Tons of fixes to the backtracker code, and also added an extra backtracker that does not require unwind tables to work and it is used if unwind tables are absent

Marlin/src/HAL/HAL_DUE/DebugMonitor_Due.cpp

@@ -24,7 +24,7 @@
 
 #include "../../inc/MarlinConfig.h"
 #include "../../Marlin.h"
-#include "backtrace/backtrace.h"
+#include "backtrace/unwinder.h"
 
 // Debug monitor that dumps to the Programming port all status when
 // an exception or WDT timeout happens - And then resets the board
@@ -34,6 +34,19 @@
 // Serial interrupt routines or any C runtime, as we don't know the
 // state we are when running them
 
+
+/* These symbols point to the start and end of stack */
+extern "C" const int _sstack;
+extern "C" const int _estack;
+
+/* These symbols point to the start and end of the code section */
+extern "C" const int _sfixed;
+extern "C" const int _efixed;
+
+/* These symbols point to the start and end of initialized data (could be SRAM functions!) */
+extern "C" const int _srelocate;
+extern "C" const int _erelocate;
+
 // A SW memory barrier, to ensure GCC does not overoptimize loops
 #define sw_barrier() asm volatile("": : :"memory");
 
@@ -112,13 +125,72 @@ static void TXDec(uint32_t v) {
   } while (p != &nbrs[0]);
 }
 
-// Dump a backtrace entry
-static void backtrace_dump_fn(int idx, const backtrace_t* bte, void* ctx) {
-  TX('#'); TXDec(idx); TX(' ');
-  TX(bte->name); TX('@');TXHex((uint32_t)bte->function); TX('+'); TXDec((uint32_t)bte->address - (uint32_t)bte->function);
-  TX(" PC:");TXHex((uint32_t)bte->address); TX('\n');
+/* Validate address */
+static bool validate_addr(uint16_t addr) {
+
+  // PC must point into the text (CODE) area
+  if (addr >= (uint32_t)&_sfixed && addr <= (uint32_t)&_efixed)
+    return true;
+
+  // Or into the SRAM function area
+  if (addr >= (uint32_t)&_srelocate && addr <= (uint32_t)&_erelocate)
+    return true;
+
+  // SP must point into the allocated stack area
+  if (addr >= (uint32_t)&_sstack && addr <= (uint32_t)&_estack)
+    return true;
+
+  return false;
 }
 
+static bool UnwReadW(const uint32_t a, uint32_t *v) {
+
+  if (!validate_addr(a))
+    return false;
+
+  *v = *(uint32_t *)a;
+  return true;
+}
+
+static bool UnwReadH(const uint32_t a, uint16_t *v) {
+
+  if (!validate_addr(a))
+    return false;
+
+  *v = *(uint16_t *)a;
+  return true;
+}
+
+static bool UnwReadB(const uint32_t a, uint8_t *v) {
+
+  if (!validate_addr(a))
+    return false;
+
+  *v = *(uint8_t *)a;
+  return true;
+}
+
+
+// Dump a backtrace entry
+static bool UnwReportOut(void* ctx, const UnwReport* bte) {
+
+  TX(bte->name?bte->name:"unknown"); TX('@');TXHex(bte->function);
+  TX('+'); TXDec(bte->address - bte->function);
+  TX(" PC:");TXHex(bte->address); TX('\n');
+  return true;
+}
+
+/* Table of function pointers for passing to the unwinder */
+static const UnwindCallbacks UnwCallbacks = {
+  UnwReportOut,
+  UnwReadW,
+  UnwReadH,
+  UnwReadB
+#if defined(UNW_DEBUG)
+ ,printf
+#endif
+};
+
 /**
  * HardFaultHandler_C:
  * This is called from the HardFault_HandlerAsm with a pointer the Fault stack
@@ -171,12 +243,12 @@ void HardFault_HandlerC(unsigned long *hardfault_args, unsigned long cause) {
 
   // Perform a backtrace
   TX("\nBacktrace:\n\n");
-  backtrace_frame_t btf;
+  UnwindFrame btf;
   btf.sp = ((unsigned long)hardfault_args[7]);
   btf.fp = btf.sp;
   btf.lr = ((unsigned long)hardfault_args[5]);
   btf.pc = ((unsigned long)hardfault_args[6]);
-  backtrace_dump(&btf, backtrace_dump_fn, nullptr);
+  UnwindStart(&btf, &UnwCallbacks, nullptr);
 
   // Disable all NVIC interrupts
   NVIC->ICER[0] = 0xFFFFFFFF;