(This is in the context of x86-64 Linux.)
I am trying to write a high-reliability userland executable, and I have total control over the generated assembly. I don't want to rely on automatic stack allocation, so I would like to put the stack in a known location. Suppose I have calculated that my program uses at most 414 bytes of stack space (exactly). Is it safe to allocate 414 bytes in the .bss section and point RSP to the top? I want to ensure that no bytes outside this region are touched by stack management at any point.
While I can be sure that my program won't write outside the region, I need to make some syscalls (using the
syscall instruction), and I think at least some part of the kernel code operates in the calling executable context. Will it smash my stack?
Also, interrupts can happen at any point in the program, and the story behind the "Red Zone" seems to suggest that an arbitrarily large region beyond RSP-128 can be written to at will by interrupt handlers, possibly mangling my data. What kinds of guarantees do I have about this behavior?