388 lines
10 KiB
C
388 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* This kernel test validates architecture page table helpers and
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* accessors and helps in verifying their continued compliance with
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* expected generic MM semantics.
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*
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* Copyright (C) 2019 ARM Ltd.
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*
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* Author: Anshuman Khandual <anshuman.khandual@arm.com>
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*/
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#define pr_fmt(fmt) "debug_vm_pgtable: %s: " fmt, __func__
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#include <linux/gfp.h>
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#include <linux/highmem.h>
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#include <linux/hugetlb.h>
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#include <linux/kernel.h>
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#include <linux/kconfig.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/mm_types.h>
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#include <linux/module.h>
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#include <linux/pfn_t.h>
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#include <linux/printk.h>
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#include <linux/random.h>
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#include <linux/spinlock.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/start_kernel.h>
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#include <linux/sched/mm.h>
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#include <asm/pgalloc.h>
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#define VMFLAGS (VM_READ|VM_WRITE|VM_EXEC)
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/*
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* On s390 platform, the lower 4 bits are used to identify given page table
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* entry type. But these bits might affect the ability to clear entries with
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* pxx_clear() because of how dynamic page table folding works on s390. So
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* while loading up the entries do not change the lower 4 bits. It does not
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* have affect any other platform.
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*/
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#define S390_MASK_BITS 4
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#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
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#define RANDOM_NZVALUE GENMASK(7, 0)
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static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
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{
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pte_t pte = pfn_pte(pfn, prot);
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WARN_ON(!pte_same(pte, pte));
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WARN_ON(!pte_young(pte_mkyoung(pte_mkold(pte))));
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WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte))));
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WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte))));
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WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte))));
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WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte))));
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WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte))));
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}
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
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{
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pmd_t pmd = pfn_pmd(pfn, prot);
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if (!has_transparent_hugepage())
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return;
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WARN_ON(!pmd_same(pmd, pmd));
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WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd))));
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WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd))));
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WARN_ON(!pmd_write(pmd_mkwrite(pmd_wrprotect(pmd))));
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WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd))));
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WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd))));
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WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd))));
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/*
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* A huge page does not point to next level page table
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* entry. Hence this must qualify as pmd_bad().
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*/
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WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
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}
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#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
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static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot)
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{
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pud_t pud = pfn_pud(pfn, prot);
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if (!has_transparent_hugepage())
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return;
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WARN_ON(!pud_same(pud, pud));
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WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud))));
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WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud))));
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WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud))));
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WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud))));
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if (mm_pmd_folded(mm))
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return;
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/*
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* A huge page does not point to next level page table
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* entry. Hence this must qualify as pud_bad().
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*/
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WARN_ON(!pud_bad(pud_mkhuge(pud)));
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}
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#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
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static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
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#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
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#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
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static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { }
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static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot)
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{
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p4d_t p4d;
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memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t));
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WARN_ON(!p4d_same(p4d, p4d));
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}
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static void __init pgd_basic_tests(unsigned long pfn, pgprot_t prot)
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{
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pgd_t pgd;
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memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t));
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WARN_ON(!pgd_same(pgd, pgd));
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}
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#ifndef __PAGETABLE_PUD_FOLDED
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static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp)
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{
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pud_t pud = READ_ONCE(*pudp);
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if (mm_pmd_folded(mm))
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return;
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pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
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WRITE_ONCE(*pudp, pud);
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pud_clear(pudp);
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pud = READ_ONCE(*pudp);
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WARN_ON(!pud_none(pud));
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}
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static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
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pmd_t *pmdp)
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{
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pud_t pud;
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if (mm_pmd_folded(mm))
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return;
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/*
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* This entry points to next level page table page.
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* Hence this must not qualify as pud_bad().
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*/
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pmd_clear(pmdp);
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pud_clear(pudp);
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pud_populate(mm, pudp, pmdp);
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pud = READ_ONCE(*pudp);
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WARN_ON(pud_bad(pud));
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}
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#else /* !__PAGETABLE_PUD_FOLDED */
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static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { }
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static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
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pmd_t *pmdp)
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{
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}
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#endif /* PAGETABLE_PUD_FOLDED */
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#ifndef __PAGETABLE_P4D_FOLDED
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static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp)
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{
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p4d_t p4d = READ_ONCE(*p4dp);
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if (mm_pud_folded(mm))
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return;
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p4d = __p4d(p4d_val(p4d) | RANDOM_ORVALUE);
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WRITE_ONCE(*p4dp, p4d);
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p4d_clear(p4dp);
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p4d = READ_ONCE(*p4dp);
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WARN_ON(!p4d_none(p4d));
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}
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static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
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pud_t *pudp)
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{
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p4d_t p4d;
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if (mm_pud_folded(mm))
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return;
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/*
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* This entry points to next level page table page.
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* Hence this must not qualify as p4d_bad().
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*/
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pud_clear(pudp);
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p4d_clear(p4dp);
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p4d_populate(mm, p4dp, pudp);
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p4d = READ_ONCE(*p4dp);
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WARN_ON(p4d_bad(p4d));
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}
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static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp)
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{
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pgd_t pgd = READ_ONCE(*pgdp);
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if (mm_p4d_folded(mm))
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return;
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pgd = __pgd(pgd_val(pgd) | RANDOM_ORVALUE);
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WRITE_ONCE(*pgdp, pgd);
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pgd_clear(pgdp);
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pgd = READ_ONCE(*pgdp);
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WARN_ON(!pgd_none(pgd));
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}
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static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
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p4d_t *p4dp)
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{
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pgd_t pgd;
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if (mm_p4d_folded(mm))
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return;
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/*
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* This entry points to next level page table page.
