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    SubjectRe: 4k stacks
    Date
    On Wednesday 28 December 2005 15:14, linux-os (Dick Johnson) wrote:
    > >> Anyway, getting down to 20 bytes of stack-space available
    > >> seems to be pretty scary.
    > >
    > > + movl %esp, %edi
    > > + movl %edi, %ecx
    > > + andl $~0x1000, %edi
    > > + subl %edi, %ecx
    > >
    > > ecx will be equal to ?
    >
    > Whatever the stack was minus that value ANDed with NOT 0x1000,
    > i.e. 0x1000 minus the stack already in use. The code assumes
    > that the stack starts and ends on a 0x1000 (page) boundary.
    > If that's not true, then all bets are off.

    Hmm. I must be thick today. (esp - (esp & 0xffffefff))
    is always equal to (esp & 0x00001000). Which is either 0 or 0x1000.
    --
    vda
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