Replace the SDK's use of ets_intr_lock/unlock with nestable versions

Testing has shown that there are several paths in the SDK that result in nested
calls to ets_intr_lock() / ets_intr_unlock() which may be a problem.

These functions also do not preserve the enabled interrupt level and may
result in code running with interrupts enabled when that is not intended.
This issue has recently been fixed in the Arduino code by using
xt_rsil() / xt_wsr_ps() but still exists in the Espressif SDK code.

This commit is intended to fix that and should be used in addition to the above.

The maximum nesting I have seen is 2 and lock/unlock calls appear to be balanced.
A max of 7 levels of nesting leaves plenty of room for that to change.

Author: ChocolateFrogsNuts

cores/esp8266/core_esp8266_main.cpp

@@ -60,6 +60,13 @@ static os_event_t s_loop_queue[LOOP_QUEUE_SIZE];
 /* Used to implement optimistic_yield */
 static uint32_t s_micros_at_task_start;
 
+/* For ets_intr_lock_nest / ets_intr_unlock_nest
+ * Max nesting seen by SDK so far is 2.
+ */
+#define ETS_INTR_LOCK_NEST_MAX 7
+byte ets_intr_lock_stack[ETS_INTR_LOCK_NEST_MAX];
+byte ets_intr_lock_stack_ptr=0;
+
 
 extern "C" {
 extern const uint32_t __attribute__((section(".ver_number"))) core_version = ARDUINO_ESP8266_GIT_VER;
@@ -121,6 +128,17 @@ extern "C" void optimistic_yield(uint32_t interval_us) {
     }
 }
 
+extern "C" void ets_intr_lock_nest() {
+  if (ets_intr_lock_stack_ptr < ETS_INTR_LOCK_NEST_MAX)
+     ets_intr_lock_stack[ets_intr_lock_stack_ptr++] = xt_rsil(3);
+}
+
+extern "C" void ets_intr_unlock_nest() {
+  if (ets_intr_lock_stack_ptr > 0)
+     xt_wsr_ps(ets_intr_lock_stack[--ets_intr_lock_stack_ptr]);
+}
+
+
 extern "C" void __loop_end (void)
 {
     run_scheduled_functions();

tools/sdk/lib/fix_sdk_libs.sh

@@ -16,3 +16,10 @@ xtensa-lx106-elf-objcopy --redefine-sym default_hostname=wifi_station_default_ho
 xtensa-lx106-elf-objcopy --redefine-sym default_hostname=wifi_station_default_hostname eagle_lwip_if.o 
 xtensa-lx106-elf-ar r libmain.a eagle_lwip_if.o user_interface.o 
 rm -f eagle_lwip_if.o user_interface.o
+
+# Replace use of ROM ets_intr_(un)lock with nestable ets_intr_(un)lock_nest
+for f in libmain.a libpp.a libnet80211.a; do
+  xtensa-lx106-elf-objcopy  --redefine-sym ets_intr_lock=ets_intr_lock_nest $f;
+  xtensa-lx106-elf-objcopy  --redefine-sym ets_intr_unlock=ets_intr_unlock_nest $f;
+done
+