Messages in this thread | | | Date | Wed, 27 Nov 2013 15:04:41 -0800 | Subject | Re: [PATCH] Add a text_poke syscall v2 | From | Linus Torvalds <> |
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On Wed, Nov 27, 2013 at 2:31 PM, H. Peter Anvin <hpa@zytor.com> wrote: > No, we're not... sysexit/sysret doesn't count.
So sysexit/sysret doesn't count as a serializing instruction, no. But it doesn't need to, because *self*-modifying code doesn't need a serializing instruction, only a branch. It's only *cross*-modifying code that needs a serializing instruction.
So the IPI is sufficient for the cross-modifying case, and the sysret is sufficient for the self-modifying case. And we also don't need to worry about "what happens if we schedule to another CPU, and self-modifying becomes cross-modifying", because the scheduling will then do the serializing instruction.
So IPI for other CPU's (limited to the mm-mask) and just a system call for local CPU should be perfectly fine.
Linus
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