Messages in this thread | | | Date | Wed, 7 Feb 2018 13:17:19 +0100 | From | Martin Schwidefsky <> | Subject | Re: [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.
| |