ARCv2/v3: Implemented ftrace

[BrunoASMauricio]

Implementation of ftrace with function graphing for ARCv2.

It has the exact same functionality as with ARCv3 (more information in this PR #146) except ARCv2 ABI requires special GCC support (provided here foss-for-synopsys-dwc-arc-processors/gcc@c52b7ec)

[pavelvkozlov]

I've checked this patch with a set of ftrace tests from the kselftes package.

First of all, failed to build modules with enabled FTRACE.

ERROR: modpost: "_mcount" [net/ife/ife.ko] undefined!
ERROR: modpost: "_mcount" [net/psample/psample.ko] undefined!
ERROR: modpost: "_mcount" [net/can/can-gw.ko] undefined!
ERROR: modpost: "_mcount" [net/can/can-bcm.ko] undefined!
ERROR: modpost: "_mcount" [net/can/can-raw.ko] undefined!
ERROR: modpost: "_mcount" [net/can/can.ko] undefined!
ERROR: modpost: "_mcount" [net/mptcp/mptcp_diag.ko] undefined!
ERROR: modpost: "_mcount" [net/mpls/mpls_iptunnel.ko] undefined!
ERROR: modpost: "_mcount" [net/mpls/mpls_router.ko] undefined!
ERROR: modpost: "_mcount" [net/mpls/mpls_gso.ko] undefined!
WARNING: modpost: suppressed 85 unresolved symbol warnings because there were too many)

Please, add EXPORT_SYMBOL(_mcount) after _mcount function definition.

The following results on ARCHS QEMU:

# selftests: ftrace: ftracetest
# === Ftrace unit tests ===
# [1] Basic trace file check    [PASS]
# [2] Basic test for tracers    [PASS]
# [3] Basic trace clock test    [PASS]
# [4] Basic event tracing check [PASS]
# [5] Change the ringbuffer size        [PASS]
# [6] Snapshot and tracing setting      [PASS]
# [7] trace_pipe and trace_marker       [PASS]
# [8] Test ftrace direct functions against tracers      [UNRESOLVED]
# [9] Test ftrace direct functions against kprobes      [UNSUPPORTED]
# [10] Generic dynamic event - add/remove eprobe events [UNSUPPORTED]
# [11] Generic dynamic event - add/remove kprobe events [UNSUPPORTED]
# [12] Generic dynamic event - add/remove synthetic events      [UNSUPPORTED]
# [13] Generic dynamic event - selective clear (compatibility)  [UNSUPPORTED]
# [14] Generic dynamic event - generic clear event      [UNSUPPORTED]
# [15] Generic dynamic event - check if duplicate events are caught     [UNSUPPORTED]
# [16] event tracing - enable/disable with event level files    [PASS]
# [17] event tracing - restricts events based on pid notrace filtering  [PASS]
# [18] event tracing - restricts events based on pid    [PASS]
# [19] event tracing - enable/disable with subsystem level files        [PASS]
# [20] event tracing - enable/disable with top level files      [PASS]
 
**********************************************************
**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
**                                                      **
** trace_printk() being used. Allocating extra memory.  **
**                                                      **
** This means that this is a DEBUG kernel and it is     **
** unsafe for production use.                           **
**                                                      **
** If you see this message and you are not debugging    **
** the kernel, report this immediately to your vendor!  **
**                                                      **
**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
**********************************************************
# [21] Test trace_printk from module    [PASS]
# [22] ftrace - function graph filters with stack tracer        [UNSUPPORTED]
# [23] ftrace - function graph filters  [UNSUPPORTED]
# [24] ftrace - function glob filters   [UNSUPPORTED]
# [25] ftrace - function pid notrace filters    [UNSUPPORTED]
# [26] ftrace - function pid filters    [UNSUPPORTED]
# [27] ftrace - stacktrace filter command       [UNSUPPORTED]
# [28] ftrace - function trace with cpumask     [UNRESOLVED]
# [29] ftrace - test for function event triggers        [UNSUPPORTED]
# [30] ftrace - function trace on module        [UNSUPPORTED]
# [31] ftrace - function profiling      [PASS]
# [32] ftrace - function profiler with function tracing [UNSUPPORTED]
# [33] ftrace - test reading of set_ftrace_filter       [UNSUPPORTED]
# [34] ftrace - Max stack tracer        [UNSUPPORTED]
# [35] ftrace - test for function traceon/off triggers  [UNSUPPORTED]
# [36] ftrace - test tracing error log support  [FAIL]
# [37] Test creation and deletion of trace instances while setting an event     [PASS]
# [38] Test creation and deletion of trace instances    [PASS]
# [39] Kprobe dynamic event - adding and removing       [UNSUPPORTED]
# [40] Kprobe dynamic event - busy event check  [UNSUPPORTED]
# [41] Kprobe dynamic event with arguments      [UNSUPPORTED]
# [42] Kprobe event with comm arguments [UNSUPPORTED]
# [43] Kprobe event string type argument        [UNSUPPORTED]
# [44] Kprobe event symbol argument     [UNSUPPORTED]
# [45] Kprobe event argument syntax     [UNSUPPORTED]
# [46] Kprobes event arguments with types       [UNSUPPORTED]
# [47] Kprobe event user-memory access  [UNSUPPORTED]
# [48] Kprobe event auto/manual naming  [UNSUPPORTED]
# [49] Kprobe dynamic event with function tracer        [UNSUPPORTED]
# [50] Kprobe dynamic event - probing module    [UNSUPPORTED]
# [51] Create/delete multiprobe on kprobe event [UNSUPPORTED]
# [52] Kprobe event parser error log check      [UNSUPPORTED]
# [53] Kretprobe dynamic event with arguments   [UNSUPPORTED]
# [54] Kretprobe dynamic event with maxactive   [UNSUPPORTED]
# [55] Kretprobe %return suffix test    [UNSUPPORTED]
# [56] Register/unregister many kprobe events   [UNSUPPORTED]
# [57] Kprobe events - probe points     [UNSUPPORTED]
# [58] Kprobe dynamic event - adding and removing       [UNSUPPORTED]
# [59] Uprobe event parser error log check      [UNSUPPORTED]
random: crng init done
 
