From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tycho Andersen Date: Wed, 9 Aug 2017 14:07:51 -0600 Message-Id: <20170809200755.11234-7-tycho@docker.com> In-Reply-To: <20170809200755.11234-1-tycho@docker.com> References: <20170809200755.11234-1-tycho@docker.com> Subject: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, kernel-hardening@lists.openwall.com, Marco Benatto , Juerg Haefliger , Juerg Haefliger List-ID: From: Juerg Haefliger XPFO (eXclusive Page Frame Ownership) doesn't support section mappings yet, so disable it if XPFO is turned on. Signed-off-by: Juerg Haefliger Tested-by: Tycho Andersen --- 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); -- 2.11.0