Message-ID: <CAJ9a7ViieBazkBckF+2Bb0eeQyp14EpUAJ0j_GmU_Kibj9OBMg@mail.gmail.com>
Date:   Fri, 16 Jul 2021 11:25:47 +0100
From:   Mike Leach <mike.leach@...aro.org>
To:     Branislav Rankov <branislav.rankov@....com>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 00/10] CoreSight configuration management; ETM strobing

HI Mathieu,

Below my change notes for the patches changed between v7 and v8 in this set.

Regards

Mike

0001, 0003, 0004, 0006, 0007, 0008, 0010 - no change

0002 -
coresight-syscfg.c
    top of file - mutex declaration removed.
    cscfg_add_csdev_cfg()
        Spinlock replaces mutex
    cscfg_load_feat_csdev()
        Spinlock replaces mutex
    cscsg_list_add_csdev()
        Init spinlock
coresight.h
    struct coresight_device {}
        Add spinlock cscfg_csdev_lock alongside the csdev feature and
config lists that it protects.

0005 -
coresight-syscfg.c
    cscfg_csdev_reset_feats()
            Spinlock replaces mutex.

    cscfg_csdev_enable_active_config()
            Spinlock replaces mutex. In enable flag to avoid race with disable.
    cscfg_csdev_disable_active_config()
            Spinlock replaces mutex. In enable flag to avoid race with enable.


coresight.h
    struct coresight_device {}
        In enable flag introduced to control possible race between
enable and disable. E.g. if we are enabling a config, but a power
event tries to shut down the CPU/ETM causing a disable call. We don’t
want to hold the cscfg_csdev_lock spinlock throughout the entire
enable process - especially as the programming call will claim the
internal driver spinlock when writing internal driver data, but we
need to ensure that if there is a condition that permits a disable
call out of normal sequence then we are able to see it and handle it.

0009 -
    KConfig
    add in dependency on CONFIGFS_FS to eliminate problem highlighted
by the kernel bot tests. This had configured coresight as Y, but
configfs as M - meaning link issues for configfs code introduced in
this set.

