Question

How can a get a address from the call stack? I am writing an exception handler and I want to make it show were the CPU exception happened?

Answer 1

Get yourself a copy of the CPU manual from intel.com or amd.com. Look up the chapters on interrupt and exception handling. Find the diagrams showing the stack contents when an interrupt or exception occurs. For example, from INTEL 80386 PROGRAMMER’S REFERENCE MANUAL 1986:

Figure 9-5.  Stack Layout after Exception of Interrupt 

                           WITHOUT PRIVILEGE TRANSITION

      D  O      31          0                     31          0
      I  F    ╠═══════╦═══════╣                 ╠═══════╦═══════╣
      R       ║▒▒▒▒▒▒▒║▒▒▒▒▒▒▒║    OLD          ║▒▒▒▒▒▒▒║▒▒▒▒▒▒▒║    OLD
      E  E    ╠═══════╬═══════╣   SS:ESP        ╠═══════╬═══════╣   SS:ESP
      C  X    ║▒▒▒▒▒▒▒║▒▒▒▒▒▒▒║     │           ║▒▒▒▒▒▒▒║▒▒▒▒▒▒▒║     │
      T  P    ╠═══════╩═══════╣<────┘           ╠═══════╩═══════╣<────┘
      I  A    ║  OLD EFLAGS   ║                 ║  OLD EFLAGS   ║
      O  N    ╠═══════╦═══════╣                 ╠═══════╦═══════╣
      N  S    ║▒▒▒▒▒▒▒║OLD CS ║    NEW          ║▒▒▒▒▒▒▒║OLD CS ║
         I    ╠═══════╩═══════╣   SS:ESP        ╠═══════╩═══════╣
       │ O    ║    OLD EIP    ║     │           ║    OLD EIP    ║    NEW
       │ N    ╠═══════════════╣<────┘           ╠═══════════════╣   SS:ESP
       │      ║               ║                 ║  ERROR CODE   ║     │
       v                                        ╠═══════════════╣<────┘
                                                ║               ║

              WITHOUT ERROR CODE                 WITH ERROR CODE

So, there it is, the last things your interrupt handler receives on the stack are the error code (optional; not all exceptions have it and you’ll need to pop it off before doing iret), then eip and cs of the location that has caused an exception or has been interrupted.