diff options
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/boottime-trace.rst | 4 | ||||
| -rw-r--r-- | Documentation/trace/coresight/coresight-config.rst | 78 | ||||
| -rw-r--r-- | Documentation/trace/events.rst | 19 |
3 files changed, 84 insertions, 17 deletions
diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst index 6dcfbc64014d..d594597201fd 100644 --- a/Documentation/trace/boottime-trace.rst +++ b/Documentation/trace/boottime-trace.rst @@ -131,9 +131,7 @@ Ftrace Histogram Options Since it is too long to write a histogram action as a string for per-event action option, there are tree-style options under per-event 'hist' subkey for the histogram actions. For the detail of the each parameter, -please read the event histogram document [3]_. - -.. [3] See :ref:`Documentation/trace/histogram.rst <histogram>` +please read the event histogram document (Documentation/trace/histogram.rst) ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist.[N.]keys = KEY1[, KEY2[...]] Set histogram key parameters. (Mandatory) diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst index a4e3ef295240..6d5ffa6f7347 100644 --- a/Documentation/trace/coresight/coresight-config.rst +++ b/Documentation/trace/coresight/coresight-config.rst @@ -155,14 +155,14 @@ follows:: autofdo $ cd autofdo/ $ ls - description preset1 preset3 preset5 preset7 preset9 - feature_refs preset2 preset4 preset6 preset8 + description feature_refs preset1 preset3 preset5 preset7 preset9 + enable preset preset2 preset4 preset6 preset8 $ cat description Setup ETMs with strobing for autofdo $ cat feature_refs strobing -Each preset declared has a preset<n> subdirectory declared. The values for +Each preset declared has a 'preset<n>' subdirectory declared. The values for the preset can be examined:: $ cat preset1/values @@ -170,6 +170,9 @@ the preset can be examined:: $ cat preset2/values strobing.window = 0x1388 strobing.period = 0x4 +The 'enable' and 'preset' files allow the control of a configuration when +using CoreSight with sysfs. + The features referenced by the configuration can be examined in the features directory:: @@ -211,19 +214,13 @@ also declared in the perf 'cs_etm' event infrastructure so that they can be selected when running trace under perf:: $ ls /sys/devices/cs_etm - configurations format perf_event_mux_interval_ms sinks type - events nr_addr_filters power - -Key directories here are 'configurations' - which lists the loaded -configurations, and 'events' - a generic perf directory which allows -selection on the perf command line.:: + cpu0 cpu2 events nr_addr_filters power subsystem uevent + cpu1 cpu3 format perf_event_mux_interval_ms sinks type - $ ls configurations/ - autofdo - $ cat configurations/autofdo - 0xa7c3dddd +The key directory here is 'events' - a generic perf directory which allows +selection on the perf command line. As with the sinks entries, this provides +a hash of the configuration name. -As with the sinks entries, this provides a hash of the configuration name. The entry in the 'events' directory uses perfs built in syntax generator to substitute the syntax for the name when evaluating the command:: @@ -242,3 +239,56 @@ A preset to override the current parameter values can also be selected:: When configurations are selected in this way, then the trace sink used is automatically selected. + +Using Configurations in sysfs +============================= + +Coresight can be controlled using sysfs. When this is in use then a configuration +can be made active for the devices that are used in the sysfs session. + +In a configuration there are 'enable' and 'preset' files. + +To enable a configuration for use with sysfs:: + + $ cd configurations/autofdo + $ echo 1 > enable + +This will then use any default parameter values in the features - which can be +adjusted as described above. + +To use a preset<n> set of parameter values:: + + $ echo 3 > preset + +This will select preset3 for the configuration. +The valid values for preset are 0 - to deselect presets, and any value of +<n> where a preset<n> sub-directory is present. + +Note that the active sysfs configuration is a global parameter, therefore +only a single configuration can be active for sysfs at any one time. +Attempting to enable a second configuration will result in an error. +Additionally, attempting to disable the configuration while in use will +also result in an error. + +The use of the active configuration by sysfs is independent of the configuration +used in perf. + + +Creating and Loading Custom Configurations +========================================== + +Custom configurations and / or features can be dynamically loaded into the +system by using a loadable module. + +An example of a custom configuration is found in ./samples/coresight. + +This creates a new configuration that uses the existing built in +strobing feature, but provides a different set of presets. + +When the module is loaded, then the configuration appears in the configfs +file system and is selectable in the same way as the built in configuration +described above. + +Configurations can use previously loaded features. The system will ensure +that it is not possible to unload a feature that is currently in use, by +enforcing the unload order as the strict reverse of the load order. diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst index 8ddb9b09451c..c47f381d0c00 100644 --- a/Documentation/trace/events.rst +++ b/Documentation/trace/events.rst @@ -198,6 +198,15 @@ The glob (~) accepts a wild card character (\*,?) and character classes prev_comm ~ "*sh*" prev_comm ~ "ba*sh" +If the field is a pointer that points into user space (for example +"filename" from sys_enter_openat), then you have to append ".ustring" to the +field name:: + + filename.ustring ~ "password" + +As the kernel will have to know how to retrieve the memory that the pointer +is at from user space. + 5.2 Setting filters ------------------- @@ -230,6 +239,16 @@ Currently the caret ('^') for an error always appears at the beginning of the filter string; the error message should still be useful though even without more accurate position info. +5.2.1 Filter limitations +------------------------ + +If a filter is placed on a string pointer ``(char *)`` that does not point +to a string on the ring buffer, but instead points to kernel or user space +memory, then, for safety reasons, at most 1024 bytes of the content is +copied onto a temporary buffer to do the compare. If the copy of the memory +faults (the pointer points to memory that should not be accessed), then the +string compare will be treated as not matching. + 5.3 Clearing filters -------------------- |