diff options
Diffstat (limited to 'vm/vm_page.c')
| -rw-r--r-- | vm/vm_page.c | 735 |
1 files changed, 735 insertions, 0 deletions
diff --git a/vm/vm_page.c b/vm/vm_page.c new file mode 100644 index 0000000..cc184ca --- /dev/null +++ b/vm/vm_page.c @@ -0,0 +1,735 @@ +/* + * Copyright (c) 2010-2014 Richard Braun. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * + * This implementation uses the binary buddy system to manage its heap. + * Descriptions of the buddy system can be found in the following works : + * - "UNIX Internals: The New Frontiers", by Uresh Vahalia. + * - "Dynamic Storage Allocation: A Survey and Critical Review", + * by Paul R. Wilson, Mark S. Johnstone, Michael Neely, and David Boles. + * + * In addition, this allocator uses per-CPU pools of pages for order 0 + * (i.e. single page) allocations. These pools act as caches (but are named + * differently to avoid confusion with CPU caches) that reduce contention on + * multiprocessor systems. When a pool is empty and cannot provide a page, + * it is filled by transferring multiple pages from the backend buddy system. + * The symmetric case is handled likewise. + */ + +#include <kern/assert.h> +#include <kern/init.h> +#include <kern/list.h> +#include <kern/macros.h> +#include <kern/mutex.h> +#include <kern/panic.h> +#include <kern/param.h> +#include <kern/printk.h> +#include <kern/sprintf.h> +#include <kern/stddef.h> +#include <kern/string.h> +#include <kern/thread.h> +#include <kern/types.h> +#include <machine/cpu.h> +#include <machine/pmap.h> +#include <vm/vm_kmem.h> +#include <vm/vm_page.h> + +/* + * Number of free block lists per segment. + */ +#define VM_PAGE_NR_FREE_LISTS 11 + +/* + * The size of a CPU pool is computed by dividing the number of pages in its + * containing segment by this value. + */ +#define VM_PAGE_CPU_POOL_RATIO 1024 + +/* + * Maximum number of pages in a CPU pool. + */ +#define VM_PAGE_CPU_POOL_MAX_SIZE 128 + +/* + * The transfer size of a CPU pool is computed by dividing the pool size by + * this value. + */ +#define VM_PAGE_CPU_POOL_TRANSFER_RATIO 2 + +/* + * Per-processor cache of pages. + */ +struct vm_page_cpu_pool { + struct mutex lock; + int size; + int transfer_size; + int nr_pages; + struct list pages; +} __aligned(CPU_L1_SIZE); + +/* + * Special order value for pages that aren't in a free list. Such pages are + * either allocated, or part of a free block of pages but not the head page. + */ +#define VM_PAGE_ORDER_UNLISTED ((unsigned short)-1) + +/* + * Doubly-linked list of free blocks. + */ +struct vm_page_free_list { + unsigned long size; + struct list blocks; +}; + +/* + * Segment name buffer size. + */ +#define VM_PAGE_NAME_SIZE 16 + +/* + * Segment of contiguous memory. + */ +struct vm_page_seg { + struct vm_page_cpu_pool cpu_pools[MAX_CPUS]; + + phys_addr_t start; + phys_addr_t end; + struct vm_page *pages; + struct vm_page *pages_end; + struct mutex lock; + struct vm_page_free_list free_lists[VM_PAGE_NR_FREE_LISTS]; + unsigned long nr_free_pages; +}; + +/* + * Bootstrap information about a segment. + */ +struct vm_page_boot_seg { + phys_addr_t start; + phys_addr_t end; + phys_addr_t avail_start; + phys_addr_t avail_end; +}; + +static int vm_page_is_ready __read_mostly; + +/* + * Segment table. + * + * The system supports a maximum of 4 segments : + * - DMA: suitable for DMA + * - DMA32: suitable for DMA when devices support 32-bits addressing + * - DIRECTMAP: direct physical mapping, allows direct access from + * the kernel with a simple offset translation + * - HIGHMEM: must