X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/d07db7c15d6cf9d6c0fd07ea29cca77a89b02a79..4b61c735d6ab7cb250c9a170b87784746476434f:/lunaix-os/kernel/mm/kalloc.c diff --git a/lunaix-os/kernel/mm/kalloc.c b/lunaix-os/kernel/mm/kalloc.c index c932bb5..0ce97e9 100644 --- a/lunaix-os/kernel/mm/kalloc.c +++ b/lunaix-os/kernel/mm/kalloc.c @@ -1,38 +1,284 @@ -#include -#include -#include +/**** DO NOT USE ****/ -#include +/** + * @file kalloc.c + * @author Lunaixsky + * @brief Implicit free list implementation of malloc family, for kernel use. + * + * This version of code is however the simplest and yet insecured, thread unsafe + * it just to demonstrate how the malloc/free works behind the curtain + * @version 0.1 + * @date 2022-03-05 + * + * @copyright Copyright (c) 2022 + * + */ +// #include +// #include +// #include -extern uint8_t __kernel_heap_start; +// #include +// #include -heap_context_t __kalloc_kheap; +// #include -int -kalloc_init() { - __kalloc_kheap.start = &__kernel_heap_start; - __kalloc_kheap.brk = 0; +// #include - return dmm_init(&__kalloc_kheap); -} +// extern uint8_t __kernel_heap_start; -void* -kmalloc(size_t size) { - return lx_malloc(&__kalloc_kheap, size); -} +// void* +// lx_malloc_internal(heap_context_t* heap, size_t size); -void* -kcalloc(size_t size) { - void* ptr = kmalloc(size); - if (!ptr) { - return NULL; - } +// void +// place_chunk(uint8_t* ptr, size_t size); - return memset(ptr, 0, size); -} +// void +// lx_free_internal(void* ptr); -void -kfree(void* ptr) { - lx_free(ptr); -} \ No newline at end of file +// void* +// coalesce(uint8_t* chunk_ptr); + +// void* +// lx_grow_heap(heap_context_t* heap, size_t sz); + +// /* +// At the beginning, we allocate an empty page and put our initial marker + +// | 4/1 | 0/1 | +// ^ ^ brk +// start + +// Then, expand the heap further, with HEAP_INIT_SIZE (evaluated to 4096, +// i.e., +// 1 pg size) This will allocate as much pages and override old epilogue +// marker with a free region hdr and put new epilogue marker. These are +// handled by lx_grow_heap which is internally used by alloc to expand the +// heap at many moment when needed. + +// | 4/1 | 4096/0 | ....... | 4096/0 | 0/1 | +// ^ ^ brk_old ^ +// start brk + +// Note: the brk always point to the beginning of epilogue. +// */ + +// static heap_context_t kheap; + +// int +// kalloc_init() +// { +// kheap.start = KHEAP_START; +// kheap.brk = NULL; +// kheap.max_addr = +// (void*)PROC_START; // 在新的布局中，堆结束的地方即为进程表开始的地方 + +// for (size_t i = 0; i < KHEAP_SIZE_MB >> 2; i++) { +// vmm_set_mapping(PD_REFERENCED, +// (uintptr_t)kheap.start + (i << 22), +// 0, +// PG_PREM_RW, +// VMAP_NOMAP); +// } + +// if (!dmm_init(&kheap)) { +// return 0; +// } + +// SW(kheap.start, PACK(4, M_ALLOCATED)); +// SW(kheap.start + WSIZE, PACK(0, M_ALLOCATED)); +// kheap.brk += WSIZE; + +// return lx_grow_heap(&kheap, HEAP_INIT_SIZE) != NULL; +// } + +// void* +// lxmalloc(size_t size) +// { +// mutex_lock(&kheap.lock); +// void* r = lx_malloc_internal(&kheap, size); +// mutex_unlock(&kheap.lock); + +// return r; +// } + +// void* +// lxcalloc(size_t n, size_t elem) +// { +// size_t pd = n * elem; + +// // overflow detection +// if (pd < elem || pd < n) { +// return