Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 16 Apr 2018 09:13:22 -0700 | Subject | Re: [PATCH 00/35 v5] PTI support for x32 |
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On Mon, Apr 16, 2018 at 9:01 AM, Joerg Roedel <joro@8bytes.org> wrote: > > Okay, I verify if there are any global bits left in the page-tables. > According to the PTDUMP_X86 the cpu_entry_area is mapped with G=1 (which > should be fine?) and another 4M range in the kernel mapping. I need to > check what that is.
All the kernel entry code that is both in the user mapping and the kernel mapping should be marked G.
We had missed a lot of it (and the impact is very small with PCID), but if you rebased on top of 4.17-rc1 you should have it fixed at least on 64-bit.
See for example commit 8c06c7740d19 ("x86/pti: Leave kernel text global for !PCID") and in particular the performance numbers (that's an Atom microserver, but it was chosen due to lack of PCID).
Linus
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