be mapped before it can be accessed + * + * Segments are ordered by priority, 0 being the lowest priority. Their + * relative priorities are DMA < DMA32 < DIRECTMAP < HIGHMEM. Some segments + * may actually be aliases for others, e.g. if DMA is always possible from + * the direct physical mapping, DMA and DMA32 are aliases for DIRECTMAP, + * in which case the segment table contains DIRECTMAP and HIGHMEM only. + */ +static struct vm_page_seg vm_page_segs[VM_PAGE_MAX_SEGS]; + +/* + * Bootstrap segment table. + */ +static struct vm_page_boot_seg vm_page_boot_segs[VM_PAGE_MAX_SEGS] __initdata; + +/* + * Number of loaded segments. + */ +static unsigned int vm_page_segs_size __read_mostly; + +static void __init +vm_page_init(struct vm_page *page, unsigned short seg_index, phys_addr_t pa) +{ + memset(page, 0, sizeof(*page)); + page->type = VM_PAGE_RESERVED; + page->seg_index = seg_index; + page->order = VM_PAGE_ORDER_UNLISTED; + page->phys_addr = pa; +} + +void +vm_page_set_type(struct vm_page *page, unsigned int order, unsigned short type) +{ + unsigned int i, nr_pages; + + nr_pages = 1 << order; + + for (i = 0; i < nr_pages; i++) + page[i].type = type; +} + +static void __init +vm_page_free_list_init(struct vm_page_free_list *free_list) +{ + free_list->size = 0; + list_init(&free_list->blocks); +} + +static inline void +vm_page_free_list_insert(struct vm_page_free_list *free_list, + struct vm_page *page) +{ + assert(page->order == VM_PAGE_ORDER_UNLISTED); + + free_list->size++; + list_insert_head(&free_list->blocks, &page->node); +} + +static inline void +vm_page_free_list_remove(struct vm_page_free_list *free_list, + struct vm_page *page) +{ + assert(page->order != VM_PAGE_ORDER_UNLISTED); + + free_list->size--; + list_remove(&page->node); +} + +static struct vm_page * +vm_page_seg_alloc_from_buddy(struct vm_page_seg *seg, unsigned int order) +{ + struct vm_page_free_list *free_list = free_list; + struct vm_page *page, *buddy; + unsigned int i; + + assert(order < VM_PAGE_NR_FREE_LISTS); + + for (i = order; i < VM_PAGE_NR_FREE_LISTS; i++) { + free_list = &seg->free_lists[i]; + + if (free_list->size != 0) + break; + } + + if (i == VM_PAGE_NR_FREE_LISTS) + return NULL; + + page = list_first_entry(&free_list->blocks, struct vm_page, node); + vm_page_free_list_remove(free_list, page); + page->order = VM_PAGE_ORDER_UNLISTED; + + while (i > order) { + i--; + buddy = &page[1 << i]; + vm_page_free_list_insert(&seg->free_lists[i], buddy); + buddy->order = i; + } + + seg->nr_free_pages -= (1 << order); + return page; +} + +static void +vm_page_seg_free_to_buddy(struct vm_page_seg *seg, struct vm_page *page, + unsigned int order) +{ + struct vm_page *buddy; + phys_addr_t pa, buddy_pa; + unsigned int nr_pages; + + assert(page >= seg->pages); + assert(page < seg->pages_end); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + assert(order < VM_PAGE_NR_FREE_LISTS); + + nr_pages = (1 << order); + pa = page->phys_addr; + + while (order < (VM_PAGE_NR_FREE_LISTS - 1)) { + buddy_pa = pa ^ vm_page_ptoa(1 << order); + + if ((buddy_pa < seg->start) || (buddy_pa >= seg->end)) + break; + + buddy = &seg->pages[vm_page_atop(buddy_pa - seg->start)]; + + if (buddy->order != order) + break; + + vm_page_free_list_remove(&seg->free_lists[order], buddy); + buddy->order = VM_PAGE_ORDER_UNLISTED; + order++; + pa &= -vm_page_ptoa(1 << order); + page = &seg->pages[vm_page_atop(pa - seg->start)]; + } + + vm_page_free_list_insert(&seg->free_lists[order], page); + page->order = order; + seg->nr_free_pages += nr_pages; +} + +static