# [60] test for the preemptirqsoff tracer       [PASS]
# [61] Meta-selftest: Checkbashisms     [UNRESOLVED]
# [62] Test wakeup tracer       [PASS]
# [63] Test wakeup RT tracer    [PASS]
# [64] event trigger - test inter-event histogram trigger expected fail actions [UNSUPPORTED]
# [65] event trigger - test field variable support      [UNSUPPORTED]
# [66] event trigger - test inter-event combined histogram trigger      [UNSUPPORTED]
# [67] event trigger - test multiple actions on hist trigger    [UNSUPPORTED]
# [68] event trigger - test inter-event histogram trigger onchange action       [UNSUPPORTED]
# [69] event trigger - test inter-event histogram trigger onmatch action        [UNSUPPORTED]
# [70] event trigger - test inter-event histogram trigger onmatch-onmax action  [UNSUPPORTED]
# [71] event trigger - test inter-event histogram trigger onmax action  [UNSUPPORTED]
# [72] event trigger - test inter-event histogram trigger snapshot action       [UNSUPPORTED]
# [73] event trigger - test inter-event histogram trigger eprobe on synthetic event     [UNSUPPORTED]
# [74] event trigger - test synthetic event create remove       [UNSUPPORTED]
# [75] event trigger - test inter-event histogram trigger trace action with dynamic string param        [UNSUPPORTED]
# [76] event trigger - test synthetic_events syntax parser      [UNSUPPORTED]
# [77] event trigger - test synthetic_events syntax parser errors       [UNSUPPORTED]
# [78] event trigger - test inter-event histogram trigger trace action  [UNSUPPORTED]
# [79] event trigger - test event enable/disable trigger        [PASS]
# [80] event trigger - test trigger filter      [PASS]
# [81] event trigger - test histogram expression parsing        [UNSUPPORTED]
# [82] event trigger - test histogram modifiers [UNSUPPORTED]
# [83] event trigger - test histogram parser errors     [UNSUPPORTED]
# [84] event trigger - test histogram trigger   [UNSUPPORTED]
# [85] event trigger - test multiple histogram triggers [UNSUPPORTED]
# [86] event trigger - test snapshot-trigger    [PASS]
# [87] event trigger - test stacktrace-trigger  [PASS]
# [88] trace_marker trigger - test histogram trigger    [UNSUPPORTED]
# [89] trace_marker trigger - test snapshot trigger     [PASS]
# [90] trace_marker trigger - test histogram with synthetic event against kernel event  [UNSUPPORTED]
# [91] trace_marker trigger - test histogram with synthetic event       [UNSUPPORTED]
# [92] event trigger - test traceon/off trigger [PASS]
# [93] (instance)  Basic test for tracers       [PASS]
# [94] (instance)  Basic trace clock test       [PASS]
# [95] (instance)  Change the ringbuffer size   [PASS]
# [96] (instance)  Snapshot and tracing setting [PASS]
# [97] (instance)  trace_pipe and trace_marker  [PASS]
# [98] (instance)  event tracing - enable/disable with event level files        [PASS]
# [99] (instance)  event tracing - restricts events based on pid notrace filtering      [PASS]
# [100] (instance)  event tracing - restricts events based on pid       [PASS]
# [101] (instance)  event tracing - enable/disable with subsystem level files   [PASS]
# [102] (instance)  ftrace - function pid notrace filters       [UNSUPPORTED]
# [103] (instance)  ftrace - function pid filters       [UNSUPPORTED]
# [104] (instance)  ftrace - stacktrace filter command  [UNSUPPORTED]
# [105] (instance)  ftrace - test for function event triggers   [UNSUPPORTED]
# [106] (instance)  ftrace - test for function traceon/off triggers     [UNSUPPORTED]
# [107] (instance)  event trigger - test event enable/disable trigger   [PASS]
# [108] (instance)  event trigger - test trigger filter [PASS]
# [109] (instance)  event trigger - test histogram modifiers    [UNSUPPORTED]
# [110] (instance)  event trigger - test histogram trigger      [UNSUPPORTED]
# [111] (instance)  event trigger - test multiple histogram triggers    [UNSUPPORTED]
# [112] (instance)  trace_marker trigger - test histogram trigger       [UNSUPPORTED]
# [113] (instance)  trace_marker trigger - test snapshot trigger        [PASS]
# grep: dynamic_events: No such file or directory
#
# # of passed:  37
# # of failed:  1
# # of unresolved:  3
# # of untested:  0
# # of unsupported:  72
# # of xfailed:  0
# # of undefined(test bug):  0
not ok 1 selftests: ftrace: ftracetest # exit=1

Too many unsupported results. Some of skips are because of absence of DYNAMIC_FTRACE support and dynamic events.
Do you plan to add DYNAMIC_FTRACE optimization for ARC ftrace?

[BrunoASMauricio]

Hello @pavelvkozlov !
I have added the missing export, thank you for the tip!
There is no plan to implement DYNAMIC_FTRACE.

[pavelvkozlov]

Looks good for me.
I think it is ready for merge.