || b < cur->next))
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break;
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if (b + b->units == cur->next) {
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b->units += cur->next->units;
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b->next = cur->next->next;
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} else
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b->next = cur->next;
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if (cur + cur->units == b) {
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cur->units += b->units;
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cur->next = b->next;
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} else
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cur->next = b;
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slobfree = cur;
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spin_unlock_irqrestore(&slob_lock, flags);
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}
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void
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slob_init(void) {
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cprintf("use SLOB allocator\n");
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}
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inline void
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kmalloc_init(void) {
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slob_init();
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cprintf("kmalloc_init() succeeded!\n");
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}
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size_t
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slob_allocated(void) {
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return 0;
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}
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size_t
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kallocated(void) {
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return slob_allocated();
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}
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static int find_order(int size)
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{
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int order = 0;
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for ( ; size > 4096 ; size >>=1)
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order++;
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return order;
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}
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static void *__kmalloc(size_t size, gfp_t gfp)
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{
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slob_t *m;
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bigblock_t *bb;
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unsigned long flags;
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if (size < PAGE_SIZE - SLOB_UNIT) {
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m = slob_alloc(size + SLOB_UNIT, gfp, 0);
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return m ? (void *)(m + 1) : 0;
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}
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bb = slob_alloc(sizeof(bigblock_t), gfp, 0);
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if (!bb)
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return 0;
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bb->order = find_order(size);
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bb->pages = (void *)__slob_get_free_pages(gfp, bb->order);
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if (bb->pages) {
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spin_lock_irqsave(&block_lock, flags);
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bb->next = bigblocks;
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bigblocks = bb;
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spin_unlock_irqrestore(&block_lock, flags);
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return bb->pages;
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}
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slob_free(bb, sizeof(bigblock_t));
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return 0;
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}
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void *
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kmalloc(size_t size)
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{
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return __kmalloc(size, 0);
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}
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void kfree(void *block)
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{
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bigblock_t *bb, **last = &bigblocks;
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unsigned long flags;
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if (!block)
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return;
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if (!((unsigned long)block & (PAGE_SIZE-1))) {
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/* might be on the big block list */
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spin_lock_irqsave(&block_lock, flags);
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for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) {
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if (bb->pages == block) {
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*last = bb->next;
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spin_unlock_irqrestore(&block_lock, flags);
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__slob_free_pages((unsigned long)block, bb->order);
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slob_free(bb, sizeof(bigblock_t));
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return;
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}
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}
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spin_unlock_irqrestore(&block_lock, flags);
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}
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slob_free((slob_t *)block - 1, 0);
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return;
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}
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unsigned int ksize(const void *block)
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{
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bigblock_t *bb;
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unsigned long flags;
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if (!block)
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return 0;
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if (!((unsigned long)block & (PAGE_SIZE-1))) {
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spin_lock_irqsave(&block_lock, flags);
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for (bb = bigblocks; bb; bb = bb->next)
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if (bb->pages == block) {
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spin_unlock_irqrestore(&slob_lock, flags);
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return PAGE_SIZE << bb->order;
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}
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spin_unlock_irqrestore(&block_lock, flags);
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}
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return ((slob_t *)block - 1)->units * SLOB_UNIT;
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}
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