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Shutemov" To: Anshuman Khandual Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Greg Kroah-Hartman , Thomas Gleixner , Mike Rapoport , Jason Gunthorpe , Dan Williams , Peter Zijlstra , Michal Hocko , Mark Rutland , Mark Brown , Steven Price , Ard Biesheuvel , Masahiro Yamada , Kees Cook , Tetsuo Handa , Matthew Wilcox , Sri Krishna chowdary , Dave Hansen , Russell King - ARM Linux , Michael Ellerman , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , "David S. Miller" , Vineet Gupta , James Hogan , Paul Burton , Ralf Baechle , linux-snps-arc@lists.infradead.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] mm/pgtable/debug: Add test validating architecture page table helpers Message-ID: <20190904141950.ykoe3h7b4hcvnysu@box> References: <1567497706-8649-1-git-send-email-anshuman.khandual@arm.com> <1567497706-8649-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1567497706-8649-2-git-send-email-anshuman.khandual@arm.com> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 03, 2019 at 01:31:46PM +0530, Anshuman Khandual wrote: > This adds a test module which will validate architecture page table helpers > and accessors regarding compliance with generic MM semantics expectations. > This will help various architectures in validating changes to the existing > page table helpers or addition of new ones. > > Test page table and memory pages creating it's entries at various level are > all allocated from system memory with required alignments. If memory pages > with required size and alignment could not be allocated, then all depending > individual tests are skipped. See my comments below. > > 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: 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 > > Suggested-by: Catalin Marinas > Signed-off-by: Anshuman Khandual > --- > mm/Kconfig.debug | 14 ++ > mm/Makefile | 1 + > mm/arch_pgtable_test.c | 425 +++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 440 insertions(+) > create mode 100644 mm/arch_pgtable_test.c > > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 327b3ebf23bf..ce9c397f7b07 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -117,3 +117,17 @@ config DEBUG_RODATA_TEST > depends on STRICT_KERNEL_RWX > ---help--- > This option enables a testcase for the setting rodata read-only. > + > +config DEBUG_ARCH_PGTABLE_TEST > + bool "Test arch page table helpers for semantics compliance" > + depends on MMU > + depends on DEBUG_KERNEL > + help > + This options provides a kernel module which can be used to test > + architecture page table helper functions on various platform in > + verifying if they comply with expected generic MM semantics. This > + will help architectures code in making sure that any changes or > + new additions of these helpers will still conform to generic MM > + expected semantics. > + > + If unsure, say N. > diff --git a/mm/Makefile b/mm/Makefile > index d996846697ef..bb572c5aa8c5 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-$(CONFIG_DEBUG_ARCH_PGTABLE_TEST) += arch_pgtable_test.o > obj-$(CONFIG_PAGE_OWNER) += page_owner.o > obj-$(CONFIG_CLEANCACHE) += cleancache.o > obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o > diff --git a/mm/arch_pgtable_test.c b/mm/arch_pgtable_test.c > new file mode 100644 > index 000000000000..f15be8a73723 > --- /dev/null > +++ b/mm/arch_pgtable_test.c > @@ -0,0 +1,425 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * This kernel module validates architecture page table helpers & > + * accessors and helps in