From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 1BC1D6B0069 for ; Tue, 31 Oct 2017 18:31:53 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id g6so441482pgn.11 for ; Tue, 31 Oct 2017 15:31:53 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTPS id v184si2487572pgd.402.2017.10.31.15.31.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 31 Oct 2017 15:31:52 -0700 (PDT) Subject: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page tables From: Dave Hansen Date: Tue, 31 Oct 2017 15:31:50 -0700 References: <20171031223146.6B47C861@viggo.jf.intel.com> In-Reply-To: <20171031223146.6B47C861@viggo.jf.intel.com> Message-Id: <20171031223150.AB41C68F@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org init_mm is for kernel-exclusive use. If someone is allocating page tables in it, do not set _PAGE_USER on them. This ensures that we do *not* set NX on these page tables in the KAISER code. Signed-off-by: Dave Hansen Cc: Moritz Lipp Cc: Daniel Gruss Cc: Michael Schwarz Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: x86@kernel.org --- b/arch/x86/include/asm/pgalloc.h | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) diff -puN arch/x86/include/asm/pgalloc.h~kaiser-prep-clear-_PAGE_USER-for-init_mm arch/x86/include/asm/pgalloc.h --- a/arch/x86/include/asm/pgalloc.h~kaiser-prep-clear-_PAGE_USER-for-init_mm 2017-10-31 15:03:48.745037506 -0700 +++ b/arch/x86/include/asm/pgalloc.h 2017-10-31 15:03:48.749037695 -0700 @@ -61,20 +61,36 @@ static inline void __pte_free_tlb(struct ___pte_free_tlb(tlb, pte); } +/* + * _KERNPG_TABLE has _PAGE_USER clear which tells the KAISER code + * that this mapping is for kernel use only. That makes sure that + * we leave the mapping usable by the kernel and do not try to + * sabotage it by doing stuff like setting _PAGE_NX on it. + */ +static inline pteval_t mm_pgtable_flags(struct mm_struct *mm) +{ + if (!mm || (mm == &init_mm)) + return _KERNPG_TABLE; + return _PAGE_TABLE; +} + static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte) { + pteval_t pgtable_flags = mm_pgtable_flags(mm); + paravirt_alloc_pte(mm, __pa(pte) >> PAGE_SHIFT); - set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE)); + set_pmd(pmd, __pmd(__pa(pte) | pgtable_flags)); } static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, struct page *pte) { + pteval_t pgtable_flags = mm_pgtable_flags(mm); unsigned long pfn = page_to_pfn(pte); paravirt_alloc_pte(mm, pfn); - set_pmd(pmd, __pmd(((pteval_t)pfn << PAGE_SHIFT) | _PAGE_TABLE)); + set_pmd(pmd, __pmd(((pteval_t)pfn << PAGE_SHIFT) | pgtable_flags)); } #define pmd_pgtable(pmd) pmd_page(pmd) @@ -117,16 +133,20 @@ extern void pud_populate(struct mm_struc #else /* !CONFIG_X86_PAE */ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd) { + pteval_t pgtable_flags = mm_pgtable_flags(mm); + paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT); - set_pud(pud, __pud(_PAGE_TABLE | __pa(pmd))); + set_pud(pud, __pud(__pa(pmd) | pgtable_flags)); } #endif /* CONFIG_X86_PAE */ #if CONFIG_PGTABLE_LEVELS > 3 static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4d, pud_t *pud) { + pteval_t pgtable_flags = mm_pgtable_flags(mm); + paravirt_alloc_pud(mm, __pa(pud) >> PAGE_SHIFT); - set_p4d(p4d, __p4d(_PAGE_TABLE | __pa(pud))); + set_p4d(p4d, __p4d(__pa(pud) | pgtable_flags)); } static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr) @@ -155,8 +175,10 @@ static inline void __pud_free_tlb(struct #if CONFIG_PGTABLE_LEVELS > 4 static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d) { + pteval_t pgtable_flags = mm_pgtable_flags(mm); + paravirt_alloc_p4d(mm, __pa(p4d) >> PAGE_SHIFT); - set_pgd(pgd, __pgd(_PAGE_TABLE | __pa(p4d))); + set_pgd(pgd, __pgd(__pa(p4d) | pgtable_flags)); } static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr) _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org