Messages in this thread | | | Date | Mon, 27 Jan 2014 14:01:15 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH v3 3/4] x86, mpx: add prctl commands PR_MPX_INIT, PR_MPX_RELEASE |
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On 01/27/2014 01:54 PM, Andy Lutomirski wrote: > On 01/26/2014 06:10 PM, H. Peter Anvin wrote: >> On 01/26/2014 05:55 PM, Ren Qiaowei wrote: >>> >>> Peter, you mean we should remove these two call and do what they do in >>> user-space, right? >>> >> >> Unless we think there is a benefit to the kernel to have a on/off switch >> for the #BR exception (if disabled, all #BR exceptions are signals, >> regardless of source.) > > Yes. > > For example, wouldn't UML want to have all of this stuff disabled? > Presumably it would much prefer to receive the exception directly. > > The same goes for seccomp users -- as it currently stands, this code > allows mmap without a system call. > > This probably means that the prctl should (optionally) take a parameter > that fixes the address of the L1 table -- seccomp users would probably > want that. (Actually, everyone might -- this is going to have weird > results if the L1 table moves.) >
That seems like a good argument. If the table has been moved by userspace we can deliver the signal as a violation.
-hpa
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