Messages in this thread | | | Date | Sun, 21 Aug 2011 22:03:33 -0700 | From | "H. Peter Anvin" <> | Subject | Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
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On 08/21/2011 09:26 PM, Al Viro wrote: > On Sun, Aug 21, 2011 at 09:11:54PM -0700, H. Peter Anvin wrote: >>> lack of point - the *only* CPU where it would matter would be K6-2, IIRC, >>> and (again, IIRC) it had some differences in SYSCALL semantics compared to >>> K7 (which supports SYSENTER as well). Bugger if I remember what those >>> differences might've been... Some flag not cleared? >> >> The most likely reason for a binary to execute a stray SYSCALL is >> because they read it out of the vdso. Totally daft, but we certainly >> see a lot of stupid things as evidenced by the JIT thread earlier this >> month. > > Um... What, blindly, no matter what surrounds it in there? What will > happen to the same eager JIT when it steps on SYSENTER?
The JIT will have had to manage SYSENTER already. It's not a change, whereas SYSCALL would be. We could just try it, and see if anything breaks, of course.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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