[RFC PATCH 3/8] coresight: syscfg: Example CoreSight configuration loadable module

Tue May 18 14:15:56 PDT 2021

On Tue, 18 May 2021 at 10:38, Mike Leach <mike.leach at linaro.org> wrote:
>
> Hi Mathieu,
>
> On Tue, 18 May 2021 at 16:52, Mathieu Poirier
> <mathieu.poirier at linaro.org> wrote:
> >
> > Good day Mike,
> >
> > On Wed, May 12, 2021 at 10:17:47PM +0100, Mike Leach wrote:
> > > An example of creating a loadable module to add CoreSight configurations
> > > into a system.
> > >
> > > In the Kernel samples/coresight directory.
> > >
> > > Signed-off-by: Mike Leach <mike.leach at linaro.org>
> > > ---
> > >  MAINTAINERS                              |  1 +
> > >  samples/Kconfig                          |  9 +++
> > >  samples/Makefile                         |  1 +
> > >  samples/coresight/Makefile               |  4 ++
> > >  samples/coresight/coresight-cfg-sample.c | 73 ++++++++++++++++++++++++
> > >  5 files changed, 88 insertions(+)
> > >  create mode 100644 samples/coresight/Makefile
> > >  create mode 100644 samples/coresight/coresight-cfg-sample.c
> > >
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index bd7aff0c120f..9ff5f5e7dd06 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -1789,6 +1789,7 @@ F:      Documentation/trace/coresight/*
> > >  F:   drivers/hwtracing/coresight/*
> > >  F:   include/dt-bindings/arm/coresight-cti-dt.h
> > >  F:   include/linux/coresight*
> > > +F:   samples/coresight/*
> > >  F:   tools/perf/arch/arm/util/auxtrace.c
> > >  F:   tools/perf/arch/arm/util/cs-etm.c
> > >  F:   tools/perf/arch/arm/util/cs-etm.h
> > > diff --git a/samples/Kconfig b/samples/Kconfig
> > > index b5a1a7aa7e23..0cd618e15571 100644
> > > --- a/samples/Kconfig
> > > +++ b/samples/Kconfig
> > > @@ -223,4 +223,13 @@ config SAMPLE_WATCH_QUEUE
> > >         Build example userspace program to use the new mount_notify(),
> > >         sb_notify() syscalls and the KEYCTL_WATCH_KEY keyctl() function.
> > >
> > > +config SAMPLE_CORESIGHT_SYSCFG
> > > +     tristate "Build example loadable module for CoreSight config"
> > > +     depends on CORESIGHT && m
> > > +     help
> > > +       Build an example loadable module that adds new CoreSight features
> > > +       and configuration using the CoreSight system configuration API.
> > > +       This demonstrates how a user may create their own CoreSight
> > > +       configurations and easily load them into the system at runtime.
> > > +
> > >  endif # SAMPLES
> > > diff --git a/samples/Makefile b/samples/Makefile
> > > index 087e0988ccc5..6c96297001a8 100644
> > > --- a/samples/Makefile
> > > +++ b/samples/Makefile
> > > @@ -30,3 +30,4 @@ obj-$(CONFIG_SAMPLE_INTEL_MEI)              += mei/
> > >  subdir-$(CONFIG_SAMPLE_WATCHDOG)     += watchdog
> > >  subdir-$(CONFIG_SAMPLE_WATCH_QUEUE)  += watch_queue
> > >  obj-$(CONFIG_DEBUG_KMEMLEAK_TEST)    += kmemleak/
> > > +obj-$(CONFIG_SAMPLE_CORESIGHT_SYSCFG)        += coresight/
> > > diff --git a/samples/coresight/Makefile b/samples/coresight/Makefile
> > > new file mode 100644
> > > index 000000000000..09126aabf43d
> > > --- /dev/null
> > > +++ b/samples/coresight/Makefile
> > > @@ -0,0 +1,4 @@
> > > +# SPDX-License-Identifier: GPL-2.0-only
> > > +
> > > +obj-$(CONFIG_SAMPLE_CORESIGHT_SYSCFG) += coresight-cfg-sample.o
> > > +ccflags-y += -I$(src)/../../drivers/hwtracing/coresight
> >
> > On my side this really doesn't work and it's baffling.  I double checked the
> > path that gets generated with V=1 and it is correct.  I ended up replacing
> > $(src) with $(srctree), which gave me a full path rather than a relative path,
> > to get things going.  Please see if that works on your side.
> >
> > I looked at other Makefiles and $(srctree) is predominant.  As such I suggest to
> > go with that to avoid further headaches.
> >
>
> If I substitute $(srctree) instead of $(src) I get the header file as not found.
> Paths generated...
> using $(src) : -Isamples/coresight/../../drivers/hwtracing/coresight
> using $(srctree):  -I./../../drivers/hwtracing/coresight
>
> However if I drop some of the relative path to make the line
> ccflags-y += -I$(srctree)/drivers/hwtracing/coresight

Yes, that's exactly what I did - I should have been more precise.

