user: Document event recording

Close #3904.

user/tracing/eventrecording.rst

@@ -1,6 +1,6 @@
 .. SPDX-License-Identifier: CC-BY-SA-4.0
 
-.. Copyright (C) 2019 embedded brains GmbH
+.. Copyright (C) 2019, 2020 embedded brains GmbH
 .. Copyright (C) 2019 Sebastian Huber
 
 .. _EventRecording:
@@ -35,12 +35,26 @@ operations.  The CPU counter is used to get the time of events. It is combined
 with periodic uptime events to synchronize it with the monotonic system clock
 (:c:macro:`CLOCK_MONOTONIC`).
 
-The application must configure the event recording via the configuration options
+To use the event recording three things come into play. Firstly, there is the
-:c:macro:`CONFIGURE_RECORD_PER_PROCESSOR_ITEMS` and
+generation of event records on the target system (the application running with
-:c:macro:`CONFIGURE_RECORD_EXTENSIONS_ENABLED`.
+RTEMS).  Secondly, means to transfer the recorded events to the host computer
+for analysis.  Thirdly, the analysis of the recorded events on the host
+computer.
 
-Events can be recorded for example with the :c:func:`rtems_record_produce`
+Target System: Configuration and Event Generation
-function.
+-------------------------------------------------
+
+The application enables the event recording support via the configuration
+option :c:macro:`CONFIGURE_RECORD_PER_PROCESSOR_ITEMS`.  The configuration
+option :c:macro:`CONFIGURE_RECORD_EXTENSIONS_ENABLED` enables the generation of
+thread create, start, restart, delete, switch, begin, exitted and terminate
+events.  Dumps of the event records in a fatal error handler can be enabled by
+the mutually exclusive :c:macro:`CONFIGURE_RECORD_FATAL_DUMP_BASE64` and
+:c:macro:`CONFIGURE_RECORD_FATAL_DUMP_BASE64_ZLIB` configuration options.
+
+Custom events can be recorded for example with the
+:c:func:`rtems_record_produce`, :c:func:`rtems_record_line`,
+:c:func:`rtems_record_caller`, etc. functions.
 
 .. code-block:: c
 
@@ -49,10 +63,198 @@ function.
     void f( void )
     {
       rtems_record_produce( RTEMS_RECORD_USER( 0 ), 123 );
+      rtems_record_line();
+      rtems_record_caller();
     }
 
-Recorded events can be sent to a host computer with a very simple record server
+The variants of :c:func:`rtems_record_line` and :c:func:`rtems_record_caller`
-started by :c:func:`rtems_record_start_server` via a TCP connection.
+can be used to easily generate control flow events in the area of interest.
+The :file:`rtems-record-lttng` tool can use these events to associate source
+code files and line numbers to them using the ELF file of the application.
 
