Re: [PATCH v8 09/24] coresight: etm3x: allow etm3x to be built as a module

Mathieu Poirier
2020-08-13T17:02:14Z

On Thu, 13 Aug 2020 at 04:57, Tingwei Zhang <tingweiz@codeaurora.org> wrote:
>
> On Thu, Aug 13, 2020 at 05:47:22PM +0800, Suzuki K Poulose wrote:
> > On 08/07/2020 12:11 PM, Tingwei Zhang wrote:
> > >From: Kim Phillips <kim.phillips@arm.com>
> > >
> > >Allow to build coresight-etm3x as a module, for ease of development.
> > >
> > >- Kconfig becomes a tristate, to allow =m
> > >- append -core to source file name to allow module to
> > > be called coresight-etm3x by the Makefile
> > >- add an etm_remove function, for module unload
> > >- add a MODULE_DEVICE_TABLE for autoloading on boot
> > >
> > >Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> > >Cc: Leo Yan <leo.yan@linaro.org>
> > >Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > >Cc: Randy Dunlap <rdunlap@infradead.org>
> > >Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
> > >Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > >Cc: Russell King <linux@armlinux.org.uk>
> > >Signed-off-by: Kim Phillips <kim.phillips@arm.com>
> > >Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
> > >Reviewed-by: Mike Leach <mike.leach@linaro.org>
> > >---
> > > drivers/hwtracing/coresight/Kconfig | 5 +++-
> > > drivers/hwtracing/coresight/Makefile | 3 ++-
> > > ...resight-etm3x.c => coresight-etm3x-core.c} | 27 ++++++++++++++++++-
> > > 3 files changed, 32 insertions(+), 3 deletions(-)
> > > rename drivers/hwtracing/coresight/{coresight-etm3x.c =>
> > >coresight-etm3x-core.c} (97%)
> > >
> > >diff --git a/drivers/hwtracing/coresight/Kconfig
> > >b/drivers/hwtracing/coresight/Kconfig
> > >index 6433f835fc97..8fd9fd139cf3 100644
> > >--- a/drivers/hwtracing/coresight/Kconfig
> > >+++ b/drivers/hwtracing/coresight/Kconfig
> > >@@ -65,7 +65,7 @@ config CORESIGHT_SINK_ETBV10
> > > special enhancement or added features.
> > >
> > > config CORESIGHT_SOURCE_ETM3X
> > >- bool "CoreSight Embedded Trace Macrocell 3.x driver"
> > >+ tristate "CoreSight Embedded Trace Macrocell 3.x driver"
> > > depends on !ARM64
> > > select CORESIGHT_LINKS_AND_SINKS
> > > help
> > >@@ -74,6 +74,9 @@ config CORESIGHT_SOURCE_ETM3X
> > > This is primarily useful for instruction level tracing. Depending
> > > the ETM version data tracing may also be available.
> > >
> > >+ To compile this driver as a module, choose M here: the
> > >+ module will be called coresight-etm3x.
> > >+
> > > config CORESIGHT_SOURCE_ETM4X
> > > bool "CoreSight Embedded Trace Macrocell 4.x driver"
> > > depends on ARM64
> > >diff --git a/drivers/hwtracing/coresight/Makefile
> > >b/drivers/hwtracing/coresight/Makefile
> > >index 19497d1d92bf..d619cfd0abd8 100644
> > >--- a/drivers/hwtracing/coresight/Makefile
> > >+++ b/drivers/hwtracing/coresight/Makefile
> > >@@ -11,7 +11,8 @@ obj-$(CONFIG_CORESIGHT_SINK_TPIU) += coresight-tpiu.o
> > > obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
> > > obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
> > > coresight-replicator.o
> > >-obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
> > >coresight-etm-cp14.o \
> > >+obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
> > >+coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
> > > coresight-etm3x-sysfs.o
> > > obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
> > > coresight-etm4x-sysfs.o
> > >diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c
> > >b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > >similarity index 97%
> > >rename from drivers/hwtracing/coresight/coresight-etm3x.c
> > >rename to drivers/hwtracing/coresight/coresight-etm3x-core.c
> > >index bf22dcfd3327..82b333c40006 100644
> > >--- a/drivers/hwtracing/coresight/coresight-etm3x.c
> > >+++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > >@@ -895,6 +895,23 @@ static int etm_probe(struct amba_device *adev, const
> > >struct amba_id *id)
> > > return ret;
> > > }
> > >
> > >+static int __exit etm_remove(struct amba_device *adev)
> > >+{
> > >+ struct etm_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> > >+
> > >+ etm_perf_symlink(drvdata->csdev, false);
> > >+
> > >+ if (--etm_count == 0) {
> > >+ cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
> > >+ if (hp_online)
> > >+ cpuhp_remove_state_nocalls(hp_online);
> > >+ }
> > >+
> >
> > As mentioned in the previous version, this needs fixing
> > similar to the etm4x to avoid races with etm_count. I understand
> > that it is an exisiting problem. But this set exposes it more
> > due to etm_remove() calls and is much more probable to hit it.
> >
> OK. I'll fix this. Can you help to review ETM4 fix? If that's fine,
> I'll make similar fix here.
>
> Unfortunately, I don't have any device with ETM3. Can anyone help
> to verify the function on ETM3? I'll really appreciate that.

I'll take care of ETMv3. Please wait before sending a new revision
since I am still reviewing the current set. I will let you know when
I am done.

>
> Thanks,
> Tingwei
> >
> > Suzuki