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    SubjectRe: [RFC] de-asmify the x86-64 system call slowpath
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    On Mon, Jan 27, 2014 at 2:32 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
    >
    > do_signal() is also a place where arbitrary changes to regs might've
    > been done by tracer, so regs->cs might need to be checked in the same
    > place where we validate regs->rip ;-/

    Fair enough. But it would still be really easy, and make the common
    case signal delivery a bit faster.

    Now, sadly, most signal delivery is then followed by sigreturn (the
    exceptions being dying or doing a longjmp), so we'd still get the
    iretq then. But it would cut the iretq's related to signals in half.

    We *could* try to do sigreturn with sysret and a small trampoline too,
    of course. But I'm not sure how far I'd want to take it.

    Linus


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