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Commit aa8c6248 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86/mm/pti: Add infrastructure for page table isolation 



Add the initial files for kernel page table isolation, with a minimal init
function and the boot time detection for this misfeature.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 8a09317b

Documentation/admin-guide/kernel-parameters.txt

+2 −0
Original line number Diff line number Diff line
@@ -2685,6 +2685,8 @@ 
			steal time is computed, but won't influence scheduler

			behaviour



	nopti		[X86-64] Disable kernel page table isolation



	nolapic		[X86-32,APIC] Do not enable or use the local APIC.



	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.

arch/x86/boot/compressed/pagetable.c

+3 −0
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ 
 */

#undef CONFIG_AMD_MEM_ENCRYPT



/* No PAGE_TABLE_ISOLATION support needed either: */

#undef CONFIG_PAGE_TABLE_ISOLATION



#include "misc.h"



/* These actually do the work of building the kernel identity maps. */

arch/x86/entry/calling.h

+7 −0
Original line number Diff line number Diff line
@@ -205,18 +205,23 @@ For 32-bit we have the following conventions - kernel is built with 
.endm



.macro SWITCH_TO_KERNEL_CR3 scratch_reg:req

	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI

	mov	%cr3, \scratch_reg

	ADJUST_KERNEL_CR3 \scratch_reg

	mov	\scratch_reg, %cr3

.Lend_\@:

.endm



.macro SWITCH_TO_USER_CR3 scratch_reg:req

	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI

	mov	%cr3, \scratch_reg

	ADJUST_USER_CR3 \scratch_reg

	mov	\scratch_reg, %cr3

.Lend_\@:

.endm



.macro SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg:req save_reg:req

	ALTERNATIVE "jmp .Ldone_\@", "", X86_FEATURE_PTI

	movq	%cr3, \scratch_reg

	movq	\scratch_reg, \save_reg

	/*
@@ -233,11 +238,13 @@ For 32-bit we have the following conventions - kernel is built with 
.endm



.macro RESTORE_CR3 save_reg:req

	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI

	/*

	 * The CR3 write could be avoided when not changing its value,

	 * but would require a CR3 read *and* a scratch register.

	 */

	movq	\save_reg, %cr3

.Lend_\@:

.endm



#else /* CONFIG_PAGE_TABLE_ISOLATION=n: */

arch/x86/include/asm/pti.h

0 → 100644
+14 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#ifndef _ASM_X86_PTI_H

#define _ASM_X86_PTI_H

#ifndef __ASSEMBLY__



#ifdef CONFIG_PAGE_TABLE_ISOLATION

extern void pti_init(void);

extern void pti_check_boottime_disable(void);

#else

static inline void pti_check_boottime_disable(void) { }

#endif



#endif /* __ASSEMBLY__ */

#endif /* _ASM_X86_PTI_H */

arch/x86/mm/Makefile

+4 −3
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ obj-$(CONFIG_NUMA_EMU) += numa_emulation.o 
obj-$(CONFIG_X86_INTEL_MPX)			+= mpx.o

obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)	+= pkeys.o

obj-$(CONFIG_RANDOMIZE_MEMORY)			+= kaslr.o

obj-$(CONFIG_PAGE_TABLE_ISOLATION)		+= pti.o



obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt.o

obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_boot.o