Messages in this thread | | | Subject | Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled | From | Laura Abbott <> | Date | Fri, 11 Aug 2017 10:25:14 -0700 |
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On 08/09/2017 01:07 PM, Tycho Andersen wrote: > From: Juerg Haefliger <juerg.haefliger@hpe.com> > > XPFO (eXclusive Page Frame Ownership) doesn't support section mappings > yet, so disable it if XPFO is turned on. > > Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com> > Tested-by: Tycho Andersen <tycho@docker.com> > --- > arch/arm64/mm/mmu.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index f1eb15e0e864..38026b3ccb46 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -176,6 +176,18 @@ static void alloc_init_cont_pte(pmd_t *pmd, unsigned long addr, > } while (addr = next, addr != end); > } > > +static inline bool use_section_mapping(unsigned long addr, unsigned long next, > + unsigned long phys) > +{ > + if (IS_ENABLED(CONFIG_XPFO)) > + return false; > + > + if (((addr | next | phys) & ~SECTION_MASK) != 0) > + return false; > + > + return true; > +} > + > static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end, > phys_addr_t phys, pgprot_t prot, > phys_addr_t (*pgtable_alloc)(void), int flags) > @@ -190,7 +202,7 @@ static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end, > next = pmd_addr_end(addr, end); > > /* try section mapping first */ > - if (((addr | next | phys) & ~SECTION_MASK) == 0 && > + if (use_section_mapping(addr, next, phys) && > (flags & NO_BLOCK_MAPPINGS) == 0) { > pmd_set_huge(pmd, phys, prot); > >
There is already similar logic to disable section mappings for debug_pagealloc at the start of map_mem, can you take advantage of that?
Thanks, Laura
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