From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtMsFzpl+xMGMvrJe/wcnEKM30Vyh5GTf+/k/qVicjZ27O13VFBOHAIuNkLFnltGj+lTY4A ARC-Seal: i=1; a=rsa-sha256; t=1521228609; cv=none; d=google.com; s=arc-20160816; b=BucpDcn57NBOjngV6hKnr1c0mx5pLVzcHZ7Gj5FGPdz0KqfqF+A7ZL1pKTPb0Kg1oR lnOcia5r/AZlIcPWk6G70LKIuDaAHY2XCaLohb27Imuk/ziiHwGLxb7SIpRhfk7/Trp/ 2B/3ZSOZvm9w5wPAE00Xl3KzNSoCgjbgNxePnGqelFz2D49n5EKFzIyKosQHDzedx0DE K4BJLz0NBMK91a7y0tLIVUrX55uRRNUTSJPD1VAcUyE6rOe1y8VtmPicmPY+BwLI18s3 MAjbUxypu9ils+ogXY79mmHWVXxESdgN54mp32oX2II0+YcoJjbv9PD8qGv1TgFS1kqF L0tg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=fxqqdR30HdE5nJ4R83bfo1x7u9xYefePfoB7rp7Zl2Y=; b=VgqGs3CKMTNpp4P2qHvGs9cEJSahfVXnonYTllnTv9Cckqd3LmXA7t6VcKsQzxa0mR mGgSVanhK8R3Vm+8Kunn5Uy2wssiQhmScBJkDxovzO/uY4506ajRlwd5hJmEX746BMLq PQ/EV/pgwUNKFRiakpw3FIw/DfpFiMwDW8oW3zGV8ONJUIFoUFuPK2EI5i0CH862UNxo TunNAOyDyjHhgPae4u9ZQbKeTDYkx9NYhMAo9TXA9m+ALAJS3FLA0iaAMSbAXow6z/4S NCRoN0nYdlG7pxvKYquRe6/+vfGJrVfX+61b9Id9ApKA7Y2N+5yG/h3rfx22rcES2EJk 2eyQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=lD1brQnM; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=lD1brQnM; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 26/35] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32 Date: Fri, 16 Mar 2018 20:29:44 +0100 Message-Id: <1521228593-3820-27-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521228593-3820-1-git-send-email-joro@8bytes.org> References: <1521228593-3820-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595123810026068250?= X-GMAIL-MSGID: =?utf-8?q?1595123810026068250?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Joerg Roedel Cloning on the P4D level would clone the complete kernel address space into the user-space page-tables for PAE kernels. Cloning on PMD level is fine for PAE and legacy paging. Signed-off-by: Joerg Roedel --- arch/x86/mm/pti.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 96a690e..3ffd923 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -312,6 +312,7 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) } } +#ifdef CONFIG_X86_64 /* * Clone a single p4d (i.e. a top-level entry on 4-level systems and a * next-level entry on 5-level systems. @@ -335,6 +336,25 @@ static void __init pti_clone_user_shared(void) pti_clone_p4d(CPU_ENTRY_AREA_BASE); } +#else /* CONFIG_X86_64 */ + +/* + * On 32 bit PAE systems with 1GB of Kernel address space there is only + * one pgd/p4d for the whole kernel. Cloning that would map the whole + * address space into the user page-tables, making PTI useless. So clone + * the page-table on the PMD level to prevent that. + */ +static void __init pti_clone_user_shared(void) +{ + unsigned long start, end; + + start = CPU_ENTRY_AREA_BASE; + end = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES); + + pti_clone_pmds(start, end, _PAGE_GLOBAL); +} +#endif /* CONFIG_X86_64 */ + /* * Clone the ESPFIX P4D into the user space visinble page table */ -- 2.7.4