Commit 64e68263 authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov
Browse files

x86/boot/compressed/64: Add IDT Infrastructure 



Add code needed to setup an IDT in the early pre-decompression
boot-code. The IDT is loaded first in startup_64, which is after
EfiExitBootServices() has been called, and later reloaded when the
kernel image has been relocated to the end of the decompression area.

This allows to setup different IDT handlers before and after the
relocation.

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-14-joro@8bytes.org
parent 6ba0efa4

arch/x86/boot/compressed/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ vmlinux-objs-$(CONFIG_EARLY_PRINTK) += $(obj)/early_serial_console.o 
vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr.o

ifdef CONFIG_X86_64

	vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr_64.o

	vmlinux-objs-y += $(obj)/idt_64.o $(obj)/idt_handlers_64.o

	vmlinux-objs-y += $(obj)/mem_encrypt.o

	vmlinux-objs-y += $(obj)/pgtable_64.o

endif

arch/x86/boot/compressed/head_64.S

+24 −1
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <asm/processor-flags.h>

#include <asm/asm-offsets.h>

#include <asm/bootparam.h>

#include <asm/desc_defs.h>

#include "pgtable.h"



/*
@@ -410,6 +411,10 @@ SYM_CODE_START(startup_64) 


.Lon_kernel_cs:



	pushq	%rsi

	call	load_stage1_idt

	popq	%rsi



	/*

	 * paging_prepare() sets up the trampoline and checks if we need to

	 * enable 5-level paging.
@@ -537,6 +542,13 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) 
	shrq	$3, %rcx

	rep	stosq



/*

 * Load stage2 IDT

 */

	pushq	%rsi

	call	load_stage2_idt

	popq	%rsi



/*

 * Do the extraction, and jump to the new kernel..

 */
@@ -690,10 +702,21 @@ SYM_DATA_START_LOCAL(gdt) 
	.quad   0x0000000000000000	/* TS continued */

SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)



SYM_DATA_START(boot_idt_desc)

	.word	boot_idt_end - boot_idt - 1

	.quad	0

SYM_DATA_END(boot_idt_desc)

	.balign 8

SYM_DATA_START(boot_idt)

	.rept	BOOT_IDT_ENTRIES

	.quad	0

	.quad	0

	.endr

SYM_DATA_END_LABEL(boot_idt, SYM_L_GLOBAL, boot_idt_end)



#ifdef CONFIG_EFI_STUB

SYM_DATA(image_offset, .long 0)

#endif



#ifdef CONFIG_EFI_MIXED

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

SYM_DATA(efi_is64, .byte 1)

arch/x86/boot/compressed/idt_64.c

0 → 100644
+44 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

#include <asm/trap_pf.h>

#include <asm/segment.h>

#include <asm/trapnr.h>

#include "misc.h"



static void set_idt_entry(int vector, void (*handler)(void))

{

	unsigned long address = (unsigned long)handler;

	gate_desc entry;



	memset(&entry, 0, sizeof(entry));



	entry.offset_low    = (u16)(address & 0xffff);

	entry.segment       = __KERNEL_CS;

	entry.bits.type     = GATE_TRAP;

	entry.bits.p        = 1;

	entry.offset_middle = (u16)((address >> 16) & 0xffff);

	entry.offset_high   = (u32)(address >> 32);



	memcpy(&boot_idt[vector], &entry, sizeof(entry));

}



/* Have this here so we don't need to include <asm/desc.h> */

static void load_boot_idt(const struct desc_ptr *dtr)

{

	asm volatile("lidt %0"::"m" (*dtr));

}



/* Setup IDT before kernel jumping to  .Lrelocated */

void load_stage1_idt(void)

{

	boot_idt_desc.address = (unsigned long)boot_idt;



	load_boot_idt(&boot_idt_desc);

}



/* Setup IDT after kernel jumping to  .Lrelocated */

void load_stage2_idt(void)

{

	boot_idt_desc.address = (unsigned long)boot_idt;



	load_boot_idt(&boot_idt_desc);

}

arch/x86/boot/compressed/idt_handlers_64.S

0 → 100644
+70 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Early IDT handler entry points

 *

 * Copyright (C) 2019 SUSE

 *

 * Author: Joerg Roedel <jroedel@suse.de>

 */



#include <asm/segment.h>



/* For ORIG_RAX */

#include "../../entry/calling.h"



.macro EXCEPTION_HANDLER name function error_code=0

SYM_FUNC_START(\name)



	/* Build pt_regs */

	.if \error_code == 0

	pushq   $0

	.endif



	pushq   %rdi

	pushq   %rsi

	pushq   %rdx

	pushq   %rcx

	pushq   %rax

	pushq   %r8

	pushq   %r9

	pushq   %r10

	pushq   %r11

	pushq   %rbx

	pushq   %rbp

	pushq   %r12

	pushq   %r13

	pushq   %r14

	pushq   %r15



	/* Call handler with pt_regs */

	movq    %rsp, %rdi

	/* Error code is second parameter */

	movq	ORIG_RAX(%rsp), %rsi

	call    \function



	/* Restore regs */

	popq    %r15

	popq    %r14

	popq    %r13

	popq    %r12

	popq    %rbp

	popq    %rbx

	popq    %r11

	popq    %r10

	popq    %r9

	popq    %r8

	popq    %rax

	popq    %rcx

	popq    %rdx

	popq    %rsi

	popq    %rdi



	/* Remove error code and return */

	addq    $8, %rsp



	iretq

SYM_FUNC_END(\name)

	.endm



	.text

	.code64

arch/x86/boot/compressed/misc.h

+5 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <asm/page.h>

#include <asm/boot.h>

#include <asm/bootparam.h>

#include <asm/desc_defs.h>



#define BOOT_CTYPE_H

#include <linux/acpi.h>
@@ -133,4 +134,8 @@ int count_immovable_mem_regions(void); 
static inline int count_immovable_mem_regions(void) { return 0; }

#endif



/* idt_64.c */

extern gate_desc boot_idt[BOOT_IDT_ENTRIES];

extern struct desc_ptr boot_idt_desc;



#endif /* BOOT_COMPRESSED_MISC_H */

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