From 19c0498ccc635ae9e9cc9f574588f12c5636738a Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gbeutner@serenityos.org>
Date: Thu, 24 Jun 2021 12:58:57 +0200
Subject: [PATCH] Kernel: Update the x86_64 boot code to match i386's code

---
 Kernel/Arch/x86/x86_64/Boot/boot.S | 46 ++++++++++++++++++------------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/Kernel/Arch/x86/x86_64/Boot/boot.S b/Kernel/Arch/x86/x86_64/Boot/boot.S
index 3a6f624dba9920..1716536df47c7c 100644
--- a/Kernel/Arch/x86/x86_64/Boot/boot.S
+++ b/Kernel/Arch/x86/x86_64/Boot/boot.S
@@ -52,17 +52,17 @@ boot_pd0_pt0:
 .skip 4096 * 4
 .global boot_pd3_pts
 boot_pd3_pts:
-.skip 4096 * 8
+.skip 4096 * 16
 .global boot_pd3_pt1023
 boot_pd3_pt1023:
 .skip 4096
 
-.section .text
+.section .boot_text, "ax"
 
 .global start
 .type start, @function
 
-.extern init 
+.extern init
 .type init, @function
 
 .extern multiboot_info_ptr
@@ -92,7 +92,17 @@ boot_pd3 : 512 pde's
     5: boot_pd3_pts[5] (3082-3084MB) (pseudo 512 4KB pages)
     6: boot_pd3_pts[6] (3084-3086MB) (pseudo 512 4KB pages)
     7: boot_pd3_pts[7] (3086-3088MB) (pseudo 512 4KB pages)
-    8: boot_pd3_pt1023 (4094-4096MB) (for page table mappings)
+    
+    8: boot_pd3_pts[8] (3088-3090MB) (pseudo 512 4KB pages)
+    9: boot_pd3_pts[9] (3090-3076MB) (pseudo 512 4KB pages)
+    10: boot_pd3_pts[10] (3092-3094MB) (pseudo 512 4KB pages)
+    11: boot_pd3_pts[11] (3094-3096MB) (pseudo 512 4KB pages)
+    12: boot_pd3_pts[12] (3096-3098MB) (pseudo 512 4KB pages)
+    13: boot_pd3_pts[13] (3098-3100MB) (pseudo 512 4KB pages)
+    14: boot_pd3_pts[14] (3100-3102MB) (pseudo 512 4KB pages)
+    15: boot_pd3_pts[15] (3102-3104MB) (pseudo 512 4KB pages)
+    
+    16: boot_pd3_pt1023 (4094-4096MB) (for page table mappings)
 
 the 9 page tables each contain 512 pte's that map individual 4KB pages
 
@@ -146,7 +156,7 @@ start:
 
     /* clear pd3's pt's */
     movl $(boot_pd3_pts - 0xc0000000), %edi
-    movl $(1024 * 9), %ecx
+    movl $(1024 * 17), %ecx
     xorl %eax, %eax
     rep stosl
 
@@ -158,7 +168,7 @@ start:
     orl $0x3, 0(%edi)
 
     /* add boot_pd3_pts to boot_pd3 */
-    movl $8, %ecx
+    movl $16, %ecx
     movl $(boot_pd3 - 0xc0000000), %edi
     movl $(boot_pd3_pts - 0xc0000000), %eax
 
@@ -183,8 +193,8 @@ start:
     addl $4096, %eax
     loop 1b
 
-    /* pseudo identity map the 3072-3090MB range */
-    movl $(512 * 8), %ecx
+    /* pseudo identity map the 3072-3102MB range */
+    movl $(512 * 16), %ecx
     movl $(boot_pd3_pts - 0xc0000000), %edi
     xorl %eax, %eax
 
@@ -239,6 +249,7 @@ start:
     movl $256, %ecx
     movl $(boot_pd0_pt0 - 0xc0000000), %edi
     xorl %eax, %eax
+
 1:
     movl %eax, 0(%edi)
     addl $8, %edi
@@ -317,19 +328,18 @@ apic_ap_start32:
     movl $0x80000001, %eax
     cpuid
     testl $0x100000, %edx
-    // TODO: Uncomment this
-    //je (1f - apic_ap_start + 0x8000)
+    je (1f - apic_ap_start + 0x8000)
     /* turn on IA32_EFER.NXE */
     movl $0xc0000080, %ecx
     rdmsr
     orl $0x800, %eax
     wrmsr
 1:
-    
+
     /* load the bsp's cr3 value */
     movl (ap_cpu_init_cr3 - apic_ap_start)(%ebp), %eax
     movl %eax, %cr3
-    
+
     /* enable PAE + PSE */
     movl %cr4, %eax
     orl $0x60, %eax
@@ -349,9 +359,9 @@ apic_ap_start32_2:
     /* flush the TLB */
     movl %cr3, %eax
     movl %eax, %cr3
-    
+
     movl $0xc0008000, %ebp
-    
+
     /* now load the final gdt and idt from the identity mapped area */
     movl (ap_cpu_gdtr - apic_ap_start)(%ebp), %eax
     lgdt (%eax)
@@ -363,20 +373,20 @@ apic_ap_start32_2:
     movl %eax, %cr0
     movl (ap_cpu_init_cr4 - apic_ap_start)(%ebp), %eax
     movl %eax, %cr4
-    
+
     /* push the Processor pointer this CPU is going to use */
     movl (ap_cpu_init_processor_info_array - apic_ap_start)(%ebp), %eax
     addl $0xc0000000, %eax
     movl 0(%eax, %esi, 4), %eax
     push %eax
-    
+
     /* push the cpu id, 0 representing the bsp and call into c++ */
     incl %esi
     push %esi
-    
+
     xor %ebp, %ebp
     cld
-    
+
     /* We are in identity mapped P0x8000 and the BSP will unload this code
        once all APs are initialized, so call init_ap but return to our
        infinite loop */