Messages in this thread | | | Date | Mon, 23 Apr 2018 19:45:06 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH 00/37 v6] PTI support for x86-32 |
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On Mon, Apr 23, 2018 at 09:45:38AM -0700, Linus Torvalds wrote: > Just one question: have you checked the page table setup for the > basics wrt the USER bit in particular?
Just checked that and there are no pages with GLB and USR set, not even a vdso page.
> No global pages should be marked PAGE_USER, with the possible > exception of that nasty old vsyscall page.
The vsyscall page does not exist on plain 32 bit, no? All I could find there is the vdso page, and that has no compat mapping anymore in recent upstream kernels. To my understanding the vdso page is mapped into the user-space portion of the address space. At least that is what I found while looking at this, but I might have missed something.
I actually ran into a vdso issue when porting these changes to 3.0 (where there still is a compat vdso mapping in the fixmap) so I checked my upstream code too, but didn't find the code to setup a vdso in the fixmap.
> And it would be nice to verify that the page tables for kernel > mappings also don't have PAGE_USER on them, although again that > vsyscall page can cause problems.
Checked that too, all USR mappings are below PAGE_OFFSET.
Regards,
Joerg
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