How to Cause Different Types of Exceptions

Reset

• Power on
• Hit reset button

Data Abort

int *p = 0;
int a = *p;

Prefetch Abort

void (*funcPtr)(void);
funcPtr = (void(*)(void)) 0x10000000;
funcPtr();

Interrupt

• Configure VIC
• Set timer

FIQ

• Setup interrupt vector to use FIQ

SWI

Call SWI instruction using a assembly function:

swi:
     SWI 0x12345
     MOV pc,lr

Undefined

Call undefined instruction using a assembly function:

undefined:
     .word 0xE3000000   @ causes an undefined exception
     MOV pc,lr

Calling undefined instruction using an in memory function defined in C:

// Allocate memory for in memory function
struct
{
    unsigned int line1;
    unsigned int line2;
} myFunc;

int callUndefinedInstruction(void)
{
    // Fill in assembly for myFunc function
    myFunc.line1 = 0x12345678;    // undefined instruction
    myFunc.line2 = 0xe1a0f00e;    // mov pc, lr  (return)

    // Cast the address of myFunc to function pointer then call it.
    ((void(*)(void))&myFunc)();
}

Warning

There is a bug in this code. Can you find it? Hint it has to with the ARM architecture.