X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/7b0dccbab69e806a63c4504c3ddb82e45241985b..b0c2a4be2d1f4f93ab01d0858979a12ef0735ec1:/lunaix-os/kernel/mm/dmm.c diff --git a/lunaix-os/kernel/mm/dmm.c b/lunaix-os/kernel/mm/dmm.c index e5f2ec5..ae89908 100644 --- a/lunaix-os/kernel/mm/dmm.c +++ b/lunaix-os/kernel/mm/dmm.c @@ -1,238 +1,71 @@ /** * @file dmm.c * @author Lunaixsky - * @brief Dynamic memory manager dedicated to kernel heap. It is not portable at - * this moment. Implicit free list implementation. - * @version 0.1 - * @date 2022-02-28 + * @brief Dynamic memory manager for heap. This design do not incorporate any\ + * specific implementation of malloc family. The main purpose of this routines is to + * provide handy method to initialize & grow the heap as needed by upstream implementation. + * + * This is designed to be portable, so it can serve as syscalls to malloc/free in the c std lib. + * + * @version 0.2 + * @date 2022-03-3 * * @copyright Copyright (c) Lunaixsky 2022 * */ -// TODO: Make the dmm portable - #include -#include #include +#include -#include #include -#define M_ALLOCATED 0x1 -#define M_PREV_FREE 0x2 - -#define M_NOT_ALLOCATED 0x0 -#define M_PREV_ALLOCATED 0x0 - -#define CHUNK_S(header) ((header) & ~0x3) -#define CHUNK_PF(header) ((header)&M_PREV_FREE) -#define CHUNK_A(header) ((header)&M_ALLOCATED) - -#define PACK(size, flags) (((size) & ~0x3) | (flags)) - -#define SW(p, w) (*((uint32_t*)(p)) = w) -#define LW(p) (*((uint32_t*)(p))) - -#define HPTR(bp) ((uint32_t*)(bp)-1) -#define BPTR(bp) ((uint8_t*)(bp) + WSIZE) -#define FPTR(hp, size) ((uint32_t*)(hp + size - WSIZE)) -#define NEXT_CHK(hp) ((uint8_t*)(hp) + CHUNK_S(LW(hp))) - -#define BOUNDARY 4 -#define WSIZE 4 - -extern uint8_t __kernel_heap_start; - -void* current_heap_top = NULL; - -void* -coalesce(uint8_t* chunk_ptr); - -void* -lx_grow_heap(size_t sz); - -void place_chunk(uint8_t* ptr, size_t size); - int -dmm_init() +dmm_init(heap_context_t* heap) { - assert((uintptr_t)&__kernel_heap_start % BOUNDARY == 0); + assert((uintptr_t)heap->start % BOUNDARY == 0); - current_heap_top = &__kernel_heap_start; - uint8_t* heap_start = &__kernel_heap_start; - - vmm_alloc_page(current_heap_top, PG_PREM_RW); + heap->brk = heap->start; - SW(heap_start, PACK(4, M_ALLOCATED)); - SW(heap_start + WSIZE, PACK(0, M_ALLOCATED)); - current_heap_top += WSIZE; - - return lx_grow_heap(HEAP_INIT_SIZE) != NULL; + return vmm_alloc_page(heap->brk, PG_PREM_RW) != NULL; } int -lxsbrk(void* addr) +lxsbrk(heap_context_t* heap, void* addr) { - return lxbrk(addr - current_heap_top) != NULL; + return lxbrk(heap, addr - heap->brk) != NULL; } void* -lxbrk(size_t size) -{ +lxbrk(heap_context_t* heap, size_t size) +{ if (size == 0) { - return current_heap_top; + return heap->brk; } - // plus WSIZE is the overhead for epilogue marker - size += WSIZE; - void* next = current_heap_top + ROUNDUP((uintptr_t)size, WSIZE); + void* current_brk = heap->brk; - if ((uintptr_t)next >= K_STACK_START) { + // The upper bound of our next brk of heap given the size. + // This will be used to calculate the page we need to allocate. + void* next = current_brk + ROUNDUP(size, BOUNDARY); + + // any invalid situations + if (next >= heap->max_addr || next < current_brk) { return NULL; } - // Check the invariant - assert(size % BOUNDARY == 0) - - uintptr_t heap_top_pg = PG_ALIGN(current_heap_top); - if (heap_top_pg != PG_ALIGN(next)) - { + uintptr_t diff = PG_ALIGN(next) - PG_ALIGN(current_brk); + if (diff) { // if next do require new pages to be allocated - if (!vmm_alloc_pages((void*)(heap_top_pg + PG_SIZE), ROUNDUP(size, PG_SIZE), PG_PREM_RW)) { + if (!vmm_alloc_pages((void*)(PG_ALIGN(current_brk) + PG_SIZE), + diff, + PG_PREM_RW)) { + // for debugging + assert_msg(0, "unable to brk"); return NULL; } - - } - - void* old = current_heap_top; - current_heap_top = next - WSIZE; - return old; -} - -void* -lx_grow_heap(size_t sz) { - void* start; - - sz = ROUNDUP(sz, BOUNDARY); - if (!