我正在开发 cortex-m3 的微内核。我创建了一个故意导致错误的小型测试应用程序。

现在我不确定如何从故障中返回。我知道堆栈可能需要使用不同函数的地址进行更新。我也知道在某些情况下从错误返回可能是一个坏主意，但我的内核是相应编写的。

这是一些示例代码:

#include "core_cm3.h"

// PSR flags

// EPSR flags
#define TFLG (1<<24)
#define puts printk
#define printf printk
#define error printk
// APSR flags
#define NFLG (1<<31)
#define ZFLG (1<<30)
#define CFLG (1<<29)
#define VFLG (1<<28)
#define QFLG (1<<27)
// IPSR flags
#define ISR_THREADMODE 0
#define ISR_NMI 2
#define ISR_HARDFAULT 3
#define ISR_MEMMANAGE 4
#define ISR_BUSFAULT 5
#define ISR_USAGEFAULT 6
#define ISR_SVCALL 11
#define ISR_PENDSV 14
#define ISR_SYSTICK 15
#define ISR_IRQ0 16

// HFSR flags
#define VECTTBL (1<<1)
#define FORCED (1<<30)
#define DEBUGEVT (1<<31)

// CFSR flags

// BFSR flags
#define IBUSERR (1<<0)
#define PRECISERR (1<<1)
#define IMPRECISERR (1<<2)
#define UNSTKERR (1<<3)
#define STKERR (1<<4)
#define BFARVALID (1<<7)

// UFSR flags
#define UNDEFINSTR (1<<0)
#define INVSTATE (1<<1)
#define INVPC (1<<2)
#define NOCP (1<<3)
#define UNALIGNED (1<<8)
#define DIVBYZERO (1<<9)

// MMFSR flags
#define IACCVIOL (1<<0)
#define DACCVIOL (1<<1)
#define MUNSTKERR (1<<3)
#define MSTKERR (1<<4)
#define MMARVALID (1<<7)

// DFSR
#define EXTERNAL (1<<4)
#define VCATCH (1<<3)
#define DWTTRAP (1<<2)
#define BKPT (1<<1)
#define HALTED (1<<0)

/** Hard Fault Handler code comes from these spots:
 *
 * http://blog.frankvh.com/2011/12/07/cortex-m3-m4-hard-fault-handler/
 * http://blog.feabhas.com/2013/02/developing-a-generic-hard-fault-handler-for-arm-cortex-m3cortex-m4/
 */

/**
 * This is the actual handler, which sets up the data to be used by the C function, then calls it.
 */
void __attribute__((naked)) HardFault_Handler(void)
{
    __asm__(
            ".thumb \n"
            " tst lr, #4 \n" // for priv/non-priv, test for msp or psp in return (thread or handler mode)
            " ite eq \n"
            " mrseq r0, MSP \n" // move main stack pointer into r0
            " mrsne r0, PSP \n" // move process stack pointer into r0
            " b hard_fault_handler \n" // jump to the c function
            :
            :
            :
            );
}

/**
 * Here we print out the junk in the stack and some special registers to help with debugging.
 */
void hard_fault_handler(unsigned int *hardfault_args)
{
      unsigned int stacked_r0;
      unsigned int stacked_r1;
      unsigned int stacked_r2;
      unsigned int stacked_r3;
      unsigned int stacked_r12;
      unsigned int stacked_lr;
      unsigned int stacked_pc;
      unsigned int stacked_psr;
      unsigned int cfsr, bfsr, ufsr, mmfsr;
      //unsigned int control;

      stacked_r0 = ((unsigned long) hardfault_args[0]);
      stacked_r1 = ((unsigned long) hardfault_args[1]);
      stacked_r2 = ((unsigned long) hardfault_args[2]);
      stacked_r3 = ((unsigned long) hardfault_args[3]);

      stacked_r12 = ((unsigned long) hardfault_args[4]);
      stacked_lr = ((unsigned long) hardfault_args[5]);
      stacked_pc = ((unsigned long) hardfault_args[6]);
      stacked_psr = ((unsigned long) hardfault_args[7]);
      //control = __get_CONTROL();

      // TODO 2: Eliminate printf

      puts("\n\n[Hard fault]\n");
      printf("R0 = 0x%08x\n", stacked_r0);
      printf("R1 = 0x%08x\n", stacked_r1);
      printf("R2 = 0x%08x\n", stacked_r2);
      printf("R3 = 0x%08x\n", stacked_r3);
      printf("R12 = 0x%08x\n", stacked_r12);
      printf("LR [R14] = 0x%08x subroutine call return address.\n", stacked_lr);
      printf("PC [R15] = 0x%08x program counter\n", stacked_pc);

      // PSR
      printf("PSR = 0x%04x ", stacked_psr);
      if (stacked_psr & NFLG) printf("N");
      if (stacked_psr & ZFLG) printf("Z");
      if (stacked_psr & CFLG) printf("C");
      if (stacked_psr & VFLG) printf("V");
      if (stacked_psr & QFLG) printf("Q");
      puts(" ");
      unsigned int isrnum = (stacked_psr & 0xff);
      switch (isrnum) {
      case ISR_THREADMODE:
          puts("Thread mode ");
          phá vỡ;
      case ISR_NMI:
          puts("NMI ");
          phá vỡ;
      case ISR_HARDFAULT:
          puts("HardFault ");
          phá vỡ;
      case ISR_MEMMANAGE:
          puts("MemManage ");
          phá vỡ;
      case ISR_BUSFAULT:
          puts("BusFault ");
          phá vỡ;
      case ISR_USAGEFAULT:
          puts("UsageFault ");
          phá vỡ;
      case ISR_SVCALL:
          puts("SVCall ");
          phá vỡ;
      case ISR_PENDSV:
          puts("PendSV ");
          phá vỡ;
      case ISR_SYSTICK:
          puts("SysTick ");
          phá vỡ;
      case ISR_IRQ0:
          puts("IRQ0 ");
          phá vỡ;
      }
      printf(" ");
      if (stacked_psr & TFLG)
          printf("thumb");
      khác
          printf("non-thumb");
      puts("\n");

