| Message ID | 1571625739-29943-2-git-send-email-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [V7] mm/debug: Add tests validating architecture page table helpers | expand |
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 <akpm@linux-foundation.org> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> > Cc: Jason Gunthorpe <jgg@ziepe.ca> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Mark Brown <broonie@kernel.org> > Cc: Steven Price <Steven.Price@arm.com> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Sri Krishna chowdary <schowdary@nvidia.com> > Cc: Dave Hansen <dave.hansen@intel.com> > Cc: Russell King - ARM Linux <linux@armlinux.org.uk> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Vineet Gupta <vgupta@synopsys.com> > Cc: James Hogan <jhogan@kernel.org> > Cc: Paul Burton <paul.burton@mips.com> > Cc: Ralf Baechle <ralf@linux-mips.org> > Cc: Kirill A. Shutemov <kirill@shutemov.name> > Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> > Cc: Christophe Leroy <christophe.leroy@c-s.fr> > Cc: Ingo Molnar <mingo@kernel.org> > 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 <christophe.leroy@c-s.fr> #PPC32 > Suggested-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- The cover letter have the exact same title as this patch. I think a cover letter is not necessary for a singleton series. 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. > .../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 > + | 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 > 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 > 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 <anshuman.khandual@arm.com> > + */ > +#define pr_fmt(fmt) "arch_pgtable_test: %s " fmt, __func__ > + > +#include <linux/gfp.h> > +#include <linux/highmem.h> > +#include <linux/hugetlb.h> > +#include <linux/kernel.h> > +#include <linux/kconfig.h> > +#include <linux/mm.h> > +#include <linux/mman.h> > +#include <linux/mm_types.h> > +#include <linux/module.h> > +#include <linux/pfn_t.h> > +#include <linux/printk.h> > +#include <linux/random.h> > +#include <linux/spinlock.h> > +#include <linux/swap.h> > +#include <linux/swapops.h> > +#include <linux/start_kernel.h> > +#include <linux/sched/mm.h> > +#include <asm/pgalloc.h> > +#include <asm/pgtable.h> > + > +/* > + * 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(); 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); > +} >
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 <akpm@linux-foundation.org> >> Cc: Vlastimil Babka <vbabka@suse.cz> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> >> Cc: Jason Gunthorpe <jgg@ziepe.ca> >> Cc: Dan Williams <dan.j.williams@intel.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Michal Hocko <mhocko@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: Mark Brown <broonie@kernel.org> >> Cc: Steven Price <Steven.Price@arm.com> >> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> >> Cc: Kees Cook <keescook@chromium.org> >> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Sri Krishna chowdary <schowdary@nvidia.com> >> Cc: Dave Hansen <dave.hansen@intel.com> >> Cc: Russell King - ARM Linux <linux@armlinux.org.uk> >> Cc: Michael Ellerman <mpe@ellerman.id.au> >> Cc: Paul Mackerras <paulus@samba.org> >> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> >> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> >> Cc: "David S. Miller" <davem@davemloft.net> >> Cc: Vineet Gupta <vgupta@synopsys.com> >> Cc: James Hogan <jhogan@kernel.org> >> Cc: Paul Burton <paul.burton@mips.com> >> Cc: Ralf Baechle <ralf@linux-mips.org> >> Cc: Kirill A. Shutemov <kirill@shutemov.name> >> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> >> Cc: Christophe Leroy <christophe.leroy@c-s.fr> >> Cc: Ingo Molnar <mingo@kernel.org> >> 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 <christophe.leroy@c-s.fr> #PPC32 >> Suggested-by: Catalin Marinas <catalin.marinas@arm.com> >> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >> --- > > 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 <anshuman.khandual@arm.com> >> + */ >> +#define pr_fmt(fmt) "arch_pgtable_test: %s " fmt, __func__ >> + >> +#include <linux/gfp.h> >> +#include <linux/highmem.h> >> +#include <linux/hugetlb.h> >> +#include <linux/kernel.h> >> +#include <linux/kconfig.h> >> +#include <linux/mm.h> >> +#include <linux/mman.h> >> +#include <linux/mm_types.h> >> +#include <linux/module.h> >> +#include <linux/pfn_t.h> >> +#include <linux/printk.h> >> +#include <linux/random.h> >> +#include <linux/spinlock.h> >> +#include <linux/swap.h> >> +#include <linux/swapops.h> >> +#include <linux/start_kernel.h> >> +#include <linux/sched/mm.h> >> +#include <asm/pgalloc.h> >> +#include <asm/pgtable.h> >> + >> +/* >> + * 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); >> +} >> >
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 <anshuman.khandual@arm.com> + */ +#define pr_fmt(fmt) "arch_pgtable_test: %s " fmt, __func__ + +#include <linux/gfp.h> +#include <linux/highmem.h> +#include <linux/hugetlb.h> +#include <linux/kernel.h> +#include <linux/kconfig.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/mm_types.h> +#include <linux/module.h> +#include <linux/pfn_t.h> +#include <linux/printk.h> +#include <linux/random.h> +#include <linux/spinlock.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/start_kernel.h> +#include <linux/sched/mm.h> +#include <asm/pgalloc.h> +#include <asm/pgtable.h> + +/* + * 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); +}