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* Hence this must not qualify as pgd_bad().
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*/
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p4d_clear(p4dp);
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pgd_clear(pgdp);
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pgd_populate(mm, pgdp, p4dp);
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pgd = READ_ONCE(*pgdp);
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WARN_ON(pgd_bad(pgd));
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}
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#else /* !__PAGETABLE_P4D_FOLDED */
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static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) { }
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static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) { }
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static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
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pud_t *pudp)
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{
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}
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static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
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p4d_t *p4dp)
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{
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}
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#endif /* PAGETABLE_P4D_FOLDED */
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static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
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unsigned long vaddr)
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{
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pte_t pte = READ_ONCE(*ptep);
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pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
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set_pte_at(mm, vaddr, ptep, pte);
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barrier();
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pte_clear(mm, vaddr, ptep);
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pte = READ_ONCE(*ptep);
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WARN_ON(!pte_none(pte));
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}
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static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
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{
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pmd_t pmd = READ_ONCE(*pmdp);
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pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
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WRITE_ONCE(*pmdp, pmd);
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pmd_clear(pmdp);
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pmd = READ_ONCE(*pmdp);
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WARN_ON(!pmd_none(pmd));
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}
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static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
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pgtable_t pgtable)
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{
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pmd_t pmd;
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/*
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* This entry points to next level page table page.
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* Hence this must not qualify as pmd_bad().
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*/
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pmd_clear(pmdp);
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pmd_populate(mm, pmdp, pgtable);
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pmd = READ_ONCE(*pmdp);
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WARN_ON(pmd_bad(pmd));
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}
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static unsigned long __init get_random_vaddr(void)
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{
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unsigned long random_vaddr, random_pages, total_user_pages;
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total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE;
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random_pages = get_random_long() % total_user_pages;
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random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE;
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return random_vaddr;
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}
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static int __init debug_vm_pgtable(void)
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{
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struct mm_struct *mm;
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pgd_t *pgdp;
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p4d_t *p4dp, *saved_p4dp;
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pud_t *pudp, *saved_pudp;
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pmd_t *pmdp, *saved_pmdp, pmd;
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pte_t *ptep;
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pgtable_t saved_ptep;
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pgprot_t prot;
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phys_addr_t paddr;
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unsigned long vaddr, pte_aligned, pmd_aligned;
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unsigned long pud_aligned, p4d_aligned, pgd_aligned;
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spinlock_t *uninitialized_var(ptl);
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pr_info("Validating architecture page table helpers\n");
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prot = vm_get_page_prot(VMFLAGS);
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vaddr = get_random_vaddr();
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mm = mm_alloc();
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if (!mm) {
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pr_err("mm_struct allocation failed\n");
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return 1;
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}
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/*
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* PFN for mapping at PTE level is determined from a standard kernel
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* text symbol. But pfns for higher page table levels are derived by
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* masking lower bits of this real pfn. These derived pfns might not
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* exist on the platform but that does not really matter as pfn_pxx()
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* helpers will still create appropriate entries for the test. This
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* helps avoid large memory block allocations to be used for mapping
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* at higher page table levels.
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*/
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paddr = __pa_symbol(&start_kernel);
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pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT;
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pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
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pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
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p4d_aligned = (paddr & P4D_MASK) >> PAGE_SHIFT;
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pgd_aligned = (paddr & PGDIR_MASK) >> PAGE_SHIFT;
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WARN_ON(!pfn_valid(pte_aligned));
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pgdp = pgd_offset(mm, vaddr);
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p4dp = p4d_alloc(mm, pgdp, vaddr);
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pudp = pud_alloc(mm, p4dp, vaddr);
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pmdp = pmd_alloc(mm, pudp, vaddr);
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ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
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/*
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* Save all the page table page addresses as the page table
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* entries will be used for testing with random or garbage
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* values. These saved addresses will be used for freeing
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* page table pages.
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*/
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pmd = READ_ONCE(*pmdp);
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saved_p4dp = p4d_offset(pgdp, 0UL);
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saved_pudp = pud_offset(p4dp, 0UL);
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saved_pmdp = pmd_offset(pudp, 0UL);
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saved_ptep = pmd_pgtable(pmd);
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pte_basic_tests(pte_aligned, prot);
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pmd_basic_tests(pmd_aligned, prot);
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pud_basic_tests(pud_aligned, prot);
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p4d_basic_tests(p4d_aligned, prot);
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pgd_basic_tests(pgd_aligned, prot);
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pte_clear_tests(mm, ptep, vaddr);
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pmd_clear_tests(mm, pmdp);
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pud_clear_tests(mm, pudp);
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p4d_clear_tests(mm, p4dp);
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pgd_clear_tests(mm, pgdp);
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pte_unmap_unlock(ptep, ptl);
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pmd_populate_tests(mm, pmdp, saved_ptep);
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pud_populate_tests(mm, pudp, saved_pmdp);
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p4d_populate_tests(mm, p4dp, saved_pudp);
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pgd_populate_tests(mm, pgdp, saved_p4dp);
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p4d_free(mm, saved_p4dp);
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pud_free(mm, saved_pudp);
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pmd_free(mm, saved_pmdp);
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pte_free(mm, saved_ptep);
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mm_dec_nr_puds(mm);
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mm_dec_nr_pmds(mm);
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mm_dec_nr_ptes(mm);
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mmdrop(mm);
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return 0;
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}
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late_initcall(debug_vm_pgtable);
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