From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id A7491440D29 for ; Fri, 10 Nov 2017 14:31:26 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id g6so10045949pgn.11 for ; Fri, 10 Nov 2017 11:31:26 -0800 (PST) Received: from mga06.intel.com (mga06.intel.com. [134.134.136.31]) by mx.google.com with ESMTPS id c4si9090045pgt.539.2017.11.10.11.31.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Nov 2017 11:31:25 -0800 (PST) Subject: [PATCH 01/30] x86, mm: do not set _PAGE_USER for init_mm page tables From: Dave Hansen Date: Fri, 10 Nov 2017 11:31:00 -0800 References: <20171110193058.BECA7D88@viggo.jf.intel.com> In-Reply-To: <20171110193058.BECA7D88@viggo.jf.intel.com> Message-Id: <20171110193100.C2E67756@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, tglx@linutronix.de, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, richard.fellner@student.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org From: Dave Hansen init_mm is for kernel-exclusive use. If someone is allocating page tables for it, do not set _PAGE_USER on them. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Moritz Lipp Cc: Daniel Gruss Cc: Michael Schwarz Cc: Richard Fellner Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: x86@kernel.org --- b/arch/x86/include/asm/pgalloc.h | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 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 2017-11-10 11:22:04.991244960 -0800 +++ b/arch/x86/include/asm/pgalloc.h 2017-11-10 11:22:04.994244960 -0800 @@ -61,20 +61,41 @@ static inline void __pte_free_tlb(struct ___pte_free_tlb(tlb, pte); } +/* + * init_mm is for kernel-exclusive use. Any page tables that + * are setup for it should not be usable by userspace. + * + * This also *signals* to code (like KAISER) that this page table + * entry is for kernel-exclusive use. + */ +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) { + /* + * Since we are populating a kernel pmd, always use + * _KERNPG_TABLE and ignore mm + */ + pteval_t pgtable_flags = _KERNPG_TABLE; + 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 +138,20 @@ 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 +180,10 @@ 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