Messages in this thread | | | From | Michael Ellerman <> | Subject | Re: [PATCH 2/5] powerpc/mm: split store_updates_sp() in two parts in do_page_fault() | Date | Fri, 02 Jun 2017 19:26:34 +1000 |
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Christophe Leroy <christophe.leroy@c-s.fr> writes:
> Only the get_user() in store_updates_sp() has to be done outside > the mm semaphore. All the comparison can be done within the semaphore, > so only when really needed. > > As we got a DSI exception, the address pointed by regs->nip is > obviously valid, otherwise we would have had a instruction exception. > So __get_user() can be used instead of get_user()
I don't think that part is true.
You took a DSI so there *was* an instruction at NIP, but since then it may have been unmapped by another thread.
So I don't think you can assume the get_user() will succeed.
cheers
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