Messages in this thread | | | Subject | Re: [PATCH v2 5/7] x86/mm, tracing: Fix CR2 corruption | From | Andy Lutomirski <> | Date | Thu, 4 Jul 2019 20:16:54 -0700 |
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> On Jul 4, 2019, at 7:18 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > >> On Fri, Jul 5, 2019 at 5:03 AM Peter Zijlstra <peterz@infradead.org> wrote: >> >> Despire the current efforts to read CR2 before tracing happens there >> still exist a number of possible holes: > > So this whole series disturbs me for the simple reason that I thought > tracing was supposed to save/restore cr2 and make it unnecessary to > worry about this in non-tracing code. > > That is very much what the NMI code explicitly does. Why shouldn't all > the other tracing code do the same thing in case they can take page > faults? >
If nothing else, MOV to CR2 is architecturally serializing, so, unless there’s some fancy unwinding involved, this will be quite slow.
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