diff options
Diffstat (limited to '')
| -rw-r--r-- | kernel/memory/physalloc.c | 93 |
1 files changed, 73 insertions, 20 deletions
diff --git a/kernel/memory/physalloc.c b/kernel/memory/physalloc.c index b164358..8971bcf 100644 --- a/kernel/memory/physalloc.c +++ b/kernel/memory/physalloc.c @@ -4,20 +4,19 @@ #include "physalloc.h" -extern char kernel_start; -extern char kernel_end; -#define kaddr(addr) ((uintptr_t)(&addr)) +extern char kernel_start[]; +extern char kernel_end[]; // between memory_start and kernel_start will be the bitmap static uintptr_t memory_start = 0; -static uint64_t *bitmap; +static uint64_t *bitmap = NULL; static uint64_t total_memory; static uint64_t free_memory; static uint64_t page_count; static uint64_t segment_count; struct memory_map phys_mmap; -struct memory_segment *page_start; +struct memory_segment *page_start = NULL; static const char *segment_type_str[] = { [SEG_TYPE_FREE] = "Free", [SEG_TYPE_RESERVED] = "Reserved", @@ -50,6 +49,9 @@ static long page_idx(void *page) int cur_page = 0; for (uint64_t idx = 0; idx < segment_count; idx++) { const struct memory_segment *m = page_start; + if (addr < m->addr) { + return -1; + } if ((uintptr_t)m + m->len > addr) { return cur_page + ((addr - m->addr) / PAGE_SIZE); } @@ -58,12 +60,12 @@ static long page_idx(void *page) return -1; } -static inline bool bitmap_get(int i) +static inline bool bitmap_get(size_t i) { return (bitmap[i / 64] >> i % 64) & 1; } -static inline void bitmap_set(int i, bool v) +static inline void bitmap_set(size_t i, bool v) { if (v) free_memory -= PAGE_SIZE; @@ -76,17 +78,26 @@ static inline void bitmap_set(int i, bool v) void *alloc_phys_page(void) { - return alloc_phys_pages(1); + return alloc_phys_pages_exact(1); } -void *alloc_phys_pages(int pages) +void *alloc_phys_pages_exact(size_t pages) { if (pages < 1) return NULL; - int n_contiguous = 0; - int free_region_start = 0; - for (uint64_t i = 0; i < page_count; i++) { + if (bitmap == NULL || page_start == NULL) { + // temporary bump allocator + void *addr = (void *)memory_start; + assert(pages == 1, + "caller expects more pages, but is only getting one"); + memory_start += PAGE_SIZE; + return addr; + } + + size_t n_contiguous = 0; + size_t free_region_start = 0; + for (size_t i = 0; i < page_count; i++) { bool free = !bitmap_get(i); if (free) { @@ -94,7 +105,7 @@ void *alloc_phys_pages(int pages) free_region_start = i; n_contiguous++; if (n_contiguous == pages) { - for (int j = 0; j < pages; j++) + for (size_t j = 0; j < pages; j++) bitmap_set(free_region_start + j, true); return page_at(free_region_start); } @@ -105,12 +116,54 @@ void *alloc_phys_pages(int pages) return NULL; } +struct phys_page_slice alloc_phys_page_withextra(size_t max_pages) +{ + if (max_pages == 0) + return PHYS_PAGE_SLICE_NULL; + + for (size_t i = 0; i < page_count; i++) { + const bool free = !bitmap_get(i); + if (!free) + continue; + + // now allocated + bitmap_set(i, true); + + // found at least one page, guaranteed to return valid slice at this + // point + struct phys_page_slice out = { + .pagestart = page_at(i), + .num_pages = 1, + }; + + // add some extra pages if possible + for (; out.num_pages < MIN(page_count - i, max_pages); + ++out.num_pages) { + // early return if max_pages isn't available + if (bitmap_get(i + out.num_pages)) { + return out; + } + bitmap_set(i + out.num_pages, true); + } + + return out; + } + + // only reachable if there is not a single free page in the bitmap + return PHYS_PAGE_SLICE_NULL; +} + void free_phys_page(void *ptr) { free_phys_pages(ptr, 1); } -void free_phys_pages(void *ptr, int pages) +void free_phys_pages_slice(struct phys_page_slice slice) +{ + free_phys_pages(slice.pagestart, slice.num_pages); +} + +void free_phys_pages(void *ptr, size_t pages) { if (ptr == NULL) return; @@ -119,8 +172,8 @@ void free_phys_pages(void *ptr, int pages) if (idx == -1) return; - for (int i = 0; i < pages; i++) - bitmap_set(idx + pages, false); + for (size_t i = 0; i < pages; i++) + bitmap_set(idx + i, false); } static bool segment_invalid(const struct memory_segment *segment) @@ -129,11 +182,11 @@ static bool segment_invalid(const struct memory_segment *segment) return true; if (segment->type != SEG_TYPE_FREE) return true; - if (segment->addr < kaddr(kernel_start)) + if (segment->addr < (uintptr_t)kernel_start) return true; if (segment->addr + segment->len < memory_start) return true; - if (segment->addr + segment->len < kaddr(kernel_start)) + if (segment->addr + segment->len < (uintptr_t)kernel_start) return true; return false; } @@ -147,7 +200,7 @@ static struct memory_segment clamp_segment(const struct memory_segment *segment) if (memory_start) start = memory_start; else - start = kaddr(kernel_end); + start = (uintptr_t)kernel_end; if (segment->addr < start) { addr = start; @@ -192,7 +245,7 @@ void physalloc_init(struct memory_map *map) long bitmap_pages = (page_count / 64 / PAGE_SIZE) + 1; long bitmap_size = bitmap_pages * PAGE_SIZE; - bitmap = (uint64_t *)page_align(kaddr(kernel_end)); + bitmap = (uint64_t *)page_align((uintptr_t)kernel_end); long page_area_size = segment_count * sizeof(struct memory_segment); char *page_area_addr = (char *)bitmap + bitmap_size; 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