From: David Woodhouse <dwmw2@infradead.org>
To: "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
David Laight <David.Laight@ACULAB.COM>,
'Andi Kleen' <andi@firstfloor.org>,
"tglx@linutronix.de" <tglx@linutronix.de>
Cc: "torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"peterz@infradead.org" <peterz@infradead.org>,
Andi Kleen <ak@linux.intel.com>,
"jeyu@kernel.org" <jeyu@kernel.org>
Subject: Re: [PATCH] retpoline/module: Taint kernel for missing retpoline in module
Date: Mon, 15 Jan 2018 14:01:08 +0100 [thread overview]
Message-ID: <1516021268.22147.156.camel@infradead.org> (raw)
In-Reply-To: <0575AF4FD06DD142AD198903C74E1CC87A5CB32D@FMSMSX151.amr.corp.intel.com>
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On Mon, 2018-01-15 at 12:53 +0000, Van De Ven, Arjan wrote:
>
> binary what? ;-)
>
> retpoline (or lack thereof) is part of the kernel ABI at this point....
Strictly speaking, only lack thereof.
If you build the kernel without CONFIG_RETPOLINE, you can't build
modules with retpoline and then expect them to load — because the thunk
symbols aren't exported.
If you build the kernel with the retpoline though, you *can*
successfully load modules which aren't built with retpoline.
It's not even that unlikely, if the kernel engineers are ensuring they
have the latest unreleased toolchain for kernel builds, but you're
using out-of-tree modules built separately or even on the target system
using DKMS, and you *haven't* got the shiny new compiler.
That's what Andi's attempting to protect against.
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next prev parent reply other threads:[~2018-01-15 13:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 17:55 [PATCH] retpoline/module: Taint kernel for missing retpoline in module Andi Kleen
2018-01-12 19:01 ` David Woodhouse
2018-01-12 19:17 ` Andi Kleen
2018-01-13 14:12 ` Greg KH
2018-01-13 14:38 ` Van De Ven, Arjan
2018-01-13 15:37 ` Greg KH
2018-01-13 14:53 ` Andi Kleen
2018-01-13 15:36 ` Greg KH
2018-01-13 18:20 ` Andi Kleen
2018-01-16 20:08 ` Andi Kleen
2018-01-15 12:47 ` David Laight
2018-01-15 12:53 ` Van De Ven, Arjan
2018-01-15 13:01 ` David Woodhouse [this message]
2018-01-15 14:08 ` David Laight
2018-01-15 16:48 ` Andi Kleen
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