Messages in this thread | | | Subject | Re: [PATCH] coresight: trbe: Move check for kernelspace unmapped at EL0 to probe | From | Anshuman Khandual <> | Date | Thu, 3 Feb 2022 11:55:58 +0530 |
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On 2/1/22 5:52 PM, Sudeep Holla wrote: > Currently with the check present in the module initialisation, it shouts > on all the systems irrespective of presence of coresight trace buffer > extensions.
IIUC a system with CONFIG_CORESIGHT_TRBE enabled but without a TRBE DT i.e "arm,trace-buffer-extension" complains about kernel space unmapping at EL0 (even though it does not even really have TRBE HW to initialize).
> > Similar to Arm SPE perf driver, move the check for kernelspace unmapping > when running at EL0 to the device probe instead of module initialisation.
Makes sense.
> > 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> > --- > drivers/hwtracing/coresight/coresight-trbe.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 276862c07e32..3fe2ce1ba5bf 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -1423,6 +1423,11 @@ static int arm_trbe_device_probe(struct platform_device *pdev) > struct device *dev = &pdev->dev; > int ret; >
Could you please add a similar comment like SPE driver regarding how the TRBE buffer will be inaccessible, if kernel gets unmapped at EL0 and trace capture will terminate.
> + 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; > @@ -1484,11 +1489,6 @@ 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; >
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