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    SubjectRe: [patch 1/1] x86-64: forgot asmlinkage on sys_mmap
    Date
    On Wednesday 09 March 2005 20:34, Andi Kleen wrote:
    > On Wed, Mar 09, 2005 at 07:24:00PM +0100, Blaisorblade wrote:
    > > On Wednesday 09 March 2005 18:24, Andi Kleen wrote:
    > > > blaisorblade@yahoo.it writes:
    > > > > CC: Andi Kleen <ak@suse.de>
    > > > >
    > > > > I think it should be there, please check better.
    > > >
    > > > It doesn't matter. asmlinkage is a nop on x86-64.
    > >
    > > Yes, otherwise nothing would work on x86-64 with mmap broken, but for
    > > cleanness and for the case this change it should be there (otherwise why
    > > asmlinkage is used in the rest of the file).
    >
    > Only because it was cut'n'pasted from i386 originally.
    >
    > > And for i386 asmlinkage acquired significance only recently.
    >
    > Actually it doesn't neither on i386. That's because entry.S happens to put
    > the arguments both into registers and the stack in the right order, so both
    > register and stack argument calling conventions work.
    >
    > But it is slightly safer to have it. When you use the stack arguments
    > the C code is allowed to modify it, and when the system call is restarted
    > later you could see garbage. In practice that's not a big issue because
    > only very few system calls are restartable.
    >
    > ptrace also could see corrupted state, but that's in general a non issue.
    Ok, thanks for the info, I hope it's applied anyway.
    --
    Paolo Giarrusso, aka Blaisorblade
    Linux registered user n. 292729
    http://www.user-mode-linux.org/~blaisorblade


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