From: David Woodhouse <dwmw2@infradead.org>
To: Pavel Machek <pavel@ucw.cz>, Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
David Hildenbrand <david@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jon Masters <jcm@redhat.com>, Marcus Meissner <meissner@suse.de>,
Jiri Kosina <jkosina@suse.cz>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH 6/6] s390: introduce execute-trampolines for branches
Date: Wed, 07 Feb 2018 12:07:55 +0000 [thread overview]
Message-ID: <1518005275.3677.112.camel@infradead.org> (raw)
In-Reply-To: <20180207100726.GB31392@amd>
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On Wed, 2018-02-07 at 11:07 +0100, Pavel Machek wrote:
> This is really unfortunate naming of kernel option.
>
> spectre_v2=off sounds like we are turning the "bug" off, but i somehow
> suspect you are turning the bug _workaround_ off.
That's consistent with what we have on x86.
> > +ifdef CONFIG_EXPOLINE
> > + ifeq ($(call cc-option-yn,$(CC_FLAGS_MARCH) -mindirect-branch=thunk),y)
> > + CC_FLAGS_EXPOLINE := -mindirect-branch=thunk
> > + CC_FLAGS_EXPOLINE += -mfunction-return=thunk
> > + CC_FLAGS_EXPOLINE += -mindirect-branch-table
> > + export CC_FLAGS_EXPOLINE
> > + cflags-y += $(CC_FLAGS_EXPOLINE)
> > + else
> > + $(warning "Your gcc lacks the -mindirect-branch= option")
> > + endif
> > +endif
That isn't, though. Linus asked us to drop the $(warning) part.
... and then spent a week building with a non-retpoline compiler and
not noticing, so he might have changed his mind ;)
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next prev parent reply other threads:[~2018-02-07 12:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 7:00 [PATCH 0/6] s390: improve speculative execution handling v3 Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 1/6] s390: scrub registers on kernel entry and KVM exit Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 2/6] s390: add optimized array_index_mask_nospec Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 3/6] s390/alternative: use a copy of the facility bit mask Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 4/6] s390: add options to change branch prediction behaviour for the kernel Martin Schwidefsky
2018-02-07 10:02 ` Pavel Machek
2018-02-07 11:49 ` Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 5/6] s390: run user space and KVM guests with modified branch prediction Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 6/6] s390: introduce execute-trampolines for branches Martin Schwidefsky
2018-02-07 10:07 ` Pavel Machek
2018-02-07 11:51 ` Martin Schwidefsky
2018-02-07 12:07 ` David Woodhouse [this message]
2018-02-07 12:17 ` Martin Schwidefsky
2018-02-07 12:20 ` David Woodhouse
2018-02-07 17:55 ` Linus Torvalds
2018-02-07 23:44 ` Masahiro Yamada
2018-02-08 0:05 ` Linus Torvalds
2018-02-08 0:57 ` Kees Cook
2018-02-08 17:11 ` Masahiro Yamada
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