third_party/mahcinarium/gdb: mm gdb support (#635)

* third_party/mahcinarium/gdb: mm gdb support

There are many situations in odyssey that must be debugged.
But now it is really hard to do it because of machinarium coroutines engine.

This patch series will add gdb support for machinarium's
coroutines in golang's goroutines style.

For the first step command 'info mmcoros' was added, and now it
can be used to display the list of running coroutines for each thread (mm_machine).

See gdb/README.md for more.

Signed-off-by: Roman Khapov <[email protected]>

* machinarium-gdb.py: move out function to iterate coros

All coroutines list of the current thread will be used in the next
command, to find specified coroutine.

This commit move out function to create coroutines list out of
MMCoroutines command.

Signed-off-by: Roman Khapov <[email protected]>

* machinarium-gdb.py: add mmcoro command

This command can be used to perform some gdb command
on the context of the coroutine.

It will be extremely helpful with debugging various problems in odyssey
logic.

Example:
(gdb) mmcoro 3 0 info stack
(gdb) mmcoro 3 0 frame apply 3 info locals

Signed-off-by: Roman Khapov <[email protected]>

third_party/machinarium/gdb/README.md

@@ -0,0 +1,86 @@
+# GDB scripts for machinarium easy debugging
+
+## How to use
+
+Run gdb and then initialize the script:
+```bash
+(gdb) source ~/odyssey/third_party/machinarium/gdb/machinarium-gdb.py
+```
+
+## Commnands
+
+### info mmcoros
+List all machinarium coroutines for threads.
+Shows list of active and ready coroutines from scheduler of the thread.
+Current coroutine are marked by *.
+See `(gdb) help info mmcoros` for more.
+
+Ex:
+```
+(gdb) info mmcoros
+Thread 3 (benchmark_csw) machinarium coroutines:
+ Id	State		errno	Function
+ 0	MM_CACTIVE	0	0x555555557fe0 <benchmark_runner>
+*1	MM_CACTIVE	0	0x555555557f70 <benchmark_worker>
+
+Thread 2 (resolver: 0) machinarium coroutines:
+ Id	State		errno	Function
+ 0	MM_CACTIVE	0	0x5555555596e3 <mm_taskmgr_main>
+
+Thread 1 (benchmark_csw) machinarium coroutines:
+ The mm_self is NULL, so no coroutines in this thread available.
+
+(gdb) info mmcoros 'benchmark_csw'
+Thread 3 (benchmark_csw) machinarium coroutines:
+ Id	State		errno	Function
+ 0	MM_CACTIVE	0	0x555555557fe0 <benchmark_runner>
+*1	MM_CACTIVE	0	0x555555557f70 <benchmark_worker>
+
+Thread 1 (benchmark_csw) machinarium coroutines:
+ The mm_self is NULL, so no coroutines in this thread available.
+
+(gdb) info mmcoros 2 3
+Thread 3 (benchmark_csw) machinarium coroutines:
+ Id	State		errno	Function
+ 0	MM_CACTIVE	0	0x555555557fe0 <benchmark_runner>
+*1	MM_CACTIVE	0	0x555555557f70 <benchmark_worker>
+
+Thread 2 (resolver: 0) machinarium coroutines:
+ Id	State		errno	Function
+ 0	MM_CACTIVE	0	0x5555555596e3 <mm_taskmgr_main>
+
+```
+
+### mmcoro
+
+Execute gdb command in context of the specified coroutine.
+
+Please note, that coroutine is determined with pair thread id and coroutine id.
+
+See `help mmcoro` for more.
+
+Ex:
+```
+(gdb) mmcoro 3 0 info stack
+#0  mm_scheduler_yield (scheduler=0x0) at /home/rkhapov/odyssey/build/third_party/machinarium/sources/scheduler.c:167
+#1  0x0000555555557f43 in foo (arg=0x0) at benchmark_csw.c:31
+#2  0x0000555555557f8e in benchmark_worker (arg=0x0) at benchmark_csw.c:39
+#3  0x000055555555d657 in mm_scheduler_main (arg=0x7fffe8001010) at /home/rkhapov/odyssey/build/third_party/machinarium/sources/scheduler.c:17
+#4  0x0000555555560908 in mm_context_runner () at /home/rkhapov/odyssey/build/third_party/machinarium/sources/context.c:28
+#5  0x0000000000000000 in ?? ()
+
+(gdb) mmcoro 3 0 frame apply 3 info locals
+#0  mm_scheduler_yield (scheduler=0x0) at /home/rkhapov/odyssey/build/third_party/machinarium/sources/scheduler.c:167
+current = 0x55555556101d
+resume = 0x5d0f7680faa
+__PRETTY_FUNCTION__ = "mm_scheduler_yield"
+#1  0x0000555555557f43 in foo (arg=0x0) at benchmark_csw.c:31
+foo_var = 52
+#2  0x0000555555557f8e in benchmark_worker (arg=0x0) at benchmark_csw.c:39
+bench_worker_var = 99 'c'
+
+(gdb) mmcoro 3 0
+$1 = {id = 0, state = MM_CACTIVE, cancel = 0, errno_ = 0, function = 0x55555555803b <benchmark_runner>, function_arg = 0x0, stack = {pointer = 0x7ffff7fa8000 "", 
+    size = 16384, size_guard = 4096}, context = {sp = 0x7ffff7fabdf8}, resume = 0x55555557cca0, call_ptr = 0x7ffff7fabeb0, joiners = {next = 0x7fffe8000bc8, 
+    prev = 0x7fffe8000bc8}, link_join = {next = 0x7fffe8000bd8, prev = 0x7fffe8000bd8}, link = {next = 0x7fffe8001088, prev = 0x55555557cd40}}
+```