-/**
- * @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
- *
- * @copyright Copyright (c) Lunaixsky 2022
- *
- */
-
-// TODO: Make the dmm portable
-
-#include <lunaix/mm/dmm.h>
#include <lunaix/mm/page.h>
#include <lunaix/mm/vmm.h>
+#include <lunaix/status.h>
-#include <lunaix/constants.h>
#include <lunaix/spike.h>
+#include <lunaix/syscall.h>
-#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()
-{
- assert((uintptr_t)&__kernel_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);
-
- 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;
-}
-
-int
-lxsbrk(void* addr)
-{
- return lxbrk(addr - current_heap_top) != NULL;
-}
-
-void*
-lxbrk(size_t size)
-{
- if (size == 0) {
- return current_heap_top;
- }
-
- // plus WSIZE is the overhead for epilogue marker
- size += WSIZE;
- void* next = current_heap_top + ROUNDUP((uintptr_t)size, WSIZE);
-
- if ((uintptr_t)next >= K_STACK_START) {
- 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))
- {
- // 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;
- }
-
- }
-
- 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)
+__DEFINE_LXSYSCALL1(int, sbrk, 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;
+ // TODO mem_remap to expand heap region
+ return 0;
}
-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)
+__DEFINE_LXSYSCALL1(void*, brk, void*, addr)
{
- 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;
+ // TODO mem_remap to expand heap region
+ return 0;
}
\ No newline at end of file
git://scm.lunaixsky.com / lunaix-os.git / blobdiff