Quoting Vivek Gautam (2019-08-22 23:32:46)
There are scnenarios where drivers are required to make a
scm call in atomic context, such as in one of the qcom's
arm-smmu-500 errata [1].
[1] ("https://source.codeaurora.org/quic/la/kernel/msm-4.9/
tree/drivers/iommu/arm-smmu.c?h=msm-4.9#n4842")
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---
drivers/firmware/qcom_scm-64.c | 136
++++++++++++++++++++++++++++-------------
1 file changed, 92 insertions(+), 44 deletions(-)
diff --git a/drivers/firmware/qcom_scm-64.c
b/drivers/firmware/qcom_scm-64.c
index 91d5ad7cf58b..b6dca32c5ac4 100644
--- a/drivers/firmware/qcom_scm-64.c
+++ b/drivers/firmware/qcom_scm-64.c
@@ -62,32 +62,71 @@ static DEFINE_MUTEX(qcom_scm_lock);
#define FIRST_EXT_ARG_IDX 3
#define N_REGISTER_ARGS (MAX_QCOM_SCM_ARGS - N_EXT_QCOM_SCM_ARGS + 1)
-/**
- * qcom_scm_call() - Invoke a syscall in the secure world
- * @dev: device
- * @svc_id: service identifier
- * @cmd_id: command identifier
- * @desc: Descriptor structure containing arguments and return
values
- *
- * Sends a command to the SCM and waits for the command to finish
processing.
- * This should *only* be called in pre-emptible context.
-*/
-static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
- const struct qcom_scm_desc *desc,
- struct arm_smccc_res *res)
+static void __qcom_scm_call_do(const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, u32 fn_id,
+ u64 x5, u32 type)
+{
+ u64 cmd;
+ struct arm_smccc_quirk quirk = {.id =
ARM_SMCCC_QUIRK_QCOM_A6};
Nitpick: Put spaces around braces please.
+
+ cmd = ARM_SMCCC_CALL_VAL(type, qcom_smccc_convention,
+ ARM_SMCCC_OWNER_SIP, fn_id);
+
+ quirk.state.a6 = 0;
+
+ do {
+ arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
+ desc->args[1], desc->args[2], x5,
+ quirk.state.a6, 0, res, &quirk);
+
+ if (res->a0 == QCOM_SCM_INTERRUPTED)
+ cmd = res->a0;
+
+ } while (res->a0 == QCOM_SCM_INTERRUPTED);
+}
+
+static void qcom_scm_call_do(const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, u32 fn_id,
+ u64 x5, bool atomic)
+{
+ int retry_count = 0;
+
+ if (!atomic) {
+ do {
+ mutex_lock(&qcom_scm_lock);
+
+ __qcom_scm_call_do(desc, res, fn_id, x5,
+ ARM_SMCCC_STD_CALL);
+
+ mutex_unlock(&qcom_scm_lock);
+
+ if (res->a0 == QCOM_SCM_V2_EBUSY) {
+ if (retry_count++ >
QCOM_SCM_EBUSY_MAX_RETRY)
+ break;
+ msleep(QCOM_SCM_EBUSY_WAIT_MS);
+ }
+ } while (res->a0 == QCOM_SCM_V2_EBUSY);
+ } else {
+ __qcom_scm_call_do(desc, res, fn_id, x5,
ARM_SMCCC_FAST_CALL);
+ }
To save on some indentation maybe you could write it like:
if (atomic) {
__qcom_scm_call_do(..)
return;
}
do {
mutex_lock(..)
...
} while (..);
+}
+
+static int ___qcom_scm_call(struct device *dev, u32 svc_id, u32
cmd_id,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, bool atomic)
{
int arglen = desc->arginfo & 0xf;
- int retry_count = 0, i;
+ int i;
u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
- u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
+ u64 x5 = desc->args[FIRST_EXT_ARG_IDX];
dma_addr_t args_phys = 0;
void *args_virt = NULL;
size_t alloc_len;
- struct arm_smccc_quirk quirk = {.id =
ARM_SMCCC_QUIRK_QCOM_A6};
+ gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
if (unlikely(arglen > N_REGISTER_ARGS)) {
alloc_len = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
- args_virt = kzalloc(PAGE_ALIGN(alloc_len),
GFP_KERNEL);
+ args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
if (!args_virt)
return -ENOMEM;
@@ -156,6 +169,41 @@ static int qcom_scm_call(struct device *dev, u32
svc_id, u32 cmd_id,
return 0;
}
+/**
+ * qcom_scm_call() - Invoke a syscall in the secure world
+ * @dev: device
+ * @svc_id: service identifier
+ * @cmd_id: command identifier
+ * @desc: Descriptor structure containing arguments and return
values
+ *
+ * Sends a command to the SCM and waits for the command to finish
processing.
+ * This should *only* be called in pre-emptible context.
Add a might_sleep() then?
+ */
+static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res)
+{
+ return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res,
false);
+}
+
+/**
+ * qcom_scm_call_atomic() - atomic variation of qcom_scm_call()
+ * @dev: device
+ * @svc_id: service identifier
+ * @cmd_id: command identifier
+ * @desc: Descriptor structure containing arguments and return
values
+ * @res: Structure containing results from SMC/HVC call
+ *
+ * Sends a command to the SCM and waits for the command to finish
processing.
+ * This should be called in atomic context only.
Maybe add a cant_sleep()?
+ */
+static int qcom_scm_call_atomic(struct device *dev, u32 svc_id, u32
cmd_id,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res)
+{
+ return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res, true);
+}
+
