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From: Andy Lutomirski <luto@kernel.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Paul Turner <pjt@google.com>, Jiri Kosina <jikos@kernel.org>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andi Kleen <ak@linux.intel.com>, Kees Cook <keescook@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/pti] x86/retpoline: Fill return stack buffer on vmexit
Date: Thu, 25 Jan 2018 09:05:37 -0800	[thread overview]
Message-ID: <CALCETrWHJZXqDC-PUStHAJrNVMO_QEC0PG0PKAEHD+8TB-eqqQ@mail.gmail.com> (raw)
In-Reply-To: <1516899639.30244.145.camel@infradead.org>

On Thu, Jan 25, 2018 at 9:00 AM, David Woodhouse <dwmw2@infradead.org> wrote:
> On Thu, 2018-01-25 at 10:56 -0600, Josh Poimboeuf wrote:
>> On Thu, Jan 25, 2018 at 04:03:18PM +0000, David Woodhouse wrote:
>> > On Thu, 2018-01-25 at 16:51 +0100, Borislav Petkov wrote:
>> > >
>> > > > And the seg fault is objtool's way of telling you you need a
>> > > > ANNOTATE_NOSPEC_ALTERNATIVE above the alternative ;-)
>> > >
>> > > Except that it blew up when I did this which doesn't have ALTERNATIVE
>> > > (it's the diff I saved :-))
>> >
>> > Yeah, ANNOTATE_NOSPEC_ALTERNATIVE just tells objtool "don't look at the
>> > alternative; you're not going to like it".
>> >
>> > If you start putting a __fill_rsb() function out of line somewhere and
>> > only *calling* it from alternatives, then objtool is going to shit
>> > itself when it sees that function, regardless.
>>
>> Right, if you *really* want it always inline, the short term solution is
>> to just patch it in with X86_FEATURE_ALWAYS.
>
> And the whole problem here is that patching it in with alternatives is
> painful on kernels < 4.1 because back then, we didn't cope with
> oldinstr and altinstr being different lengths.
>
> And they don't want to fix *that* because kABI...
>
> I just stopped caring.

Screw kABI.

Distros that use retpolines need their driver vendors to recompile no
matter what.  Distros that use IBRS and refuse to use retpolines
should get put on a list of "didn't actually adequately mitigate
spectre".

  reply	other threads:[~2018-01-25 17:05 UTC|newest]

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-11 21:46 [PATCH v8 00/12] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-11 21:46 ` [PATCH v8 01/12] objtool: Detect jumps to retpoline thunks David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-11 21:46 ` [PATCH v8 02/12] objtool: Allow alternatives to be ignored David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-18 19:09   ` [v8,02/12] " Guenter Roeck
2018-01-18 19:33     ` Josh Poimboeuf
2018-01-18 19:41       ` Guenter Roeck
2018-01-22 19:34         ` David Woodhouse
2018-01-22 20:25           ` Guenter Roeck
2018-01-22 20:27             ` David Woodhouse
2018-01-28 21:06             ` Josh Poimboeuf
2018-01-29  1:26               ` Guenter Roeck
2018-01-29 17:15               ` Guenter Roeck
2018-01-29 17:30                 ` Josh Poimboeuf
2018-01-22 19:27       ` Guenter Roeck
2018-01-11 21:46 ` [PATCH v8 03/12] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-11 23:23   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 23:58   ` [PATCH v8 03/12] " Tom Lendacky
2018-01-12 10:28     ` David Woodhouse
2018-01-12 14:02       ` Tom Lendacky
2018-01-14 15:02   ` Borislav Petkov
2018-01-14 15:53     ` Josh Poimboeuf
2018-01-14 15:59       ` Borislav Petkov
2018-01-11 21:46 ` [PATCH v8 04/12] x86/spectre: Add boot time option to select Spectre v2 mitigation David Woodhouse
2018-01-11 23:23   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-23 22:40   ` [PATCH v8 04/12] " Borislav Petkov
2018-01-23 22:53     ` David Woodhouse
2018-01-23 23:05       ` Andi Kleen
2018-01-23 22:55     ` Jiri Kosina
2018-01-23 23:05       ` Borislav Petkov
2018-01-24  0:32         ` Kees Cook
2018-01-24  9:58           ` Borislav Petkov
2018-01-23 23:06       ` Jiri Kosina
2018-01-23 23:21       ` Andi Kleen
2018-01-23 23:24         ` Jiri Kosina
2018-01-23 23:45           ` Andi Kleen
2018-01-23 23:49             ` Jiri Kosina
2018-01-24  4:26               ` Greg Kroah-Hartman
2018-01-24  9:56                 ` Jiri Kosina
2018-01-24 13:58                   ` Greg Kroah-Hartman
2018-01-24 14:03                     ` Jiri Kosina
2018-01-24 14:22                       ` Greg Kroah-Hartman
2018-01-11 21:46 ` [PATCH v8 05/12] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-11 23:24   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 06/12] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-11 23:24   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 07/12] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 08/12] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 09/12] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 10/12] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 11/12] x86/retpoline/irq32: " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-11 21:46 ` [PATCH v8 12/12] x86/retpoline: Fill return stack buffer on vmexit David Woodhouse
2018-01-11 23:27   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 23:51   ` [PATCH v8 12/12] " Andi Kleen
2018-01-12 11:11     ` [PATCH v8.1 " David Woodhouse
2018-01-12 11:15       ` Thomas Gleixner
2018-01-12 11:21         ` Woodhouse, David
2018-01-12 11:37       ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-14 14:50         ` Borislav Petkov
2018-01-14 15:28           ` Thomas Gleixner
2018-01-14 15:35         ` Borislav Petkov
2018-01-25 12:07         ` Borislav Petkov
2018-01-25 12:20           ` David Woodhouse
2018-01-25 12:45             ` Borislav Petkov
2018-01-25 15:10               ` Josh Poimboeuf
2018-01-25 15:51                 ` Borislav Petkov
2018-01-25 16:03                   ` David Woodhouse
2018-01-25 16:56                     ` Josh Poimboeuf
2018-01-25 17:00                       ` David Woodhouse
2018-01-25 17:05                         ` Andy Lutomirski [this message]
2018-01-25 17:44                           ` Josh Poimboeuf
2018-01-25 18:41                           ` Jiri Kosina
2018-01-25 17:10                         ` Thomas Gleixner
2018-01-25 17:32                         ` Josh Poimboeuf
2018-01-25 17:53                         ` Borislav Petkov
2018-01-25 18:04                           ` David Woodhouse
2018-01-25 18:32                             ` Josh Poimboeuf
2018-01-25 19:07                             ` Borislav Petkov
2018-01-25 19:10                               ` Borislav Petkov

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