Enrico Fraccaroli (Galfurian)
124 lines
4.7 KiB
C
124 lines
4.7 KiB
C
/// @file buddysystem.h
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/// @brief Buddy System.
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/// @copyright (c) 2014-2022 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "klib/list_head.h"
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#include "klib/stdatomic.h"
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#include "stdint.h"
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/// @brief Max gfp pages order of buddysystem blocks.
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#define MAX_BUDDYSYSTEM_GFP_ORDER 14
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/// @brief Provide the offset of the element inside the given type of page.
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#define BBSTRUCT_OFFSET(page, element) \
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((uint32_t) & (((page *)NULL)->element))
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/// @brief Returns the address of the given element of a given type of page,
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/// based on the provided bbstruct.
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#define PG_FROM_BBSTRUCT(bbstruct, page, element) \
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((page *)(((uint32_t)(bbstruct)) - BBSTRUCT_OFFSET(page, element)))
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/// The base structure representing a bb page
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typedef struct bb_page_t {
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/// The flags of the page.
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volatile unsigned long flags;
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/// The current page order.
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uint32_t order;
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/// Keep track of where the page is located.
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union {
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/// The page siblings when not allocated.
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list_head siblings;
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/// The cache list pointer when allocated but on cache.
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list_head cache;
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} location;
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} bb_page_t;
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/// @brief Buddy system descriptor: collection of free page blocks.
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/// Each block represents 2^k free contiguous page.
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typedef struct bb_free_area_t {
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/// free_list collectes the first page descriptors of a blocks of 2^k frames
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list_head free_list;
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/// nr_free specifies the number of blocks of free pages.
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int nr_free;
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} bb_free_area_t;
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/// @brief Buddy system instance,
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/// that represents a memory area managed by the buddy system
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typedef struct bb_instance_t {
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/// Name of this bb instance
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const char *name;
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/// List of buddy system pages grouped by level.
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bb_free_area_t free_area[MAX_BUDDYSYSTEM_GFP_ORDER];
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/// Pointer to start of free pages cache
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list_head free_pages_cache_list;
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/// Size of the current cache
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unsigned long free_pages_cache_size;
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/// Buddysystem instance size in number of pages.
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unsigned long size;
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/// Address of the first managed page
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bb_page_t *base_page;
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/// Size of the (padded) wrapper page structure
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unsigned long pgs_size;
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/// Offset of the bb_page_t struct from the start of the whole structure
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unsigned long bbpg_offset;
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} bb_instance_t;
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/// @brief Allocate a block of page frames of size 2^order.
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/// @param instance A buddy system instance.
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/// @param order The logarithm of the size of the block.
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/// @return The address of the first page descriptor of the block, or NULL.
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bb_page_t *bb_alloc_pages(bb_instance_t *instance, unsigned int order);
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/// @brief Free a block of page frames of size 2^order.
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/// @param instance A buddy system instance.
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/// @param page The address of the first page descriptor of the block.
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void bb_free_pages(bb_instance_t *instance, bb_page_t *page);
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/// @brief Alloc a page using bb cache.
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/// @param instance Buddy system instance.
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/// @return An allocated page.
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bb_page_t *bb_alloc_page_cached(bb_instance_t *instance);
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/// @brief Free a page allocated with bb_alloc_page_cached.
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/// @param instance Buddy system instance.
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/// @param page The address of the first page descriptor of the block.
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void bb_free_page_cached(bb_instance_t *instance, bb_page_t *page);
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/// @brief Initialize Buddy System.
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/// @param instance A buddysystem instance.
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/// @param name The name of the current instance (for debug purposes)
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/// @param pages_start The start address of the page structures
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/// @param bbpage_offset The offset from the start of the whole page of the
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/// bb_page_t struct.
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/// @param pages_stride The (padded) size of the whole page structure
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/// @param pages_count The number of pages in this region
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void buddy_system_init(
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bb_instance_t *instance,
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const char *name,
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void *pages_start,
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uint32_t bbpage_offset,
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uint32_t pages_stride,
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uint32_t pages_count);
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/// @brief Print the size of free_list of each free_area.
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/// @param instance A buddy system instance.
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void buddy_system_dump(bb_instance_t *instance);
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/// @brief Returns the total space for the given instance.
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/// @param instance A buddy system instance.
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/// @return The requested total sapce.
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unsigned long buddy_system_get_total_space(bb_instance_t *instance);
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/// @brief Returns the free space for the given instance.
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/// @param instance A buddy system instance.
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/// @return The requested total sapce.
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unsigned long buddy_system_get_free_space(bb_instance_t *instance);
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/// @brief Returns the cached space for the given instance.
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/// @param instance A buddy system instance.
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/// @return The requested total sapce.
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unsigned long buddy_system_get_cached_space(bb_instance_t *instance);
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