Commit 3337a6fe authored by Kathiravan Thirumoorthy's avatar Kathiravan Thirumoorthy Committed by Bjorn Andersson
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firmware: qcom_scm: use 64-bit calling convention only when client is 64-bit 



Per the "SMC calling convention specification", the 64-bit calling
convention can only be used when the client is 64-bit. Whereas the
32-bit calling convention can be used by either a 32-bit or a 64-bit
client.

Currently during SCM probe, irrespective of the client, 64-bit calling
convention is made, which is incorrect and may lead to the undefined
behaviour when the client is 32-bit. Let's fix it.

Cc: stable@vger.kernel.org
Fixes: 9a434cee ("firmware: qcom_scm: Dynamically support SMCCC and legacy conventions")
Reviewed-By: default avatarElliot Berman <quic_eberman@quicinc.com>
Signed-off-by: default avatarKathiravan Thirumoorthy <quic_kathirav@quicinc.com>
Link: https://lore.kernel.org/r/20230925-scm-v3-1-8790dff6a749@quicinc.com


Signed-off-by: default avatarBjorn Andersson <andersson@kernel.org>
parent f1a1bc87

drivers/firmware/qcom_scm.c

+7 −0
Original line number Diff line number Diff line
@@ -215,6 +215,12 @@ static enum qcom_scm_convention __get_convention(void) 
	if (likely(qcom_scm_convention != SMC_CONVENTION_UNKNOWN))

		return qcom_scm_convention;



	/*

	 * Per the "SMC calling convention specification", the 64-bit calling

	 * convention can only be used when the client is 64-bit, otherwise

	 * system will encounter the undefined behaviour.

	 */

#if IS_ENABLED(CONFIG_ARM64)

	/*

	 * Device isn't required as there is only one argument - no device

	 * needed to dma_map_single to secure world
@@ -235,6 +241,7 @@ static enum qcom_scm_convention __get_convention(void) 
		forced = true;

		goto found;

	}

#endif



	probed_convention = SMC_CONVENTION_ARM_32;

	ret = __scm_smc_call(NULL, &desc, probed_convention, &res, true);