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| author | Dave Airlie <airlied@redhat.com> | 2018-01-18 09:32:15 +1000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2018-01-18 09:32:15 +1000 |
| commit | 4a6cc7a44e98a0460bd094b68c75f0705fdc450a (patch) | |
| tree | b8c86a1e0342b1166ab52c4d79e404eede57abec /arch/x86/kernel/tboot.c | |
| parent | 8563188e37b000979ab66521f4337df9a3453223 (diff) | |
| parent | a8750ddca918032d6349adbf9a4b6555e7db20da (diff) | |
| download | linux-4a6cc7a44e98a0460bd094b68c75f0705fdc450a.tar.bz2 | |
BackMerge tag 'v4.15-rc8' into drm-next
Linux 4.15-rc8
Daniel requested this for so the intel CI won't fall over on drm-next
so often.
Diffstat (limited to 'arch/x86/kernel/tboot.c')
| -rw-r--r-- | arch/x86/kernel/tboot.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c index a4eb27918ceb..a2486f444073 100644 --- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -138,6 +138,17 @@ static int map_tboot_page(unsigned long vaddr, unsigned long pfn, return -1; set_pte_at(&tboot_mm, vaddr, pte, pfn_pte(pfn, prot)); pte_unmap(pte); + + /* + * PTI poisons low addresses in the kernel page tables in the + * name of making them unusable for userspace. To execute + * code at such a low address, the poison must be cleared. + * + * Note: 'pgd' actually gets set in p4d_alloc() _or_ + * pud_alloc() depending on 4/5-level paging. + */ + pgd->pgd &= ~_PAGE_NX; + return 0; } |