void __init +vm_page_cpu_pool_init(struct vm_page_cpu_pool *cpu_pool, int size) +{ + mutex_init(&cpu_pool->lock); + cpu_pool->size = size; + cpu_pool->transfer_size = (size + VM_PAGE_CPU_POOL_TRANSFER_RATIO - 1) + / VM_PAGE_CPU_POOL_TRANSFER_RATIO; + cpu_pool->nr_pages = 0; + list_init(&cpu_pool->pages); +} + +static inline struct vm_page_cpu_pool * +vm_page_cpu_pool_get(struct vm_page_seg *seg) +{ + return &seg->cpu_pools[cpu_id()]; +} + +static inline struct vm_page * +vm_page_cpu_pool_pop(struct vm_page_cpu_pool *cpu_pool) +{ + struct vm_page *page; + + assert(cpu_pool->nr_pages != 0); + cpu_pool->nr_pages--; + page = list_first_entry(&cpu_pool->pages, struct vm_page, node); + list_remove(&page->node); + return page; +} + +static inline void +vm_page_cpu_pool_push(struct vm_page_cpu_pool *cpu_pool, struct vm_page *page) +{ + assert(cpu_pool->nr_pages < cpu_pool->size); + cpu_pool->nr_pages++; + list_insert_head(&cpu_pool->pages, &page->node); +} + +static int +vm_page_cpu_pool_fill(struct vm_page_cpu_pool *cpu_pool, + struct vm_page_seg *seg) +{ + struct vm_page *page; + int i; + + assert(cpu_pool->nr_pages == 0); + + mutex_lock(&seg->lock); + + for (i = 0; i < cpu_pool->transfer_size; i++) { + page = vm_page_seg_alloc_from_buddy(seg, 0); + + if (page == NULL) + break; + + vm_page_cpu_pool_push(cpu_pool, page); + } + + mutex_unlock(&seg->lock); + + return i; +} + +static void +vm_page_cpu_pool_drain(struct vm_page_cpu_pool *cpu_pool, + struct vm_page_seg *seg) +{ + struct vm_page *page; + int i; + + assert(cpu_pool->nr_pages == cpu_pool->size); + + mutex_lock(&seg->lock); + + for (i = cpu_pool->transfer_size; i > 0; i--) { + page = vm_page_cpu_pool_pop(cpu_pool); + vm_page_seg_free_to_buddy(seg, page, 0); + } + + mutex_unlock(&seg->lock); +} + +static phys_addr_t __init +vm_page_seg_size(struct vm_page_seg *seg) +{ + return seg->end - seg->start; +} + +static int __init +vm_page_seg_compute_pool_size(struct vm_page_seg *seg) +{ + phys_addr_t size; + + size = vm_page_atop(vm_page_seg_size(seg)) / VM_PAGE_CPU_POOL_RATIO; + + if (size == 0) + size = 1; + else if (size > VM_PAGE_CPU_POOL_MAX_SIZE) + size = VM_PAGE_CPU_POOL_MAX_SIZE; + + return size; +} + +static void __init +vm_page_seg_init(struct vm_page_seg *seg, phys_addr_t start, phys_addr_t end, + struct vm_page *pages) +{ + phys_addr_t pa; + int pool_size; + unsigned int i; + + seg->start = start; + seg->end = end; + pool_size = vm_page_seg_compute_pool_size(seg); + + for (i = 0; i < ARRAY_SIZE(seg->cpu_pools); i++) + vm_page_cpu_pool_init(&seg->cpu_pools[i], pool_size); + + seg->pages = pages; + seg->pages_end = pages + vm_page_atop(vm_page_seg_size(seg)); + mutex_init(&seg->lock); + + for (i = 0; i < ARRAY_SIZE(seg->free_lists); i++) + vm_page_free_list_init(&seg->free_lists[i]); + + seg->nr_free_pages = 0; + i = seg - vm_page_segs; + + for (pa = seg->start; pa < seg->end; pa += PAGE_SIZE) + vm_page_init(&pages[vm_page_atop(pa - seg->start)], i, pa); +} + +static struct vm_page * +vm_page_seg_alloc(struct vm_page_seg *seg, unsigned int order, + unsigned short type) +{ + struct vm_page_cpu_pool *cpu_pool; + struct vm_page *page; + int filled; + + assert(order < VM_PAGE_NR_FREE_LISTS); + + if (order == 0) { + thread_pin(); + cpu_pool = vm_page_cpu_pool_get(seg); + mutex_lock(&cpu_pool->lock); + + if (cpu_pool->nr_pages == 0) { + filled = vm_page_cpu_pool_fill(cpu_pool, seg); + + if (!filled) { + mutex_unlock(&cpu_pool->lock); + thread_unpin(); + return NULL; + } + } + + page = vm_page_cpu_pool_pop(cpu_pool); + mutex_unlock(&cpu_pool->lock); + thread_unpin(); + } else { + mutex_lock(&seg->lock); + page = vm_page_seg_alloc_from_buddy(seg, order); + mutex_unlock(&seg->lock); + } + + assert(page->type == VM_PAGE_FREE); + vm_page_set_type(page, order, type); + return page; +} + +static void +vm_page_seg_free(struct vm_page_seg *seg, struct vm_page *page, + unsigned int order) +{ + struct vm_page_cpu_pool *cpu_pool; + + assert(page->type != VM_PAGE_FREE); + assert(order < VM_PAGE_NR_FREE_LISTS); + + vm_page_set_type(page, order, VM_PAGE_FREE); + + if (order == 0) { + thread_pin(); + cpu_pool = vm_page_cpu_pool_get(seg); + mutex_lock(&cpu_pool->lock); + + if (cpu_pool->nr_pages == cpu_pool->size) + vm_page_cpu_pool_drain(cpu_pool, seg); + + vm_page_cpu_pool_push(cpu_pool, page); + mutex_unlock(&cpu_pool->lock); + thread_unpin(); + } else { + mutex_lock(&seg->lock); + vm_page_seg_free_to_buddy(seg, page, order); + mutex_unlock(&seg->lock); + } +} + +void __init +vm_page_load(unsigned int seg_index, phys_addr_t start, phys_addr_t end, + phys_addr_t avail_start, phys_addr_t avail_end) +{ + struct vm_page_boot_seg *seg; + + assert(seg_index < ARRAY_SIZE(vm_page_boot_segs)); + assert(vm_page_aligned(start)); + assert(vm_page_aligned(end)); + assert(vm_page_aligned(avail_start)); + assert(vm_page_aligned(avail_end)); + assert(start < end); + assert(start <= avail_start); + assert(avail_end <= end); + assert(vm_page_segs_size < ARRAY_SIZE(vm_page_boot_segs)); + + seg = &vm_page_boot_segs[seg_index]; + seg->start = start; + seg->end = end; + seg->avail_start = avail_start; + seg->avail_end = avail_end; + vm_page_segs_size++; +} + +int +vm_page_ready(void) +{ + return vm_page_is_ready; +} + +static unsigned int +vm_page_select_alloc_seg(unsigned int selector) +{ + unsigned int seg_index; + + switch (selector) { + case VM_PAGE_SEL_DMA: + seg_index = VM_PAGE_SEG_DMA; + break; + case VM_PAGE_SEL_DMA32: + seg_index = VM_PAGE_SEG_DMA32; + break; + case VM_PAGE_SEL_DIRECTMAP: + seg_index = VM_PAGE_SEG_DIRECTMAP; + break; + case VM_PAGE_SEL_HIGHMEM: + seg_index = VM_PAGE_SEG_HIGHMEM; + break; + default: + panic("vm_page: invalid selector"); + } + + return MIN(vm_page_segs_size - 1, seg_index); +} + +static int __init +vm_page_boot_seg_loaded(const struct vm_page_boot_seg *seg) +{ + return (seg->end != 0); +} + +static void __init +vm_page_check_boot_segs(void) +{ + unsigned int i; + int expect_loaded; + + if (vm_page_segs_size == 0) + panic("vm_page: no physical memory loaded"); + + for (i = 0; i < ARRAY_SIZE(vm_page_boot_segs); i++) { + expect_loaded = (i < vm_page_segs_size); + + if (vm_page_boot_seg_loaded(&vm_page_boot_segs[i]) == expect_loaded) + continue; + + panic("vm_page: invalid boot segment table"); + } +} + +static phys_addr_t __init +vm_page_boot_seg_size(struct vm_page_boot_seg *seg) +{ + return seg->end - seg->start; +} + +static phys_addr_t __init +vm_page_boot_seg_avail_size(struct vm_page_boot_seg *seg) +{ + return seg->avail_end - seg->avail_start; +} + +static void * __init +vm_page_bootalloc(size_t size) +{ + struct vm_page_boot_seg *seg; + phys_addr_t pa; + unsigned int i; + + for (i = vm_page_select_alloc_seg(VM_PAGE_SEL_DIRECTMAP); + i < vm_page_segs_size; + i--) { + seg = &vm_page_boot_segs[i]; + + if (size <= vm_page_boot_seg_avail_size(seg)) { + pa = seg->avail_start; + seg->avail_start += vm_page_round(size); + return (void *)vm_page_direct_va(pa); + } + } + + panic("vm_page: no physical memory available"); +} + +void __init +vm_page_setup(void) +{ + struct vm_page_boot_seg *boot_seg; + struct