[PATCH 1/2] arm64: kernel: Add SMC Session ID to results

[Andy Gross]

This patch adds the SMC Session ID to the results passed back from SMC
calls.  The Qualcomm SMC implementation provides for interrupted SMC
functions.  When this occurs, the SMC call will return a session ID that
is required to be used when resuming the interrupted SMC call.

Signed-off-by: Andy Gross <andy.gross@xxxxxxxxxx>
---
 arch/arm64/kernel/asm-offsets.c | 1 +
 arch/arm64/kernel/smccc-call.S  | 1 +
 include/linux/arm-smccc.h       | 4 +++-
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 05070b7..ff38c58 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -141,6 +141,7 @@ int main(void)
 #endif
   DEFINE(ARM_SMCCC_RES_X0_OFFS,	offsetof(struct arm_smccc_res, a0));
   DEFINE(ARM_SMCCC_RES_X2_OFFS,	offsetof(struct arm_smccc_res, a2));
+  DEFINE(ARM_SMCCC_RES_X6_OFFS,	offsetof(struct arm_smccc_res, a6));
   BLANK();
   DEFINE(HIBERN_PBE_ORIG,	offsetof(struct pbe, orig_address));
   DEFINE(HIBERN_PBE_ADDR,	offsetof(struct pbe, address));
diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index ae0496f..278dc9a 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -20,6 +20,7 @@
 	ldr	x4, [sp]
 	stp	x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
 	stp	x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
+	str	x6, [x4, #ARM_SMCCC_RES_X6_OFFS]
 	ret
 	.cfi_endproc
 	.endm
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index b5abfda..82d919f 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -63,18 +63,20 @@
 /**
  * struct arm_smccc_res - Result from SMC/HVC call
  * @a0-a3 result values from registers 0 to 3
+ * @a6 Session ID register (optional)
  */
 struct arm_smccc_res {
 	unsigned long a0;
 	unsigned long a1;
 	unsigned long a2;
 	unsigned long a3;
+	unsigned long a6;
 };
 
 /**
  * arm_smccc_smc() - make SMC calls
  * @a0-a7: arguments passed in registers 0 to 7
- * @res: result values from registers 0 to 3
+ * @res: result values from registers 0 to 3 and optional register 6
  *
  * This function is used to make SMC calls following SMC Calling Convention.
  * The content of the supplied param are copied to registers 0 to 7 prior
-- 
1.9.1