      // CONTROL (not sure this works...)
      //printf("CONTROL = 0x%04x ", control);
      //printf("\n");

      // HFSR
      printf("HFSR = 0x%08x ", SCB->HFSR);
      if (SCB->HFSR & DEBUGEVT) printf("DEBUGEVT ");
      if (SCB->HFSR & FORCED) printf("Forced Hard fault ");
      if (SCB->HFSR & VECTTBL) printf("VECTTBL ");
      puts("\n");
      // CFSR
      printf("CFSR = 0x%08x\n", SCB->CFSR);
      cfsr = SCB->CFSR;
      ufsr = (cfsr>>16);
      printf("UFSR = 0x%04x ", ufsr);
      if (ufsr & DIVBYZERO) printf("Divide by zero UsageFault ");
      if (ufsr & UNALIGNED) printf("Unaligned access UsageFault ");
      if (ufsr & NOCP) printf("No coprocessor UsageFault ");
      if (ufsr & INVPC) printf("Invalid PC load UsageFault ");
      if (ufsr & INVSTATE) printf("Invalid state UsageFault ");
      if (ufsr & UNDEFINSTR) printf("Undefined instruction UsageFault ");
      puts("\n");

      // BFSR
      bfsr = ((cfsr >> 8) & 0xff);
      printf("BFSR = 0x%02x ", bfsr);
      if ((bfsr & IBUSERR) != 0) printf("IBUSERR ");
      if ((bfsr & PRECISERR) != 0) printf("Precise Data Bus Error ");
      if ((bfsr & IMPRECISERR) != 0) printf("Imprecise Data Bus Error ");
      if (bfsr & UNSTKERR) printf("Unstacking Error ");
      if (bfsr & STKERR) printf("Stacking error ");
      if (bfsr & BFARVALID) printf("Bus Fault Address Register Valid ");
      printf("\n");
      // BFAR
      //The value of SCB->BFAR indicates the memory address that caused a Bus Fault and is valid if the bit BFARVALID in the
      //SCB->CFSR register is set.
      puts("BFAR = ");
      if (bfsr & BFARVALID) {
          printf("0x%08x\n", SCB->BFAR);
      } khác {
          puts("invalid\n");
      }

      // MMFSR
      mmfsr = (cfsr & 0xff);
      printf("MMFSR = 0x%02x ", mmfsr);
      if (mmfsr & IACCVIOL) printf("Instruction Access Violation ");
      if (mmfsr & DACCVIOL) printf("Data Access Violation ");
      if (mmfsr & MUNSTKERR) printf("Memory Unstacking Error ");
      if (mmfsr & MSTKERR) printf("Memory Stacking Error ");
      if (mmfsr & MMARVALID) printf("MMARVALID ");
      puts("\n");
      // MMFAR
      // The value of SCB->MMFAR indicates the memory address that caused a Memory Management Fault and is valid if the bit
      // MMARVALID in the SCB->CFSR register is set.
      puts("MMFAR = ");
      if (mmfsr & MMARVALID) {
          printf("0x%08x ", SCB->MMFAR);
      } khác {
          printf("invalid\n");
      }

      // DFSR
      printf("DFSR = 0x%08lx ", SCB->DFSR);
      if (SCB->DFSR & EXTERNAL) printf("EXTERNAL ");
      if (SCB->DFSR & VCATCH) printf("VCATCH ");
      if (SCB->DFSR & DWTTRAP) printf("DWTTRAP ");
      if (SCB->DFSR & BKPT) printf("BKPT ");
      if (SCB->DFSR & HALTED) printf("HALTED ");
      puts("\n");

      printf("AFSR = 0x%08lx\n", SCB->AFSR);
      printf("SHCSR = 0x%08lx\n", SCB->SHCSR);
      __asm volatile("BKPT #01\n"); // <-- **I want to return here**
      while (1); 
}

/*
void HardFault_Handler(void) {
    while(1);
    error("\n\n%% Hard Fault %%\n");
}
*/

void UsageFault_Handler(void) {
    error("\n\n%% Usage Fault %%\n");
}

void BusFault_Handler() {
    error("\n\n%% Bus Fault %%\n");
}

void MemMang_Handler() {
    error("\n\n%% MemMang Fault %%\n");
}

我已经标记了要返回的行。我目前禁用了使用/总线/内存故障，但可以根据需要启用它们。

1 Câu trả lời

您需要的所有信息都可以在 ARM cortex M3 技术引用手册中找到。

您可以查询发出导致故障的指令的PC、导致故障的取指地址、原因等。您可以重建故障发生之前的确切处理器状态。例如，这就是按需分页的实现方式。

但是，如果遇到“硬故障”，则无法保证系统的其余部分(包括硬件外设和总线基础设施)能够以任何有意义的方式继续运行。你的总线仲裁器可能被锁定；您的内存 Controller 可能已损坏，您的代码内存可能已损坏。您可能经历过电力供应不足，并且某些逻辑出现了问题。有无数的事情可能是错误的，您无法知道也无法真正从中恢复。

关于c - 如何从 Cortex-M3 硬/使用/总线故障中恢复？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40855088/