From 15559b0a565a185f96dd4da35dcc23737f744992 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Mon, 21 Mar 2022 16:31:01 -0400
Subject: [PATCH] Add HULK header; map virtual memory for HULK bss section

---
 Rsconscript       | 14 ++++++++++----
 src/hello/hello.d | 17 ++++++++++-------
 src/hulk/header.d | 23 +++++++++++++++++++++++
 src/hulk/hulk.d   | 10 +++++++++-
 src/hulk/hulk.ld  | 15 +++++++--------
 5 files changed, 59 insertions(+), 20 deletions(-)
 create mode 100644 src/hulk/header.d

diff --git a/Rsconscript b/Rsconscript
index 28a721a..1c1ec15 100644
--- a/Rsconscript
+++ b/Rsconscript
@@ -19,15 +19,16 @@ KFONT_SIZE = 15
 
 class HulkBinObj < Builder
   def run(options)
+    FileUtils.mkdir_p(File.dirname(@target))
     File.write(@target, <<EOF)
 .section ".rodata"
 .balign 4096
-.global hulk_start
-hulk_start:
+.global hulk_bin_start
+hulk_bin_start:
 .incbin "#{@sources.first}"
 .balign 4096
-.global hulk_end
-hulk_end:
+.global hulk_bin_end
+hulk_bin_end:
 EOF
     unless @cache.up_to_date?(@target, nil, @sources, @env)
       print_run_message("Creating HULK binary object <target>#{@target}<reset>", nil)
@@ -86,6 +87,11 @@ hulk_env = env "hulk", use: %w[ldc2 x86_64-elf-gcc] do |env|
   env.Command("^/hulk.bin", "^/hulk.elf",
               "CMD" => %W[${OBJCOPY} -O binary ${_SOURCES} ${_TARGET}],
               "CMD_DESC" => "Convert ELF to binary:")
+  env.add_build_hook do |builder|
+    if builder.target.end_with?(".o")
+      env.Disassemble("#{builder.target}.txt", builder.target)
+    end
+  end
 end
 
 hello_env = env "hello", use: %w[ldc2 x86_64-w64-mingw32-gcc] do |env|
diff --git a/src/hello/hello.d b/src/hello/hello.d
index d1ac80f..62bebbf 100644
--- a/src/hello/hello.d
+++ b/src/hello/hello.d
@@ -7,6 +7,7 @@ import uefi;
 import console = hello.console;
 import scratch = hello.scratch;
 import hulk.bootinfo;
+import hulk.header : HulkHeader = Header;
 import hos.page_table;
 import hos.cpu;
 import hos.memory;
@@ -14,8 +15,7 @@ import hos.memory;
 __gshared EFI_SYSTEM_TABLE * st;
 private __gshared BootInfo bootinfo;
 private __gshared UINTN memory_map_key;
-extern extern(C) __gshared ubyte hulk_start;
-extern extern(C) __gshared ubyte hulk_end;
+extern extern(C) __gshared ubyte hulk_bin_start;
 
 /**
  * Detect if we're running in QEMU.
@@ -237,8 +237,10 @@ private void map2m(ulong source_page, ulong dest_page, PageTableEntry * pt_base)
 private void map_hulk(PageTableEntry * pt_base)
 {
     ulong virt = HULK_VIRTUAL_START;
-    ulong phys = cast(ulong)&hulk_start;
-    while (phys < cast(ulong)&hulk_end)
+    ulong phys = cast(ulong)&hulk_bin_start;
+    HulkHeader * hulk_header = cast(HulkHeader *)&hulk_bin_start;
+    size_t end_phys = phys + cast(size_t)hulk_header.total_size;
+    while (phys < end_phys)
     {
         map4k(virt, phys, pt_base);
         virt += 4096u;
@@ -272,8 +274,8 @@ private void build_page_tables(ulong max_physical_address)
         }
     }
     /* Map graphics framebuffer. */
-    ulong framebuffer_size = bootinfo.fb.height * bootinfo.fb.stride;
-    for (size_t offset = 0u; offset < framebuffer_size; offset++)
+    ulong framebuffer_size = bootinfo.fb.height * bootinfo.fb.stride * 4u;
+    for (size_t offset = 0u; offset < framebuffer_size; offset += 4096u)
     {
         ulong addr = cast(ulong)bootinfo.fb.buffer + offset;
         map4k(addr, addr, pt_base);
@@ -289,7 +291,8 @@ private void build_page_tables(ulong max_physical_address)
  */
 private void jump_to_hulk()
 {
-    void function(BootInfo *) hulk_start = cast(void function(BootInfo *))HULK_VIRTUAL_START;
+    HulkHeader * hulk_header = cast(HulkHeader *)&hulk_bin_start;
+    void function(BootInfo *) hulk_start = cast(void function(BootInfo *))hulk_header.entry;
     hulk_start(&bootinfo);
 }
 
diff --git a/src/hulk/header.d b/src/hulk/header.d
new file mode 100644
index 0000000..c8ad5a8
--- /dev/null
+++ b/src/hulk/header.d
@@ -0,0 +1,23 @@
+/**
+ * HULK image header.
+ */
+module hulk.header;
+
+/**
+ * Header describing the HULK image.
+ */
+struct Header
+{
+    /**
+     * Total size of memory to be mapped.
+     *
+     * The OS loader must ensure that virtual memory is mapped for this entire
+     * size.
+     * This value is really an integer, but is stored as a pointer because it
+     * is provided by the linker and LDC does not like us to cast it.
+     */
+    void * total_size;
+
+    /** Entry point. */
+    void * entry;
+}
diff --git a/src/hulk/hulk.d b/src/hulk/hulk.d
index 3fc4984..cbb5510 100644
--- a/src/hulk/hulk.d
+++ b/src/hulk/hulk.d
@@ -3,16 +3,24 @@
  */
 module hulk.hulk;
 
+import hulk.header;
 import hulk.bootinfo;
 import hos.memory;
 import ldc.attributes;
 
+extern extern(C) __gshared ubyte _hulk_total_size;
+
+@(ldc.attributes.section(".hulk_header"))
+private __gshared Header hulk_header = {
+    &_hulk_total_size,
+    &hulk_start,
+};
+
 /**
  * HULK entry point.
  *
  * @param bootinfo Pointer to HULK boot information structure.
  */
-@(ldc.attributes.section(".hulk_start"))
 extern(C) void hulk_start(ulong rdi, ulong rsi, ulong rdx, BootInfo * bootinfo)
 {
     for (size_t y = 100u; y < 120u; y++)
diff --git a/src/hulk/hulk.ld b/src/hulk/hulk.ld
index 686df43..8c19cdb 100644
--- a/src/hulk/hulk.ld
+++ b/src/hulk/hulk.ld
@@ -1,21 +1,19 @@
-ENTRY(hulk_start)
-
 SECTIONS
 {
     . = 0x0000400000000000;
     _hulk_mem_start = .;
 
-    .text BLOCK(4K) : ALIGN(4K)
-    {
-        *(.hulk_start)
-        *(.text)
-    }
-
     .rodata BLOCK(4K) : ALIGN(4K)
     {
+        *(.hulk_header)
         *(.rodata)
     }
 
+    .text BLOCK(4K) : ALIGN(4K)
+    {
+        *(.text)
+    }
+
     .data BLOCK(4K) : ALIGN(4K)
     {
         *(.data)
@@ -30,4 +28,5 @@ SECTIONS
     . = ALIGN(4K);
 
     _hulk_mem_end = .;
+    _hulk_total_size = _hulk_mem_end - _hulk_mem_start;
 }