arm64: barriers: add dmb barrier

Commit 8adbf57fc429 ("irqchip: gic: use dmb ishst instead of dsb when
raising a softirq") added an explicit dmb(...) call to the GIC driver.

This patch adds a simple dmb() macro to arm64, which expands to a DMB SY
instruction.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 409ca370cfe2..66eb7648043b 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -25,6 +25,7 @@
 #define wfi()           asm volatile("wfi" : : : "memory")
 
 #define isb()           asm volatile("isb" : : : "memory")
+#define dmb(opt)        asm volatile("dmb sy" : : : "memory")
 #define dsb(opt)        asm volatile("dsb sy" : : : "memory")
 
 #define mb()            dsb()