[PATCH v3 4/5] riscv: compat_vdso: Build with zacas if available

[Thomas Weißschuh]

On Fri, Jul 17, 2026 at 10:06:37AM +0200, Nam Cao wrote:
> The compat vdso Makefile does not enable zacas, disallowing source
> files from using zacas instructions. This is an obstacle to adding
> robust __vdso_futex_robust_list32_try_unlock() in a follow-up commit.

"obstacle" is a bit hard. It prevents using the optimized variant.

> Build with zacas, if compiler supports it.
> 
> Signed-off-by: Nam Cao <namcao at linutronix.de>

Reviewed-by: Thomas Weißschuh <thomas.weissschuh at linutronix.de>

> ---
>  arch/riscv/kernel/compat_vdso/Makefile | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
> index 63580b33e3ce..ffbf84aeb081 100644
> --- a/arch/riscv/kernel/compat_vdso/Makefile
> +++ b/arch/riscv/kernel/compat_vdso/Makefile
> @@ -18,6 +18,10 @@ else
>  	COMPAT_MARCH := rv32imafd
>  endif
>  
> +ifneq ($(call cc-option,-mabi=ilp32 -march=rv32ima_zacas),)
> +COMPAT_MARCH := $(COMPAT_MARCH)_zacas
> +endif

Could be :

ifeq ($(call cc-option-yn,-mabi=ilp32 -march=rv32ima_zacas),y)

> +
>  COMPAT_CC_FLAGS := -march=$(COMPAT_MARCH) -mabi=ilp32
>  
>  COMPAT_LD_FLAGS := -melf32lriscv
> -- 
> 2.47.3
>