X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/4c6d990440cdba6c7dd294adb7e435770ffcbcc4..61bcf0c65dac58d2f29ab40e016489c89ec8eec0:/lunaix-os/kernel/mm/dmm.c diff --git a/lunaix-os/kernel/mm/dmm.c b/lunaix-os/kernel/mm/dmm.c index 02d094c..cb87202 100644 --- a/lunaix-os/kernel/mm/dmm.c +++ b/lunaix-os/kernel/mm/dmm.c @@ -1,13 +1,14 @@ /** * @file dmm.c * @author Lunaixsky - * @brief Dynamic memory manager dedicated to kernel heap. Using implicit free - * list implementation. This is designed to be portable, so it can serve as - * syscalls to malloc/free in the c std lib. - * - * This version of code is however the simplest and yet insecured, - * it just to demonstrate how the malloc/free works behind the stage - * + * @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 * @@ -18,41 +19,30 @@ #include #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))) +extern void __kernel_heap_start; -#define BOUNDARY 4 -#define WSIZE 4 - -void* -coalesce(uint8_t* chunk_ptr); - -void* -lx_grow_heap(heap_context_t* heap, size_t sz); +__DEFINE_LXSYSCALL1(int, sbrk, size_t, size) +{ + heap_context_t* uheap = &__current->mm.u_heap; + mutex_lock(&uheap->lock); + void* r = lxsbrk(uheap, size, PG_ALLOW_USER); + mutex_unlock(&uheap->lock); + return r; +} -void -place_chunk(uint8_t* ptr, size_t size); +__DEFINE_LXSYSCALL1(void*, brk, void*, addr) +{ + heap_context_t* uheap = &__current->mm.u_heap; + mutex_lock(&uheap->lock); + int r = lxbrk(uheap, addr, PG_ALLOW_USER); + mutex_unlock(&uheap->lock); + return r; +} int dmm_init(heap_context_t* heap) @@ -60,188 +50,53 @@ dmm_init(heap_context_t* heap) assert((uintptr_t)heap->start % BOUNDARY == 0); heap->brk = heap->start; + mutex_init(&heap->lock); - vmm_alloc_page(heap->brk, PG_PREM_RW); - - SW(heap->start, PACK(4, M_ALLOCATED)); - SW(heap->start + WSIZE, PACK(0, M_ALLOCATED)); - heap->brk += WSIZE; + int perm = PG_ALLOW_USER; + if (heap->brk >= &__kernel_heap_start) { + perm = 0; + } - return lx_grow_heap(heap, HEAP_INIT_SIZE) != NULL; + return vmm_set_mapping(PD_REFERENCED, heap->brk, 0, PG_WRITE | perm) != + NULL; } int -lxsbrk(heap_context_t* heap, void* addr) +lxbrk(heap_context_t* heap, void* addr, int user) { - return lxbrk(heap, addr - heap->brk) != NULL; + return -(lxsbrk(heap, addr - heap->brk, user) == (void*)-1); } void* -lxbrk(heap_context_t* heap, size_t size) +lxsbrk(heap_context_t* heap, size_t size, int user) { if (size == 0) { return heap->brk; } + void* current_brk = heap->brk; + // The upper bound of our next brk of heap given the size. // This will be used to calculate the page we need to allocate. - // The "+ WSIZE" capture the overhead for epilogue marker - void* next = heap->brk + ROUNDUP(size + WSIZE, WSIZE); + void* next = current_brk + ROUNDUP(size, BOUNDARY); - if ((uintptr_t)next >= K_STACK_START) { - return NULL; + // any invalid situations + if (next >= heap->max_addr || next < current_brk) { + __current->k_status = LXINVLDPTR; + return (void*)-1; } - uintptr_t heap_top_pg = PG_ALIGN(heap->brk); - if (heap_top_pg != PG_ALIGN(next)) { - // 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)) { - return NULL; + uintptr_t diff = PG_ALIGN(next) - PG_ALIGN(current_brk); + if (diff) { + // if next do require new pages to be mapped + for (size_t i = 0; i < diff; i += PG_SIZE) { + vmm_set_mapping(PD_REFERENCED, + PG_ALIGN(current_brk) + PG_SIZE + i, + 0, + PG_WRITE | user); } } - void* old = heap->brk; heap->brk += size; - return old; -} - -void* -lx_grow_heap(heap_context_t* heap, size_t sz) -{ - void* start; - - if (!(start = lxbrk(heap, sz))) { - return NULL; - } - sz = ROUNDUP(sz, BOUNDARY); - - 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(heap_context_t* heap, size_t size) -{ - // Simplest first fit approach. - - uint8_t* ptr = heap->start; - // round to largest 4B aligned value - // and space for header - size = ROUNDUP(size, BOUNDARY) + WSIZE; - while (ptr < (uint8_t*)heap->brk) { - 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(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); - 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 comes from: - // https://sourceware.org/git/?p=glibc.git;a=blob;f=malloc/malloc.c;h=1a1ac1d8f05b6f9bf295d7fdd0f12c2e4650a33c;hb=HEAD#l4437 - assert_msg(((uintptr_t)ptr < (uintptr_t)(-sz)) && !((uintptr_t)ptr & ~0x3), - "free(): invalid pointer"); - assert_msg(sz > WSIZE && (sz & ~0x3), - "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); -} - -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; + return current_brk; } \ No newline at end of file