From patchwork Wed Apr 17 14:34:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 10905443 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 68293922 for ; Wed, 17 Apr 2019 14:34:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4A7EF284C9 for ; Wed, 17 Apr 2019 14:34:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3C4B228751; Wed, 17 Apr 2019 14:34:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id ABEE928725 for ; Wed, 17 Apr 2019 14:34:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZJj3YHpPiScpDJXaGHYvTABGtBHr+GDDKyZKatFDXSQ=; b=rVp+thLT7e/fEi FQNdqJwiPHMSxsWwvx0t4QxcXXIr3/vto4MrlykIc1RpvMsNQk/edMR7yEI3NrepQPmjpi1SQnv5V 3UxDyOG0QPbTzBs0iwDnQ3vfyyCHJkKxbPdrolu5c3lOtH9ORs3+4eIfK1NvhadLuAKQZZrF7ZCw7 DDAFPstI5gJE9qadOSZV9HILoHCi26L8hRRjy4IJ68PWS7lksMYYpr6/xYZxFBUNxlwOeAr58tl52 IuU189OVFvX2cCI7k/NT9EoJAEZIq+JNipu++q+kVOSe2yhOuY5RHmk/Q4TmxScKgCFAFCFrjEx9n QZqT9S6LCEB7sF71FZxQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hGle0-0005gg-Qp; Wed, 17 Apr 2019 14:34:36 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hGldx-0005gB-Lh for linux-arm-kernel@lists.infradead.org; Wed, 17 Apr 2019 14:34:35 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 71BB9A78; Wed, 17 Apr 2019 07:34:33 -0700 (PDT) Received: from e112269-lin.arm.com (e112269-lin.cambridge.arm.com [10.1.196.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E3E333F557; Wed, 17 Apr 2019 07:34:29 -0700 (PDT) From: Steven Price To: Dave Hansen , linux-mm@kvack.org, Linus Torvalds Subject: [RFC PATCH 1/3] mm: Add generic ptdump Date: Wed, 17 Apr 2019 15:34:21 +0100 Message-Id: <20190417143423.26665-1-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <3acbf061-8c97-55eb-f4b6-163a33ea4d73@arm.com> References: <3acbf061-8c97-55eb-f4b6-163a33ea4d73@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190417_073433_917698_8B63352F X-CRM114-Status: GOOD ( 19.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Arnd Bergmann , Ard Biesheuvel , Peter Zijlstra , Catalin Marinas , x86@kernel.org, Will Deacon , linux-kernel@vger.kernel.org, Steven Price , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , James Morse , Thomas Gleixner , Andrew Morton , linux-arm-kernel@lists.infradead.org, "Liang, Kan" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Add a generic version of page table dumping that architectures can opt-in to Signed-off-by: Steven Price --- include/linux/ptdump.h | 19 +++++ mm/Kconfig.debug | 21 ++++++ mm/Makefile | 1 + mm/ptdump.c | 159 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 200 insertions(+) create mode 100644 include/linux/ptdump.h create mode 100644 mm/ptdump.c diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h new file mode 100644 index 000000000000..eb8e78154be3 --- /dev/null +++ b/include/linux/ptdump.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_PTDUMP_H +#define _LINUX_PTDUMP_H + +struct ptdump_range { + unsigned long start; + unsigned long end; +}; + +struct ptdump_state { + void (*note_page)(struct ptdump_state *st, unsigned long addr, + int level, unsigned long val); + const struct ptdump_range *range; +}; + +void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm); + +#endif /* _LINUX_PTDUMP_H */ diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index e3df921208c0..21bbf559408b 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -111,3 +111,24 @@ config DEBUG_RODATA_TEST depends on STRICT_KERNEL_RWX ---help--- This option enables a testcase for the setting rodata read-only. + +config GENERIC_PTDUMP + bool + +config PTDUMP_CORE + bool + +config PTDUMP_DEBUGFS + bool "Export kerenl pagetable layout to userspace via debugfs" + depends on DEBUG_KERNEL + depends on DEBUG_FS + depends on GENERIC_PTDUMP + select PTDUMP_CORE + help + Say Y here if you want to show the kernel pagetable layout in a + debugfs file. This information is only useful for kernel developers + who are working in architecture specific areas of the kernel. + It is probably not a good idea to enable this feature in a production + kernel. + + If in doubt, say N. diff --git a/mm/Makefile b/mm/Makefile index d210cc9d6f80..59d653c3250d 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -99,3 +99,4 @@ obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o obj-$(CONFIG_HMM) += hmm.o obj-$(CONFIG_MEMFD_CREATE) += memfd.o +obj-$(CONFIG_PTDUMP_CORE) += ptdump.o diff --git a/mm/ptdump.c b/mm/ptdump.c new file mode 100644 index 000000000000..c8e4c08ce206 --- /dev/null +++ b/mm/ptdump.c @@ -0,0 +1,159 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pgd_t val = READ_ONCE(*pgd); + + if (pgd_large(val)) + st->note_page(st, addr, 1, pgd_val(val)); + + return 0; +} + +static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + p4d_t val = READ_ONCE(*p4d); + + if (p4d_large(val)) + st->note_page(st, addr, 2, p4d_val(val)); + + return 0; +} + +static int ptdump_pud_entry(pud_t *pud, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pud_t val = READ_ONCE(*pud); + + if (pud_large(val)) + st->note_page(st, addr, 3, pud_val(val)); + + return 0; +} + +static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pmd_t val = READ_ONCE(*pmd); + + if (pmd_large(val)) + st->note_page(st, addr, 4, pmd_val(val)); + + return 0; +} + +static int ptdump_pte_entry(pte_t *pte, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + + st->note_page(st, addr, 5, pte_val(READ_ONCE(*pte))); + + return 0; +} + +#ifdef CONFIG_KASAN +/* + * This is an optimization for KASAN=y case. Since all kasan page tables + * eventually point to the kasan_early_shadow_page we could call note_page() + * right away without walking through lower level page tables. This saves + * us dozens of seconds (minutes for 5-level config) while checking for + * W+X mapping or reading kernel_page_tables debugfs file. + */ +static inline bool kasan_page_table(struct ptdump_state *st, void *pt, + unsigned long addr) +{ + if (__pa(pt) == __pa(kasan_early_shadow_pmd) || + (pgtable_l5_enabled() && + __pa(pt) == __pa(kasan_early_shadow_p4d)) || + __pa(pt) == __pa(kasan_early_shadow_pud)) { + st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0])); + return true; + } + return false; +} +#else +static inline bool kasan_page_table(struct ptdump_state *st, void *pt, + unsigned long addr) +{ + return false; +} +#endif + +static int ptdump_test_p4d(unsigned long addr, unsigned long next, + p4d_t *p4d, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + + if (kasan_page_table(st, p4d, addr)) + return 1; + return 0; +} + +static int ptdump_test_pud(unsigned long addr, unsigned long next, + pud_t *pud, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + + if (kasan_page_table(st, pud, addr)) + return 1; + return 0; +} + +static int ptdump_test_pmd(unsigned long addr, unsigned long next, + pmd_t *pmd, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + + if (kasan_page_table(st, pmd, addr)) + return 1; + return 0; +} + +static int ptdump_hole(unsigned long addr, unsigned long next, + struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + + st->note_page(st, addr, -1, 0); + + return 0; +} + +void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm) +{ + struct mm_walk walk = { + .mm = mm, + .pgd_entry = ptdump_pgd_entry, + .p4d_entry = ptdump_p4d_entry, + .pud_entry = ptdump_pud_entry, + .pmd_entry = ptdump_pmd_entry, + .pte_entry = ptdump_pte_entry, + .test_p4d = ptdump_test_p4d, + .test_pud = ptdump_test_pud, + .test_pmd = ptdump_test_pmd, + .pte_hole = ptdump_hole, + .private = st + }; + const struct ptdump_range *range = st->range; + + down_read(&mm->mmap_sem); + while (range->start != range->end) { + walk_page_range(range->start, range->end, &walk); + range++; + } + up_read(&mm->mmap_sem); + + /* Flush out the last page */ + st->note_page(st, 0, 0, 0); +}