From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtAGlSDLke1XrWWb1fnx88PQ/o8Vsm/9Li1F14s71rPacNAtDYFWahUGqXQpVtfEu+p7Qrb ARC-Seal: i=1; a=rsa-sha256; t=1520245578; cv=none; d=google.com; s=arc-20160816; b=R3TWCTCQK3DmblTB71coSzFCW6Ssvi7SLepbPRZsdT6APdVpj58aYh2QWU5GT/XJU+ vdWNuhTxsXiMAiVfwOHflQcZP9m0sCZ5AZofjbsrB4C+I8MmItauCnrsOiTPTyLjVjpa mHvIJTWfkMLDN4Bb9vTHGqvMjj+Vu3CC0FLKTQ483j1qMm1duDvjHuLd9Tm9rSAoV46r KhzTaXQ5NN6gGBSeBoa8oMIm9KY0IWbABYf5oIrBPN7m2U84/TovVjHKPC+UKI/yB9sM rwUTcR6DcFy0Tm76QXD6O++b6PXLZwOIYD+08LgT4wyfQz8eSTwnCxuBdMGAvz9p2cVO y+rQ== 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=kLSkIU8ZwWWhwGEo66e4pDFLXvc08MUZM4d04gtWFw1Rjp15gP4nm+IZMKbwXNwq5j qIswKW9FazBcBdUlAqfjCKHrjBq5EnjwKqfpokk781U+sDqrCEyxowXPtzPJoBEOTNna 8pXSOD5LtJpKtqvqQOFV0o767miwc/OLAfyiezzLQUwMkFpB34gnaAlBiYHY+g/d6Ulx U0aY9ih8A/Mbv6MeasckHjpACljBxNRuOrJujb2BnO8U8yQO3flKBNlTC4zlKXw5N/o1 LY3a8cu2s6kdrxIlocTBMCTC4fY+0deQE0BjN0PYwX3lR7m5fF3Y4g3Gm7hhJi0Twn4w HuhA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=bdBLHE7Q; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 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=bdBLHE7Q; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 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 26/34] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32 Date: Mon, 5 Mar 2018 11:25:55 +0100 Message-Id: <1520245563-8444-27-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1520245563-8444-1-git-send-email-joro@8bytes.org> References: <1520245563-8444-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594093028419811410?= X-GMAIL-MSGID: =?utf-8?q?1594093028419811410?= 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