Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 177 insertions, 0 deletions

diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
new file mode 100644
index 000000000..24bb75987
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -0,0 +1,177 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ *	Trampoline.S	Derived from Setup.S by Linus Torvalds
+ *
+ *	4 Jan 1997 Michael Chastain: changed to gnu as.
+ *	15 Sept 2005 Eric Biederman: 64bit PIC support
+ *
+ *	Entry: CS:IP point to the start of our code, we are
+ *	in real mode with no stack, but the rest of the
+ *	trampoline page to make our stack and everything else
+ *	is a mystery.
+ *
+ *	On entry to trampoline_start, the processor is in real mode
+ *	with 16-bit addressing and 16-bit data.  CS has some value
+ *	and IP is zero.  Thus, data addresses need to be absolute
+ *	(no relocation) and are taken with regard to r_base.
+ *
+ *	With the addition of trampoline_level4_pgt this code can
+ *	now enter a 64bit kernel that lives at arbitrary 64bit
+ *	physical addresses.
+ *
+ *	If you work on this file, check the object module with objdump
+ *	--full-contents --reloc to make sure there are no relocation
+ *	entries.
+ */
+
+#include <linux/linkage.h>
+#include <asm/pgtable_types.h>
+#include <asm/page_types.h>
+#include <asm/msr.h>
+#include <asm/segment.h>
+#include <asm/processor-flags.h>
+#include <asm/realmode.h>
+#include "realmode.h"
+
+	.text
+	.code16
+
+	.balign	PAGE_SIZE
+ENTRY(trampoline_start)
+	cli			# We should be safe anyway
+	wbinvd
+
+	LJMPW_RM(1f)
+1:
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+	mov	%ax, %es
+	mov	%ax, %ss
+
+	movl	$0xA5A5A5A5, trampoline_status
+	# write marker for master knows we're running
+
+	# Setup stack
+	movl	$rm_stack_end, %esp
+
+	call	verify_cpu		# Verify the cpu supports long mode
+	testl   %eax, %eax		# Check for return code
+	jnz	no_longmode
+
+	/*
+	 * GDT tables in non default location kernel can be beyond 16MB and
+	 * lgdt will not be able to load the address as in real mode default
+	 * operand size is 16bit. Use lgdtl instead to force operand size
+	 * to 32 bit.
+	 */
+
+	lidtl	tr_idt	# load idt with 0, 0
+	lgdtl	tr_gdt	# load gdt with whatever is appropriate
+
+	movw	$__KERNEL_DS, %dx	# Data segment descriptor
+
+	# Enable protected mode
+	movl	$X86_CR0_PE, %eax	# protected mode (PE) bit
+	movl	%eax, %cr0		# into protected mode
+
+	# flush prefetch and jump to startup_32
+	ljmpl	$__KERNEL32_CS, $pa_startup_32
+
+no_longmode:
+	hlt
+	jmp no_longmode
+#include "../kernel/verify_cpu.S"
+
+	.section ".text32","ax"
+	.code32
+	.balign 4
+ENTRY(startup_32)
+	movl	%edx, %ss
+	addl	$pa_real_mode_base, %esp
+	movl	%edx, %ds
+	movl	%edx, %es
+	movl	%edx, %fs
+	movl	%edx, %gs
+
+	/*
+	 * Check for memory encryption support. This is a safety net in
+	 * case BIOS hasn't done the necessary step of setting the bit in
+	 * the MSR for this AP. If SME is active and we've gotten this far
+	 * then it is safe for us to set the MSR bit and continue. If we
+	 * don't we'll eventually crash trying to execute encrypted
+	 * instructions.
+	 */
+	btl	$TH_FLAGS_SME_ACTIVE_BIT, pa_tr_flags
+	jnc	.Ldone
+	movl	$MSR_K8_SYSCFG, %ecx
+	rdmsr
+	bts	$MSR_K8_SYSCFG_MEM_ENCRYPT_BIT, %eax
+	jc	.Ldone
+
+	/*
+	 * Memory encryption is enabled but the SME enable bit for this
+	 * CPU has has not been set.  It is safe to set it, so do so.
+	 */
+	wrmsr
+.Ldone:
+
+	movl	pa_tr_cr4, %eax
+	movl	%eax, %cr4		# Enable PAE mode
+
+	# Setup trampoline 4 level pagetables
+	movl	$pa_trampoline_pgd, %eax
+	movl	%eax, %cr3
+
+	# Set up EFER
+	movl	pa_tr_efer, %eax
+	movl	pa_tr_efer + 4, %edx
+	movl	$MSR_EFER, %ecx
+	wrmsr
+
+	# Enable paging and in turn activate Long Mode
+	movl	$(X86_CR0_PG | X86_CR0_WP | X86_CR0_PE), %eax
+	movl	%eax, %cr0
+
+	/*
+	 * At this point we're in long mode but in 32bit compatibility mode
+	 * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
+	 * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
+	 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
+	 */
+	ljmpl	$__KERNEL_CS, $pa_startup_64
+
+	.section ".text64","ax"
+	.code64
+	.balign 4
+ENTRY(startup_64)
+	# Now jump into the kernel using virtual addresses
+	jmpq	*tr_start(%rip)
+
+	.section ".rodata","a"
+	# Duplicate the global descriptor table
+	# so the kernel can live anywhere
+	.balign	16
+	.globl tr_gdt
+tr_gdt:
+	.short	tr_gdt_end - tr_gdt - 1	# gdt limit
+	.long	pa_tr_gdt
+	.short	0
+	.quad	0x00cf9b000000ffff	# __KERNEL32_CS
+	.quad	0x00af9b000000ffff	# __KERNEL_CS
+	.quad	0x00cf93000000ffff	# __KERNEL_DS
+tr_gdt_end:
+
+	.bss
+	.balign	PAGE_SIZE
+GLOBAL(trampoline_pgd)		.space	PAGE_SIZE
+
+	.balign	8
+GLOBAL(trampoline_header)
+	tr_start:		.space	8
+	GLOBAL(tr_efer)		.space	8
+	GLOBAL(tr_cr4)		.space	4
+	GLOBAL(tr_flags)	.space	4
+END(trampoline_header)
+
+#include "trampoline_common.S"