(start = lxbrk(sz))) { - return NULL; - } - - uint32_t old_marker = *((uint32_t*)start); - uint32_t free_hdr = PACK(sz, CHUNK_PF(old_marker)); - SW(start, free_hdr); - SW(FPTR(start, sz), free_hdr); - SW(NEXT_CHK(start), PACK(0, M_ALLOCATED | M_PREV_FREE)); - - return coalesce(start); -} - -void* -lx_malloc(size_t size) -{ - // Simplest first fit approach. - - uint8_t* ptr = &__kernel_heap_start; - // round to largest 4B aligned value - // and space for header - size = ROUNDUP(size, BOUNDARY) + WSIZE; - while (ptr < (uint8_t*)current_heap_top) { - uint32_t header = *((uint32_t*)ptr); - size_t chunk_size = CHUNK_S(header); - if (chunk_size >= size && !CHUNK_A(header)) { - // found! - place_chunk(ptr, size); - return BPTR(ptr); - } - ptr += chunk_size; - } - - // if heap is full (seems to be!), then allocate more space (if it's okay...) - if ((ptr = lx_grow_heap(size))) { - place_chunk(ptr, size); - return BPTR(ptr); - } - - // Well, we are officially OOM! - return NULL; -} - -void place_chunk(uint8_t* ptr, size_t size) { - uint32_t header = *((uint32_t*)ptr); - size_t chunk_size = CHUNK_S(header); - *((uint32_t*)ptr) = PACK(size, CHUNK_PF(header) | M_ALLOCATED); - uint8_t* n_hdrptr = (uint8_t*)(ptr + size); - uint32_t diff = chunk_size - size; - if (!diff) { - // if the current free block is fully occupied - uint32_t n_hdr = LW(n_hdrptr); - // notify the next block about our avaliability - SW(n_hdrptr, n_hdr & ~0x2); - } else { - // if there is remaining free space left - uint32_t remainder_hdr = - PACK(diff, M_NOT_ALLOCATED | M_PREV_ALLOCATED); - SW(n_hdrptr, remainder_hdr); - SW(FPTR(n_hdrptr, diff), remainder_hdr); - - coalesce(n_hdrptr); - } -} - -void -lx_free(void* ptr) -{ - if (!ptr) { - return; - } - - uint8_t* chunk_ptr = (uint8_t*)ptr - WSIZE; - uint32_t hdr = LW(chunk_ptr); - uint8_t* next_hdr = chunk_ptr + CHUNK_S(hdr); - - SW(chunk_ptr, hdr & ~M_ALLOCATED); - SW(FPTR(chunk_ptr, CHUNK_S(hdr)), hdr & ~M_ALLOCATED); - SW(next_hdr, LW(next_hdr) | M_PREV_FREE); - - coalesce(chunk_ptr); -} - -void* -coalesce(uint8_t* chunk_ptr) -{ - uint32_t hdr = LW(chunk_ptr); - uint32_t pf = CHUNK_PF(hdr); - uint32_t sz = CHUNK_S(hdr); - - uint32_t n_hdr = LW(chunk_ptr + sz); - - if (CHUNK_A(n_hdr) && pf) { - // case 1: prev is free - uint32_t prev_ftr = LW(chunk_ptr - WSIZE); - size_t prev_chunk_sz = CHUNK_S(prev_ftr); - uint32_t new_hdr = PACK(prev_chunk_sz + sz, CHUNK_PF(prev_ftr)); - SW(chunk_ptr - prev_chunk_sz, new_hdr); - SW(FPTR(chunk_ptr, sz), new_hdr); - chunk_ptr -= prev_chunk_sz; - } else if (!CHUNK_A(n_hdr) && !pf) { - // case 2: next is free - size_t next_chunk_sz = CHUNK_S(n_hdr); - uint32_t new_hdr = PACK(next_chunk_sz + sz, pf); - SW(chunk_ptr, new_hdr); - SW(FPTR(chunk_ptr, sz + next_chunk_sz), new_hdr); - } else if (!CHUNK_A(n_hdr) && pf) { - // case 3: both free - uint32_t prev_ftr = LW(chunk_ptr - WSIZE); - size_t next_chunk_sz = CHUNK_S(n_hdr); - size_t prev_chunk_sz = CHUNK_S(prev_ftr); - uint32_t new_hdr = - PACK(next_chunk_sz + prev_chunk_sz + sz, CHUNK_PF(prev_ftr)); - SW(chunk_ptr - prev_chunk_sz, new_hdr); - SW(FPTR(chunk_ptr, sz + next_chunk_sz), new_hdr); - chunk_ptr -= prev_chunk_sz; } - // case 4: prev and next are not free - return chunk_ptr; + heap->brk += size; + return current_brk; } \ No newline at end of file