Messages in this thread | | | Date | Tue, 23 Aug 2011 18:22:51 +0200 | From | Borislav Petkov <> | Subject | Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
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On Tue, Aug 23, 2011 at 12:11:43PM -0400, Andrew Lutomirski wrote: > In any case, this seems insanely overcomplicated. I'd be less afraid > of something like my approach (which, I think, makes all of the > SYSCALL weirdness pretty much transparent to ptrace users) or of just > removing SYSCALL entirely from 32-bit code.
I don't think that removing SYSCALL from 32-bit code just so that UML trapped syscalls work is something we'd like since SYSCALL is much cheaper than INT $0x80:
"As a result, SYSCALL and SYSRET can take fewer than one-fourth the number of internal clock cycles to complete than the legacy CALL and RET instructions."
http://support.amd.com/us/Processor_TechDocs/24593.pdf, p. 152.
I know, it is 32-bit syscall on 64-bit kernel which should be pretty rare but still...
Thanks.
-- Regards/Gruss, Boris.
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