Hi! On Tue, Oct 20, 2020 at 07:40:09AM +0000, Christophe Leroy wrote: > In several places, inline assembly uses the "%Un" modifier > to enable the use of instruction with update form addressing, > but the associated "<>" constraint is missing. > > As mentioned in previous patch, this fails with gcc 4.9, so > "<>" can't be used directly. > > Use UPD_CONSTR macro everywhere %Un modifier is used. > > Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
Oh well, it will be easy enough to remove this wart later, so Reviewed-by: Segher Boessenkool <seg...@kernel.crashing.org> > --- a/arch/powerpc/include/asm/book3s/32/pgtable.h > +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h > @@ -525,7 +525,7 @@ static inline void __set_pte_at(struct mm_struct *mm, > unsigned long addr, > stw%U0%X0 %2,%0\n\ > eieio\n\ > stw%U1%X1 %L2,%1" > - : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4)) > + : "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4)) > : "r" (pte) : "memory"); Here it would pre-increment ptep+4. That can never be something useful afaics? The order the two operands are (either or not) pre-modified in the asm is not specified (GCC does not parse the asm template, by design), so I fail to see how this could ever work. > --- a/arch/powerpc/include/asm/nohash/pgtable.h > +++ b/arch/powerpc/include/asm/nohash/pgtable.h > @@ -200,7 +200,7 @@ static inline void __set_pte_at(struct mm_struct *mm, > unsigned long addr, > stw%U0%X0 %2,%0\n\ > eieio\n\ > stw%U1%X1 %L2,%1" > - : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4)) > + : "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char > *)ptep+4)) > : "r" (pte) : "memory"); Same here. The rest looks fine. Segher
