From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/x86/realmode/rm/wakeup_asm.S | 177 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 177 insertions(+)
 create mode 100644 arch/x86/realmode/rm/wakeup_asm.S

(limited to 'arch/x86/realmode/rm/wakeup_asm.S')

diff --git a/arch/x86/realmode/rm/wakeup_asm.S b/arch/x86/realmode/rm/wakeup_asm.S
new file mode 100644
index 000000000..9e7e14797
--- /dev/null
+++ b/arch/x86/realmode/rm/wakeup_asm.S
@@ -0,0 +1,177 @@
+/*
+ * ACPI wakeup real mode startup stub
+ */
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/msr-index.h>
+#include <asm/page_types.h>
+#include <asm/pgtable_types.h>
+#include <asm/processor-flags.h>
+#include "realmode.h"
+#include "wakeup.h"
+
+	.code16
+
+/* This should match the structure in wakeup.h */
+	.section ".data", "aw"
+
+	.balign	16
+GLOBAL(wakeup_header)
+	video_mode:	.short	0	/* Video mode number */
+	pmode_entry:	.long	0
+	pmode_cs:	.short	__KERNEL_CS
+	pmode_cr0:	.long	0	/* Saved %cr0 */
+	pmode_cr3:	.long	0	/* Saved %cr3 */
+	pmode_cr4:	.long	0	/* Saved %cr4 */
+	pmode_efer:	.quad	0	/* Saved EFER */
+	pmode_gdt:	.quad	0
+	pmode_misc_en:	.quad	0	/* Saved MISC_ENABLE MSR */
+	pmode_behavior:	.long	0	/* Wakeup behavior flags */
+	realmode_flags:	.long	0
+	real_magic:	.long	0
+	signature:	.long	WAKEUP_HEADER_SIGNATURE
+END(wakeup_header)
+
+	.text
+	.code16
+
+	.balign	16
+ENTRY(wakeup_start)
+	cli
+	cld
+
+	LJMPW_RM(3f)
+3:
+	/* Apparently some dimwit BIOS programmers don't know how to
+	   program a PM to RM transition, and we might end up here with
+	   junk in the data segment descriptor registers.  The only way
+	   to repair that is to go into PM and fix it ourselves... */
+	movw	$16, %cx
+	lgdtl	%cs:wakeup_gdt
+	movl	%cr0, %eax
+	orb	$X86_CR0_PE, %al
+	movl	%eax, %cr0
+	ljmpw	$8, $2f
+2:
+	movw	%cx, %ds
+	movw	%cx, %es
+	movw	%cx, %ss
+	movw	%cx, %fs
+	movw	%cx, %gs
+
+	andb	$~X86_CR0_PE, %al
+	movl	%eax, %cr0
+	LJMPW_RM(3f)
+3:
+	/* Set up segments */
+	movw	%cs, %ax
+	movw	%ax, %ss
+	movl	$rm_stack_end, %esp
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+
+	lidtl	wakeup_idt
+
+	/* Clear the EFLAGS */
+	pushl $0
+	popfl
+
+	/* Check header signature... */
+	movl	signature, %eax
+	cmpl	$WAKEUP_HEADER_SIGNATURE, %eax
+	jne	bogus_real_magic
+
+	/* Check we really have everything... */
+	movl	end_signature, %eax
+	cmpl	$REALMODE_END_SIGNATURE, %eax
+	jne	bogus_real_magic
+
+	/* Call the C code */
+	calll	main
+
+	/* Restore MISC_ENABLE before entering protected mode, in case
+	   BIOS decided to clear XD_DISABLE during S3. */
+	movl	pmode_behavior, %edi
+	btl	$WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE, %edi
+	jnc	1f
+
+	movl	pmode_misc_en, %eax
+	movl	pmode_misc_en + 4, %edx
+	movl	$MSR_IA32_MISC_ENABLE, %ecx
+	wrmsr
+1:
+
+	/* Do any other stuff... */
+
+#ifndef CONFIG_64BIT
+	/* This could also be done in C code... */
+	movl	pmode_cr3, %eax
+	movl	%eax, %cr3
+
+	btl	$WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
+	jnc	1f
+	movl	pmode_cr4, %eax
+	movl	%eax, %cr4
+1:
+	btl	$WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
+	jnc	1f
+	movl	pmode_efer, %eax
+	movl	pmode_efer + 4, %edx
+	movl	$MSR_EFER, %ecx
+	wrmsr
+1:
+
+	lgdtl	pmode_gdt
+
+	/* This really couldn't... */
+	movl	pmode_entry, %eax
+	movl	pmode_cr0, %ecx
+	movl	%ecx, %cr0
+	ljmpl	$__KERNEL_CS, $pa_startup_32
+	/* -> jmp *%eax in trampoline_32.S */
+#else
+	jmp	trampoline_start
+#endif
+
+bogus_real_magic:
+1:
+	hlt
+	jmp	1b
+
+	.section ".rodata","a"
+
+	/*
+	 * Set up the wakeup GDT.  We set these up as Big Real Mode,
+	 * that is, with limits set to 4 GB.  At least the Lenovo
+	 * Thinkpad X61 is known to need this for the video BIOS
+	 * initialization quirk to work; this is likely to also
+	 * be the case for other laptops or integrated video devices.
+	 */
+
+	.balign	16
+GLOBAL(wakeup_gdt)
+	.word	3*8-1		/* Self-descriptor */
+	.long	pa_wakeup_gdt
+	.word	0
+
+	.word	0xffff		/* 16-bit code segment @ real_mode_base */
+	.long	0x9b000000 + pa_real_mode_base
+	.word	0x008f		/* big real mode */
+
+	.word	0xffff		/* 16-bit data segment @ real_mode_base */
+	.long	0x93000000 + pa_real_mode_base
+	.word	0x008f		/* big real mode */
+END(wakeup_gdt)
+
+	.section ".rodata","a"
+	.balign	8
+
+	/* This is the standard real-mode IDT */
+	.balign	16
+GLOBAL(wakeup_idt)
+	.word	0xffff		/* limit */
+	.long	0		/* address */
+	.word	0
+END(wakeup_idt)
-- 
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