On Tue, 13 Jul 2021 at 10:43, Branislav Rankov <branislav.rankov@....com> wrote:
>
> Hi Mathieu,
>
> On 7/12/21 5:44 PM, Mathieu Poirier wrote:
> > Good morning Mike,
> >
> > On Wed, Jul 07, 2021 at 02:29:53PM +0100, Mike Leach wrote:
> >> This patchset introduces initial concepts in CoreSight system
> >> configuration management support. to allow more detailed and complex
> >> programming to be applied to CoreSight systems during trace capture.
> >>
> >> Configurations consist of 2 elements:-
> >> 1) Features - programming combinations for devices, applied to a class of
> >> device on the system (all ETMv4), or individual devices.
> >> 2) Configurations - a set of programmed features used when the named
> >> configuration is selected.
> >>
> >> Features and configurations are declared as a data table, a set of register,
> >> resource and parameter requirements. Features and configurations are loaded
> >> into the system by the virtual cs_syscfg device. This then matches features
> >> to any registered devices and loads the feature into them.
> >>
> >> Individual device classes that support feature and configuration register
> >> with cs_syscfg.
> >>
> >> Once loaded a configuration can be enabled for a specific trace run.
> >> Configurations are registered with the perf cs_etm event as entries in
> >> cs_etm/events. These can be selected on the perf command line as follows:-
> >>
> >> perf record -e cs_etm/<config_name>/ ...
> >>
> >> This patch set has one pre-loaded configuration and feature.
> >> A named "strobing" feature is provided for ETMv4.
> >> A named "autofdo" configuration is provided. This configuration enables
> >> strobing on any ETM in used.
> >>
> >> Thus the command:
> >> perf record -e cs_etm/autofdo/ ...
> >>
> >> will trace the supplied application while enabling the "autofdo" configuation
> >> on each ETM as it is enabled by perf. This in turn will enable strobing for
> >> the ETM - with default parameters. Parameters can be adjusted using configfs.
> >>
> >> The sink used in the trace run will be automatically selected.
> >>
> >> A configuration can supply up to 15 of preset parameter values, which will
> >> subsitute in parameter values for any feature used in the configuration.
> >>
> >> Selection of preset values as follows
> >> perf record -e cs_etm/autofdo,preset=1/ ...
> >>
> >> (valid presets 1-N, where N is the number supplied in the configuration, not
> >> exceeding 15. preset=0 is the same as not selecting a preset.)
> >>
> >> Applies to & tested against coresight/next (5.13-rc6 base)
> >>
> >> Changes since v7:
> >>
> >> Fixed kernel test robot issue - config with CORESIGHT=y & CONFIGFS_FS=m causes
> >> build error. Altered CORESIGHT config to select CONFIGFS_FS.
> >> Reported-by: kernel test robot <lkp@...el.com>
> >>
> >> Replaced mutex use to protect loaded config lists in coresight devices with per
> >> device spinlock to remove issue when disable called in interrupt context.
> >> Reported-by: Branislav Rankov <branislav.rankov@....com>
> >>
> >
> > Can you indicate which patches have changed so I don't have to review the whole
> > thing again?   It is also common practice to remove the RB tag when patches
> > have changed enough to mandate another review.  In this case all patches still
> > bare my RB tags.
> >
> > Branislav reported the problem but he is not a recipient.  I would like to have
> > a confirmation from him that this set fixes the problem he observed before I
> > start looking at it.
>
> I have tested this series and the issue I reported is fixed.
> >
> > Thanks,
> > Mathieu
> >
> >>
> >> Changes since v6:
> >> Fixed kernel test robot issues-
> >> Reported-by: kernel test robot <lkp@...el.com>
> >>
> >> Changes since v5:
> >>
> >> 1) Fix code style issues from auto-build reports, as
> >> Reported-by: kernel test robot <lkp@...el.com>
> >> 2) Update comments to get consistent docs for API functions.
> >> 3) remove unused #define from autofdo example.
> >> 4) fix perf code style issues from patch 4 (Mathieu)
> >> 5) fix configfs code style issues from patch 9. (Mathieu)
> >>
> >> Changes since v4: (based on comments from Matthieu and Suzuki).
> >> No large functional changes - primarily code improvements and naming schema.
> >> 1) Updated entire set to ensure a consistent naming scheme was used for
> >> variables and struct members that refer to the key objects in the system.
> >> Suffixes _desc used for all references to feature and configuraion descriptors,
> >> suffix _csdev used for all references to load feature and configs in the csdev
> >> instances. (Mathieu & Suzuki).
> >> 2) Dropped the 'configurations' sub dir in cs_etm perf directories as superfluous
> >> with the configfs containing the same information. (Mathieu).
> >> 3) Simplified perf handling code (suzuki)
> >> 4) Multiple simplifications and improvements for code readability (Matthieu
> >> and Suzuki)
> >>
> >> Changes since v3: (Primarily based on comments from Matthieu)
> >> 1) Locking mechanisms simplified.
> >> 2) Removed the possibility to enable features independently from
> >> configurations.Only configurations can be enabled now. Simplifies programming
> >> logic.
> >> 3) Configuration now uses an activate->enable mechanism. This means that perf
> >> will activate a selected configuration at the start of a session (during
> >> setup_aux), and disable at the end of a session (around free_aux)
