From cd8fe59acca8d65e01f8a8a47504eecab3342c4d Mon Sep 17 00:00:00 2001
From: CleverMouse <theclevermouse@yandex.ru>
Date: Fri, 15 Aug 2014 11:18:27 +0000
Subject: [PATCH] don't rely on BIOS for returning to real mode

git-svn-id: svn://kolibrios.org@5032 a494cfbc-eb01-0410-851d-a64ba20cac60
---
 kernel/trunk/boot/shutdown.inc | 18 ++++++++++-
 kernel/trunk/core/memory.inc   | 28 ++++++++++++++++
 kernel/trunk/kernel.asm        | 59 ++++++++++++++++------------------
 3 files changed, 72 insertions(+), 33 deletions(-)

diff --git a/kernel/trunk/boot/shutdown.inc b/kernel/trunk/boot/shutdown.inc
index 3214bda107..7b2977fc8f 100644
--- a/kernel/trunk/boot/shutdown.inc
+++ b/kernel/trunk/boot/shutdown.inc
@@ -13,8 +13,24 @@
 
 $Revision$
 
+use32
+become_real:
+        cli
+        lgdt    [realmode_gdt-OS_BASE]
+        jmp     8:@f
+use16
+@@:
+        mov     ax, 10h
+        mov     ds, ax
+        mov     es, ax
+        mov     fs, ax
+        mov     gs, ax
+        mov     ss, ax
+        mov     eax, cr0
+        and     eax, not 80000001h
+        mov     cr0, eax
+        jmp     0x1000:pr_mode_exit
 
-align 4
 pr_mode_exit:
 
 ; setup stack
diff --git a/kernel/trunk/core/memory.inc b/kernel/trunk/core/memory.inc
index f69f600556..a2416bd954 100644
--- a/kernel/trunk/core/memory.inc
+++ b/kernel/trunk/core/memory.inc
@@ -350,6 +350,34 @@ proc map_page_table stdcall, lin_addr:dword, phis_addr:dword
         ret
 endp
 
+; Allocates a physical page for master page table
+; that duplicates first Mb of OS_BASE at address 0;
+; used for starting APs and for shutting down,
+; where it is important to execute code in trivial-mapped pages.
+; Returns eax = allocated physical page.
+proc create_trampoline_pgmap
+; The only non-trivial moment:
+; we need a linear address to fill information,
+; but we don't need it outside of this function,
+; so we're returning physical address.
+; Therefore, allocate memory with kernel_alloc,
+; this will allocate physical page and a linear address somewhere,
+; and deallocate only linear address with free_kernel_space.
+        stdcall kernel_alloc, 0x1000
+        mov     edi, eax
+        mov     esi, master_tab
+        mov     ecx, 1024
+        rep movsd
+        mov     ecx, [master_tab+(OS_BASE shr 20)]
+        mov     [eax], ecx
+        mov     edi, eax
+        call    get_pg_addr
+        push    eax
+        stdcall free_kernel_space, edi
+        pop     eax
+        ret
+endp
+
 align 4
 proc init_LFB
            locals
diff --git a/kernel/trunk/kernel.asm b/kernel/trunk/kernel.asm
index cd32e38fe6..8c375abda6 100644
--- a/kernel/trunk/kernel.asm
+++ b/kernel/trunk/kernel.asm
@@ -5452,22 +5452,6 @@ end if
 
         call    IRQ_mask_all
 
-if 0
-        mov     word [OS_BASE+0x467+0], pr_mode_exit
-        mov     word [OS_BASE+0x467+2], 0x1000
-
-        mov     al, 0x0F
-        out     0x70, al
-        mov     al, 0x05
-        out     0x71, al
-
-        mov     al, 0xFE
-        out     0x64, al
-
-        hlt
-        jmp     $-1
-
-else
         cmp     byte [OS_BASE + 0x9030], 2
         jnz     no_acpi_power_off
 
@@ -5613,21 +5597,6 @@ do_acpi_power_off:
         jmp     $
 
 
-no_acpi_power_off:
-        mov     word [OS_BASE+0x467+0], pr_mode_exit
-        mov     word [OS_BASE+0x467+2], 0x1000
-
-        mov     al, 0x0F
-        out     0x70, al
-        mov     al, 0x05
-        out     0x71, al
-
-        mov     al, 0xFE
-        out     0x64, al
-
-        hlt
-        jmp     $-1
-
 scan_rsdp:
         add     eax, OS_BASE
 .s:
@@ -5650,7 +5619,33 @@ scan_rsdp:
         stc
 .ok:
         ret
-end if
+
+no_acpi_power_off:
+        call    create_trampoline_pgmap
+        mov     cr3, eax
+        jmp     become_real+0x10000
+iglobal
+align 4
+realmode_gdt:
+; selector 0 - not used
+        dw      23
+        dd      realmode_gdt-OS_BASE
+        dw      0
+; selector 8 - code from 1000:0000 to 1000:FFFF
+        dw      0FFFFh
+        dw      0
+        db      1
+        db      10011011b
+        db      00000000b
+        db      0
+; selector 10h - data from 1000:0000 to 1000:FFFF
+        dw      0FFFFh
+        dw      0
+        db      1
+        db      10010011b
+        db      00000000b
+        db      0
+endg
 
 if ~ lang eq sp
 diff16 "end of .text segment",0,$