From patchwork Mon Oct 21 02:42:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 1180156 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="K0Csc9sa"; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 46xLXh6Nb6z9sPV for ; Mon, 21 Oct 2019 13:43:00 +1100 (AEDT) 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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: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=B2avYr4LzRQnGXVFCTn7Zkoz+2NGb28AX4XgCI5k21U=; b=K0Csc9saDlHRaPwQ0cc9db9A41 7A/tQ5H/3X5buSZ7dWzv2dROrv5gVekmHXjg6Gh8apysRa2F95qumlZNUNDEG6bJnoE9wgMGpHnre Tu97l36rImlxwXqWoHEuEq1/KmXCRjXJTPBxKpGhKuZJx0HquKVUVeS24Y4TlTPZMHJuAEcNU1SrC 7XG3k3XkcwWd97EA46eVmf/dRB8VD1skGKT+pRBkVGdvG2ZmPx/OG6iVLw2z8XPrLMOHpMNgyz86f kTW7JXztxYjNjdARUxQ/HUtxRpQhi8lqlSdr9dbpUHqsZt2rSwz2+GW2jbLld/hVFL62tW5+aPT6r c0tvEenw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iMNer-0003HA-1d; Mon, 21 Oct 2019 02:42:57 +0000 Received: from [217.140.110.172] (helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iMNec-0002sP-8L; Mon, 21 Oct 2019 02:42:45 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A537637B; Sun, 20 Oct 2019 19:42:31 -0700 (PDT) Received: from p8cg001049571a15.arm.com (unknown [10.163.1.2]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D358C3F71F; Sun, 20 Oct 2019 19:42:16 -0700 (PDT) From: Anshuman Khandual To: linux-mm@kvack.org Subject: [PATCH V7] mm/debug: Add tests validating architecture page table helpers Date: Mon, 21 Oct 2019 08:12:19 +0530 Message-Id: <1571625739-29943-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1571625739-29943-1-git-send-email-anshuman.khandual@arm.com> References: <1571625739-29943-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191020_194242_400120_E2A213C1 X-CRM114-Status: GOOD ( 22.68 ) X-Spam-Score: 1.3 (+) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (1.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 1.3 RDNS_NONE Delivered to internal network by a host with no rDNS X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , James Hogan , Tetsuo Handa , Heiko Carstens , Michal Hocko , Dave Hansen , Paul Mackerras , sparclinux@vger.kernel.org, Thomas Gleixner , linux-s390@vger.kernel.org, Michael Ellerman , x86@kernel.org, Russell King - ARM Linux , Matthew Wilcox , Steven Price , Jason Gunthorpe , Gerald Schaefer , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Ingo Molnar , Kees Cook , Anshuman Khandual , Masahiro Yamada , Mark Brown , "Kirill A . Shutemov" , Dan Williams , Vlastimil Babka , Christophe Leroy , Sri Krishna chowdary , Ard Biesheuvel , Greg Kroah-Hartman , linux-mips@vger.kernel.org, Ralf Baechle , linux-kernel@vger.kernel.org, Paul Burton , Mike Rapoport , Vineet Gupta , Martin Schwidefsky , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" MIME-Version: 1.0 Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org This adds tests which will validate architecture page table helpers and other accessors in their compliance with expected generic MM semantics. This will help various architectures in validating changes to existing page table helpers or addition of new ones. This test covers basic page table entry transformations including but not limited to old, young, dirty, clean, write, write protect etc at various level along with populating intermediate entries with next page table page and validating them. Test page table pages are allocated from system memory with required size and alignments. The mapped pfns at page table levels are derived from a real pfn representing a valid kernel text symbol. This test gets called right after page_alloc_init_late(). This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and arm64. Going forward, other architectures too can enable this after fixing build or runtime problems (if any) with their page table helpers. Folks interested in making sure that a given platform's page table helpers conform to expected generic MM semantics should enable the above config which