arm64: barrier: Add CSDB macros to control data-value prediction

Commit 669474e772b9 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@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index c8ec722cc85538ad5a00f5b3427029f10782cf63..20f5845e529533e8024866cb2c19548949be7ad0 100644 (file)
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -95,6 +95,13 @@
        dmb     \opt
        .endm
 
+/*
+ * Value prediction barrier
+ */
+       .macro  csdb
+       hint    #20
+       .endm
+
 /*
  * NOP sequence
  */

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 0fe7e43b7fbc26bf2f6f2a47354a21943ae56ab9..c68fdc5707edbcac307884988337844c3d0d0c9c 100644 (file)
--- 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)