On Mon, 2020-02-17 at 08:47 +0530, 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 > inside kernel_init() right after async_synchronize_full(). > > This test gets built and run when CONFIG_DEBUG_VM_PGTABLE is selected. Any > architecture, which is willing to subscribe this test will need to select > ARCH_HAS_DEBUG_VM_PGTABLE. For now this is limited to arc, arm64, x86, s390 > and ppc32 platforms where the test is known to build and run successfully. > Going forward, other architectures too can subscribe the test after fixing > any build or runtime problems with their page table helpers. Meanwhile for > better platform coverage, the test can also be enabled with CONFIG_EXPERT > even without ARCH_HAS_DEBUG_VM_PGTABLE. > > 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. How useful is this that straightly crash the powerpc? [ 23.263425][ T1] debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers [ 23.263625][ T1] ------------[ cut here ]------------ [ 23.263649][ T1] kernel BUG at arch/powerpc/mm/pgtable.c:274! [ 23.263675][ T1] Oops: Exception in kernel mode, sig: 5 [#1] [ 23.263698][ T1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV [ 23.263731][ T1] Modules linked in: [ 23.263752][ T1] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc3-next- 20200226 #1 [ 23.263776][ T1] NIP: c00000000007308c LR: c00000000103dbd8 CTR: 0000000000000000 [ 23.263810][ T1] REGS: c00000003ddaf9c0 TRAP: 0700 Not tainted (5.6.0- rc3-next-20200226) [ 23.263846][ T1] MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 22000228 XER: 00000000 [ 23.263888][ T1] CFAR: c000000000073030 IRQMASK: 0 [ 23.263888][ T1] GPR00: c00000000103dbd8 c00000003ddafc50 c000000001656f00 c000001d7b4ca080 [ 23.263888][ T1] GPR04: 0000000000000000 0000000000000009 c00000003ddafc04 0000000000000000 [ 23.263888][ T1] GPR08: f0ffffffffffffff 0000000000000001 c0000000016279d0 00000000000a0000 [ 23.263888][ T1] GPR12: 0000000000000000 c000001fffffae00 c000000000010e84 0000000000000000 [ 23.263888][ T1] GPR16: 0000000000000000 8000000000000105 0000000000000100 c000000001689a18 [ 23.263888][ T1] GPR20: c00020032c660000 c00020032c620000 c000000001716030 c00020032c600000 [ 23.263888][ T1] GPR24: 000000000000000d c000000001716030 c000001d7b4ca080 c000000001716040 [ 23.263888][ T1] GPR28: c000000001716038 0000000000000000 0000000000000000 0000000000000000 [ 23.264122][ T1] NIP [c00000000007308c] assert_pte_locked+0x11c/0x320 [ 23.264154][ T1] LR [c00000000103dbd8] debug_vm_pgtable+0x770/0xb7c [ 23.264186][ T1] Call Trace: [ 23.264206][ T1] [c00000003ddafc50] [c000000000999760] _raw_spin_unlock+0x30/0x70 (unreliable) [ 23.264244][ T1] [c00000003ddafcd0] [c00000000103d924] debug_vm_pgtable+0x4bc/0xb7c [ 23.264279][ T1] [c00000003ddafdb0] [c000000000010eac] kernel_init+0x30/0x194 [ 23.264315][ T1] [c00000003ddafe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74 [ 23.264349][ T1] Instruction dump: [ 23.264368][ T1] 60000000 3be00001 7fbef436 eafa0040 7fffc030 3bffffff 7fff07b4 7ffff038 [ 23.264409][ T1] 7bff1f24 7d37f82a 7d290074 7929d182 <0b090000> ebdb0000 e93c0000 7fde4a14 [ 23.264460][ T1] ---[ end trace 72d2931022e9ab24 ]--- [ 23.627311][ T1] [ 24.627407][ T1] Kernel panic - not syncing: Fatal exception [ 26.5 > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx> > Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Will Deacon <will@xxxxxxxxxx> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Cc: Paul Mackerras <paulus@xxxxxxxxx> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx> > Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> > Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> > Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> > Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> > Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx > Cc: linux-s390@xxxxxxxxxxxxxxx > Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx > Cc: x86@xxxxxxxxxx > Cc: linux-arch@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > > Suggested-by: Catalin Marinas <catalin.marinas@xxxxxxx> > Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> > Tested-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx> # s390 > Tested-by: Christophe Leroy <christophe.leroy@xxxxxx> # ppc32 > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx> > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> > --- > This adds a test validation for architecture exported page table helpers. > Patch adds basic transformation tests at