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

"Linux Kernel Mailing List" <[email protected]>
Newsgroups gmane.linux.kernel.commits.head
Message-ID <[email protected]>
Web:        https://git.kernel.org/torvalds/c/669474e772b952b14f4de4845a1558fd4c0414a4
Commit:     669474e772b952b14f4de4845a1558fd4c0414a4
Parent:     439e70e27a51fe374806f460848066b237b0c10b
Refname:    refs/heads/master
Author:     Will Deacon <[email protected]>
AuthorDate: Mon Feb 5 15:34:16 2018 +0000
Committer:  Catalin Marinas <[email protected]>
CommitDate: Tue Feb 6 22:53:28 2018 +0000

    arm64: barrier: Add CSDB macros to control data-value prediction
    
    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 <[email protected]>
    Signed-off-by: Will Deacon <[email protected]>
    Signed-off-by: Catalin Marinas <[email protected]>
---
 arch/arm64/include/asm/assembler.h | 7 +++++++
 arch/arm64/include/asm/barrier.h   | 1 +
 2 files changed, 8 insertions(+)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 544878a9f29e..1f44b4255a28 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -115,6 +115,13 @@
 	hint    #16
 	.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 77651c49ef44..c0a846d2c602 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -32,6 +32,7 @@
 #define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
 
 #define psb_csync()	asm volatile("hint #17" : : : "memory")
+#define csdb()		asm volatile("hint #20" : : : "memory")
 
 #define mb()		dsb(sy)
 #define rmb()		dsb(ld)
--
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