Print stack on exception and soft WDT reset

Author: igrr

cores/esp8266/core_esp8266_main.cpp

@@ -129,9 +129,6 @@ void user_init(void) {
     uart_div_modify(0, UART_CLK_FREQ / (74480));
 
     system_rtc_mem_read(0, &resetInfo, sizeof(struct rst_info));
-    if(resetInfo.reason == REASON_WDT_RST || resetInfo.reason == REASON_EXCEPTION_RST) {
-        os_printf("Last Reset:\n - flag=%d\n - Fatal exception (%d):\n - epc1=0x%08x,epc2=0x%08x,epc3=0x%08x,excvaddr=0x%08x,depc=0x%08x\n", resetInfo.reason, resetInfo.exccause, resetInfo.epc1, resetInfo.epc2, resetInfo.epc3, resetInfo.excvaddr, resetInfo.depc);
-    }
     struct rst_info info = { 0 };
     system_rtc_mem_write(0, &info, sizeof(struct rst_info));
 

cores/esp8266/core_esp8266_postmortem.c

@@ -0,0 +1,130 @@
+/* 
+ postmortem.c - output of debug info on sketch crash
+ Copyright (c) 2015 Ivan Grokhotkov. All rights reserved.
+ This file is part of the esp8266 core for Arduino environment.
+ 
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include "ets_sys.h"
+#include "user_interface.h"
+#include "esp8266_peri.h"
+#include "cont.h"
+
+extern void __real_system_restart_local();
+extern cont_t g_cont;
+
+static void uart0_write_char_d(char c);
+static void print_stack(uint32_t start, uint32_t end);
+static void print_pcs(uint32_t start, uint32_t end);
+
+void __wrap_system_restart_local() {
+    register uint32_t sp asm("a1");
+
+    struct rst_info rst_info = {0};
+    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) 
+    {
+        return;
+    }
+
+    ets_install_putc1(&uart0_write_char_d);
+
+    if (rst_info.reason == REASON_EXCEPTION_RST) {
+        ets_printf("\nException (%d):\nepc1=0x%08x epc2=0x%08x epc3=0x%08x excvaddr=0x%08x depc=0x%08x\n", 
+            rst_info.exccause, rst_info.epc1, rst_info.epc2, rst_info.epc3, rst_info.excvaddr, rst_info.depc);
+    }
+
+    uint32_t cont_stack_start = (uint32_t) &(g_cont.stack);
+    uint32_t cont_stack_end = (uint32_t) g_cont.stack_end;
+    uint32_t stack_end;
+
+    // amount of stack taken by interrupt or exception handler 
+    // and everything up to __wrap_system_restart_local
+    // (determined empirically, might break)
+    uint32_t offset = 0;
+    if (rst_info.reason == REASON_SOFT_WDT_RST) {
+        offset = 0x1b0;
+    }
+    else if (rst_info.reason == REASON_EXCEPTION_RST) {
+        offset = 0x1a0;
+    }
+    else if (rst_info.reason == REASON_WDT_RST) {
+        offset = 0x10;
+    }
+
+    if (sp > cont_stack_start && sp < cont_stack_end) {
+        ets_printf("\nctx: cont \n");
+        stack_end = cont_stack_end;
+    }
+    else {
+        ets_printf("\nctx: sys \n");
+        stack_end = 0x3fffffb0;  
+        // it's actually 0x3ffffff0, but the stuff below ets_run 
+        // is likely not really relevant to the crash
+    }
+    
+    ets_printf("sp: %08x end: %08x offset: %04x\n", sp, stack_end, offset);
+    
+    // print_pcs(sp + offset, stack_end);
+    print_stack(sp + offset, stack_end);
+    delayMicroseconds(10000);
+    __real_system_restart_local();
+}
+
+
+static void print_stack(uint32_t start, uint32_t end) {
+    ets_printf("\n>>>stack>>>\n");
+    for (uint32_t pos = start; pos < end; pos += 0x10) {
+        uint32_t* values = (uint32_t*)(pos);
+
+        // rough indicator: stack frames usually have SP saved as the second word
+        bool looksLikeStackFrame = (values[2] == pos + 0x10);
+
+        ets_printf("%08x:  %08x %08x %08x %08x %c\n", 
+            pos, values[0], values[1], values[2], values[3], (looksLikeStackFrame)?'<':' ');
+    }
+    ets_printf("<<<stack<<<\n");
+}
+
+static void print_pcs(uint32_t start, uint32_t end) {
+    uint32_t n = 0;
+    ets_printf("\n>>>pc>>>\n");
+    for (uint32_t pos = start; pos < end; pos += 16, ++n) {
+        uint32_t* sf = (uint32_t*) pos;
+
+        uint32_t pc_ret = sf[3];
+        uint32_t sp_ret = sf[2];
+        if (pc_ret < 0x40000000 || pc_ret > 0x40f00000 || sp_ret != pos + 16)
+            continue;
+        ets_printf("%08x\n", pc_ret);
+    }
+    ets_printf("<<<pc<<<\n");
+}
+
+void uart0_write_char_d(char c) {
+    while (((USS(0) >> USTXC) & 0xff) >= 0x7e) { }
+
+    if (c == '\n') {
+        USF(0) = '\r';
+    }
+    USF(0) = c;
+}

platform.txt

@@ -21,7 +21,7 @@ compiler.c.flags=-c -Os -g -Wpointer-arith -Wno-implicit-function-declaration -W
 compiler.S.cmd=xtensa-lx106-elf-gcc
 compiler.S.flags=-c -g -x assembler-with-cpp -MMD
 
-compiler.c.elf.flags=-g -Os -nostdlib -Wl,--no-check-sections -u call_user_start -Wl,-static "-L{compiler.sdk.path}/lib" "-L{compiler.sdk.path}/ld" "-T{build.flash_ld}"
+compiler.c.elf.flags=-g -Os -nostdlib -Wl,--no-check-sections -u call_user_start -Wl,-static "-L{compiler.sdk.path}/lib" "-L{compiler.sdk.path}/ld" "-T{build.flash_ld}" -Wl,-wrap,system_restart_local 
 compiler.c.elf.cmd=xtensa-lx106-elf-gcc
 compiler.c.elf.libs=-lm -lgcc -lhal -lphy -lnet80211 -llwip -lwpa -lmain -lpp -lsmartconfig