Just re-pinging this thread. We're looking into enabling CONFIG_ARM64_LSE_ATOMICS on some devices, and this patch is required for building them with Clang. On Mon, Oct 29, 2018 at 11:13 AM Tri Vo <trong@xxxxxxxxxxx> wrote: > > On Mon, Oct 29, 2018 at 10:10 AM <ndesaulniers@xxxxxxxxxx> wrote: > > > > From: Tri Vo <trong@xxxxxxxxxxx> > > > > commit 2a6c7c367de82951c98a290a21156770f6f82c84 upstream > > > > x0 is not callee-saved in the PCS. So there is no need to specify > > -fcall-used-x0. > > > > Clang doesn't currently support -fcall-used flags. This patch will help > > building the kernel with clang. > > > > Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > Acked-by: Will Deacon <will.deacon@xxxxxxx> > > Signed-off-by: Tri Vo <trong@xxxxxxxxxxx> > > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> > > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > --- > > Sending to stable for inclusion in 4.14. Needed for > > CONFIG_ARM64_LSE_ATOMICS. > > Please take this patch into 4.9 too. > > > > > > arch/arm64/lib/Makefile | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile > > index f28f91fd96a2..69ff9887f724 100644 > > --- a/arch/arm64/lib/Makefile > > +++ b/arch/arm64/lib/Makefile > > @@ -12,7 +12,7 @@ lib-y := clear_user.o delay.o copy_from_user.o \ > > # when supported by the CPU. Result and argument registers are handled > > # correctly, based on the function prototype. > > lib-$(CONFIG_ARM64_LSE_ATOMICS) += atomic_ll_sc.o > > -CFLAGS_atomic_ll_sc.o := -fcall-used-x0 -ffixed-x1 -ffixed-x2 \ > > +CFLAGS_atomic_ll_sc.o := -ffixed-x1 -ffixed-x2 \ > > -ffixed-x3 -ffixed-x4 -ffixed-x5 -ffixed-x6 \ > > -ffixed-x7 -fcall-saved-x8 -fcall-saved-x9 \ > > -fcall-saved-x10 -fcall-saved-x11 -fcall-saved-x12 \ > > -- > > 2.19.1.568.g152ad8e336-goog > > -- Thanks, ~Nick Desaulniers
