From: Andi Kleen <ak@linux.intel.com>
To: Dominik Brodowski <law@dominikbrodowski.net>
Cc: Andi Kleen <andi@firstfloor.org>,
tglx@linutronix.de, x86@kernel.org, dwmw@amazon.co.uk,
linux-kernel@vger.kernel.org, pjt@google.com,
torvalds@linux-foundation.org, gregkh@linux-foundation.org,
peterz@infradead.org, luto@amacapital.net,
thomas.lendacky@amd.com, arjan.van.de.ven@intel.com
Subject: Re: [PATCH 1/4] x86/retpoline: Add new mode RETPOLINE_UNDERFLOW
Date: Fri, 12 Jan 2018 14:57:14 -0800 [thread overview]
Message-ID: <20180112225714.GQ6718@tassilo.jf.intel.com> (raw)
In-Reply-To: <20180112221313.GA13035@light.dominikbrodowski.net>
On Fri, Jan 12, 2018 at 11:13:13PM +0100, Dominik Brodowski wrote:
> > @@ -209,6 +234,11 @@ static void __init spectre_v2_select_mitigation(void)
> > mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_GENERIC :
> > SPECTRE_V2_RETPOLINE_MINIMAL;
> > setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
> > + if (mode == SPECTRE_V2_RETPOLINE_GENERIC &&
> > + cpu_needs_underflow_protection()) {
> > + mode = SPECTRE_V2_RETPOLINE_UNDERFLOW;
> > + setup_force_cpu_cap(X86_FEATURE_RETURN_UNDERFLOW);
> > + }
> > }
>
> Why does this require a retp-compatible compiler to be enabled?
Without the compiler you have a lot of other problems already,
so it's fairly pointless.
-Andi
next prev parent reply other threads:[~2018-01-12 22:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 18:45 Improve retpoline for Skylake Andi Kleen
2018-01-12 18:45 ` [PATCH 1/4] x86/retpoline: Add new mode RETPOLINE_UNDERFLOW Andi Kleen
2018-01-12 22:13 ` Dominik Brodowski
2018-01-12 22:57 ` Andi Kleen [this message]
2018-01-12 18:45 ` [PATCH 2/4] x86/retpoline: Avoid return buffer underflows on context switch Andi Kleen
2018-01-12 18:45 ` [PATCH 3/4] x86/retpoline: Fill return buffer after idle Andi Kleen
2018-01-12 18:45 ` [PATCH 4/4] x86/retpoline: Fill return buffer on interrupt return to kernel Andi Kleen
2018-01-12 19:12 ` Improve retpoline for Skylake David Woodhouse
2018-01-12 19:21 ` Andi Kleen
2018-01-12 22:03 ` Henrique de Moraes Holschuh
2018-01-15 8:26 ` Jon Masters
2018-01-15 9:06 ` David Woodhouse
2018-01-15 10:03 ` Thomas Gleixner
2018-01-15 10:20 ` David Woodhouse
2018-01-15 16:57 ` Andy Lutomirski
2018-01-15 17:38 ` Andrew Cooper
2018-01-15 17:56 ` Van De Ven, Arjan
2018-01-15 18:06 ` Andy Lutomirski
2018-01-15 18:07 ` David Woodhouse
2018-01-15 18:10 ` Andy Lutomirski
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