will just trigger this test during boot. Any non conformity here will be reported as an warning which would need to be fixed. This test will help catch any changes to the agreed upon semantics expected from generic MM and enable platforms to accommodate it thereafter. Cc: Andrew Morton Cc: Vlastimil Babka Cc: Greg Kroah-Hartman Cc: Thomas Gleixner Cc: Mike Rapoport Cc: Jason Gunthorpe Cc: Dan Williams Cc: Peter Zijlstra Cc: Michal Hocko Cc: Mark Rutland Cc: Mark Brown Cc: Steven Price Cc: Ard Biesheuvel Cc: Masahiro Yamada Cc: Kees Cook Cc: Tetsuo Handa Cc: Matthew Wilcox Cc: Sri Krishna chowdary Cc: Dave Hansen Cc: Russell King - ARM Linux Cc: Michael Ellerman Cc: Paul Mackerras Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: "David S. Miller" Cc: Vineet Gupta Cc: James Hogan Cc: Paul Burton Cc: Ralf Baechle Cc: Kirill A. Shutemov Cc: Gerald Schaefer Cc: Christophe Leroy Cc: Ingo Molnar Cc: linux-snps-arc@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: sparclinux@vger.kernel.org Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Tested-by: Christophe Leroy #PPC32 Suggested-by: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Christophe Leroy Signed-off-by: Anshuman Khandual --- .../debug/debug-vm-pgtable/arch-support.txt | 34 ++ arch/arm64/Kconfig | 1 + arch/x86/Kconfig | 1 + arch/x86/include/asm/pgtable_64.h | 6 + include/asm-generic/pgtable.h | 6 + init/main.c | 1 + lib/Kconfig.debug | 21 ++ mm/Makefile | 1 + mm/debug_vm_pgtable.c | 388 +++++++++++++++++++++ 9 files changed, 459 insertions(+) create mode 100644 Documentation/features/debug/debug-vm-pgtable/arch-support.txt create mode 100644 mm/debug_vm_pgtable.c diff --git a/Documentation/features/debug/debug-vm-pgtable/arch-support.txt b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt new file mode 100644 index 0000000..d6b8185 --- /dev/null +++ b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt @@ -0,0 +1,34 @@ +# +# Feature name: debug-vm-pgtable +# Kconfig: ARCH_HAS_DEBUG_VM_PGTABLE +# description: arch supports pgtable tests for semantics compliance +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | TODO | + | arc: | TODO | + | arm: | TODO | + | arm64: | ok | + | c6x: | TODO | + | csky: | TODO | + | h8300: | TODO | + | hexagon: | TODO | + | ia64: | TODO | + | m68k: | TODO | + | microblaze: | TODO | + | mips: | TODO | + | nds32: | TODO | + | nios2: | TODO | + | openrisc: | TODO | + | parisc: | TODO | + | powerpc: | TODO | + | riscv: | TODO | + | s390: | TODO | + | sh: | TODO | + | sparc: | TODO | + | um: | TODO | + | unicore32: | TODO | + | x86: | ok | + | xtensa: | TODO | + ----------------------- diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1b6ea5a..ea62c87 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -11,6 +11,7 @@ config ARM64 select ACPI_PPTT if ACPI select ARCH_CLOCKSOURCE_DATA select ARCH_HAS_DEBUG_VIRTUAL + select ARCH_HAS_DEBUG_VM_PGTABLE select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_DMA_COHERENT_TO_PFN select ARCH_HAS_DMA_PREP_COHERENT diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index abe822d..13c9bd9 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -61,6 +61,7 @@ config X86 select ARCH_CLOCKSOURCE_INIT select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI select ARCH_HAS_DEBUG_VIRTUAL + select ARCH_HAS_DEBUG_VM_PGTABLE select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FAST_MULTIPLIER diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h index 0b6c4042..fb0e76d 100644 --- a/arch/x86/include/asm/pgtable_64.h +++ b/arch/x86/include/asm/pgtable_64.h @@ -53,6 +53,12 @@ static inline void sync_initial_page_table(void) { } struct mm_struct; +#define mm_p4d_folded mm_p4d_folded +static inline bool mm_p4d_folded(struct mm_struct *mm) +{ + return !pgtable_l5_enabled(); +} + void set_pte_vaddr_p4d(p4d_t *p4d_page, unsigned long vaddr, pte_t new_pte); void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte); diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 9cdcbc7..9eb02e1 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -1168,6 +1168,12 @@ static inline bool arch_has_pfn_modify_check(void) # define PAGE_KERNEL_EXEC PAGE_KERNEL #endif +#ifdef CONFIG_DEBUG_VM_PGTABLE +extern void debug_vm_pgtable(void); +#else +static inline void debug_vm_pgtable(void) { } +#endif + #endif /* !