amaps

include/zinnia/amap.h

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: ISC
+
+#pragma once
+
+#include <zinnia/atomic.h>
+#include <zinnia/errno.h>
+#include <zinnia/mutex.h>
+#include <zinnia/radix.h>
+#include <zinnia/refcount.h>
+#include <zinnia/virt.h>
+#include <stddef.h>
+
+struct vm_anon {
+    _Atomic(size_t) rc;
+    struct page* page;
+};
+
+struct amap {
+    struct refcount rc;
+    mutex_t lock;
+    struct radix_tree anons;
+};
+
+errno_t anon_new(struct page* src, struct vm_anon** out);
+void anon_ref(struct vm_anon* anon);
+void anon_unref(struct vm_anon* anon);
+
+errno_t amap_new(struct amap** out);
+void amap_ref(struct amap* amap);
+void amap_unref(struct amap* amap);
+bool amap_is_shared(struct amap* amap);
+errno_t amap_copy(struct amap* src, size_t offset, size_t num_slots, struct amap** out);

include/zinnia/virt.h

@@ -2,6 +2,9 @@
 
 #pragma once
 
+#include <zinnia/alloc.h>
+#include <zinnia/atomic.h>
+#include <zinnia/errno.h>
 #include <zinnia/hashmap.h>
 #include <zinnia/types.h>
 #include <stddef.h>
@@ -11,15 +14,26 @@ enum page_type : uint8_t {
     PAGE_PHYS = 0, // Regular physical memory.
 };
 
+enum page_flags : uint32_t {
+    PAGE_BUSY = 1 << 0,
+    PAGE_WANTED = 1 << 1,
+    PAGE_DIRTY = 1 << 2,
+    PAGE_ANON = 1 << 3,
+};
+
 struct page {
     enum page_type type;
-    uint32_t flags;
-    size_t refcount;
+    _Atomic(uint32_t) flags;
+    _Atomic(size_t) holds;
     union {
         struct {
             struct page* next; // Pointer to the next chunk.
             size_t count;      // Amount of free pages.
         } freelist;
+        struct {
+            void* owner;
+            uint64_t index;
+        } obj;
     };
 };
 static_assert(0x1000 % sizeof(struct page) == 0, "struct must fit cleanly inside a page!");
@@ -29,6 +43,14 @@ static_assert(sizeof(struct page) <= 64, "struct must be smaller than 64 bytes!"
 extern struct page* vm_pfndb;
 
 uintptr_t vm_page_addr(struct page* page);
+struct page* vm_page_from_addr(phys_t addr);
+
+errno_t page_alloc(enum alloc_flags flags, struct page** out);
+void page_hold(struct page* page);
+void page_unhold(struct page* page);
+bool page_try_busy(struct page* page);
+void page_unbusy(struct page* page);
+void page_wait(struct page* page);
 
 // Allocator for virtual memory.
 struct vm_alloc {