[PATCH 1/4] arm64: barrier: Restore spec_bar() macro

[Mark Rutland]

Upcoming errata workarounds will need to use SB from C code. Restore the
spec_bar() macro so that we can use SB.

This is effectively a revert of commit:

  4f30ba1cce36d413 ("arm64: barrier: Remove spec_bar() macro")

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: James Morse <james.morse at arm.com>
Cc: Will Deacon <will at kernel.org>
---
 arch/arm64/include/asm/barrier.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index cf2987464c186..1ca947d5c9396 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -40,6 +40,10 @@
  */
 #define dgh()		asm volatile("hint #6" : : : "memory")
 
+#define spec_bar()	asm volatile(ALTERNATIVE("dsb nsh\nisb\n",		\
+						 SB_BARRIER_INSN"nop\n",	\
+						 ARM64_HAS_SB))
+
 #ifdef CONFIG_ARM64_PSEUDO_NMI
 #define pmr_sync()						\
 	do {							\
-- 
2.30.2