various levels of the page table. > > This test was originally suggested by Catalin during arm64 THP migration > RFC discussion earlier. Going forward it can include more specific tests > with respect to various generic MM functions like THP, HugeTLB etc and > platform specific tests. > > https://lore.kernel.org/linux-mm/20190628102003.GA56463@xxxxxxxxxxxxxxxxxxxx/ > > Needs to be applied on linux V5.6-rc2 > > Changes in V14: > > - Disabled DEBUG_VM_PGFLAGS for IA64 and ARM (32 Bit) per Andrew and Christophe > - Updated DEBUG_VM_PGFLAGS documentation wrt EXPERT and disabled platforms > - Updated RANDOM_[OR|NZ]VALUE open encodings with GENMASK() per Catalin > - Updated s390 constraint bits from 12 to 4 (S390_MASK_BITS) per Gerald > - Updated in-code documentation for RANDOM_ORVALUE per Gerald > - Updated pxx_basic_tests() to use invert functions first per Catalin > - Dropped ARCH_HAS_4LEVEL_HACK check from pud_basic_tests() > - Replaced __ARCH_HAS_[4|5]LEVEL_HACK with __PAGETABLE_[PUD|P4D]_FOLDED per Catalin > - Trimmed the CC list on the commit message per Catalin > > Changes in V13: (https://patchwork.kernel.org/project/linux-mm/list/?series=237125) > > - Subscribed s390 platform and updated debug-vm-pgtable/arch-support.txt per Gerald > - Dropped keyword 'extern' from debug_vm_pgtable() declaration per Christophe > - Moved debug_vm_pgtable() declarations to <linux/mmdebug.h> per Christophe > - Moved debug_vm_pgtable() call site into kernel_init() per Christophe > - Changed CONFIG_DEBUG_VM_PGTABLE rules per Christophe > - Updated commit to include new supported platforms and changed config selection > > Changes in V12: (https://patchwork.kernel.org/project/linux-mm/list/?series=233905) > > - Replaced __mmdrop() with mmdrop() > - Enable ARCH_HAS_DEBUG_VM_PGTABLE on X86 for non CONFIG_X86_PAE platforms as the > test procedure interfere with pre-allocated PMDs attached to the PGD resulting > in runtime failures with VM_BUG_ON() > > Changes in V11: (https://patchwork.kernel.org/project/linux-mm/list/?series=221135) > > - Rebased the patch on V5.4 > > Changes in V10: (https://patchwork.kernel.org/project/linux-mm/list/?series=205529) > > - Always enable DEBUG_VM_PGTABLE when DEBUG_VM is enabled per Ingo > - Added tags from Ingo > > Changes in V9: (https://patchwork.kernel.org/project/linux-mm/list/?series=201429) > > - Changed feature support enumeration for powerpc platforms per Christophe > - Changed config wrapper for basic_[pmd|pud]_tests() to enable ARC platform > - Enabled the test on ARC platform > > Changes in V8: (https://patchwork.kernel.org/project/linux-mm/list/?series=194297) > > - Enabled ARCH_HAS_DEBUG_VM_PGTABLE on PPC32 platform per Christophe > - Updated feature documentation as DEBUG_VM_PGTABLE is now enabled on PPC32 platform > - Moved ARCH_HAS_DEBUG_VM_PGTABLE earlier to indent it with DEBUG_VM per Christophe > - Added an information message in debug_vm_pgtable() per Christophe > - Dropped random_vaddr boundary condition checks per Christophe and Qian > - Replaced virt_addr_valid() check with pfn_valid() check in debug_vm_pgtable() > - Slightly changed pr_fmt(fmt) information > > Changes in V7: (https://patchwork.kernel.org/project/linux-mm/list/?series=193051) > > - Memory allocation and free routines for mapped pages have been droped > - Mapped pfns are derived from standard kernel text symbol per Matthew > - Moved debug_vm_pgtaable() after page_alloc_init_late() per Michal and Qian > - Updated the commit message per Michal > - Updated W=1 GCC warning problem on x86 per Qian Cai > - Addition of new alloc_contig_pages() helper has been submitted separately > > Changes in V6: (https://patchwork.kernel.org/project/linux-mm/list/?series=187589) > > - Moved alloc_gigantic_page_order() into mm/page_alloc.c per Michal > - Moved alloc_gigantic_page_order() within CONFIG_CONTIG_ALLOC in the test > - Folded Andrew's include/asm-generic/pgtable.h fix into the test patch 2/2 > > Changes in V5: (https://patchwork.kernel.org/project/linux-mm/list/?series=185991) > > - Redefined and moved X86 mm_p4d_folded() into a different header per Kirill/Ingo > - Updated the config option comment per Ingo and dropped 'kernel module' reference > - Updated the commit message and dropped 'kernel module' reference > - Changed DEBUG_ARCH_PGTABLE_TEST into DEBUG_VM_PGTABLE per Ingo > - Moved config option from mm/Kconfig.debug into lib/Kconfig.debug > - Renamed core test function arch_pgtable_tests() as