The document discusses the use of functions related to stack management such as 'setjmp' and 'longjmp' along with their interactions in programming contexts. It examines stack frames, return addresses, and the implications of not using the 'exec' wrapper for certain operations. The content highlights the complexity of stack behavior and variable accessibility during function calls and returns.

1. Stack
cr()
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

2. Stack
cr()
setjmp(caller)
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

3. Stack
cr()
setjmp(caller)
exec()
EBP3 EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

4. Stack
cr()
setjmp(caller)
exec() test
test() ???+x
???
EBP3
exec+x
exec
EBP3 EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

5. Stack
cr() yield
setjmp(caller) test+x
exec() test
test() ???+x
yield(0) ???
EBP3
exec+x
exec
EBP3 EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

6. Stack
cr() callee yield
setjmp(caller) test+x
exec() test
test() ???+x
yield(0) ???
setjmp(callee) EBP3
exec+x
exec
EBP3 EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

7. Saved.
Stack
cr() callee yield
setjmp(caller) test+x
exec() test
test() ???+x
yield(0) ???
setjmp(callee) EBP3
longjmp(caller) exec+x
exec
EBP3 EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

8. Stack
cr()
setjmp(caller)
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

9. Return to main
Stack
EBP1 main
… Return address

10. Stack
test2()
EBP2 EBP1
main+x
EBP1 main
… Return address

11. Stack
test2()
cr()
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

12. Stack
test2()
cr()
setjmp(caller)
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

13. Stack
test2()
cr()
setjmp(caller)
longjmp(callee)
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

14. Restored.
Stack
cr() callee yield
setjmp(caller) test+x
exec() test
test() ???+x
yield(0) ???
setjmp(callee) EBP3
exec+x
exec
EBP3 EBP2
cr+x
_alloca
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

15. Stack
cr() callee
setjmp(caller)
exec() test
test() ???+x
Return ???
EBP3
exec+x
exec
EBP3 EBP2
cr+x
_alloca
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

16. Stack
cr() callee
setjmp(caller)
exec()
test()
longjmp(caller)
exec
EBP3 EBP2
cr+x
_alloca
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

17. Stack
callee
test2()
cr()
setjmp(caller)
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

18. Stack
callee
test2()
Return
caller
EBP2 EBP1
main+x
EBP1 main
… Return address

19. WHAT IF WE DON’T USE THE `EXEC’
WRAPPER?

20. Stack
cr()
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

21. Stack
cr()
setjmp(caller)
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

22. Stack
cr()
setjmp(caller)
test()
test
???+x
???
EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

23. Stack
cr()
setjmp(caller)
test()
yield(0) callee yield
setjmp(callee) test+x
test
???+x
???
EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

24. Saved. Stack
cr()
setjmp(caller)
test()
yield(0) callee yield
setjmp(callee) test+x
longjmp(caller) test
???+x
???
EBP2
cr+x
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

25. Stack
cr()
setjmp(caller)
caller
cr
(_alloca)
EBP2 EBP1
main+x
EBP1 main
… Return address

26. Return to main
Stack
EBP1 main
… Return address

27. Stack
test2()
EBP2 EBP1
main+x
EBP1 main
… Return address

28. Stack
test2()
cr()
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

29. Stack
test2()
cr()
setjmp(caller)
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

30. Stack
test2()
cr()
setjmp(caller)
longjmp(callee)
caller
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

31. Restored. Stack
cr()
setjmp(caller)
test()
yield(0) callee yield
setjmp(callee) test+x
longjmp(caller) test
???+x
???
EBP2
cr+x
cr
caller (_alloca)
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

32. Stack
cr()
setjmp(caller)
test()
Return callee
test
???+x
???
EBP2
cr+x
cr
caller (_alloca)
EBP3’ EBP2
test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

33. Stack
cr()
Return
callee
EBP2
cr
caller (_alloca)
EBP3’ EBP2
Current EBP test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address

34. Stack
cr()
callee
EBP2
EBP points to the
wrong place. cr
-> caller (_alloca)
Access to local EBP3’ EBP2
variables fails.
Current EBP test2+x
EBP2 EBP1
main+x
EBP1 main
… Return address