From: Will Deacon <will.deacon@xxxxxxx>
commit 669474e772b952b14f4de4845a1558fd4c0414a4 upstream.
For CPUs capable of data value prediction, CSDB waits for any outstanding
predictions to architecturally resolve before allowing speculative execution
to continue. Provide macros to expose it to the arch code.
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx [v4.9 backport]
---
arch/arm64/include/asm/assembler.h | 7 +++++++
arch/arm64/include/asm/barrier.h | 2 ++
2 files changed, 9 insertions(+)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 7193bf97b8da..b223b1b4d5cd 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -87,6 +87,13 @@
.endm
/*
+ * Value prediction barrier
+ */
+ .macro csdb
+ hint #20
+ .endm
+
+/*
* NOP sequence
*/
.macro nops, num
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 0fe7e43b7fbc..c68fdc5707ed 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -31,6 +31,8 @@
#define dmb(opt) asm volatile("dmb " #opt : : : "memory")
#define dsb(opt) asm volatile("dsb " #opt : : : "memory")
+#define csdb() asm volatile("hint #20" : : : "memory")
+
#define mb() dsb(sy)
#define rmb() dsb(ld)
#define wmb() dsb(st)
--
2.11.0