vm_page_seg *seg; + struct vm_page *table, *page, *end; + size_t nr_pages, table_size; + unsigned long va; + unsigned int i; + phys_addr_t pa; + + vm_page_check_boot_segs(); + + /* + * Compute the page table size. + */ + nr_pages = 0; + + for (i = 0; i < vm_page_segs_size; i++) + nr_pages += vm_page_atop(vm_page_boot_seg_size(&vm_page_boot_segs[i])); + + table_size = vm_page_round(nr_pages * sizeof(struct vm_page)); + printk("vm_page: page table size: %zu entries (%zuk)\n", nr_pages, + table_size >> 10); + table = vm_page_bootalloc(table_size); + va = (unsigned long)table; + + /* + * Initialize the segments, associating them to the page table. When + * the segments are initialized, all their pages are set allocated. + * Pages are then released, which populates the free lists. + */ + for (i = 0; i < vm_page_segs_size; i++) { + seg = &vm_page_segs[i]; + boot_seg = &vm_page_boot_segs[i]; + vm_page_seg_init(seg, boot_seg->start, boot_seg->end, table); + page = seg->pages + vm_page_atop(boot_seg->avail_start + - boot_seg->start); + end = seg->pages + vm_page_atop(boot_seg->avail_end + - boot_seg->start); + + while (page < end) { + page->type = VM_PAGE_FREE; + vm_page_seg_free_to_buddy(seg, page, 0); + page++; + } + + table += vm_page_atop(vm_page_seg_size(seg)); + } + + while (va < (unsigned long)table) { + pa = vm_page_direct_pa(va); + page = vm_page_lookup(pa); + assert((page != NULL) && (page->type == VM_PAGE_RESERVED)); + page->type = VM_PAGE_TABLE; + va += PAGE_SIZE; + } + + vm_page_is_ready = 1; +} + +void __init +vm_page_manage(struct vm_page *page) +{ + assert(page->seg_index < ARRAY_SIZE(vm_page_segs)); + assert(page->type == VM_PAGE_RESERVED); + + vm_page_set_type(page, 0, VM_PAGE_FREE); + vm_page_seg_free_to_buddy(&vm_page_segs[page->seg_index], page, 0); +} + +struct vm_page * +vm_page_lookup(phys_addr_t pa) +{ + struct vm_page_seg *seg; + unsigned int i; + + for (i = 0; i < vm_page_segs_size; i++) { + seg = &vm_page_segs[i]; + + if ((pa >= seg->start) && (pa < seg->end)) + return &seg->pages[vm_page_atop(pa - seg->start)]; + } + + return NULL; +} + +struct vm_page * +vm_page_alloc(unsigned int order, unsigned int selector, unsigned short type) +{ + struct vm_page *page; + unsigned int i; + + for (i = vm_page_select_alloc_seg(selector); i < vm_page_segs_size; i--) { + page = vm_page_seg_alloc(&vm_page_segs[i], order, type); + + if (page != NULL) + return page; + } + + if (type == VM_PAGE_PMAP) + panic("vm_page: unable to allocate pmap page"); + + return NULL; +} + +void +vm_page_free(struct vm_page *page, unsigned int order) +{ + assert(page->seg_index < ARRAY_SIZE(vm_page_segs)); + + vm_page_seg_free(&vm_page_segs[page->seg_index], page, order); +} + +const char * +vm_page_seg_name(unsigned int seg_index) +{ + /* Don't use a switch statement since segments can be aliased */ + if (seg_index == VM_PAGE_SEG_HIGHMEM) + return "HIGHMEM"; + else if (seg_index == VM_PAGE_SEG_DIRECTMAP) + return "DIRECTMAP"; + else if (seg_index == VM_PAGE_SEG_DMA32) + return "DMA32"; + else if (seg_index == VM_PAGE_SEG_DMA) + return "DMA"; + else + panic("vm_page: invalid segment index"); +} + +void +vm_page_info(void) +{ + struct vm_page_seg *seg; + unsigned long pages; + unsigned int i; + + for (i = 0; i < vm_page_segs_size; i++) { + seg = &vm_page_segs[i]; + pages = (unsigned long)(seg->pages_end - seg->pages); + printk("vm_page: %s: pages: %lu (%luM), free: %lu (%luM)\n", + vm_page_seg_name(i), pages, pages >> (20 - PAGE_SHIFT), + seg->nr_free_pages, seg->nr_free_pages >> (20 - PAGE_SHIFT)); + } +} |