Commit d545e182 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

x86/efi/mixed: Set up 1:1 mapping of lower 4GiB in the stub 



In preparation for dropping the dependency on startup_32 entirely in the
next patch, add the code that sets up the 1:1 mapping of the lower 4 GiB
of system RAM to the mixed mode stub.

The reload of CR3 after the long mode switch will be removed in a
subsequent patch, when it is no longer needed.

Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent ff38bbba

arch/x86/boot/compressed/efi_mixed.S

+29 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <asm/asm-offsets.h>

#include <asm/msr.h>

#include <asm/page_types.h>

#include <asm/pgtable_types.h>

#include <asm/processor-flags.h>

#include <asm/segment.h>

#include <asm/setup.h>
@@ -52,6 +53,9 @@ SYM_FUNC_START(startup_64_mixed_mode) 
	mov	0(%rdx), %edi

	mov	4(%rdx), %esi



	leaq	(pte + 5 * PAGE_SIZE)(%rip), %rax

	movq	%rax, %cr3		// reload after startup_32



	/* Switch to the firmware's stack */

	movl	efi32_boot_sp(%rip), %esp

	andl	$~7, %esp
@@ -267,11 +271,32 @@ SYM_FUNC_START_LOCAL(efi32_entry) 
	movl	$_end - 1b, BP_init_size(%esi)

	subl	$startup_32 - 1b, BP_init_size(%esi)



	call	1f

1:	pop	%edi



	/* Disable paging */

	movl	%cr0, %eax

	btrl	$X86_CR0_PG_BIT, %eax

	movl	%eax, %cr0



	/* Set up 1:1 mapping */

	leal	(pte - 1b)(%edi), %eax

	movl	$_PAGE_PRESENT | _PAGE_RW | _PAGE_PSE, %ecx

	leal	(_PAGE_PRESENT | _PAGE_RW)(%eax), %edx

2:	movl	%ecx, (%eax)

	addl	$8, %eax

	addl	$PMD_SIZE, %ecx

	jnc	2b



	movl	$PAGE_SIZE, %ecx

	.irpc	l, 0123

	movl	%edx, \l * 8(%eax)

	addl	%ecx, %edx

	.endr

	addl	%ecx, %eax

	movl	%edx, (%eax)

	movl	%eax, %cr3



	jmp	startup_32

SYM_FUNC_END(efi32_entry)
@@ -322,3 +347,7 @@ SYM_DATA_LOCAL(efi32_boot_ds, .word 0) 
SYM_DATA_LOCAL(efi32_boot_sp, .long 0)

SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)

SYM_DATA(efi_is64, .byte 1)



	.bss

	.balign PAGE_SIZE

SYM_DATA_LOCAL(pte, .fill 6 * PAGE_SIZE, 1, 0)