April 30, 2006

Linux: Who Owns The Stack?

In a short thread on the lkml, Linux creator Linus Torvalds discussed recently added hacks to prevent gcc from overwriting the argument stack in asmlinkage functions on the x86 platform. The existing fix involves using prevent_tail_call() to prevent the gcc tail call optimization, though Linus notes, "the problem isn't even really fundamentally tailcalls, that just is the detail that happens to trigger the problem (but I could imagine other situations triggering it _too_". Tail calls are when the last line of one function returns a call to another function, something commonly optimized by compilers.

Link: KernelTrap.org

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