From: Josh Poimboeuf <jpoimboe@redhat.com>
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <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>,
tglx@linutronix.de, 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, x86@kernel.org
Subject: Re: [PATCH v7 02/11] x86/retpoline: Temporarily disable objtool when CONFIG_RETPOLINE=y
Date: Tue, 9 Jan 2018 23:58:06 -0600 [thread overview]
Message-ID: <20180110055806.gqdxpk4urvew253b@treble> (raw)
In-Reply-To: <1515508997-6154-3-git-send-email-dwmw@amazon.co.uk>
On Tue, Jan 09, 2018 at 02:43:08PM +0000, David Woodhouse wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> objtool's assembler currently cannot deal with the code generated by the
> retpoline compiler and throws hundreds of warnings, mostly because it sees
> calls that don't have a symbolic target.
>
> Exclude all the options that rely on objtool when RETPOLINE is active.
>
> This mainly means that the kernel has to fallback to use the frame pointer
> unwinder and livepatch is not supported.
>
> Josh is looking into resolving the issue.
I have a fix brewing for this, in two parts:
- Part 1 will allow objtool to understand the flow *around* the
retpolines (but not *inside* them). Which basically means that ORC
will still get confused if it tries to unwind from inside a retpoline,
but otherwise it should work fine. This code is pretty much done,
just need to do some testing with it first. This should allow us to
re-enable objtool and friends: ORC, reliable stacks, livepatch
consistency model.
- Part 2 will add ORC annotations for inside the retpolines. This will
be a little harder, but I have my fingers crossed that it's do-able
within a week or so.
--
Josh
next prev parent reply other threads:[~2018-01-10 5:58 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 14:43 [PATCH v7 00/11] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-09 14:43 ` [PATCH v7 01/11] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-09 15:55 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:34 ` tip-bot for David Woodhouse
2018-01-10 18:13 ` tip-bot for David Woodhouse
2018-01-10 18:40 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 02/11] x86/retpoline: Temporarily disable objtool when CONFIG_RETPOLINE=y David Woodhouse
2018-01-09 15:56 ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-10 5:58 ` Josh Poimboeuf [this message]
2018-01-10 10:12 ` [PATCH v7 02/11] " Peter Zijlstra
2018-01-10 17:34 ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-10 18:13 ` tip-bot for Andi Kleen
2018-01-10 18:40 ` tip-bot for Andi Kleen
2018-01-09 14:43 ` [PATCH v7 03/11] x86/spectre: Add boot time option to select Spectre v2 mitigation David Woodhouse
2018-01-09 15:56 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:35 ` tip-bot for David Woodhouse
2018-01-10 18:03 ` Tom Lendacky
2018-01-10 18:06 ` Thomas Gleixner
2018-01-10 18:10 ` Thomas Gleixner
2018-01-10 18:14 ` tip-bot for David Woodhouse
2018-01-10 18:33 ` Tom Lendacky
2018-01-10 18:35 ` Thomas Gleixner
2018-01-10 18:41 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 04/11] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-09 15:56 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:35 ` tip-bot for David Woodhouse
2018-01-10 18:14 ` tip-bot for David Woodhouse
2018-01-10 18:41 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 05/11] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-09 15:57 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 3:54 ` [v7, 05/11] " Andrei Vagin
2018-01-10 4:30 ` Andi Kleen
2018-01-10 4:39 ` Dave Hansen
2018-01-10 5:23 ` Andrei Vagin
2018-01-10 17:36 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 18:15 ` tip-bot for David Woodhouse
2018-01-10 18:41 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 06/11] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-09 15:57 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:36 ` tip-bot for David Woodhouse
2018-01-10 18:15 ` tip-bot for David Woodhouse
2018-01-10 18:42 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 07/11] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-09 15:58 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:37 ` tip-bot for David Woodhouse
2018-01-10 18:15 ` tip-bot for David Woodhouse
2018-01-10 18:42 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 08/11] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-09 15:58 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:37 ` tip-bot for David Woodhouse
2018-01-10 18:16 ` tip-bot for David Woodhouse
2018-01-10 18:43 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 09/11] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-09 15:58 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-10 17:37 ` tip-bot for David Woodhouse
2018-01-10 18:16 ` tip-bot for David Woodhouse
2018-01-10 18:43 ` tip-bot for David Woodhouse
2018-01-09 14:43 ` [PATCH v7 10/11] x86/retpoline/irq32: " David Woodhouse
2018-01-09 15:59 ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-10 17:38 ` tip-bot for Andi Kleen
2018-01-10 18:17 ` tip-bot for Andi Kleen
2018-01-10 18:43 ` tip-bot for Andi Kleen
2018-01-09 14:43 ` [PATCH v7 11/11] x86/retpoline: Avoid return buffer underflows on context switch David Woodhouse
2018-01-09 15:59 ` [tip:x86/pti] " tip-bot for Andi Kleen
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