From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30B16CA9EA0 for ; Tue, 22 Oct 2019 11:23:17 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5670120B7C for ; Tue, 22 Oct 2019 11:23:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5670120B7C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46yB2T4QhmzDqKN for ; Tue, 22 Oct 2019 22:23:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=anshuman.khandual@arm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Received: from foss.arm.com (unknown [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 46y9x81XjKzDqKN for ; Tue, 22 Oct 2019 22:18:33 +1100 (AEDT) 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 D56B51000; Tue, 22 Oct 2019 04:18:21 -0700 (PDT) Received: from [10.162.40.145] (p8cg001049571a15.blr.arm.com [10.162.40.145]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5A0F93F718; Tue, 22 Oct 2019 04:18:09 -0700 (PDT) Subject: Re: [PATCH V7] mm/debug: Add tests validating architecture page table helpers To: Christophe Leroy , linux-mm@kvack.org References: <1571625739-29943-1-git-send-email-anshuman.khandual@arm.com> <1571625739-29943-2-git-send-email-anshuman.khandual@arm.com> <535564eb-65ea-69ab-977d-0038a9e4f785@c-s.fr> From: Anshuman Khandual Message-ID: Date: Tue, 22 Oct 2019 16:48:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <535564eb-65ea-69ab-977d-0038a9e4f785@c-s.fr> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List 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 , Heiko Carstens , Michal Hocko , Dave Hansen , Paul Mackerras , sparclinux@vger.kernel.org, Thomas Gleixner , linux-s390@vger.kernel.org, Jason Gunthorpe , x86@kernel.org, Russell King - ARM Linux , Matthew Wilcox , Steven Price , Tetsuo Handa , Gerald Schaefer , linux-snps-arc@lists.infradead.org, Ingo Molnar , Kees Cook , Masahiro Yamada , Mark Brown , "Kirill A . Shutemov" , Dan Williams , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, 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" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 10/22/2019 12:41 PM, Christophe Leroy wrote: > > > On 10/21/2019 02:42 AM, Anshuman Khandual wrote: >> 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 >> --- > > The cover letter have the exact same title as this patch. I think a cover letter is not necessary for a singleton series. Right, but it became singleton series in this version :) > > The history (and any other information you don't want to include in the commit message) can be added here, below the '---'. That way it is in the mail but won't be included in the commit. I was aware about that but the change log here was big, hence just choose to have that separately in a cover letter. As you said, I guess the cover letter is probably not required anymore. Will add it here in the patch, next time around. > >> .../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 | > > Say ok on ppc32 Will do. > >> + | 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/powerpc/Kconfig b/arch/powerpc/Kconfig > index 3e56c9c2f16e..c50d7cfa566b 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -120,6 +120,7 @@ config PPC > # > select ARCH_32BIT_OFF_T if PPC32 > select ARCH_HAS_DEBUG_VIRTUAL > + select ARCH_HAS_DEBUG_VM_PGTABLE if PPC32 > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > > Will add this. >> 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. >> + > > Would be nice to have that one also indented like the other DEBUG_VM_XXXXX (see below). > > Stack utilization instrumentation (DEBUG_STACK_USAGE) [N/y/?] n > Debug VM (DEBUG_VM) [N/y/?] (NEW) y > Debug VMA caching (DEBUG_VM_VMACACHE) [N/y/?] (NEW) > Debug VM red-black trees (DEBUG_VM_RB) [N/y/?] (NEW) > Debug page-flags operations (DEBUG_VM_PGFLAGS) [N/y/?] (NEW) > Debug arch page table for semantics compliance (DEBUG_VM_PGTABLE) [N/y/?] (NEW) > Debug VM translations (DEBUG_VIRTUAL) [N/y/?] n > > > For that, just move config ARCH_HAS_DEBUG_VM_PGTABLE somewhere else, maybe before DEBUG_VM or just after DEBUG_VM_PGTABLE Initially I had ARCH_HAS_DEBUG_VM_PGTABLE after DEBUG_VM_PGTABLE but reversed that because of it's dependency. So will probably move it before DEBUG_VM. > > >> 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; > > I think an information message would be nice: > > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index 9472566b7e53..ed7cc3dfc968 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -313,6 +313,8 @@ void __init debug_vm_pgtable(void) > unsigned long vaddr, pte_aligned, pmd_aligned; > unsigned long pud_aligned, p4d_aligned, pgd_aligned; > > + pr_info("Validating architecture page table helpers\n"); > + > prot = vm_get_page_prot(VMFLAGS); > vaddr = get_random_vaddr(); > mm = mm_alloc(); Sure, will add. Thanks ! > > Christophe > >> + >> + 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); >> +} >> >