> >> The active configuration and associated features will be programmed into the
> >> CoreSight device instances when they are enabled. This locks the configuration
> >> into the system while in use. Parameters cannot be altered while this is
> >> in place. This mechanism will be extended in future for dynamic load / unload
> >> of configurations to prevent removal while in use.
> >> 4) Removed the custom bus / driver as un-necessary. A single device is
> >> registered to own perf fs elements and configfs.
> >> 5) Various other minor issues addressed.
> >>
> >> Changes since v2:
> >> 1) Added documentation file.
> >> 2) Altered cs_syscfg driver to no longer be coresight_device based, and moved
> >> to its own custom bus to remove it from the main coresight bus. (Mathieu)
> >> 3) Added configfs support to inspect and control loaded configurations and
> >> features. Allows listing of preset values (Yabin Cui)
> >> 4) Dropped sysfs support for adjusting feature parameters on the per device
> >> basis, in favour of a single point adjustment in configfs that is pushed to all
> >> device instances.
> >> 5) Altered how the config and preset command line options are handled in perf
> >> and the drivers. (Mathieu and Suzuki).
> >> 6) Fixes for various issues and technical points (Mathieu, Yabin)
> >>
> >> Changes since v1:
> >> 1) Moved preloaded configurations and features out of individual drivers.
> >> 2) Added cs_syscfg driver to manage configurations and features. Individual
> >> drivers register with cs_syscfg indicating support for config, and provide
> >> matching information that the system uses to load features into the drivers.
> >> This allows individual drivers to be updated on an as needed basis - and
> >> removes the need to consider devices that cannot benefit from configuration -
> >> static replicators, funnels, tpiu.
> >> 3) Added perf selection of configuarations.
> >> 4) Rebased onto the coresight module loading set.
> >>
> >> To follow in future revisions / sets:-
> >> a) load of additional config and features by loadable module.
> >> b) load of additional config and features by configfs
> >> c) enhanced resource management for ETMv4 and checking features have sufficient
> >> resources to be enabled.
> >> d) ECT and CTI support for configuration and features.
> >>
> >> Mike Leach (10):
> >>   coresight: syscfg: Initial coresight system configuration
> >>   coresight: syscfg: Add registration and feature loading for cs devices
> >>   coresight: config: Add configuration and feature generic functions
> >>   coresight: etm-perf: update to handle configuration selection
> >>   coresight: syscfg: Add API to activate and enable configurations
> >>   coresight: etm-perf: Update to activate selected configuration
> >>   coresight: etm4x: Add complex configuration handlers to etmv4
> >>   coresight: config: Add preloaded configurations
> >>   coresight: syscfg: Add initial configfs support
> >>   Documentation: coresight: Add documentation for CoreSight config
> >>
> >>  .../trace/coresight/coresight-config.rst      | 244 ++++++
> >>  Documentation/trace/coresight/coresight.rst   |  16 +
> >>  drivers/hwtracing/coresight/Kconfig           |   1 +
> >>  drivers/hwtracing/coresight/Makefile          |   7 +-
> >>  .../hwtracing/coresight/coresight-cfg-afdo.c  | 153 ++++
> >>  .../coresight/coresight-cfg-preload.c         |  31 +
> >>  .../coresight/coresight-cfg-preload.h         |  13 +
> >>  .../hwtracing/coresight/coresight-config.c    | 275 ++++++
> >>  .../hwtracing/coresight/coresight-config.h    | 253 ++++++
> >>  drivers/hwtracing/coresight/coresight-core.c  |  12 +-
> >>  .../hwtracing/coresight/coresight-etm-perf.c  | 150 +++-
> >>  .../hwtracing/coresight/coresight-etm-perf.h  |  12 +-
> >>  .../hwtracing/coresight/coresight-etm4x-cfg.c | 182 ++++
> >>  .../hwtracing/coresight/coresight-etm4x-cfg.h |  30 +
> >>  .../coresight/coresight-etm4x-core.c          |  38 +-
> >>  .../coresight/coresight-etm4x-sysfs.c         |   3 +
> >>  .../coresight/coresight-syscfg-configfs.c     | 396 +++++++++
> >>  .../coresight/coresight-syscfg-configfs.h     |  45 +
> >>  .../hwtracing/coresight/coresight-syscfg.c    | 829 ++++++++++++++++++
> >>  .../hwtracing/coresight/coresight-syscfg.h    |  81 ++
> >>  include/linux/coresight.h                     |  11 +
> >>  21 files changed, 2746 insertions(+), 36 deletions(-)
> >>  create mode 100644 Documentation/trace/coresight/coresight-config.rst
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-cfg-afdo.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-cfg-preload.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-cfg-preload.h
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-config.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-config.h
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-etm4x-cfg.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-etm4x-cfg.h
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg-configfs.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg-configfs.h
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg.c
> >>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg.h
> >>
> >> --
> >> 2.17.1
> >>
> > _______________________________________________
> > CoreSight mailing list
> > CoreSight@...ts.linaro.org
> > https://lists.linaro.org/mailman/listinfo/coresight
> >



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

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