All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Woodhouse, David" <dwmw@amazon.co.uk>
To: Thomas Gleixner <tglx@linutronix.de>, Borislav Petkov <bpetkov@suse.de>
Cc: <ak@linux.intel.com>, Paul Turner <pjt@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	"Dave Hansen" <dave.hansen@intel.com>,
	Kees Cook <keescook@google.com>, "Rik van Riel" <riel@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Andy Lutomirski" <luto@amacapital.net>,
	Jiri Kosina <jikos@kernel.org>, <gnomes@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH v3 01/13] x86/retpoline: Add initial retpoline support
Date: Fri, 5 Jan 2018 16:41:46 +0000	[thread overview]
Message-ID: <1515170506.29312.149.camel@amazon.co.uk> (raw)
In-Reply-To: <1515160619.29312.126.camel@amazon.co.uk>

[-- Attachment #1: Type: text/plain, Size: 967 bytes --]

On Fri, 2018-01-05 at 13:56 +0000, Woodhouse, David wrote:
> 
> At some point during this whole painful mess, I had come to the
> conclusion that having relocations in altinstr didn't work, and that's
> why I had X86_xx_NO_RETPOLINE instead of X86_xx_RETPOLINE. I now think
> that something else was wrong when I was testing that, and relocs in
> altinstr do work. So sure, X86_FEATURE_RETPOLINE ought to work. I can
> change that round, and it's simpler for the IBRS patch set to take it
> into account and set it when appropriate.

+bpetkov

Nope, alternatives are broken. Only a jmp as the *first* opcode of
altinstr gets handled by recompute_jump(), while any subsequent insn is
just copied untouched.

To fix that and handle every instruction, the alternative code would
need to know about instruction lengths. I think we need to stick with
the inverted X86_FEATURE_NO_RETPOLINE flag for the moment, and not tie
it to a complex bugfix there.

[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5210 bytes --]

  reply	other threads:[~2018-01-05 16:42 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-04  9:10 [RFC] Retpoline: Binary mitigation for branch-target-injection (aka "Spectre") Paul Turner
2018-01-04  9:12 ` Paul Turner
2018-01-04  9:24 ` Paul Turner
2018-01-04  9:48   ` Greg Kroah-Hartman
2018-01-04  9:56     ` Woodhouse, David
2018-01-04  9:30 ` Woodhouse, David
2018-01-04 14:36   ` [PATCH v3 01/13] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-04 18:03     ` Linus Torvalds
2018-01-04 19:32       ` Woodhouse, David
2018-01-04 18:17     ` Alexei Starovoitov
2018-01-04 18:25       ` Linus Torvalds
2018-01-04 18:36         ` Alexei Starovoitov
2018-01-04 19:27           ` David Woodhouse
2018-01-05 10:28             ` Paul Turner
2018-01-05 10:55               ` David Woodhouse
2018-01-05 11:19                 ` Paul Turner
2018-01-05 11:25                 ` Paul Turner
2018-01-05 11:26               ` Paolo Bonzini
2018-01-05 12:20                 ` Paul Turner
2018-01-05 10:40         ` Paul Turner
2018-01-04 18:40       ` Andi Kleen
2018-01-05 10:32         ` Paul Turner
2018-01-05 12:54     ` Thomas Gleixner
2018-01-05 13:01       ` Juergen Gross
2018-01-05 13:03         ` Thomas Gleixner
2018-01-05 13:56       ` Woodhouse, David
2018-01-05 16:41         ` Woodhouse, David [this message]
2018-01-05 16:45           ` Borislav Petkov
2018-01-05 17:08             ` Josh Poimboeuf
2018-01-06  0:30               ` Borislav Petkov
2018-01-06  8:23                 ` David Woodhouse
2018-01-06 17:02                   ` Borislav Petkov
2018-01-07  9:40                     ` David Woodhouse
2018-01-07 11:46                       ` Borislav Petkov
2018-01-07 12:21                         ` David Woodhouse
2018-01-07 14:03                           ` Borislav Petkov
2018-01-08 21:50                             ` David Woodhouse
2018-01-08  5:06                 ` Josh Poimboeuf
2018-01-08  7:55                   ` Woodhouse, David
2018-01-05 17:12             ` Woodhouse, David
2018-01-05 17:28               ` Linus Torvalds
2018-01-05 17:48                 ` David Woodhouse
2018-01-05 18:05                 ` Andi Kleen
2018-01-05 20:32                 ` Woodhouse, David
2018-01-05 21:11                   ` Brian Gerst
2018-01-05 22:16                     ` Woodhouse, David
2018-01-05 22:43                       ` Borislav Petkov
2018-01-05 22:00                 ` Woodhouse, David
2018-01-05 22:06                   ` Borislav Petkov
2018-01-05 23:50                   ` Linus Torvalds
2018-01-06 10:53                     ` Woodhouse, David
2018-01-04 14:36   ` [PATCH v3 02/13] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-04 14:37   ` [PATCH v3 03/13] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-04 14:46     ` Dave Hansen
2018-01-04 14:49       ` Woodhouse, David
2018-01-04 14:37   ` [PATCH v3 04/13] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-04 14:37   ` [PATCH v3 05/13] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-04 14:37   ` [PATCH v3 06/13] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-04 15:10     ` Juergen Gross
2018-01-04 15:18       ` David Woodhouse
2018-01-04 15:54     ` Juergen Gross
2018-01-04 14:37   ` [PATCH v3 07/13] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-04 14:37   ` [PATCH v3 08/13] x86/alternatives: Add missing \n at end of ALTERNATIVE inline asm David Woodhouse
2018-01-05 13:04     ` [tip:x86/pti] x86/alternatives: Add missing '\n' " tip-bot for David Woodhouse
2018-01-04 14:37   ` [PATCH v3 09/13] x86/retpoline/irq32: Convert assembler indirect jumps David Woodhouse
2018-01-04 14:37   ` [PATCH v3 10/13] x86/retpoline/pvops: " David Woodhouse
2018-01-04 15:02     ` Juergen Gross
2018-01-04 15:12       ` Woodhouse, David
2018-01-04 15:18       ` Andrew Cooper
2018-01-04 16:04         ` Juergen Gross
2018-01-04 16:37       ` Andi Kleen
2018-01-04 14:37   ` [PATCH v3 11/13] retpoline/taint: Taint kernel for missing retpoline in compiler David Woodhouse
2018-01-04 22:06     ` Justin Forbes
2018-01-04 14:37   ` [PATCH v3 12/13] retpoline/objtool: Disable some objtool warnings David Woodhouse
2018-01-04 14:37   ` [PATCH v3 13/13] retpoline: Attempt to quiten objtool warning for unreachable code David Woodhouse
2018-01-04 16:18   ` [RFC] Retpoline: Binary mitigation for branch-target-injection (aka "Spectre") Andy Lutomirski
2018-01-04 16:24     ` David Woodhouse
2018-01-05 10:49     ` Paul Turner
2018-01-05 11:43       ` Woodhouse, David

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1515170506.29312.149.camel@amazon.co.uk \
    --to=dwmw@amazon.co.uk \
    --cc=ak@linux.intel.com \
    --cc=bpetkov@suse.de \
    --cc=dave.hansen@intel.com \
    --cc=gnomes@lxorguk.ukuu.org.uk \
    --cc=gregkh@linux-foundation.org \
    --cc=jikos@kernel.org \
    --cc=keescook@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=riel@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=tim.c.chen@linux.intel.com \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.