-On the host computer you may use the command line tool :file:`rtems-record` to
+The following code can be used together with the GCC option
-get recorded events from the record server running on the target system.
+``-finstrument-functions`` to generate function entry/exit events for
+instrumented functions:
+
+.. code-block:: c
+
+   __attribute__(( __no_instrument_function__ ))
+   void __cyg_profile_func_enter( void *this_fn, void *call_site )
+   {
+     rtems_record_produce_2(
+       RTEMS_RECORD_CALLER,
+       (rtems_record_data) call_site,
+       RTEMS_RECORD_FUNCTION_ENTRY,
+       (rtems_record_data) this_fn
+     );
+   }
+
+   __attribute__(( __no_instrument_function__ ))
+   void __cyg_profile_func_exit( void *this_fn, void *call_site )
+   {
+     rtems_record_produce(
+       RTEMS_RECORD_FUNCTION_EXIT,
+       (rtems_record_data) this_fn
+     );
+   }
+
+To generate interrupt handler entry/exit events, the following patch can be
+used:
+
+.. code-block:: diff
+
+    diff --git a/bsps/arm/shared/clock/clock-armv7m.c b/bsps/arm/shared/clock/clock-armv7m.c
+    index 255de1ca42..0d37c63ac6 100644
+    --- a/bsps/arm/shared/clock/clock-armv7m.c
+    +++ b/bsps/arm/shared/clock/clock-armv7m.c
+    @@ -29,6 +29,7 @@
+     #include <bsp/clock-armv7m.h>
+
+     #include <rtems.h>
+    +#include <rtems/record.h>
+     #include <rtems/sysinit.h>
+
+     #ifdef ARM_MULTILIB_ARCH_V7M
+    @@ -45,9 +46,11 @@ static uint32_t _ARMV7M_TC_get_timecount(struct timecounter *base)
+
+     void _ARMV7M_Clock_handler(void)
+     {
+    +  rtems_record_produce(RTEMS_RECORD_INTERRUPT_ENTRY, ARMV7M_VECTOR_SYSTICK);
+       _ARMV7M_Interrupt_service_enter();
+       Clock_isr(NULL);
+       _ARMV7M_Interrupt_service_leave();
+    +  rtems_record_produce(RTEMS_RECORD_INTERRUPT_EXIT, ARMV7M_VECTOR_SYSTICK);
+     }
+
+     static void _ARMV7M_Clock_handler_install(void)
+    diff --git a/bsps/include/bsp/irq-generic.h b/bsps/include/bsp/irq-generic.h
+    index 31835d07ba..2ab2f78b65 100644
+    --- a/bsps/include/bsp/irq-generic.h
+    +++ b/bsps/include/bsp/irq-generic.h
+    @@ -30,6 +30,7 @@
+     #include <stdbool.h>
+
+     #include <rtems/irq-extension.h>
+    +#include <rtems/record.h>
+     #include <rtems/score/assert.h>
+
+     #ifdef RTEMS_SMP
+    @@ -258,6 +259,7 @@ void bsp_interrupt_vector_disable(rtems_vector_number vector);
+      */
+     static inline void bsp_interrupt_handler_dispatch(rtems_vector_number vector)
+     {
+    +  rtems_record_produce(RTEMS_RECORD_INTERRUPT_ENTRY, vector);
+       if (bsp_interrupt_is_valid_vector(vector)) {
+         const bsp_interrupt_handler_entry *e =
+           &bsp_interrupt_handler_table [bsp_interrupt_handler_index(vector)];
+    @@ -276,6 +278,7 @@ static inline void bsp_interrupt_handler_dispatch(rtems_vector_number vector)
+       } else {
+         bsp_interrupt_handler_default(vector);
+       }
+    +  rtems_record_produce(RTEMS_RECORD_INTERRUPT_EXIT, vector);
+     }
+
+     /**
+
+Transfer of Event Records to the Host Computer
+----------------------------------------------
+
+Recorded events can be sent to a host computer with a record server started by
+:c:func:`rtems_record_start_server` via a TCP connection.
+
+In the fatal error handler, the event records can be dumped via
+:c:func:`rtems_putc` in Base64 encoding.  Optionally, the event records can be
+compressed via zlib before they are dumped in Base64 encoding.  The compression
+needs roughly 512KiB of statically allocated memory.
+
+Analysis of Event Records on the Host Computer
+----------------------------------------------
+
+Use the command line tool :file:`rtems-record-lttng` to get recorded events
+from the record server running on the target system or from a file to convert
+the event records into CTF.  It can be also used to read the dumps in Base64
+encoding generated by the fatal error handler.  The tool outputs the event
+records in the `Common Trace Format (CTF) <https://diamon.org/ctf/>`_ with some
+extra support for the
+`Linux Trace Toolkit Next Generation (LTTng) <https://lttng.org/>`_.  This
+format can be analysed using `babeltrace <https://babeltrace.org/>`_ or
+`Eclipse Trace Compass <https://www.eclipse.org/tracecompass/>`_.
+
+For example, to get the event records from the record server running on the
+target use:
+
+.. code-block:: none
+
