[PATCH] firmware: smccc: Pass only the required device probe arguments

[PATCH] firmware: smccc: Pass only the required device probe arguments

[Aneesh Kumar K.V (Arm)]

The device probe passes zeroes for all seven argument registers to
arm_smccc_1_1_invoke(). On ARM32 Thumb-2, this binds an input to r7 and
GCC 8.5 reports "r7 cannot be used in asm here".

The current smccc_devices entries need at most one argument after the
function ID: TRNG_VERSION has none and RSI_ABI_VERSION takes a requested
version. Pass zero for that argument and omit the unused arguments,
avoiding the r7 constraint. Check argument requirements when adding new
probe functions to smccc_devices.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sudeep Holla <sudeep.holla@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Fixes: d8263a131bb0 ("firmware: hwrng: arm_smccc_trng: Register as an SMCCC device")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202610070641.B8hxBJcf-lkp@intel.com/
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 drivers/firmware/smccc/smccc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
index 07b864ff079d..377d2cda2b6e 100644
--- a/drivers/firmware/smccc/smccc.c
+++ b/drivers/firmware/smccc/smccc.c
@@ -122,8 +122,7 @@ static bool __init smccc_probe_smccc_device(const struct smccc_device_info *smcc
 	if (IS_ENABLED(CONFIG_ARM) && ARM_SMCCC_IS_64(smccc_dev->func_id))
 		return false;
 
-	arm_smccc_1_1_invoke(smccc_dev->func_id,
-			     0, 0, 0, 0, 0, 0, 0, &res);
+	arm_smccc_1_1_invoke(smccc_dev->func_id, 0, &res);
 	ret = res.a0;
 
 	if (ret == SMCCC_RET_NOT_SUPPORTED)
-- 
2.43.0