coresight: trbe: Move check for kernel page table isolation from EL0 to probe

Currently with the check present in the module initialisation, it shouts
on all the systems irrespective of presence of coresight trace buffer
extensions.

Similar to Arm SPE perf driver, move the check for kernel page table
isolation from  EL0 to the device probe stage instead of the module
initialisation so that it complains only on the systems that support TRBE.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: coresight@lists.linaro.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20220203190159.3145272-1-sudeep.holla@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 75b608bc400bc2d8fde8c4fb5f5bae2de4514b96..2b386bb848f8d7cf3b1cf32c07977a440c1b814c 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1481,6 +1481,12 @@ static int arm_trbe_device_probe(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        int ret;
 
+       /* Trace capture is not possible with kernel page table isolation */
+       if (arm64_kernel_unmapped_at_el0()) {
+               pr_err("TRBE wouldn't work if kernel gets unmapped at EL0\n");
+               return -EOPNOTSUPP;
+       }
+
        drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;
@@ -1542,11 +1548,6 @@ static int __init arm_trbe_init(void)
 {
        int ret;
 
-       if (arm64_kernel_unmapped_at_el0()) {
-               pr_err("TRBE wouldn't work if kernel gets unmapped at EL0\n");
-               return -EOPNOTSUPP;
-       }
-
        ret = platform_driver_register(&arm_trbe_driver);
        if (!ret)
                return 0;