refactor: clean up the virtual memory mappings

[lunaix-os.git] / lunaix-os / kernel / mm / dmm.c

diff --git a/lunaix-os/kernel/mm/dmm.c b/lunaix-os/kernel/mm/dmm.c
index 31c28b6807173c68715e6edb1c8aab1edeffad4c..edc28efadeb77ec6f7c16b2a16a038849f9ef84d 100644 (file)
--- a/lunaix-os/kernel/mm/dmm.c
+++ b/lunaix-os/kernel/mm/dmm.c
@@ -1,53 +1,46 @@
 /**
  * @file dmm.c
  * @author Lunaixsky
 /**
  * @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.
- * @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
  *
  */
 
  *
  * @copyright Copyright (c) Lunaixsky 2022
  *
  */
 

-

 #include <lunaix/mm/dmm.h>
 #include <lunaix/mm/page.h>
 #include <lunaix/mm/vmm.h>
 #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/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)
 
 int
 dmm_init(heap_context_t* heap)


@@ -55,179 +48,52 @@ dmm_init(heap_context_t* heap)
     assert((uintptr_t)heap->start % BOUNDARY == 0);
 
     heap->brk = heap->start;
     assert((uintptr_t)heap->start % BOUNDARY == 0);
 
     heap->brk = heap->start;

-    
-    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;
+    mutex_init(&heap->lock);

 
 

-    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
 }
 
 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*
 }
 
 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;
     }
 
     if (size == 0) {
         return heap->brk;
     }
 

-    // plus WSIZE is the overhead for epilogue marker
-    size += WSIZE;
-    void* next = heap->brk + 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(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;
-        }
-    
-    }
+    void* current_brk = heap->brk;

 
 

-    void* old = heap->brk;
-    heap->brk = next - WSIZE;
-    return old;
-}
-
-void*
-lx_grow_heap(heap_context_t* heap, size_t sz) {
-    void* 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);

 
 

-    sz = ROUNDUP(sz, BOUNDARY);
-    if (!(start = lxbrk(heap, sz))) {
-        return NULL;
+    // any invalid situations
+    if (next >= heap->max_addr || next < current_brk) {
+        __current->k_status = LXINVLDPTR;
+        return (void*)-1;

     }
 
     }
 

-    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);
+    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);

         }
         }

-        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;
-
-    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;
+    heap->brk += size;
+    return current_brk;

 }
\ No newline at end of file
 }
\ No newline at end of file