Subject: [PATCH for-stable-v4.4 09/53] firmware: qcom: scm: Fix interrupted SCM calls

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 5 Nov 2019 21:58:02 +0100

From: Andy Gross <[email-masked]>

[ Upstream commit 82bcd087029f6056506ea929f11af02622230901 ]

This patch adds a Qualcomm specific quirk to the arm_smccc_smc call.

On Qualcomm ARM64 platforms, the SMC call can return before it has
completed.  If this occurs, the call can be restarted, but it requires
using the returned session ID value from the interrupted SMC call.

The quirk stores off the session ID from the interrupted call in the
quirk structure so that it can be used by the caller.

This patch folds in a fix given by Sricharan R:
https://lkml.org/lkml/2016/9/28/272

Signed-off-by: Andy Gross <[email-masked]>
Reviewed-by: Will Deacon <[email-masked]>
Signed-off-by: Will Deacon <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
[ardb: restrict to arch pieces since qcom was 32-bit only in v4.4]
Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 arch/arm64/kernel/smccc-call.S |  9 ++++++++-
 include/linux/arm-smccc.h      | 11 ++++++++---
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index ba60a8cb07d2..62522342e1e4 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -12,6 +12,7 @@
  *
  */
 #include <linux/linkage.h>
+#include <linux/arm-smccc.h>
 #include <asm/asm-offsets.h>
 
 	.macro SMCCC instr
@@ -20,7 +21,13 @@
 	ldr	x4, [sp]
 	stp	x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
 	stp	x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
-	ret
+	ldr	x4, [sp, #8]
+	cbz	x4, 1f /* no quirk structure */
+	ldr	x9, [x4, #ARM_SMCCC_QUIRK_ID_OFFS]
+	cmp	x9, #ARM_SMCCC_QUIRK_QCOM_A6
+	b.ne	1f
+	str	x6, [x4, ARM_SMCCC_QUIRK_STATE_OFFS]
+1:	ret
 	.cfi_endproc
 	.endm
 
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index c66f8ae94b5a..b67934164401 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -14,9 +14,6 @@
 #ifndef __LINUX_ARM_SMCCC_H
 #define __LINUX_ARM_SMCCC_H
 
-#include <linux/linkage.h>
-#include <linux/types.h>
-
 /*
  * This file provides common defines for ARM SMC Calling Convention as
  * specified in
@@ -60,6 +57,13 @@
 #define ARM_SMCCC_OWNER_TRUSTED_OS	50
 #define ARM_SMCCC_OWNER_TRUSTED_OS_END	63
 
+#define ARM_SMCCC_QUIRK_NONE		0
+#define ARM_SMCCC_QUIRK_QCOM_A6		1 /* Save/restore register a6 */
+
+#ifndef __ASSEMBLY__
+
+#include <linux/linkage.h>
+#include <linux/types.h>
 /**
  * struct arm_smccc_res - Result from SMC/HVC call
  * @a0-a3 result values from registers 0 to 3
@@ -125,4 +129,5 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
 
 #define arm_smccc_hvc_quirk(...) __arm_smccc_hvc(__VA_ARGS__)
 
+#endif /*__ASSEMBLY__*/
 #endif /*__LINUX_ARM_SMCCC_H*/
-- 
2.17.1

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