linux-kernel - [PATCH v2 2/2] firmware: qcom: scm: fall back to kcalloc() for no SCM device bound

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Message-Id: <20240911-tzmem-null-ptr-v2-2-7c61b1a1b463@linaro.org>
Date: Wed, 11 Sep 2024 11:07:04 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, 
 Andrew Halaney <ahalaney@...hat.com>, 
 Elliot Berman <quic_eberman@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
 Rudraksha Gupta <guptarud@...il.com>, 
 "Linux regression tracking (Thorsten Leemhuis)" <regressions@...mhuis.info>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v2 2/2] firmware: qcom: scm: fall back to kcalloc() for no
 SCM device bound

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

Older platforms don't have an actual SCM device tied into the driver
model and so there's no struct device which to use with the TZ Mem API.
We need to fall-back to kcalloc() when allocating the buffer for
additional SMC arguments on such platforms which don't even probe the SCM
driver and never create the TZMem pool.

Fixes: 449d0d84bcd8 ("firmware: qcom: scm: smc: switch to using the SCM allocator")
Reported-by: Rudraksha Gupta <guptarud@...il.com>
Closes: https://lore.kernel.org/lkml/692cfe9a-8c05-4ce4-813e-82b3f310019a@gmail.com/
Tested-by: Rudraksha Gupta <guptarud@...il.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/firmware/qcom/qcom_scm-smc.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
index 2b4c2826f572..88652c38c9a0 100644
--- a/drivers/firmware/qcom/qcom_scm-smc.c
+++ b/drivers/firmware/qcom/qcom_scm-smc.c
@@ -147,6 +147,15 @@ static int __scm_smc_do(struct device *dev, struct arm_smccc_args *smc,
 	return 0;
 }
 
+static void smc_args_free(void *ptr)
+{
+	if (likely(qcom_scm_get_tzmem_pool()))
+		qcom_tzmem_free(ptr);
+	else
+		kfree(ptr);
+}
+
+DEFINE_FREE(smc_args, void *, if (!IS_ERR_OR_NULL(_T)) smc_args_free(_T));
 
 int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 		   enum qcom_scm_convention qcom_convention,
@@ -155,7 +164,7 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 	struct qcom_tzmem_pool *mempool = qcom_scm_get_tzmem_pool();
 	int arglen = desc->arginfo & 0xf;
 	int i, ret;
-	void *args_virt __free(qcom_tzmem) = NULL;
+	void *args_virt __free(smc_args) = NULL;
 	gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
 	u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
 	u32 qcom_smccc_convention = (qcom_convention == SMC_CONVENTION_ARM_32) ?
@@ -173,9 +182,20 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 		smc.args[i + SCM_SMC_FIRST_REG_IDX] = desc->args[i];
 
 	if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
-		args_virt = qcom_tzmem_alloc(mempool,
-					     SCM_SMC_N_EXT_ARGS * sizeof(u64),
-					     flag);
+		/*
+		 * Older platforms don't have an entry for SCM in device-tree
+		 * and so no device is bound to the SCM driver. This means there
+		 * is no struct device for the TZ Mem API. Fall back to
+		 * kcalloc() on such platforms.
+		 */
+		if (mempool)
+			args_virt = qcom_tzmem_alloc(
+					mempool,
+					SCM_SMC_N_EXT_ARGS * sizeof(u64),
+					flag);
+		else
+			args_virt = kcalloc(SCM_SMC_N_EXT_ARGS, sizeof(u64),
+					    flag);
 		if (!args_virt)
 			return -ENOMEM;
 

-- 
2.43.0