+    mkdir new-trace
+    cd new-trace
+    rtems-record-lttng -e application.exe -H 192.168.188.84 -l 100000
+
+If everything is set up correctly, then the command produces a :file:`metadata`
+file and one stream file :file:`stream_0`, etc. for each processor which
+generated event records.
+
+.. code-block:: none
+
+    $ ls -l
+    total 120
+    -rw-r--r-- 1 user group 108339 Apr 11 15:28 metadata
+    -rw-r--r-- 1 user group   8701 Apr 11 15:28 stream_0
+
+This output in CTF can be used by :file:`babeltrace` and
+`Eclipse Trace Compass` for further analysis, for example:
+
+.. code-block:: none
+
+    $ babeltrace .
+    [07:28:15.909340000] (+?.?????????) RTEMS THREAD_STACK_CURRENT: { cpu_id = 0 }, { data = 0xB10 }
+    [07:28:15.909340000] (+0.000000000) RTEMS sched_switch: { cpu_id = 0 }, { prev_comm = "UI1 ", prev_tid = 167837697, prev_prio = 0, prev_state = 0, next_comm = "IDLE/0", next_tid = 0, next_prio = 0 }
+    [07:28:15.909519999] (+0.000179999) RTEMS THREAD_STACK_CURRENT: { cpu_id = 0 }, { data = 0xD68 }
+    [07:28:15.909519999] (+0.000000000) RTEMS sched_switch: { cpu_id = 0 }, { prev_comm = "IDLE/0", prev_tid = 0, prev_prio = 0, prev_state = 1026, next_comm = "UI1 ", next_tid = 167837697, next_prio = 0 }
+    [07:28:15.909579999] (+0.000060000) RTEMS THREAD_STACK_CURRENT: { cpu_id = 0 }, { data = 0xB10 }
+    ...
+    [07:28:15.999940999] (+0.000000000) RTEMS USER_4: { cpu_id = 0 }, { data = 0x4000192C }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_0: { cpu_id = 0 }, { data = 0x0 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_1: { cpu_id = 0 }, { data = 0x1 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_2: { cpu_id = 0 }, { data = 0x2 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_3: { cpu_id = 0 }, { data = 0x3 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_4: { cpu_id = 0 }, { data = 0x4 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_5: { cpu_id = 0 }, { data = 0x5 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_6: { cpu_id = 0 }, { data = 0x6 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_7: { cpu_id = 0 }, { data = 0x7 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_8: { cpu_id = 0 }, { data = 0x8 }
+    [07:28:15.999940999] (+0.000000000) RTEMS RETURN_9: { cpu_id = 0 }, { data = 0x9 }
+    [07:28:15.999940999] (+0.000000000) RTEMS ISR_DISABLE: { cpu_id = 0 }, { code = "generate_events at init.c:154" }
+    [07:28:15.999940999] (+0.000000000) RTEMS ISR_ENABLE: { cpu_id = 0 }, { code = "Init at init.c:181" }
+
+A dump from the fatal error handler looks like this:
+
+.. code-block:: none
+
+    *** BEGIN OF RECORDS BASE64 ZLIB ***
+    eNqtlE1vE1cUhsdJWgg0jU2GABILpxUVkaJcTxzH8QqThKpRKTIJlcoyeIKIhGCCEFnAAtAoKgXa
+    phqx6gKk/AAXWHTpTMYZlg0rdpBdF7Dvsuec91jYFEo+HOnq0b33Oe/9mOtks9ns7Y1TK5ZlJah1
+    Uluw8HfJstqYA1b3WJG4a+p4aZpJbZzaXOlrw+4cte+p2Zcuz15kUstS3FhmZGiWOTs6nGM65Xye
+    6TqZEeZQNnOOWZh1y8KZfEHG3ewMszyE+XJ2hHNyg7lBrs9lhtIZpuMUHObR9LDwuxNnppgDufQ0
+    c2x6Ko35nLBcKOSEeXeYOXM+P8o8lR7oZ85dXJB1HDfN6+aGnbx4/YUR3t/+zgTfUaL3xMmJSe7v
+    0X7ameTzX9N7m6d7WyNetqyOI93HVgx7xKOWtTdJHOSc7rElo6TxrgvEQfHGbxkl/PFb8F/2GSX8
+    l33wX6WMEv6rlPjJ638YpfhE8ZM3Hhml+ETxUwdOG6X4RPFTB48bpfhE+E82jBL+kw34T9eNEv7T
+    dfH3leaNUnyi+PtOzxil+ET4r1NGCf91Cv6bhFHCf5MQv+fHR0YpPlH8njtLRik+UXz7iGOU4hPF
+    t7/qM0rxifCr60YJv7oOv/rX2aLVk1QetqvP5RFoP0N9/l2R95x/TG32SsTjo8Td4qE/0dDvFB/j
+    Z94zvqch58L/zO8ltqt3cxPeZ8QO9X/fgt9F/ETrqtuo+5z4qdb/vYP6bv7fZIcVyrFtInLCCnLC
+    CnLCCnLCCnLCCnLCCnLCSj0nSdytecUW5qX4/yyxt2gdGtD8b97p/2CHjy1dr3Hco3G8p/Bxm67f
+    OH+jYZ+N4/fes//G+YcfPN/qMrzVZfb+JMJbXYa3ulz3cA/N/otN+Li35rp/tlCH+26q3394G/X4
+    Xs05EzvIwXdvzvNakId3FAXIjQLOfUhEbhQgNwqQGwXIjQLkRgFyowC5UYDcKKjn4n1GD9qRX2c9
+    /91+fb0Pjdf38bH5+j436+l5aovwaz78mg+/5sOv+fBrvvo+zr/tOh/3tuN6H/feshwf36/leT7e
+    Q22xQ3LXrii9O5L/to/11jys9x/P+wnj3l3Zx0fnvXuyz0173n05z5Z972c5/7brvF/k3nZc7/0q
+    9x6fR07sIid2kRO7yIld5MQucmIXObGLnNjVHHdJvl/L89zf5D3E7rdF6+BV4knJf1b6Uuqelb7g
+    df4FFmd4DQ==
+    *** END OF RECORDS BASE64 ZLIB ***
+
+Copy everything between the ``*** BEGIN OF RECORDS BASE64 ZLIB ***`` and the
+``*** END OF RECORDS BASE64 ZLIB ***`` markers into a file, for example
+:file:`dump.txt`.  Use this command to convert the event records into the CTF
+for further analysis:
+
+.. code-block:: none
+
+    rtems-record-lttng -e application.exe -b -z dump.txt