[GitHub] ccollins476ad commented on a change in pull request #1476: os: Add option to restore registers state on crash

[GitBox <gi...@apache.org>]

ccollins476ad commented on a change in pull request #1476: os: Add option to restore registers state on crash
URL: https://github.com/apache/mynewt-core/pull/1476#discussion_r227497196
 
 

 ##########
 File path: kernel/os/src/arch/cortex_m0/os_fault.c
 ##########
 @@ -153,6 +156,48 @@ os_default_irq(struct trap_frame *tf)
     trap_to_coredump(tf, &regs);
     coredump_dump(&regs, sizeof(regs));
 #endif
-    hal_system_reset();
+
+#if MYNEWT_VAL(OS_CRASH_RESTORE_REGS)
+    if ((SCB->ICSR & SCB_ICSR_VECTACTIVE_Msk) < 16) {
+        console_printf("Use 'set $pc = 0x%08lx' to restore PC in gdb\n",
+                       tf->ef->pc);
+
+        orig_sp = &tf->ef->r0;
+        orig_sp += 8;
+        if (tf->ef->psr & SCB_CCR_STKALIGN_Msk) {
+            orig_sp++;
+        }
+
+        console_printf("Use 'set $pc = 0x%08lx' to restore PC in gdb\n",
+                       tf->ef->pc);
+
+        __asm volatile (
+            "mov sp,  %[stack_ptr]\n"
+            "mov r0,  %[regs1]\n"
+            "mov r1,  %[regs2]\n"
+            "mov r2,  r1\n"
+            "add r2,  r2, #16\n"
+            "ldm r2!, {r4-r7}\n"
+            "mov r8,  r4\n"
+            "mov r9,  r5\n"
+            "mov r10, r6\n"
+            "mov r11, r7\n"
+            "ldm r1!, {r4-r7}\n"
+            "ldr r1,  [r0, #16]\n"
+            "mov r12, r1\n"
+            "ldr r1,  [r0, #20]\n"
+            "mov lr,  r1\n"
+            "ldm r0!, {r0-r3}\n"
+            "bkpt"
+            :
+            : [regs1] "r" (tf->ef),
+              [regs2] "r" (&tf->r4),
+              [stack_ptr] "r" (orig_sp)
+            : "r0", "r1", "r2"
+        );
+    }
+#endif
+
+    NVIC_SystemReset();
 
 Review comment:
   Should this be `hal_system_reset()` (rather than `NVIC_SystemReset()`)?

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