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    SubjectRe: i386 ABI and the stack
    On 6/23/06, Linus Torvalds <> wrote:
    > On Fri, 23 Jun 2006, H. Peter Anvin wrote:
    > > >
    > > > The x86-64 ABI has a 128-byte(*) zone that is safe from signals etc, so you
    > > > can use a small amount of stack below the stackpointer safely. Not so on
    > > > x86.
    > >
    > > Adding a small redzone like this to i386 would be easy, though -- just drop
    > > the stack pointer by that much when creating a signal frame. 128 bytes isn't
    > > enough to interfere with libraries.
    > However, any binaries created with that in mind would be
    > buggy-by-definition on older kernels, so I don't think it's worth it.

    Since gcc-2.96 would access 256 bytes below the stack pointer
    (according to the valgrind man page), the kernel needs to allow
    for this in signal handlers anyway.

    I'm pretty sure I saw that code in the kernel in fact, but I
    can't find it now. Perhaps it got lost in a cleanup accident?
    (it sure would be nice to have continuous source control history)
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      Last update: 2006-06-24 04:47    [W:0.092 / U:74.316 seconds]
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