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

[Nam Cao]

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.

Build with zacas, if compiler supports it.

Signed-off-by: Nam Cao <namcao 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 06d28a5a0368..7f222a77dbbb 100644
--- a/arch/riscv/kernel/compat_vdso/Makefile
+++ b/arch/riscv/kernel/compat_vdso/Makefile
@@ -19,6 +19,10 @@ else
 	COMPAT_MARCH := rv32imafd
 endif
 
+ifneq ($(call cc-option,-mabi=ilp32 -march=rv32ima_zacas),)
+COMPAT_MARCH := $(COMPAT_MARCH)_zacas
+endif
+
 COMPAT_CC_FLAGS := -march=$(COMPAT_MARCH) -mabi=ilp32
 
 COMPAT_LD_FLAGS := -melf32lriscv
-- 
2.47.3