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firmware: qcom_scm: use 64-bit calling convention only when client is 64-bit

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commit 3337a6fea25370d3d244ec6bb38c71ee86fcf837 upstream.

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: 9a434cee773a ("firmware: qcom_scm: Dynamically support SMCCC and legacy conventions")
Reviewed-By: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com>
Link: https://lore.kernel.org/r/20230925-scm-v3-1-8790dff6a749@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kathiravan Thirumoorthy 2023-09-25 13:59:22 +05:30 • committed by Ksawlii
parent 1ee744a4ac
commit f77b37218c
1 changed files with 7 additions and 0 deletions
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7
drivers/firmware/qcom_scm.c
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@ -136,6 +136,12 @@ 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
@ -156,6 +162,7 @@ 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);