Hi, I want to develop a discontiguous stack for the Linux/x86 kernel such that I can use, say, 512byte stacks and upon overflow jump to a new stack. I know, weird thing to do, but I have my reasons. To detect stack overflow, my first implementation leveraged the profile support (i.e., -p) and a custom mcount implementation. Unfortunately, this has the negative side effect that the call to mcount is made _after_ the stack is adjusted for the local frame --- on x86 the ret addr. push onto the stack as part of the call instruction will corrupt system state. Moreover, it only works for functions with no args --- rather rare in most programs, no?! :) So I thought I'd leverage the Stack Checking support that gcc has (i.e., -fstack-check). Was reading the online docs on Stack Checking (http://gcc.gnu.org/onlinedocs/gccint/Stack-Checking.html) and been peeking through the code in gcc/config/i386/*. Are there any examples of defining the check_stack pattern for x86? Finally, I am considering of modifying TARGET_ASM_FUNCTION_PROLOGUE, but that thing does not seem to be defined in config/i386. I did see was ix86_expand_prologue in config/i386/i386.c. Is that the right spot to do this type of hacking? Thanks, Marc
