Init: Move platform_init() before MemoryManager::init()

This enables NX before we actually use it.
Wasn't causing problems with KVM on, but crashed with KVM off with a 'reserved bit set' page fault.

kernel/src/arch/x86_64/CPU.cpp

@@ -143,6 +143,8 @@ namespace CPU
         enable_sse();
         enable_write_protect();
         if (test_nx()) enable_nx();
+        else
+            kwarnln("not setting the NX bit as it is unsupported");
         setup_gdt();
         setup_idt();
     }

kernel/src/arch/x86_64/MMU.cpp

@@ -24,6 +24,11 @@ void PageTableEntry::clear()
     raw = 0;
 }
 
+static bool has_flag(int flags, MMU::Flags flag)
+{
+    return flags & flag;
+}
+
 namespace MMU
 {
 
@@ -172,7 +177,6 @@ namespace MMU
             l4.present = true;
             l4.set_address(addr);
             memset(l3_table(virt), 0, ARCH_PAGE_SIZE);
-            l4.ignore0 = l4.ignore1 = 0;
         }
         if (flags & Flags::ReadWrite) l4.read_write = true;
         if (flags & Flags::User) l4.user = true;
@@ -184,7 +188,6 @@ namespace MMU
             l3.present = true;
             l3.set_address(addr);
             memset(l2_table(virt), 0, ARCH_PAGE_SIZE);
-            l3.ignore0 = l3.ignore1 = 0;
         }
         if (flags & Flags::ReadWrite) l3.read_write = true;
         if (flags & Flags::User) l3.user = true;
@@ -198,7 +201,6 @@ namespace MMU
             l2.present = true;
             l2.set_address(addr);
             memset(l1_table(virt), 0, ARCH_PAGE_SIZE);
-            l2.ignore0 = l2.ignore1 = 0;
         }
         if (flags & Flags::ReadWrite) l2.read_write = true;
         if (flags & Flags::User) l2.user = true;
@@ -207,13 +209,12 @@ namespace MMU
 
         auto& l1 = l1_entry(virt);
         if (l1.present) return err(EEXIST); // Please explicitly unmap the page before mapping it again.
-        l1.ignore0 = l1.ignore1 = false;
         l1.present = true;
-        l1.read_write = (flags & Flags::ReadWrite);
+        l1.read_write = has_flag(flags, Flags::ReadWrite);
-        l1.user = (flags & Flags::User);
+        l1.user = has_flag(flags, Flags::User);
-        l1.write_through = (flags & Flags::WriteThrough);
+        l1.write_through = has_flag(flags, Flags::WriteThrough);
-        l1.cache_disabled = (flags & Flags::CacheDisable);
+        l1.cache_disabled = has_flag(flags, Flags::CacheDisable);
-        l1.no_execute = (flags & Flags::NoExecute);
+        l1.no_execute = has_flag(flags, Flags::NoExecute);
         l1.set_address(phys);
         return {};
     }
@@ -222,11 +223,12 @@ namespace MMU
     {
         auto& l1 = *TRY(apply_cascading_flags(virt, flags));
         if (!l1.present) return err(EFAULT);
-        l1.read_write = (flags & Flags::ReadWrite);
+        l1.read_write = has_flag(flags, Flags::ReadWrite);
-        l1.user = (flags & Flags::User);
+        l1.user = has_flag(flags, Flags::User);
-        l1.write_through = (flags & Flags::WriteThrough);
+        l1.write_through = has_flag(flags, Flags::WriteThrough);
-        l1.cache_disabled = (flags & Flags::CacheDisable);
+        l1.cache_disabled = has_flag(flags, Flags::CacheDisable);
-        l1.no_execute = (flags & Flags::NoExecute);
+        l1.no_execute = has_flag(flags, Flags::NoExecute);
+        flush_page(virt);
         return {};
     }
 

kernel/src/boot/Init.cpp

@@ -28,10 +28,10 @@ void Init::early_init()
 
     setup_log(log_debug_enabled(), log_serial_enabled(), true);
 
+    CPU::platform_init();
+
     MemoryManager::init();
     InitRD::initialize();
 
-    CPU::platform_init();
-
     MemoryManager::protect_kernel_sections().expect_release_value("We should succeed to protect sections");
 }