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

[Mike Leach <mike.leach@linaro.org>]

Hi Mathieu,

On Tue, 18 May 2021 at 16:52, Mathieu Poirier
<mathieu.poirier@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@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

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@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@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@linaro.org>");
> > +MODULE_DESCRIPTION("CoreSight Syscfg Example");
> > --
> > 2.17.1
> >



-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

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