/**
* @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
*
#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
-
-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)
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;
-
- return lx_grow_heap(heap, HEAP_INIT_SIZE) != NULL;
+ return vmm_set_mapping(PD_REFERENCED,
+ heap->brk,
+ 0,
+ PG_WRITE | PG_ALLOW_USER,
+ VMAP_NULL) != 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,
+ VMAP_NULL);
}
}
- 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
git://scm.lunaixsky.com / lunaix-os.git / blobdiff