__ASSEMBLY__ */ #ifndef io_remap_pfn_range diff --git a/init/main.c b/init/main.c index 91f6ebb..af8379e 100644 --- a/init/main.c +++ b/init/main.c @@ -1185,6 +1185,7 @@ static noinline void __init kernel_init_freeable(void) sched_init_smp(); page_alloc_init_late(); + debug_vm_pgtable(); /* Initialize page ext after all struct pages are initialized. */ page_ext_init(); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 9c60d7d..cf48d95 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -690,6 +690,27 @@ config DEBUG_VM_PGFLAGS If unsure, say N. +config ARCH_HAS_DEBUG_VM_PGTABLE + bool + help + An architecture should select this when it can successfully + build and run DEBUG_VM_PGTABLE. + +config DEBUG_VM_PGTABLE + bool "Debug arch page table for semantics compliance" + depends on MMU + depends on DEBUG_VM + depends on ARCH_HAS_DEBUG_VM_PGTABLE + help + This option provides a debug method which can be used to test + architecture page table helper functions on various platforms in + verifying if they comply with expected generic MM semantics. This + will help architecture code in making sure that any changes or + new additions of these helpers still conform to expected + semantics of the generic MM. + + If unsure, say N. + config ARCH_HAS_DEBUG_VIRTUAL bool diff --git a/mm/Makefile b/mm/Makefile index d996846..2f085b9 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -86,6 +86,7 @@ obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o obj-$(CONFIG_DEBUG_RODATA_TEST) += rodata_test.o +obj-$(CONFIG_DEBUG_VM_PGTABLE) += debug_vm_pgtable.o obj-$(CONFIG_PAGE_OWNER) += page_owner.o obj-$(CONFIG_CLEANCACHE) += cleancache.o obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c new file mode 100644 index 0000000..9472566 --- /dev/null +++ b/mm/debug_vm_pgtable.c @@ -0,0 +1,388 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This kernel test validates architecture page table helpers and + * accessors and helps in verifying their continued compliance with + * expected generic MM semantics. + * + * Copyright (C) 2019 ARM Ltd. + * + * Author: Anshuman Khandual + */ +#define pr_fmt(fmt) "arch_pgtable_test: %s " fmt, __func__ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Basic operations + * + * mkold(entry) = An old and not a young entry + * mkyoung(entry) = A young and not an old entry + * mkdirty(entry) = A dirty and not a clean entry + * mkclean(entry) = A clean and not a dirty entry + * mkwrite(entry) = A write and not a write protected entry + * wrprotect(entry) = A write protected and not a write entry + * pxx_bad(entry) = A mapped and non-table entry + * pxx_same(entry1, entry2) = Both entries hold the exact same value + */ +#define VMFLAGS (VM_READ|VM_WRITE|VM_EXEC) + +/* + * On s390 platform, the lower 12 bits are used to identify given page table + * entry type and for other arch specific requirements. But these bits might + * affect the ability to clear entries with pxx_clear(). So while loading up + * the entries skip all lower 12 bits in order to accommodate s390 platform. + * It does not have affect any other platform. + */ +#define RANDOM_ORVALUE (0xfffffffffffff000UL) +#define RANDOM_NZVALUE (0xff) + +static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot) +{ + pte_t pte = pfn_pte(pfn, prot); + + WARN_ON(!pte_same(pte, pte)); + WARN_ON(!pte_young(pte_mkyoung(pte))); + WARN_ON(!pte_dirty(pte_mkdirty(pte))); + WARN_ON(!pte_write(pte_mkwrite(pte))); + WARN_ON(pte_young(pte_mkold(pte))); + WARN_ON(pte_dirty(pte_mkclean(pte))); + WARN_ON(pte_write(pte_wrprotect(pte))); +} + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE +static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) +{ + pmd_t pmd = pfn_pmd(pfn, prot); + + WARN_ON(!pmd_same(pmd, pmd)); + WARN_ON(!pmd_young(pmd_mkyoung(pmd))); + WARN_ON(!pmd_dirty(pmd_mkdirty(pmd))); + WARN_ON(!pmd_write(pmd_mkwrite(pmd))); + WARN_ON(pmd_young(pmd_mkold(pmd))); + WARN_ON(pmd_dirty(pmd_mkclean(pmd))); + WARN_ON(pmd_write(pmd_wrprotect(pmd))); + /* + * A huge page does not point to next level page table + * entry. Hence this must qualify as pmd_bad(). + */ + WARN_ON(!pmd_bad(pmd_mkhuge(pmd))); +} +#else +static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { } +#endif + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) +{ + pud_t pud = pfn_pud(pfn, prot); + + WARN_ON(!pud_same(pud, pud)); + WARN_ON(!pud_young(pud_mkyoung(pud))); + WARN_ON(!pud_write(pud_mkwrite(pud))); + WARN_ON(pud_write(pud_wrprotect(pud))); + WARN_ON(pud_young(pud_mkold(pud))); + + if (mm_pmd_folded(mm) || __is_defined(ARCH_HAS_4LEVEL_HACK)) + return; + + /* + * A huge page does not point to next level page table + * entry. Hence this must qualify as pud_bad(). + */ + WARN_ON(!pud_bad(pud_mkhuge(pud))); +} +#else +static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { } +#endif + +static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot) +{ + p4d_t p4d; + + memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t)); + WARN_ON(!p4d_same(p4d, p4d)); +} + +static void __init pgd_basic_tests(unsigned long pfn, pgprot_t prot) +{ + pgd_t pgd; + + memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t)); + WARN_ON(!pgd_same(pgd, pgd)); +} + +#ifndef __ARCH_HAS_4LEVEL_HACK +static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) +{ + pud_t pud = READ_ONCE(*pudp); + + if (mm_pmd_folded(mm)) + return; + + pud = __pud(pud_val(pud) | RANDOM_ORVALUE); + WRITE_ONCE(*pudp, pud); + pud_clear(pudp); + pud = READ_ONCE(*pudp); + WARN_ON(!pud_none(pud)); +} + +static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp, + pmd_t *pmdp) +{ + pud_t pud; + + if (mm_pmd_folded(mm)) + return; + /* + * This entry points to next level page table page. + * Hence this must not qualify as pud_bad(). + */ + pmd_clear(pmdp); + pud_clear(pudp); + pud_populate(mm, pudp, pmdp); + pud = READ_ONCE(*pudp); + WARN_ON(pud_bad(pud)); +} +#else +static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { } +static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp, + pmd_t *pmdp) +{ +} +#endif + +#ifndef __ARCH_HAS_5LEVEL_HACK +static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) +{ + p4d_t p4d = READ_ONCE(*p4dp); + + if (mm_pud_folded(mm)) + return; + + p4d = __p4d(p4d_val(p4d) | RANDOM_ORVALUE); + WRITE_ONCE(*p4dp, p4d); + p4d_clear(p4dp); + p4d = READ_ONCE(*p4dp); + WARN_ON(!p4d_none(p4d)); +} + +static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, + pud_t *pudp) +{ + p4d_t p4d; + + if (mm_pud_folded(mm)) + return; + + /* + * This entry points to next level page table page. + * Hence this must not qualify as p4d_bad(). + */ + pud_clear(pudp); + p4d_clear(p4dp); + p4d_populate(mm, p4dp, pudp); + p4d = READ_ONCE(*p4dp); + WARN_ON(p4d_bad(p4d)); +} + +static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) +{ + pgd_t pgd = READ_ONCE(*pgdp); + + if (mm_p4d_folded(mm)) + return; + + pgd = __pgd(pgd_val(pgd) | RANDOM_ORVALUE); + WRITE_ONCE(*pgdp, pgd); + pgd_clear(pgdp); + pgd = READ_ONCE(*pgdp); + WARN_ON(!pgd_none(pgd)); +} + +static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, + p4d_t *p4dp) +{ + pgd_t pgd; + + if (mm_p4d_folded(mm)) + return; + + /* + * This entry points to next level page table page. + * Hence this must not qualify as pgd_bad(). + */ + p4d_clear(p4dp); + pgd_clear(pgdp); + pgd_populate(mm, pgdp, p4dp); + pgd = READ_ONCE(*pgdp); + WARN_ON(pgd_bad(pgd)); +} +#else +static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) { } +static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) { } +static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, + pud_t *pudp) +{ +} +static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, + p4d_t *p4dp) +{ +} +#endif + +static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep) +{ + pte_t pte = READ_ONCE(*ptep); + + pte = __pte(pte_val(pte) | RANDOM_ORVALUE); + WRITE_ONCE(*ptep, pte); + pte_clear(mm, 0, ptep); + pte = READ_ONCE(*ptep); + WARN_ON(!pte_none(pte)); +} + +static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp) +{ + pmd_t pmd = READ_ONCE(*pmdp); + + pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE); + WRITE_ONCE(*pmdp, pmd); + pmd_clear(pmdp); + pmd = READ_ONCE(*pmdp); + WARN_ON(!pmd_none(pmd)); +} + +static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp, + pgtable_t pgtable) +{ + pmd_t pmd; + + /* + * This entry points to next level page table page. + * Hence this must not qualify as pmd_bad(). + */ + pmd_clear(pmdp); + pmd_populate(mm, pmdp, pgtable); + pmd = READ_ONCE(*pmdp); + WARN_ON(pmd_bad(pmd)); +} + +static unsigned long __init get_random_vaddr(void) +{ + unsigned long random_vaddr, random_pages, total_user_pages; + + total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE; + + random_pages = get_random_long() % total_user_pages; + random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE; + + WARN_ON((random_vaddr > TASK_SIZE) || + (random_vaddr < FIRST_USER_ADDRESS)); + return random_vaddr; +} + +void __init debug_vm_pgtable(void) +{ + struct mm_struct *mm; + pgd_t *pgdp; + p4d_t *p4dp, *saved_p4dp; + pud_t *pudp, *saved_pudp; + pmd_t *pmdp, *saved_pmdp, pmd; + pte_t *ptep; + pgtable_t saved_ptep; + pgprot_t prot; + phys_addr_t paddr; + unsigned long vaddr, pte_aligned, pmd_aligned; + unsigned long pud_aligned, p4d_aligned, pgd_aligned; + + prot = vm_get_page_prot(VMFLAGS); + vaddr = get_random_vaddr(); + mm = mm_alloc(); + if (!mm) { + pr_err("mm_struct allocation failed\n"); + return; + } + + /* + * PFN for mapping at PTE level is determined from a standard kernel + * text symbol. But pfns for higher page table levels are derived by + * masking lower bits of this real pfn. These derived pfns might not + * exist on the platform but that does not really matter as pfn_pxx() + * helpers will still create appropriate entries for the test. This + * helps avoid large memory block allocations to be used for mapping + * at higher page table levels. + */ + WARN_ON(!virt_addr_valid(&start_kernel)); + paddr = __pa(&start_kernel); + + pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT; + pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT; + pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT; + p4d_aligned = (paddr & P4D_MASK) >> PAGE_SHIFT; + pgd_aligned = (paddr & PGDIR_MASK) >> PAGE_SHIFT; + + pgdp = pgd_offset(mm, vaddr); + p4dp = p4d_alloc(mm, pgdp, vaddr); + pudp = pud_alloc(mm, p4dp, vaddr); + pmdp = pmd_alloc(mm, pudp, vaddr); + ptep = pte_alloc_map(mm, pmdp, vaddr); + + /* + * Save all the page table page addresses as the page table + * entries will be used for testing with random or garbage + * values. These saved addresses will be used for freeing + * page table pages. + */ + pmd = READ_ONCE(*pmdp); + saved_p4dp = p4d_offset(pgdp, 0UL); + saved_pudp = pud_offset(p4dp, 0UL); + saved_pmdp = pmd_offset(pudp, 0UL); + saved_ptep = pmd_pgtable(pmd); + + pte_basic_tests(pte_aligned, prot); + pmd_basic_tests(pmd_aligned, prot); + pud_basic_tests(pud_aligned, prot); + p4d_basic_tests(p4d_aligned, prot); + pgd_basic_tests(pgd_aligned, prot); + + pte_clear_tests(mm, ptep); + pmd_clear_tests(mm, pmdp); + pud_clear_tests(mm, pudp); + p4d_clear_tests(mm, p4dp); + pgd_clear_tests(mm, pgdp); + + pte_unmap(ptep); + + pmd_populate_tests(mm, pmdp, saved_ptep); + pud_populate_tests(mm, pudp, saved_pmdp); + p4d_populate_tests(mm, p4dp, saved_pudp); + pgd_populate_tests(mm, pgdp, saved_p4dp); + + p4d_free(mm, saved_p4dp); + pud_free(mm, saved_pudp); + pmd_free(mm, saved_pmdp); + pte_free(mm, saved_ptep); + + mm_dec_nr_puds(mm); + mm_dec_nr_pmds(mm); + mm_dec_nr_ptes(mm); + __mmdrop(mm); +}