Messages in this thread | | | Subject | Re: [PATCH v2] coresight: trbe: Move check for kernel page table isolation from EL0 to probe | From | Anshuman Khandual <> | Date | Fri, 4 Feb 2022 08:20:23 +0530 |
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On 2/4/22 12:31 AM, 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. > > 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> > --- > drivers/hwtracing/coresight/coresight-trbe.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > v1[1]->v2: > - Added comment about trace capture being not possible with kernel > page table isolation > [1] https://lore.kernel.org/r/20220201122212.3009461-1-sudeep.holla@arm.com > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 276862c07e32..3e37a63cb7d2 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -1423,6 +1423,12 @@ 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; > @@ -1484,11 +1490,6 @@ 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; >
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
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