>
> then $srctree does work. Can you confirm that is what you did on your system?
> If so we can go with that.
>
> >
> > > diff --git a/samples/coresight/coresight-cfg-sample.c b/samples/coresight/coresight-cfg-sample.c
> > > new file mode 100644
> > > index 000000000000..865c188fae34
> > > --- /dev/null
> > > +++ b/samples/coresight/coresight-cfg-sample.c
> > > @@ -0,0 +1,73 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Copyright(C) 2020 Linaro Limited. All rights reserved.
> > > + * Author: Mike Leach <mike.leach at linaro.org>
> > > + */
> > > +
> > > +#include "coresight-config.h"
> > > +#include "coresight-syscfg.h"
> > > +
> > > +/* create an alternate autofdo configuration */
> > > +
> > > +/* we will provide 4 sets of preset parameter values */
> > > +#define AFDO2_NR_PRESETS     4
> > > +/* the total number of parameters in used features - strobing has 2 */
> > > +#define AFDO2_NR_PARAM_SUM   2
> > > +
> > > +static const char *afdo2_ref_names[] = {
> > > +     "strobing",
> > > +};
> > > +
> > > +/*
> > > + * set of presets leaves strobing window constant while varying period to allow
> > > + * experimentation with mark / space ratios for various workloads
> > > + */
> > > +static u64 afdo2_presets[AFDO2_NR_PRESETS][AFDO2_NR_PARAM_SUM] = {
> > > +     { 1000, 100 },
> > > +     { 1000, 1000 },
> > > +     { 1000, 5000 },
> > > +     { 1000, 10000 },
> > > +};
> > > +
> > > +struct cscfg_config_desc afdo2 = {
> > > +     .name = "autofdo2",
> > > +     .description = "Setup ETMs with strobing for autofdo\n"
> > > +     "Supplied presets allow experimentation with mark-space ratio for various loads\n",
> > > +     .nr_feat_refs = ARRAY_SIZE(afdo2_ref_names),
> > > +     .feat_ref_names = afdo2_ref_names,
> > > +     .nr_presets = AFDO2_NR_PRESETS,
> > > +     .nr_total_params = AFDO2_NR_PARAM_SUM,
> > > +     .presets = &afdo2_presets[0][0],
> > > +};
> > > +
> > > +static struct cscfg_feature_desc *sample_feats[] = {
> > > +     0
> >
> > NULL
> >
> > > +};
> > > +
> > > +static struct cscfg_config_desc *sample_cfgs[] = {
> > > +     &afdo2,
> > > +     0
> >
> > NULL
> >
> > The end result is the same but it is a matter of time before it gets flagged by
> > a bot.
> >
>
> Agreed - I'll fix the Nulls
>
> Thanks
>
> Mike
>
> > With the above:
> >
> > Reviewed-by: Mathieu Poirier <mathieu.poirier at linaro.org>
> >
> > > +};
> > > +
> > > +static struct cscfg_load_owner_info mod_owner = {
> > > +     .type = CSCFG_OWNER_MODULE,
> > > +     .owner_handle = THIS_MODULE,
> > > +};
> > > +
> > > +/* module init and exit - just load and unload configs */
> > > +static int __init cscfg_sample_init(void)
> > > +{
> > > +     return cscfg_load_config_sets(sample_cfgs, sample_feats, &mod_owner);
> > > +}
> > > +
> > > +static void __exit cscfg_sample_exit(void)
> > > +{
> > > +     cscfg_unload_config_sets(&mod_owner);
> > > +}
> > > +
> > > +module_init(cscfg_sample_init);
> > > +module_exit(cscfg_sample_exit);
> > > +
> > > +MODULE_LICENSE("GPL v2");
> > > +MODULE_AUTHOR("Mike Leach <mike.leach at linaro.org>");
> > > +MODULE_DESCRIPTION("CoreSight Syscfg Example");
> > > --
> > > 2.17.1
> > >
>
>
>
> --
> Mike Leach
> Principal Engineer, ARM Ltd.
> Manchester Design Centre. UK