Kernel: Fix framebuffer resolution modesetting after boot

If we tried to change the resolution before of this patch, we triggered
a kernel crash due to mmaping the framebuffer device again.
Therefore, on mmaping of the framebuffer device, we create an entire new
set of VMObjects and Regions for the new settings.

Then, when we change the resolution, the framebuffersconsole needs to be
updated with the new resolution and also to be refreshed with the new
settings. To ensure we handle both shrinking of the resolution and
growth of it, we only copy the right amount of available data from the
cells Region.

Kernel/Graphics/BochsGraphicsAdapter.cpp

@@ -53,11 +53,11 @@ UNMAP_AFTER_INIT BochsGraphicsAdapter::BochsGraphicsAdapter(PCI::Address pci_add
     : PCI::DeviceController(pci_address)
     , m_mmio_registers(PCI::get_BAR2(pci_address) & 0xfffffff0)
 {
-    set_safe_resolution();
     // We assume safe resolutio is 1024x768x32
     m_framebuffer_console = Graphics::FramebufferConsole::initialize(PhysicalAddress(PCI::get_BAR0(pci_address) & 0xfffffff0), 1024, 768, 1024 * sizeof(u32));
     // FIXME: This is a very wrong way to do this...
     GraphicsManagement::the().m_console = m_framebuffer_console;
+    set_safe_resolution();
 }
 
 UNMAP_AFTER_INIT void BochsGraphicsAdapter::initialize_framebuffer_devices()
@@ -76,6 +76,7 @@ GraphicsDevice::Type BochsGraphicsAdapter::type() const
 
 void BochsGraphicsAdapter::set_safe_resolution()
 {
+    VERIFY(m_framebuffer_console);
     set_resolution(1024, 768);
 }
 
@@ -105,6 +106,7 @@ bool BochsGraphicsAdapter::try_to_set_resolution(size_t width, size_t height)
 
 bool BochsGraphicsAdapter::set_resolution(size_t width, size_t height)
 {
+    VERIFY(m_framebuffer_console);
     if (Checked<size_t>::multiplication_would_overflow(width, height, sizeof(u32)))
         return false;
 
@@ -112,6 +114,7 @@ bool BochsGraphicsAdapter::set_resolution(size_t width, size_t height)
         return false;
 
     dbgln("BochsGraphicsAdapter: resolution set to {}x{}", width, height);
+    m_framebuffer_console->set_resolution(width, height, width * sizeof(u32));
     return true;
 }
 

Kernel/Graphics/Console/Console.h

@@ -74,8 +74,8 @@ protected:
     Atomic<bool> m_enabled;
     Color m_default_foreground_color { Color::White };
     Color m_default_background_color { Color::Black };
-    const size_t m_width;
-    const size_t m_height;
+    size_t m_width;
+    size_t m_height;
     mutable size_t m_x { 0 };
     mutable size_t m_y { 0 };
 };

Kernel/Graphics/Console/FramebufferConsole.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <Kernel/Graphics/Console/FramebufferConsole.h>
+#include <Kernel/TTY/ConsoleManagement.h>
 
 namespace Kernel::Graphics {
 
@@ -204,17 +205,28 @@ NonnullRefPtr<FramebufferConsole> FramebufferConsole::initialize(PhysicalAddress
     return adopt_ref(*new FramebufferConsole(framebuffer_address, width, height, pitch));
 }
 
-FramebufferConsole::FramebufferConsole(PhysicalAddress framebuffer_address, size_t width, size_t height, size_t pitch)
-    : Console(width, height)
-    , m_framebuffer_address(framebuffer_address)
-    , m_pitch(pitch)
+void FramebufferConsole::set_resolution(size_t width, size_t height, size_t pitch)
 {
+    m_width = width;
+    m_height = height;
+    m_pitch = pitch;
+
     dbgln("Framebuffer Console: taking {} bytes", page_round_up(pitch * height));
     m_framebuffer_region = MM.allocate_kernel_region(m_framebuffer_address, page_round_up(pitch * height), "Framebuffer Console", Region::Access::Read | Region::Access::Write, Region::Cacheable::Yes);
     VERIFY(m_framebuffer_region);
 
     // Just to start cleanly, we clean the entire framebuffer
     memset(m_framebuffer_region->vaddr().as_ptr(), 0, pitch * height);
+
+    ConsoleManagement::the().resolution_was_changed();
+}
+
+FramebufferConsole::FramebufferConsole(PhysicalAddress framebuffer_address, size_t width, size_t height, size_t pitch)
+    : Console(width, height)
+    , m_framebuffer_address(framebuffer_address)
+    , m_pitch(pitch)
+{
+    set_resolution(width, height, pitch);
 }
 
 size_t FramebufferConsole::bytes_per_base_glyph() const

Kernel/Graphics/Console/FramebufferConsole.h

@@ -16,6 +16,8 @@ class FramebufferConsole final : public Console {
 public:
     static NonnullRefPtr<FramebufferConsole> initialize(PhysicalAddress, size_t width, size_t height, size_t pitch);
 
+    void set_resolution(size_t width, size_t height, size_t pitch);
+
     virtual size_t bytes_per_base_glyph() const override;
     virtual size_t chars_per_line() const override;
 

Kernel/Graphics/FramebufferDevice.cpp

@@ -30,16 +30,16 @@ KResultOr<Region*> FramebufferDevice::mmap(Process& process, FileDescription&, c
     if (range.size() != page_round_up(framebuffer_size_in_bytes()))
         return EOVERFLOW;
 
-    // FIXME: We rely on the fact that only the WindowServer will mmap the framebuffer
-    // and only once when starting to work with it. If other program wants to do so, we need to fix this.
-    VERIFY(!m_userspace_framebuffer_region);
-    VERIFY(!m_userspace_real_framebuffer_vmobject);
-
     auto vmobject = AnonymousVMObject::create_for_physical_range(m_framebuffer_address, page_round_up(framebuffer_size_in_bytes()));
     if (!vmobject)
         return ENOMEM;
     m_userspace_real_framebuffer_vmobject = vmobject;
 
+    m_real_framebuffer_vmobject = AnonymousVMObject::create_for_physical_range(m_framebuffer_address, page_round_up(framebuffer_size_in_bytes()));
+    m_swapped_framebuffer_vmobject = AnonymousVMObject::create_with_size(page_round_up(framebuffer_size_in_bytes()), AllocationStrategy::AllocateNow);
+    m_real_framebuffer_region = MM.allocate_kernel_region_with_vmobject(*m_real_framebuffer_vmobject, page_round_up(framebuffer_size_in_bytes()), "Framebuffer", Region::Access::Read | Region::Access::Write);
+    m_swapped_framebuffer_region = MM.allocate_kernel_region_with_vmobject(*m_swapped_framebuffer_vmobject, page_round_up(framebuffer_size_in_bytes()), "Framebuffer Swap (Blank)", Region::Access::Read | Region::Access::Write);
+
     auto result = process.space().allocate_region_with_vmobject(
         range,
         vmobject.release_nonnull(),