NULL; +// } + +// void* ptr = lxmalloc(pd); +// if (!ptr) { +// return NULL; +// } + +// return memset(ptr, 0, pd); +// } + +// void +// lxfree(void* ptr) +// { +// if (!ptr) { +// return; +// } +// mutex_lock(&kheap.lock); + +// uint8_t* chunk_ptr = (uint8_t*)ptr - WSIZE; +// u32_t hdr = LW(chunk_ptr); +// size_t sz = CHUNK_S(hdr); +// uint8_t* next_hdr = chunk_ptr + sz; + +// // make sure the ptr we are 'bout to free makes sense +// // the size trick is stolen from glibc's malloc/malloc.c:4437 ;P + +// assert_msg(((uintptr_t)ptr < (uintptr_t)(-sz)) && !((uintptr_t)ptr & +// 0x3), +// "free(): invalid pointer"); + +// assert_msg(sz > WSIZE, "free(): invalid size"); + +// SW(chunk_ptr, hdr & ~M_ALLOCATED); +// SW(FPTR(chunk_ptr, sz), hdr & ~M_ALLOCATED); +// SW(next_hdr, LW(next_hdr) | M_PREV_FREE); + +// coalesce(chunk_ptr); + +// mutex_unlock(&kheap.lock); +// } + +// void* +// lx_malloc_internal(heap_context_t* heap, size_t size) +// { +// // Simplest first fit approach. + +// if (!size) { +// return NULL; +// } + +// uint8_t* ptr = heap->start; +// // round to largest 4B aligned value +// // and space for header +// size = ROUNDUP(size + WSIZE, BOUNDARY); +// while (ptr < (uint8_t*)heap->brk) { +// u32_t header = *((u32_t*)ptr); +// size_t chunk_size = CHUNK_S(header); +// if (!chunk_size && CHUNK_A(header)) { +// break; +// } +// 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(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) +// { +// u32_t header = *((u32_t*)ptr); +// size_t chunk_size = CHUNK_S(header); +// *((u32_t*)ptr) = PACK(size, CHUNK_PF(header) | M_ALLOCATED); +// uint8_t* n_hdrptr = (uint8_t*)(ptr + size); +// u32_t diff = chunk_size - size; + +// if (!diff) { +// // if the current free block is fully occupied +// u32_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 +// u32_t remainder_hdr = PACK(diff, M_NOT_ALLOCATED | +// M_PREV_ALLOCATED); SW(n_hdrptr, remainder_hdr); SW(FPTR(n_hdrptr, +// diff), remainder_hdr); + +// /* +// | xxxx | | | + +// | +// v + +// | xxxx | | +// */ +// coalesce(n_hdrptr); +// } +// } + +// void* +// coalesce(uint8_t* chunk_ptr) +// { +// u32_t hdr = LW(chunk_ptr); +// u32_t pf = CHUNK_PF(hdr); +// u32_t sz = CHUNK_S(hdr); + +// u32_t n_hdr = LW(chunk_ptr + sz); + +// if (CHUNK_A(n_hdr) && pf) { +// // case 1: prev is free +// u32_t prev_ftr = LW(chunk_ptr - WSIZE); +// size_t prev_chunk_sz = CHUNK_S(prev_ftr); +// u32_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); +// u32_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 +// u32_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); +// u32_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; +// } + +// // (fall through) case 4: prev and next are not free +// return chunk_ptr; +// } + +// void* +// lx_grow_heap(heap_context_t* heap, size_t sz) +// { +// void* start; + +// // The "+ WSIZE" capture the overhead for epilogue marker +// if (!(start = lxsbrk(heap, sz + WSIZE, 0))) { +// return NULL; +// } +// sz = ROUNDUP(sz, BOUNDARY); + +// // minus the overhead for epilogue, keep the invariant. +// heap->brk -= WSIZE; + +// u32_t old_marker = *((u32_t*)start); +// u32_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); +// } \ No newline at end of file