我正在研究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错误中恢复过来。我知道堆栈可能需要使用不同函数的地址进行更新。我也理解在某些情况下从故障中返回可能是一个坏主意，但我的内核是相应的。
以下是一些示例代码：
#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 ");
break;
case ISR_NMI:
puts("NMI ");
break;
case ISR_HARDFAULT:
puts("HardFault ");
break;
case ISR_MEMMANAGE:
puts("MemManage ");
break;
case ISR_BUSFAULT:
puts("BusFault ");
break;
case ISR_USAGEFAULT:
puts("UsageFault ");
break;
case ISR_SVCALL:
puts("SVCall ");
break;
case ISR_PENDSV:
puts("PendSV ");
break;
case ISR_SYSTICK:
puts("SysTick ");
break;
case ISR_IRQ0:
puts("IRQ0 ");
break;
}
printf(" ");
if (stacked_psr & TFLG)
printf("thumb");
else
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);
} else {
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);
} else {
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Usage / Bus / Memory故障，但如果需要可以启用它们。
帮助将不胜感激。