kmalloc

实现kmalloc/kfree

有了buddy sys和slab的api之后，kmalloc/kfree已经呼之欲出了

kmalloc: 如果是大块，buddy sys malloc; 否则slab malloc

kfree: 由addr 得到page, 如果 page->slab , slab free; 如果 page->pool buddy free

void *_kmalloc(size_t size, bool is_record, size_t *real_size)
{
        void *addr;
        int order;

        if (unlikely(size == 0))
                return ZERO_SIZE_PTR;

        if (size <= SLAB_MAX_SIZE) {
                addr = alloc_in_slab(size, real_size);
#if ENABLE_MEMORY_USAGE_COLLECTING == ON
                if(is_record && collecting_switch) {
                        record_mem_usage(*real_size, addr);
		}
#endif
        } else {
                if (size <= BUDDY_PAGE_SIZE)
                        order = 0;
                else
                        order = size_to_page_order(size);
                addr = get_pages(order);
        }

        return addr;
}

void _kfree(void *ptr, bool is_revoke_record)
{
        struct page *page;

        if (unlikely(ptr == ZERO_SIZE_PTR))
                return;

        page = virt_to_page(ptr);
#if ENABLE_MEMORY_USAGE_COLLECTING == ON
        if (collecting_switch && is_revoke_record) {
                revoke_mem_usage(ptr);
	}
#endif
        if (page && page->slab)
                free_in_slab(ptr);
        else if (page && page->pool)
                buddy_free_pages(page->pool, page);
        else
                kwarn("unexpected state in %s\n", __func__);
}