Messages in this thread | | | Subject | bos | From | Laurent Dufour <> | Date | Tue, 23 Apr 2019 15:36:56 +0200 |
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Le 23/04/2019 à 15:34, Thomas Gleixner a écrit : > On Tue, 23 Apr 2019, Laurent Dufour wrote: >> Le 20/04/2019 à 12:31, Michael Ellerman a écrit : >>> Thomas Gleixner <tglx@linutronix.de> writes: >>>> Aside of that the powerpc variant looks suspicious: >>>> >>>> static inline void arch_unmap(struct mm_struct *mm, >>>> unsigned long start, unsigned long end) >>>> { >>>> if (start <= mm->context.vdso_base && mm->context.vdso_base < end) >>>> mm->context.vdso_base = 0; >>>> } >>>> >>>> Shouldn't that be: >>>> >>>> if (start >= mm->context.vdso_base && mm->context.vdso_base < end) >>>> >>>> Hmm? >>> >>> Yeah looks pretty suspicious. I'll follow-up with Laurent who wrote it. >>> Thanks for spotting it! >> >> I've to admit that I had to read that code carefully before answering. >> >> There are 2 assumptions here: >> 1. 'start' and 'end' are page aligned (this is guaranteed by __do_munmap(). >> 2. the VDSO is 1 page (this is guaranteed by the union vdso_data_store on >> powerpc). >> >> The idea is to handle a munmap() call surrounding the VDSO area: >> | VDSO | >> ^start ^end >> >> This is covered by this test, as the munmap() matching the exact boundaries of >> the VDSO is handled too. >> >> Am I missing something ? > > Well if this is the intention, then you missed to add a comment explaining it :) > > Thanks, > > tglx
You're right, and I was thinking the same when I read that code this morning ;)
I'll propose a patch to a add an explicit comment.
Thanks, Laurent.
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