CONT stack overflow postmortem

[mcspr]

• check in cont_run() and cont_suspend() whether a1 points after cont_t::stack[0]
• in case a1 is broken, postmortem will still report proper context in
  proper stack boundaries. previously it used sys ctx values

additionally

• as suggested in ESP8266 Crashing During Prints randomly #9069, change stack smashing to a single line that
  does not mention any Exceptions
• reduce overall stack dump length when there are know garbage values i.e. cont stackguard
• decoder.py addr search regexp should no longer skip stack lines ending with ' <'
• update decoder.py parsing so it notices both stack smashing and alloc errors

Noticed in esp-idf cfg as CONFIG_FREERTOS_CHECK_STACKOVERFLOW_PTRVAL=y, where Freertos it is a so called 'Method 1' of overflow checking happening right before ctx switch
https://www.freertos.org/Stacks-and-stack-overflow-checking.html
(also ref. #8666)

simple example like this one usually already offsets a1 when yield() happens, so the newly added check would cause a reset

#include <Arduino.h>

void setup() {
  Serial.begin(115200);
}

void loop() {
  int buf[1048]; // oops
  yield();
  printf("%p %p %p %p\n",
    &buf[0], &buf[1], &buf[2], &buf[3]);
}

and it should generate more useful info as the result

Stack overflow detected
sp: 3fffef28 end: 3fffffd0 offset: 0000

ctx: cont
0x4010015c: ets_post at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:243
0x402017f5: esp_suspend_within_cont at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:121
(inlined by) __yield at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:193
0x40201052: loop at /home/runner/dev/stack_overflow_test/src/main.cpp:10
0x402016da: loop_task(ETSEventTag*) at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:279
0x40105245: call_user_start_local at ??:?
0x4010524b: call_user_start_local at ??:?
0x4010000d: call_user_start at ??:?
0x401000ab: app_entry_redefinable at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:391
0x40225e1e: cont_ret at cont.S.o:?
0x40202761: uart_flush at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/uart.cpp:583
0x401009d8: malloc at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/umm_malloc/umm_malloc.cpp:914
0x40202ab0: uart_init at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/uart.cpp:715
0x402029d6: uart_init at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/uart.cpp:707
0x40202c2c: uart_set_debug at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/uart.cpp:989
0x402012b0: HardwareSerial::begin(unsigned long, SerialConfig, SerialMode, unsigned char, bool) at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/HardwareSerial.cpp:56
0x402018b0: loop_wrapper() at /home/runner/.platformio/packages/framework-arduinoespressif8266@src-31d658a59f41540201fc3726a1394910/cores/esp8266/core_esp8266_main.cpp:263
0x40100d4d: cont_wrapper at ??:?

0x40201052: loop at /home/runner/dev/stack_overflow_test/src/main.cpp:10

> sed -ne 10p src/main.cpp
  printf("%p %p %p %p\n",

[d-a-v]

two conditions for the same code, is it intended ?

[mcspr]

It is not, leftover from old impl... Changed to 'cond1 || cond2'

[d-a-v]

Looks good to me, can save hours of debugging