Fix raise_exception() (#6288)

* workaround when an exceptin occurs while in an ISR

* tuning for gdb

* remove dead code and rename defines/variables

* per reviews: naming, handle "unhandled return" case

* fix reset message

Author: d-a-v

cores/esp8266/core_esp8266_postmortem.cpp

@@ -52,6 +52,13 @@ static void uart0_write_char_d(char c);
 static void uart1_write_char_d(char c);
 static void print_stack(uint32_t start, uint32_t end);
 
+// using numbers different from "REASON_" in user_interface.h (=0..6)
+enum rst_reason_sw
+{
+    REASON_USER_SWEXCEPTION_RST = 254
+};
+static int s_user_reset_reason = REASON_DEFAULT_RST;
+
 // From UMM, the last caller of a malloc/realloc/calloc which failed:
 extern void *umm_last_fail_alloc_addr;
 extern int umm_last_fail_alloc_size;
@@ -86,24 +93,20 @@ void __wrap_system_restart_local() {
     register uint32_t sp asm("a1");
     uint32_t sp_dump = sp;
 
-    if (gdb_present()) {
-        /* When GDBStub is present, exceptions are handled by GDBStub,
-           but Soft WDT will still call this function.
-           Trigger an exception to break into GDB.
-           TODO: check why gdb_do_break() or asm("break.n 0") do not
-           break into GDB here. */
-        raise_exception();
-    }
-
     struct rst_info rst_info;
     memset(&rst_info, 0, sizeof(rst_info));
-    system_rtc_mem_read(0, &rst_info, sizeof(rst_info));
-    if (rst_info.reason != REASON_SOFT_WDT_RST &&
-        rst_info.reason != REASON_EXCEPTION_RST &&
-        rst_info.reason != REASON_WDT_RST)
+    if (s_user_reset_reason == REASON_DEFAULT_RST)
     {
-        return;
+        system_rtc_mem_read(0, &rst_info, sizeof(rst_info));
+        if (rst_info.reason != REASON_SOFT_WDT_RST &&
+            rst_info.reason != REASON_EXCEPTION_RST &&
+            rst_info.reason != REASON_WDT_RST)
+        {
+            rst_info.reason = REASON_DEFAULT_RST;
+        }
     }
+    else
+        rst_info.reason = s_user_reset_reason;
 
     // TODO:  ets_install_putc1 definition is wrong in ets_sys.h, need cast
     ets_install_putc1((void *)&uart_write_char_d);
@@ -128,6 +131,9 @@ void __wrap_system_restart_local() {
     else if (rst_info.reason == REASON_SOFT_WDT_RST) {
         ets_printf_P(PSTR("\nSoft WDT reset\n"));
     }
+    else {
+        ets_printf_P(PSTR("\nGeneric Reset\n"));
+    }
 
     uint32_t cont_stack_start = (uint32_t) &(g_pcont->stack);
     uint32_t cont_stack_end = (uint32_t) g_pcont->stack_end;
@@ -222,7 +228,13 @@ static void uart1_write_char_d(char c) {
 }
 
 static void raise_exception() {
-    __asm__ __volatile__ ("syscall");
+    if (gdb_present())
+        __asm__ __volatile__ ("syscall"); // triggers GDB when enabled
+
+    s_user_reset_reason = REASON_USER_SWEXCEPTION_RST;
+    ets_printf_P(PSTR("\nUser exception (panic/abort/assert)"));
+    __wrap_system_restart_local();
+
     while (1); // never reached, needed to satisfy "noreturn" attribute
 }