请问cortex-m3的权威指南这句话是否出错？

leecny2012

该书2009年7月出版的，P342页

咱对汇编不熟悉，所以一开始就暂且相信了“从(xSP-0x24)处读取入栈PC”。但后来发觉怎么都对头，一看汇编LDREQ R0,[R0,#24]，这应该是xSP+0x18的意思吧。第一不应该是减号，第二不应该是16进制的24。请熟悉的大侠帮我看看，是不是有问题？

jisaowang

应该是减回去 #20,因为栈生长方向的问题,所以是加

jisaowang

02
* HardFaultHandler_C:
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* This is called from the HardFault_HandlerAsm with a pointer the Fault stack
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* as the parameter. We can then read the values from the stack and place them
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* into local variables for ease of reading.
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* We then read the various Fault Status and Address Registers to help decode
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* cause of the fault.
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* The function ends with a BKPT instruction to force control back into the debugger
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*/
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void HardFault_HandlerC(unsigned long *hardfault_args){
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  volatile unsigned long stacked_r0 ;
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  volatile unsigned long stacked_r1 ;
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  volatile unsigned long stacked_r2 ;
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  volatile unsigned long stacked_r3 ;
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  volatile unsigned long stacked_r12 ;
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  volatile unsigned long stacked_lr ;
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  volatile unsigned long stacked_pc ;
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  volatile unsigned long stacked_psr ;
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  volatile unsigned long _CFSR ;
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  volatile unsigned long _HFSR ;
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  volatile unsigned long _DFSR ;
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  volatile unsigned long _AFSR ;
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  volatile unsigned long _BFAR ;
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  volatile unsigned long _MMAR ;
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  stacked_r0 = ((unsigned long)hardfault_args[0]) ;
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  stacked_r1 = ((unsigned long)hardfault_args[1]) ;
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  stacked_r2 = ((unsigned long)hardfault_args[2]) ;
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  stacked_r3 = ((unsigned long)hardfault_args[3]) ;
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  stacked_r12 = ((unsigned long)hardfault_args[4]) ;
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  stacked_lr = ((unsigned long)hardfault_args[5]) ;
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  stacked_pc = ((unsigned long)hardfault_args[6]) ;
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  stacked_psr = ((unsigned long)hardfault_args[7]) ;
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  // Configurable Fault Status Register
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  // Consists of MMSR, BFSR and UFSR
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  _CFSR = (*((volatile unsigned long *)(0xE000ED28))) ;
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  // Hard Fault Status Register
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  _HFSR = (*((volatile unsigned long *)(0xE000ED2C))) ;
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  // Debug Fault Status Register
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  _DFSR = (*((volatile unsigned long *)(0xE000ED30))) ;
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  // Auxiliary Fault Status Register
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  _AFSR = (*((volatile unsigned long *)(0xE000ED3C))) ;
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  // Read the Fault Address Registers. These may not contain valid values.
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  // Check BFARVALID/MMARVALID to see if they are valid values
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  // MemManage Fault Address Register
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  _MMAR = (*((volatile unsigned long *)(0xE000ED34))) ;
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  // Bus Fault Address Register
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  _BFAR = (*((volatile unsigned long *)(0xE000ED38))) ;
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  __asm("BKPT #0\n") ; // Break into the debugger
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}
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__attribute__((naked))
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PE_ISR(Cpu_ivINT_Hard_Fault)
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{
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  __asm volatile (
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    " movs r0,#4       \n"
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    " movs r1, lr      \n"
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    " tst r0, r1       \n"
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    " beq _MSP         \n"
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    " mrs r0, psp      \n"
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    " b _HALT          \n"
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  "_MSP:               \n"
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    " mrs r0, msp      \n"
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  "_HALT:              \n"
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    " ldr r1,[r0,#20]  \n"
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    " b HardFault_HandlerC \n"
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    " bkpt #0          \n"
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  );
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}

leecny2012

是啊，而且数值也不对，应该是0x18