On 01/02/18 11:46, Marc Zyngier wrote:
Function identifiers are a 32bit, unsigned quantity. But we never
tell so to the compiler, resulting in the following:
4ac: b26187e0 mov x0, #0xffffffff80000001
We thus rely on the firmware narrowing it for us, which is not
always a reasonable expectation.
I think technically it might be OK, since SMCCC states "A Function
Identifier is passed in register W0.", which implies that a conforming
implementation should also read w0, not x0, but it's certainly far
easier to be completely right than to justify being possibly wrong.
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Tested-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
include/linux/arm-smccc.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index e1ef944ef1da..dd44d8458c04 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -14,14 +14,16 @@
#ifndef __LINUX_ARM_SMCCC_H
#define __LINUX_ARM_SMCCC_H
+#include <uapi/linux/const.h>
+
/*
* This file provides common defines for ARM SMC Calling Convention as
* specified in
* http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
*/
-#define ARM_SMCCC_STD_CALL 0
-#define ARM_SMCCC_FAST_CALL 1
+#define ARM_SMCCC_STD_CALL _AC(0,U)
+#define ARM_SMCCC_FAST_CALL _AC(1,U)
#define ARM_SMCCC_TYPE_SHIFT 31
#define ARM_SMCCC_SMC_32 0
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