More MMU stuff, but writing still fails

kernel/src/arch/MMU.h

@@ -15,11 +15,11 @@ namespace MMU
         CacheDisable = 16,
     };
 
-    Result<void> map(u64 virt, u64 phys, Flags flags);
+    Result<void> map(u64 virt, u64 phys, int flags);
     Result<u64> unmap(u64 virt);
     Result<u64> get_physical(u64 virt);
-    Result<Flags> get_flags(u64 virt);
+    Result<int> get_flags(u64 virt);
-    Result<void> remap(u64 virt, Flags flags);
+    Result<void> remap(u64 virt, int flags);
 
     void switch_page_directory(PageDirectory* dir);
     PageDirectory* get_page_directory();

kernel/src/arch/x86_64/MMU.cpp

@@ -1,5 +1,6 @@
 #include "arch/MMU.h"
 #include "MemoryManager.h"
+#include <String.h>
 
 #define PAGE_SIZE 4096
 
@@ -148,7 +149,7 @@ namespace MMU
         asm volatile("invlpg (%0)" : : "r"(page) : "memory");
     }
 
-    Flags arch_flags_to_mmu(PageTableEntry& entry)
+    int arch_flags_to_mmu(PageTableEntry& entry)
     {
         int result = Flags::None;
         if (entry.read_write) result |= Flags::ReadWrite;
@@ -156,10 +157,10 @@ namespace MMU
         if (entry.no_execute) result |= Flags::NoExecute;
         if (entry.write_through) result |= Flags::WriteThrough;
         if (entry.cache_disabled) result |= Flags::CacheDisable;
-        return (Flags)result;
+        return result;
     }
 
-    Result<void> map(u64 virt, u64 phys, Flags flags)
+    Result<void> map(u64 virt, u64 phys, int flags)
     {
         auto& l4 = l4_entry(virt);
         if (!l4.present)
@@ -167,34 +168,43 @@ namespace MMU
             auto addr = MemoryManager::alloc_physical_page();
             if (addr.has_error()) return addr.release_error();
             l4.present = true;
-            if (flags & Flags::ReadWrite) l4.read_write = true;
-            if (flags & Flags::User) l4.user = true;
             l4.set_address(addr.release_value());
+            memset(l3_table(virt), 0, PAGE_SIZE);
         }
+        if (flags & Flags::ReadWrite) l4.read_write = true;
+        if (flags & Flags::User) l4.user = true;
+
         auto& l3 = l3_entry(virt);
         if (!l3.present)
         {
             auto addr = MemoryManager::alloc_physical_page();
             if (addr.has_error()) return addr.release_error();
             l3.present = true;
-            if (flags & Flags::ReadWrite) l3.read_write = true;
-            if (flags & Flags::User) l3.user = true;
             l3.set_address(addr.release_value());
+            memset(l2_table(virt), 0, PAGE_SIZE);
         }
+        if (flags & Flags::ReadWrite) l3.read_write = true;
+        if (flags & Flags::User) l3.user = true;
+
         if (l3.larger_pages) return err; // FIXME: Replacing larger pages is not supported ATM
+
         auto& l2 = l2_entry(virt);
         if (!l2.present)
         {
             auto addr = MemoryManager::alloc_physical_page();
             if (addr.has_error()) return addr.release_error();
             l2.present = true;
-            if (flags & Flags::ReadWrite) l2.read_write = true;
-            if (flags & Flags::User) l2.user = true;
             l2.set_address(addr.release_value());
+            memset(l1_table(virt), 0, PAGE_SIZE);
         }
+        if (flags & Flags::ReadWrite) l2.read_write = true;
+        if (flags & Flags::User) l2.user = true;
+
         if (l2.larger_pages) return err; // FIXME: Replacing larger pages is not supported ATM
+
         auto& l1 = l1_entry(virt);
         bool was_present = l1.present;
+        l1.present = true;
         if (flags & Flags::ReadWrite) l1.read_write = true;
         if (flags & Flags::User) l1.user = true;
         if (flags & Flags::WriteThrough) l1.write_through = true;
@@ -220,7 +230,7 @@ namespace MMU
         return l1.get_address();
     }
 
-    Result<Flags> get_flags(u64 virt)
+    Result<int> get_flags(u64 virt)
     {
         auto& l4 = l4_entry(virt);
         if (!l4.present) return err;

kernel/src/main.cpp

@@ -1,5 +1,6 @@
 #include "Framebuffer.h"
 #include "Init.h"
+#include "MemoryManager.h"
 #include "arch/MMU.h"
 #include "arch/Serial.h"
 
@@ -16,6 +17,34 @@ extern "C" void _start()
 
     Serial::println(MMU::get_physical((u64)fb).has_error() ? "fb is not mapped" : "fb is mapped!!");
 
+    const u64 address = 0xfffffffff8000000;
+
+    u64 physical = MemoryManager::alloc_physical_page().release_value();
+
+    bool success = !MMU::map(address, physical, MMU::ReadWrite | MMU::NoExecute).has_error();
+
+    if (success) Serial::println("Mapped page :)");
+    else
+        Serial::println("Failed to map page");
+
+    if (MMU::get_physical(address).release_value() == physical) Serial::println("Mapping is active ;)");
+    else
+        Serial::println("Mapping is not active");
+
+    int flags = MMU::get_flags(address).release_value();
+
+    if (flags & MMU::ReadWrite) Serial::println("Mapping is writable");
+    if (flags & MMU::NoExecute) Serial::println("Mapping is not executable");
+
+    u32* ptr = (u32*)address;
+    (void)*ptr;
+
+    Serial::println("Can read from pointer");
+
+    *ptr = 8;
+
+    Serial::println("Can write to pointer");
+
     for (;;)
         ;
 }