5-malloc.md (#25)

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

diff --git a/lunaix-os/kernel/mm/vmap.c b/lunaix-os/kernel/mm/vmap.c
index 35f61e425e45d9e464eb2635e0ee1091016f4ee9..f805adc6b13673c2c6595306c4d29bce5d4f454b 100644 (file)
--- a/lunaix-os/kernel/mm/vmap.c
+++ b/lunaix-os/kernel/mm/vmap.c
@@ -1,4 +1,5 @@
 #include <lunaix/mm/pmm.h>
+#include <lunaix/mm/valloc.h>
 #include <lunaix/mm/vmm.h>
 #include <lunaix/spike.h>
 
@@ -7,7 +8,7 @@
 static ptr_t start = VMAP;
 
 void*
-vmm_vmap(ptr_t paddr, size_t size, pt_attr attr)
+vmap(ptr_t paddr, size_t size, pt_attr attr, int flags)
 {
     // next fit
     assert_msg((paddr & 0xfff) == 0, "vmap: bad alignment");
@@ -17,12 +18,12 @@ vmm_vmap(ptr_t paddr, size_t size, pt_attr attr)
     size_t examed_size = 0, wrapped = 0;
     x86_page_table* pd = (x86_page_table*)L1_BASE_VADDR;
 
-    while (!wrapped || current_addr >= start) {
+    while (!wrapped || current_addr < start) {
         size_t l1inx = L1_INDEX(current_addr);
         if (!(pd->entry[l1inx])) {
             // empty 4mb region
-            examed_size += MEM_4MB;
-            current_addr = (current_addr & 0xffc00000) + MEM_4MB;
+            examed_size += MEM_4M;
+            current_addr = (current_addr & 0xffc00000) + MEM_4M;
         } else {
             x86_page_table* ptd = (x86_page_table*)(L2_VADDR(l1inx));
             size_t i = L2_INDEX(current_addr), j = 0;
@@ -54,11 +55,90 @@ vmm_vmap(ptr_t paddr, size_t size, pt_attr attr)
 
 done:
     ptr_t alloc_begin = current_addr - examed_size;
+    start = alloc_begin + size;
+
+    if ((flags & VMAP_NOMAP)) {
+        for (size_t i = 0; i < size; i += PG_SIZE) {
+            vmm_set_mapping(VMS_SELF, alloc_begin + i, -1, 0, 0);
+        }
+
+        return (void*)alloc_begin;
+    }
+
     for (size_t i = 0; i < size; i += PG_SIZE) {
-        vmm_set_mapping(VMS_SELF, alloc_begin + i, paddr + i, PG_PREM_RW, 0);
-        pmm_ref_page(KERNEL_PID, paddr + i);
+        vmm_set_mapping(VMS_SELF, alloc_begin + i, paddr + i, attr, 0);
+        pmm_ref_page(paddr + i);
     }
-    start = alloc_begin + size;
 
     return (void*)alloc_begin;
+}
+
+/*
+    This is a kernel memory region that represent a contiguous virtual memory
+   address such that all memory allocation/deallocation can be concentrated
+   into a single big chunk, which will help to mitigate the external
+   fragmentation in the VMAP address domain. It is significant if our
+   allocation granule is single page or in some use cases.
+
+    XXX (vmap_area)
+    A potential performance improvement on pcache? (need more analysis!)
+        -> In exchange of a fixed size buffer pool. (does it worth?)
+*/
+
+struct vmap_area*
+vmap_varea(size_t size, pt_attr attr)
+{
+    ptr_t start = (ptr_t)vmap(0, size, attr ^ PG_PRESENT, VMAP_NOMAP);
+
+    if (!start) {
+        return NULL;
+    }
+
+    struct vmap_area* varea = valloc(sizeof(struct vmap_area));
+    *varea =
+      (struct vmap_area){ .start = start, .size = size, .area_attr = attr };
+
+    return varea;
+}
+
+ptr_t
+vmap_area_page(struct vmap_area* area, ptr_t paddr, pt_attr attr)
+{
+    ptr_t current = area->start;
+    size_t bound = current + area->size;
+
+    while (current < bound) {
+        x86_pte_t* pte =
+          (x86_pte_t*)(L2_VADDR(L1_INDEX(current)) | L2_INDEX(current));
+        if (PG_IS_PRESENT(*pte)) {
+            current += PG_SIZE;
+            continue;
+        }
+
+        *pte = NEW_L2_ENTRY(attr | PG_PRESENT, paddr);
+        cpu_flush_page(current);
+        break;
+    }
+
+    return current;
+}
+
+ptr_t
+vmap_area_rmpage(struct vmap_area* area, ptr_t vaddr)
+{
+    ptr_t current = area->start;
+    size_t bound = current + area->size;
+
+    if (current > vaddr || vaddr > bound) {
+        return 0;
+    }
+
+    x86_pte_t* pte =
+      (x86_pte_t*)(L2_VADDR(L1_INDEX(current)) | L2_INDEX(current));
+    ptr_t pa = PG_ENTRY_ADDR(*pte);
+
+    *pte = NEW_L2_ENTRY(0, -1);
+    cpu_flush_page(current);
+
+    return pa;
 }
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