Messages in this thread |  | | | Date | Sun, 22 Dec 2002 10:53:49 -0800 (PST) | | From | Linus Torvalds <> | | Subject | Re: Intel P6 vs P7 system call performance |
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On Sun, 22 Dec 2002, Ingo Molnar wrote: > > On Sat, 21 Dec 2002, Linus Torvalds wrote: > > > Saving and restoring eflags in user mode avoids all of these > > complications, and means that there are no special cases. None. Zero. > > Nada. > > and i'm 100% sure the more robust eflags saving will also avoid security > holes. The amount of security-relevant complexity that comes from all the > x86 features [and their combinations] is amazing.
I looked a bit at what it would take to have the TF bit handled by the sysenter path, and it might not be so horrible - certainly not as ugly as the register restore bits.
Jamie, if you want to do it, it looks like you could add a new "work" bit in the thread flags, and add it to the _TIF_ALLWORK_MASK tests. At least that way it wouldn't touch the regular code, and I don't think that the result would have any strange "magic EIP" tests or anything horrible like that ;)
Linus
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