verifying their continued compliance with > + * 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 > + > +/* > + * 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 VADDR_TEST (PGDIR_SIZE + PUD_SIZE + PMD_SIZE + PAGE_SIZE) What is special about this address? How do you know if it is not occupied yet? > +#define VMA_TEST_FLAGS (VM_READ|VM_WRITE|VM_EXEC) > +#define RANDOM_NZVALUE (0xbe) > + > +static bool pud_aligned; > +static bool pmd_aligned; > + > +extern struct mm_struct *mm_alloc(void); > + > +static void pte_basic_tests(struct page *page, pgprot_t prot) > +{ > + pte_t pte = mk_pte(page, 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 pmd_basic_tests(struct page *page, pgprot_t prot) > +{ > + pmd_t pmd; > + > + /* > + * Memory block here must be PMD_SIZE aligned. Abort this > + * test in case we could not allocate such a memory block. > + */ > + if (!pmd_aligned) { > + pr_warn("Could not proceed with PMD tests\n"); > + return; > + } > + > + pmd = mk_pmd(page, 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 pmd_basic_tests(struct page *page, pgprot_t prot) { } > +#endif > + > +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD > +static void pud_basic_tests(struct page *page, pgprot_t prot) > +{ > + pud_t pud; > + > + /* > + * Memory block here must be PUD_SIZE aligned. Abort this > + * test in case we could not allocate such a memory block. > + */ > + if (!pud_aligned) { > + pr_warn("Could not proceed with PUD tests\n"); > + return; > + } > + > + pud = pfn_pud(page_to_pfn(page), 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 !defined(__PAGETABLE_PMD_FOLDED) && !defined(__ARCH_HAS_4LEVEL_HACK) > + /* > + * 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))); > +#endif > +} > +#else > +static void pud_basic_tests(struct page *page, pgprot_t prot) { } > +#endif > + > +static void p4d_basic_tests(struct page *page, pgprot_t prot) > +{ > + p4d_t p4d; > + > + memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t)); > + WARN_ON(!p4d_same(p4d, p4d)); > +} > + > +static void pgd_basic_tests(struct page *page, pgprot_t prot) > +{ > + pgd_t pgd; > + > + memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t)); > + WARN_ON(!pgd_same(pgd, pgd)); > +} > + > +#if !defined(__PAGETABLE_PMD_FOLDED) && !defined(__ARCH_HAS_4LEVEL_HACK) > +static void pud_clear_tests(pud_t *pudp) > +{ > + memset(pudp, RANDOM_NZVALUE, sizeof(pud_t)); > + pud_clear(pudp); > + WARN_ON(!pud_none(READ_ONCE(*pudp))); > +} > + > +static void pud_populate_tests(struct mm_struct *mm, pud_t *pudp, pmd_t *pmdp) > +{ > + /* > + * 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); > + WARN_ON(pud_bad(READ_ONCE(*pudp))); > +} > +#else > +static void pud_clear_tests(pud_t *pudp) { } > +static void pud_populate_tests(struct mm_struct *mm, pud_t *pudp, pmd_t *pmdp) > +{ > +} > +#endif > + > +#if !defined(__PAGETABLE_PUD_FOLDED) && !defined(__ARCH_HAS_5LEVEL_HACK) > +static void p4d_clear_tests(p4d_t *p4dp) > +{ > + memset(p4dp, RANDOM_NZVALUE, sizeof(p4d_t)); > + p4d_clear(p4dp); > + WARN_ON(!p4d_none(READ_ONCE(*p4dp))); > +} > + > +static void p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp) > +{ > + /* > + * 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); > + WARN_ON(p4d_bad(READ_ONCE(*p4dp))); > +} > +#else > +static void p4d_clear_tests(p4d_t *p4dp) { } > +static void p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp) > +{ > +} > +#endif > + > +#ifndef __PAGETABLE_P4D_FOLDED > +static void pgd_clear_tests(pgd_t *pgdp) > +{ > + memset(pgdp, RANDOM_NZVALUE, sizeof(pgd_t)); > + pgd_clear(pgdp); > + WARN_ON(!pgd_none(READ_ONCE(*pgdp))); > +} > + > +static void pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) > +{ > + /* > + * 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); > + WARN_ON(pgd_bad(READ_ONCE(*pgdp))); > +} > +#else > +static void pgd_clear_tests(pgd_t *pgdp) { } > +static void pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) > +{ > +} > +#endif This will not work if p4d is folded at runtime. Like for x86-64 and s390. Here's the fixup. It should work for both x86-64 and s390, but I only tested on x86-64: diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 52e5f5f2240d..b882792a3999 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -40,6 +40,8 @@ static inline bool pgtable_l5_enabled(void) #define pgtable_l5_enabled() 0 #endif /* CONFIG_X86_5LEVEL */ +#define mm_p4d_folded(mm) (!pgtable_l5_enabled()) + extern unsigned int pgdir_shift; extern unsigned int ptrs_per_p4d; diff --git a/mm/arch_pgtable_test.c b/mm/arch_pgtable_test.c index f15be8a73723..206fe3334a28 100644 --- a/mm/arch_pgtable_test.c +++ b/mm/arch_pgtable_test.c @@ -193,9 +193,11 @@ static void p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp) } #endif -#ifndef __PAGETABLE_P4D_FOLDED static void pgd_clear_tests(pgd_t *pgdp) { + if (mm_p4d_folded(mm)) + return; + memset(pgdp, RANDOM_NZVALUE, sizeof(pgd_t)); pgd_clear(pgdp); WARN_ON(!pgd_none(READ_ONCE(*pgdp))); @@ -203,6 +205,9 @@ static void pgd_clear_tests(pgd_t *pgdp) static void pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) { + if (mm_p4d_folded(mm)) + return; + /* * This entry points to next level page table page. * Hence this must not qualify as pgd_bad(). @@ -212,12 +217,6 @@ static void pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) pgd_populate(mm, pgdp, p4dp); WARN_ON(pgd_bad(READ_ONCE(*pgdp))); } -#else -static void pgd_clear_tests(pgd_t *pgdp) { } -static void pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) -{ -} -#endif static void pte_clear_tests(pte_t *ptep) { > + > +static void pte_clear_tests(pte_t *ptep) > +{ > + memset(ptep, RANDOM_NZVALUE, sizeof(pte_t)); > + pte_clear(NULL, 0, ptep); > + WARN_ON(!pte_none(READ_ONCE(*ptep))); > +} > + > +static void pmd_clear_tests(pmd_t *pmdp) > +{ > + memset(pmdp, RANDOM_NZVALUE, sizeof(pmd_t)); > + pmd_clear(pmdp); > + WARN_ON(!pmd_none(READ_ONCE(*pmdp))); > +} > + > +static void pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp, > + pgtable_t pgtable) > +{ > + /* > + * 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); > + WARN_ON(pmd_bad(READ_ONCE(*pmdp))); > +} > + > +static bool pfn_range_valid(struct zone *z, unsigned long start_pfn, > + unsigned long nr_pages) > +{ > + unsigned long i, end_pfn = start_pfn + nr_pages; > + struct page *page; > + > + for (i = start_pfn; i < end_pfn; i++) { > + if (!pfn_valid(i)) > + return false; > + > + page = pfn_to_page(i); > + > + if (page_zone(page) != z) > + return false; > + > + if (PageReserved(page)) > + return false; > + > + if (page_count(page) > 0) > + return false; > + > + if (PageHuge(page)) > + return false; > + } > + return true; > +} > + > +static struct page *alloc_gigantic_page(nodemask_t *nodemask, > + int nid, gfp_t gfp_mask, int order) > +{ > + struct zonelist *zonelist; > + struct zone *zone; > + struct zoneref *z; > + enum zone_type zonesel; > + unsigned long ret, pfn, flags, nr_pages; > + > + nr_pages = 1UL << order; > + zonesel = gfp_zone(gfp_mask); > + zonelist = node_zonelist(nid, gfp_mask); > + for_each_zone_zonelist_nodemask(zone, z, zonelist, zonesel, nodemask) { > + spin_lock_irqsave(&zone->lock, flags); > + pfn = ALIGN(zone->zone_start_pfn, nr_pages); > + while (zone_spans_pfn(zone, pfn + nr_pages - 1)) { > + if (pfn_range_valid(zone, pfn, nr_pages)) { > + spin_unlock_irqrestore(&zone->lock, flags); > + ret = alloc_contig_range(pfn, pfn + nr_pages, > + MIGRATE_MOVABLE, > + gfp_mask); > + if (!ret) > + return pfn_to_page(pfn); > + spin_lock_irqsave(&zone->lock, flags); > + } > + pfn += nr_pages; > + } > + spin_unlock_irqrestore(&zone->lock, flags); > + } > + return NULL; > +} > + > +static struct page *alloc_mapped_page(void) > +{ > + gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO; > + struct page *page = NULL; > + > + page = alloc_gigantic_page(&node_states[N_MEMORY], first_memory_node, > + gfp_mask, get_order(PUD_SIZE)); > + if (page) { > + pud_aligned = true; > + pmd_aligned = true; > + return page; > + } > + > + page = alloc_pages(gfp_mask, get_order(PMD_SIZE)); > + if (page) { > + pmd_aligned = true; > + return page; > + } > + return alloc_page(gfp_mask); > +} > + > +static void free_mapped_page(struct page *page) > +{ > + if (pud_aligned) { > + unsigned long pfn = page_to_pfn(page); > + > + free_contig_range(pfn, 1ULL << get_order(PUD_SIZE)); > + return; > + } > + > + if (pmd_aligned) { > + int order = get_order(PMD_SIZE); > + > + free_pages((unsigned long)page_address(page), order); > + return; > + } > + free_page((unsigned long)page_address(page)); > +} > + > +static int __init arch_pgtable_tests_init(void) > +{ > + struct mm_struct *mm; > + struct page *page; > + pgd_t *pgdp; > + p4d_t *p4dp, *saved_p4dp; > + pud_t *pudp, *saved_pudp; > + pmd_t *pmdp, *saved_pmdp; > + pte_t *ptep, *saved_ptep; > + pgprot_t prot = vm_get_page_prot(VMA_TEST_FLAGS); > + unsigned long vaddr = VADDR_TEST; > + > + mm = mm_alloc(); > + if (!mm) { > + pr_err("mm_struct allocation failed\n"); > + return 1; > + } > + > + page = alloc_mapped_page(); > + if (!page) { > + pr_err("memory allocation failed\n"); > + return 1; > + } > + > + 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. > + */ > + saved_p4dp = p4d_offset(pgdp, 0UL); > + saved_pudp = pud_offset(p4dp, 0UL); > + saved_pmdp = pmd_offset(pudp, 0UL); > + saved_ptep = pte_offset_map(pmdp, 0UL); > + > + pte_basic_tests(page, prot); > + pmd_basic_tests(page, prot); > + pud_basic_tests(page, prot); > + p4d_basic_tests(page, prot); > + pgd_basic_tests(page, prot); > + > + pte_clear_tests(ptep); > + pmd_clear_tests(pmdp); > + pud_clear_tests(pudp); > + p4d_clear_tests(p4dp); > + pgd_clear_tests(pgdp); > + > + pmd_populate_tests(mm, pmdp, (pgtable_t) page); This is not correct for architectures that defines pgtable_t as pte_t pointer, not struct page pointer. > + pud_populate_tests(mm, pudp, pmdp); > + p4d_populate_tests(mm, p4dp, pudp); > + pgd_populate_tests(mm, pgdp, p4dp); This is wrong. All p?dp points to the second entry in page table entry. This is not valid pointer for page table and triggers p?d_bad() on x86. Use saved_p?dp instead. > + > + p4d_free(mm, saved_p4dp); > + pud_free(mm, saved_pudp); > + pmd_free(mm, saved_pmdp); > + pte_free(mm, (pgtable_t) virt_to_page(saved_ptep)); > + > + mm_dec_nr_puds(mm); > + mm_dec_nr_pmds(mm); > + mm_dec_nr_ptes(mm); > + __mmdrop(mm); > + > + free_mapped_page(page); > + return 0; > +} > + > +static void __exit arch_pgtable_tests_exit(void) { } > + > +module_init(arch_pgtable_tests_init); > +module_exit(arch_pgtable_tests_exit); > + > +MODULE_LICENSE("GPL v2"); > +MODULE_AUTHOR("Anshuman Khandual "); > +MODULE_DESCRIPTION("Test archicture page table helpers"); > -- > 2.20.1 > > -- Kirill A. Shutemov