From d4405dfb012ca70c06dfc3217265e4e9cd01b68a Mon Sep 17 00:00:00 2001
From: Aqua-sama <aqua@iserlohn-fortress.net>
Date: Sun, 21 Mar 2021 22:14:12 +0200
Subject: Place bootstrap code into multiboot section

---
 linker.ld  |  5 ++++-
 makefile   |  2 +-
 src/boot.S | 15 ++++++++++++++-
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/linker.ld b/linker.ld
index f7010e7..8eba287 100644
--- a/linker.ld
+++ b/linker.ld
@@ -12,7 +12,11 @@ SECTIONS
     . = 0;
     .multiboot : {
         . = ALIGN(8);
+        begin_multiboot = .;
         KEEP(*(.multiboot.header))
+        *(.multiboot.text)
+        *(.multiboot.pages))
+        end_multiboot = .;
     }
 
     /* Begin putting sections at 4 MiB */
@@ -20,7 +24,6 @@ SECTIONS
 
     .text ALIGN(4K) : AT(ADDR(.text) - VADDR_BASE + 4M) {
         begin_text = .;
-        *(.multiboot.text)
         *(.text*)
         end_text = .;
     }
diff --git a/makefile b/makefile
index 7eecced..6e44faf 100644
--- a/makefile
+++ b/makefile
@@ -3,7 +3,7 @@ OBJ_DIR != echo $(CONFIG_OBJ_DIR)
 include toolchain.makefile
 
 .PHONY: default clean test todo run menuconfig
-default: $(OBJ_DIR)/glitch.elf
+all: $(OBJ_DIR)/glitch.elf
 
 include libk/makefile
 include src/makefile
diff --git a/src/boot.S b/src/boot.S
index 3a07c19..976a6f4 100644
--- a/src/boot.S
+++ b/src/boot.S
@@ -34,6 +34,11 @@ module_tag_end:
     .int 8
 header_end:
 
+.section .multiboot.pages, "aw", @nobits
+.align 4096
+bootstrap_page0:
+    .skip 1024 * 4
+
 /*  The stack on x86 must be 16-byte aligned according to the System V ABI standard and de-facto extensions. The
  *  compiler will assume the stack is properly aligned and failure to align the stack will result in undefined
  *  behavior.
@@ -60,7 +65,7 @@ kernel_ptable0:
  */
 .section .multiboot.text, "ax"
 .global VADDR_OFFSET
-    .set VADDR_OFFSET, 0xc0000000 - 0x400000
+.set VADDR_OFFSET, 0
 
 .macro map begin, end, access
     mov $\begin - VADDR_OFFSET, %esi
@@ -83,6 +88,12 @@ kernel_ptable0:
 _start:
     cli
 
+    movl $bootstrap_page0, %edi
+    movl $1024, %ecx
+    map begin_multiboot, end_multiboot, 0x003
+
+.set VADDR_OFFSET, 0xc0000000 - 0x400000
+
     # Physical address of kernel_ptable0.
     movl $(kernel_ptable0 - VADDR_OFFSET), %edi
     # Map 1024 pages
@@ -98,6 +109,7 @@ _start:
     # Use the page table at:
     #   - entry   1       starts 0x0040 0000      ends 0x007f ffff
     #   - entry 768       starts 0xc000 0000      ends 0xc03f ffff
+    movl $(bootstrap_page0 + 0x003), kernel_pagedir - VADDR_OFFSET + 0 * 4
     movl $(kernel_ptable0 - VADDR_OFFSET + 0x003), kernel_pagedir - VADDR_OFFSET + 1 * 4
     movl $(kernel_ptable0 - VADDR_OFFSET + 0x003), kernel_pagedir - VADDR_OFFSET + 768 * 4
 
@@ -120,6 +132,7 @@ _start:
 kinit:
     # At this point, paging is fully set up and enabled.
     # Unmap the identity mapping as it is now unnecessary.
+    movl $0, kernel_pagedir + 0 * 4
     movl $0, kernel_pagedir + 1 * 4
     # Reload crc3 to force a TLB flush so the changes to take effect.
     movl %cr3, %ecx
-- 
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