Add a global initrd TarStream to make the initial ramdisk accessible everywhere

It's also mapped into virtual memory instead of directly going into the physical location!!

kernel/CMakeLists.txt

@@ -15,6 +15,7 @@ set(SOURCES
     src/thread/Spinlock.cpp
     src/thread/Thread.cpp
     src/thread/Scheduler.cpp
+    src/InitRD.cpp
 )
 
 if("${ARCH}" MATCHES "x86_64")

kernel/src/InitRD.cpp

@@ -0,0 +1,18 @@
+#include "InitRD.h"
+#include "arch/MMU.h"
+#include "boot/bootboot.h"
+#include "memory/MemoryManager.h"
+#include <luna/Alignment.h>
+
+TarStream g_initrd;
+extern const BOOTBOOT bootboot;
+
+void InitRD::initialize()
+{
+    u64 virtual_initrd_address =
+        MemoryManager::get_kernel_mapping_for_frames(
+            bootboot.initrd_ptr, get_blocks_from_size(bootboot.initrd_size, ARCH_PAGE_SIZE), MMU::NoExecute)
+            .expect_value("Unable to map the initial ramdisk into virtual memory");
+
+    g_initrd.initialize((void*)virtual_initrd_address, bootboot.initrd_size);
+}

kernel/src/InitRD.h

@@ -0,0 +1,9 @@
+#pragma once
+#include <luna/TarStream.h>
+
+extern TarStream g_initrd;
+
+namespace InitRD
+{
+    void initialize();
+}

kernel/src/boot/Init.cpp

@@ -1,4 +1,5 @@
 #include "boot/Init.h"
+#include "InitRD.h"
 #include "Log.h"
 #include "arch/CPU.h"
 #include "boot/bootboot.h"
@@ -28,6 +29,7 @@ void Init::early_init()
     setup_log(log_debug_enabled(), log_serial_enabled(), true);
 
     MemoryManager::init();
+    InitRD::initialize();
 
     CPU::platform_init();
 

kernel/src/main.cpp

@@ -1,3 +1,4 @@
+#include "InitRD.h"
 #include "Log.h"
 #include "arch/CPU.h"
 #include "arch/MMU.h"
@@ -11,7 +12,6 @@
 #include "thread/Scheduler.h"
 #include <luna/CString.h>
 #include <luna/Result.h>
-#include <luna/TarStream.h>
 #include <luna/Units.h>
 
 extern const BOOTBOOT bootboot;
@@ -67,9 +67,8 @@ Result<void> init()
     kinfoln("Used memory:     %s", to_dynamic_unit(MemoryManager::used()).release_value().chars());
     kinfoln("Reserved memory: %s", to_dynamic_unit(MemoryManager::reserved()).release_value().chars());
 
-    TarStream stream((void*)bootboot.initrd_ptr, bootboot.initrd_size);
     TarStream::Entry entry;
-    while (TRY(stream.read_next_entry().try_set_value_with_specific_error(entry, 0)))
+    while (TRY(g_initrd.read_next_entry().try_set_value_with_specific_error(entry, 0)))
     {
         if (entry.type == TarStream::EntryType::RegularFile)
         {
@@ -78,7 +77,7 @@ Result<void> init()
 
             if (!strcmp(entry.name, "sys/config"))
             {
-                auto contents = TRY(stream.read_contents_as_string(entry, 0, entry.size));
+                auto contents = TRY(g_initrd.read_contents_as_string(entry, 0, entry.size));
 
                 kinfoln("%s", contents.chars());
             }

kernel/src/memory/MemoryManager.cpp

@@ -247,6 +247,32 @@ namespace MemoryManager
         return start;
     }
 
+    Result<u64> get_kernel_mapping_for_frames(u64 phys, usize count, int flags)
+    {
+        u64 start = TRY(KernelVM::alloc_several_pages(count));
+
+        usize pages_mapped = 0;
+
+        auto guard = make_scope_guard([=, &pages_mapped] {
+            KernelVM::free_several_pages(start, pages_mapped);
+            unmap_weak(start, pages_mapped);
+        });
+
+        u64 virt = start;
+
+        while (pages_mapped < count)
+        {
+            TRY(MMU::map(virt, phys, flags));
+            virt += ARCH_PAGE_SIZE;
+            phys += ARCH_PAGE_SIZE;
+            pages_mapped++;
+        }
+
+        guard.deactivate();
+
+        return start;
+    }
+
     Result<void> unmap_owned(u64 virt, usize count)
     {
         CHECK_PAGE_ALIGNED(virt);

kernel/src/memory/MemoryManager.h

@@ -25,6 +25,8 @@ namespace MemoryManager
     Result<u64> alloc_at(u64 virt, usize count, int flags);
     Result<u64> alloc_for_kernel(usize count, int flags);
 
+    Result<u64> get_kernel_mapping_for_frames(u64 phys, usize count, int flags);
+
     Result<void> unmap_owned(u64 virt, usize count);
     Result<void> unmap_owned_and_free_vm(u64 virt, usize count);
     Result<void> unmap_weak(u64 virt, usize count);

luna/include/luna/TarStream.h

@@ -24,6 +24,7 @@ class TarStream
         friend class TarStream;
     };
 
+    TarStream() = default;
     TarStream(void* base, usize size);
 
     void initialize(void* base, usize size);