[PATCH] arm64: Work around broken GCC handling of "S" constraint
ardb at kernel.org
Mon Dec 7 12:47:07 EST 2020
On Mon, 7 Dec 2020 at 18:41, Marc Zyngier <maz at kernel.org> wrote:
> On 2020-12-07 17:19, Ard Biesheuvel wrote:
> > (resend with David's email address fixed)
> Irk. Thanks for that.
> >> > +#ifdef CONFIG_CC_HAS_BROKEN_S_CONSTRAINT
> >> > +#define SYM_CONSTRAINT "i"
> >> > +#else
> >> > +#define SYM_CONSTRAINT "S"
> >> > +#endif
> >> > +
> >> Could we just check GCC_VERSION here?
> I guess we could. But I haven't investigated which exact range of
> compiler is broken (GCC 6.3 seems fixed, but that's the oldest
> I have apart from the offending 4.9).
I tried 5.4 on godbolt, and it seems happy. And the failure will be
obvious, so we can afford to get it slightly wrong and refine it
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