lkml.org 
[lkml]   [2018]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 6/6] s390: introduce execute-trampolines for branches
On Wed, 07 Feb 2018 12:07:55 +0000
David Woodhouse <dwmw2@infradead.org> wrote:

> 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 ;)

I found the warning to have some value, it helps for the case where my
fingers are faster than my brain and I type "make" instead of "smake"
which uses the alternative compiler with the required support.

@Linus: do you want a warning or prefer not to have one ?

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

\
 
 \ /
  Last update: 2018-02-07 13:18    [W:0.060 / U:0.756 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site