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Patch "x86/Documentation: Add PTI description" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jan 15, 2018

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This is a note to let you know that I've just added the patch titled

x86/Documentation: Add PTI description

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-documentation-add-pti-description.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 01c9b17bf673b05bb401b76ec763e9730ccf1376 Mon Sep 17 00:00:00 2001

From: Dave Hansen <[email protected]>
Date: Fri, 5 Jan 2018 09:44:36 -0800
Subject: x86/Documentation: Add PTI description

From: Dave Hansen <[email protected]>

commit 01c9b17bf673b05bb401b76ec763e9730ccf1376 upstream.

Add some details about how PTI works, what some of the downsides are, and how to debug it when things go wrong.

Also document the kernel parameter: 'pti/nopti'.

Signed-off-by Dave Hansen <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Reviewed-by Randy Dunlap <[email protected]>
Reviewed-by Kees Cook <[email protected]>
Cc Moritz Lipp <[email protected]>
Cc Daniel Gruss <[email protected]>
Cc Michael Schwarz <[email protected]>
Cc Richard Fellner <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Hugh Dickins <[email protected]>
Cc Andi Lutomirsky <[email protected]>
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 Documentation/kernel-parameters.txt |   21 ++--
 Documentation/x86/pti.txt           |  186 ++++++++++++++++++++++++++++++++++++
 2 files changed, 200 insertions(+), 7 deletions(-)
Documentation/kernel-parameters.txt +14 -7
@@ -2763,8 +2763,6 @@ bytes respectively. Such letter suffixes
 
 	nojitter	[IA-64] Disables jitter checking for ITC timers.
 
-	nopti		[X86-64] Disable KAISER isolation of kernel from user.
-
 	no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
 
 	no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page

@@ -3327,11 +3325,20 @@ bytes respectively. Such letter suffixes
 	pt.		[PARIDE]
 			See Documentation/blockdev/paride.txt.
 
-	pti=		[X86_64]
-			Control KAISER user/kernel address space isolation:
-			on - enable
-			off - disable
-			auto - default setting
+	pti=		[X86_64] Control Page Table Isolation of user and
+			kernel address spaces.  Disabling this feature
+			removes hardening, but improves performance of
+			system calls and interrupts.
+
+			on   - unconditionally enable
+			off  - unconditionally disable
+			auto - kernel detects whether your CPU model is
+			       vulnerable to issues that PTI mitigates
+
+			Not specifying this option is equivalent to pti=auto.
+
+	nopti		[X86_64]
+			Equivalent to pti=off
 
 	pty.legacy_count=
 			[KNL] Number of legacy pty's. Overwrites compiled-in
Documentation/x86/pti.txt new file +186 -0

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Patches currently in stable-queue which might be from [email protected] are

queue-4.9/x86-documentation-add-pti-description.patch