mm: generalize boot allocator
The boot page frame allocator is now architecture independent. This is part 2 of the mm subsystem refactor.main
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7285c2e076
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/* Copyright (C) 2021 fef <owo@fef.moe>. All rights reserved. */
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#pragma once
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/** @brief Maximum address for legacy DMA transfers */
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#define DMA_LIMIT (1 << 24)
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/* Copyright (C) 2021 fef <owo@fef.moe>. All rights reserved. */
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#include <gay/clist.h>
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#include <gay/linker.h>
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#include <gay/mm.h>
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#include <gay/systm.h>
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#include <gay/util.h>
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#include <limits.h>
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static struct _bmem_area _bmem_area_cache[16];
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static CLIST(bmem_area_freelist);
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#ifdef DEBUG
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#define debug_free_bmem_area(area) ({ (area)->start = ~(vm_paddr_t)0; })
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#define debug_get_bmem_area(area) KASSERT((area)->start != ~(vm_paddr_t)0)
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#else
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#define debug_free_bmem_area(area) ({})
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#define debug_get_bmem_area(area) ({})
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#endif
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static struct _bmem_area *get_bmem_area(void)
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{
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/* XXX this should pretty much never happen, but it would still be nice to
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* have at least some sort of error recovery rather than giving up */
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if (clist_is_empty(&bmem_area_freelist))
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panic("Boot memory allocator has run out of areas");
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struct _bmem_area *area = clist_del_first_entry(&bmem_area_freelist, typeof(*area), link);
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debug_get_bmem_area(area);
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return area;
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}
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static void free_bmem_area(struct _bmem_area *area)
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{
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debug_free_bmem_area(area);
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clist_add(&bmem_area_freelist, &area->link);
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}
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static void insert_area_unsafe(vm_paddr_t start, vm_paddr_t end, enum mm_zone_type zone_type)
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{
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KASSERT((start % PAGE_SIZE) == 0);
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KASSERT((end % PAGE_SIZE) == 0);
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struct _bmem_area *area = get_bmem_area();
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area->start = start;
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area->end = end;
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struct mm_zone *zone = &mm_zones[zone_type];
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struct _bmem_area *cursor;
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clist_foreach_entry(&zone->_bmem_areas, cursor, link) {
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if (cursor->start > area->start)
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break;
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}
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clist_insert_before(&cursor->link, &area->link);
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}
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void __boot_pmalloc_init(void)
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{
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for (int i = 0; i < ARRAY_SIZE(_bmem_area_cache); i++) {
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struct _bmem_area *area = &_bmem_area_cache[i];
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debug_free_bmem_area(area);
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clist_add(&bmem_area_freelist, &area->link);
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}
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}
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void __boot_register_mem_area(vm_paddr_t start, vm_paddr_t end, enum mm_zone_type zone_type)
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{
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KASSERT(start < end);
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start = align_ceil(start, PAGE_SIZE);
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end = align_floor(end, PAGE_SIZE);
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if (start == end)
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return;
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/* check for any overlaps with the kernel image and avoid those regions */
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if (start <= image_start_phys && end >= image_end_phys) {
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/*
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* 0x8000 ---------------------- end (-> high_end)
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* 0x7000 <free real estate>
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* 0x6000 ---------------------- image_end_phys (-> high_start)
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* 0x5000 <kernel code & data>
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* 0x4000 ---------------------- image_start_phys (-> low_end)
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* 0x3000 <free real estate>
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* 0x2000 ---------------------- start (-> low_start)
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*/
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vm_paddr_t low_start = start;
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vm_paddr_t low_end = align_floor(image_start_phys, PAGE_SIZE);
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if (low_start < low_end)
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insert_area_unsafe(low_start, low_end, zone_type);
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vm_paddr_t high_start = align_ceil(image_end_phys, PAGE_SIZE);
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vm_paddr_t high_end = end;
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if (high_start < high_end)
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insert_area_unsafe(high_start, high_end, zone_type);
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} else if (start >= image_start_phys && start <= image_end_phys) {
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/*
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* 0x8000 ---------------------- end (-> high_end)
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* 0x7000 <free real estate>
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* 0x6000 ---------------------- image_end_phys (-> high_start)
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* 0x5000 <kernel code & data>
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* 0x4000 ---------------------- start
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* 0x3000 <not part of area>
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* 0x2000 ---------------------- image_start_phys
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*/
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vm_paddr_t high_start = align_ceil(image_end_phys, PAGE_SIZE);
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vm_paddr_t high_end = end;
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if (high_start < high_end)
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insert_area_unsafe(high_start, high_end, zone_type);
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} else if (end >= image_start_phys && end <= image_end_phys) {
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/*
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* 0x8000 ---------------------- image_end_phys
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* 0x7000 <not part of area>
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* 0x6000 ---------------------- end
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* 0x5000 <kernel code & data>
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* 0x4000 ---------------------- image_start_phys (-> low_end)
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* 0x3000 <free real estate>
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* 0x2000 ---------------------- start (-> low_start)
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*/
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vm_paddr_t low_start = start;
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vm_paddr_t low_end = align_floor(image_start_phys, PAGE_SIZE);
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if (low_start < low_end)
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insert_area_unsafe(low_start, low_end, zone_type);
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} else {
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insert_area_unsafe(start, end, zone_type);
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}
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}
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vm_paddr_t __boot_pmalloc(u_int log2, enum mm_zone_type zone_type)
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{
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/* never hand out less than a full page */
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KASSERT(log2 >= PAGE_SHIFT);
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/* this might fail if someone accidentally gives us a size rather than shift */
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KASSERT(log2 < sizeof(vm_paddr_t) * CHAR_BIT);
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const vm_size_t alloc_size = (vm_size_t)1 << log2;
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struct mm_zone *zone = &mm_zones[zone_type];
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struct _bmem_area *cursor;
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clist_foreach_entry_rev(&zone->_bmem_areas, cursor, link) {
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vm_paddr_t area_start = cursor->start;
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vm_paddr_t area_end = cursor->end;
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KASSERT(area_start < area_end);
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/* XXX we should really use a best-fit algorithm for this */
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vm_paddr_t alloc_start = align_ceil(area_start, alloc_size);
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vm_paddr_t alloc_end = alloc_start + alloc_size;
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if (alloc_start >= area_start && alloc_end <= area_end) {
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/*
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* Example with log2 == 18 (alloc_size == 0x4000):
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*
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* 0x8000 ------------------- area_end
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* 0x7000 <high_rest>
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* 0x8000 ------------------- alloc_end (aligned to 0x4000)
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* : <allocated block>
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* 0x4000 ------------------- alloc_start (aligned to 0x4000)
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* 0x3000 <low_rest>
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* 0x2000 ------------------- area_start
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*/
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if (alloc_start > area_start) {
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struct _bmem_area *low_rest = get_bmem_area();
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low_rest->start = area_start;
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low_rest->end = alloc_start;
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clist_insert_before(&cursor->link, &low_rest->link);
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}
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if (alloc_end < area_end) {
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struct _bmem_area *high_rest = get_bmem_area();
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high_rest->start = alloc_end;
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high_rest->end = area_end;
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clist_insert_after(&cursor->link, &high_rest->link);
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}
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clist_del(&cursor->link);
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free_bmem_area(cursor);
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return alloc_start;
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}
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}
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return BOOT_PMALLOC_ERR;
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}
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