debug_vm_pgtable() > - Renamed mm/arch_pgtable_test.c as mm/debug_vm_pgtable.c > - debug_vm_pgtable() gets called from kernel_init_freeable() after init_mm_internals() > - Added an entry in Documentation/features/debug/ per Ingo > - Enabled the test on arm64 and x86 platforms for now > > Changes in V4: (https://patchwork.kernel.org/project/linux-mm/list/?series=183465) > > - Disable DEBUG_ARCH_PGTABLE_TEST for ARM and IA64 platforms > > Changes in V3: (https://lore.kernel.org/patchwork/project/lkml/list/?series=411216) > > - Changed test trigger from module format into late_initcall() > - Marked all functions with __init to be freed after completion > - Changed all __PGTABLE_PXX_FOLDED checks as mm_pxx_folded() > - Folded in PPC32 fixes from Christophe > > Changes in V2: > > https://lore.kernel.org/linux-mm/1568268173-31302-1-git-send-email-anshuman.khandual@xxxxxxx/T/#t > > - Fixed small typo error in MODULE_DESCRIPTION() > - Fixed m64k build problems for lvalue concerns in pmd_xxx_tests() > - Fixed dynamic page table level folding problems on x86 as per Kirril > - Fixed second pointers during pxx_populate_tests() per Kirill and Gerald > - Allocate and free pte table with pte_alloc_one/pte_free per Kirill > - Modified pxx_clear_tests() to accommodate s390 lower 12 bits situation > - Changed RANDOM_NZVALUE value from 0xbe to 0xff > - Changed allocation, usage, free sequence for saved_ptep > - Renamed VMA_FLAGS as VMFLAGS > - Implemented a new method for random vaddr generation > - Implemented some other cleanups > - Dropped extern reference to mm_alloc() > - Created and exported new alloc_gigantic_page_order() > - Dropped the custom allocator and used new alloc_gigantic_page_order() > > Changes in V1: > > https://lore.kernel.org/linux-mm/1567497706-8649-1-git-send-email-anshuman.khandual@xxxxxxx/ > > - Added fallback mechanism for PMD aligned memory allocation failure > > Changes in RFC V2: > > https://lore.kernel.org/linux-mm/1565335998-22553-1-git-send-email-anshuman.khandual@xxxxxxx/T/#u > > - Moved test module and it's config from lib/ to mm/ > - Renamed config TEST_ARCH_PGTABLE as DEBUG_ARCH_PGTABLE_TEST > - Renamed file from test_arch_pgtable.c to arch_pgtable_test.c > - Added relevant MODULE_DESCRIPTION() and MODULE_AUTHOR() details > - Dropped loadable module config option > - Basic tests now use memory blocks with required size and alignment > - PUD aligned memory block gets allocated with alloc_contig_range() > - If PUD aligned memory could not be allocated it falls back on PMD aligned > memory block from page allocator and pud_* tests are skipped > - Clear and populate tests now operate on real in memory page table entries > - Dummy mm_struct gets allocated with mm_alloc() > - Dummy page table entries get allocated with [pud|pmd|pte]_alloc_[map]() > - Simplified [p4d|pgd]_basic_tests(), now has random values in the entries > > Original RFC V1: > > https://lore.kernel.org/linux-mm/1564037723-26676-1-git-send-email-anshuman.khandual@xxxxxxx/ > > > .../debug/debug-vm-pgtable/arch-support.txt | 35 ++ > arch/arc/Kconfig | 1 + > arch/arm64/Kconfig | 1 + > arch/powerpc/Kconfig | 1 + > arch/s390/Kconfig | 1 + > arch/x86/Kconfig | 1 + > arch/x86/include/asm/pgtable_64.h | 6 + > include/linux/mmdebug.h | 5 + > init/main.c | 2 + > lib/Kconfig.debug | 26 ++ > mm/Makefile | 1 + > mm/debug_vm_pgtable.c | 389 ++++++++++++++++++ > 12 files changed, 469 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 000000000000..64d0f9b15c49 > --- /dev/null > +++ b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt > @@ -0,0 +1,35 @@ > +# > +# Feature name: debug-vm-pgtable > +# Kconfig: ARCH_HAS_DEBUG_VM_PGTABLE > +# description: arch supports pgtable tests for semantics compliance > +# > + ----------------------- > + | arch |status| > + ----------------------- > + | alpha: | TODO | > + | arc: | ok | > + | 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/32: | ok | > + | powerpc/64: | TODO | > + | riscv: | TODO | > + | s390: | ok | > + | sh: | TODO | > + | sparc: | TODO | > + | um: | TODO | > + | unicore32: | TODO | > + | x86: | ok | > + | xtensa: | TODO | > + ----------------------- > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > index ff2a393b635c..3e72e6cf0e42 100644 > --- a/arch/arc/Kconfig > +++ b/arch/arc/Kconfig > @@ -6,6 +6,7 @@ > config ARC > def_bool y > select ARC_TIMERS > + select ARCH_HAS_DEBUG_VM_PGTABLE > select ARCH_HAS_DMA_PREP_COHERENT > select ARCH_HAS_PTE_SPECIAL > select ARCH_HAS_SETUP_DMA_OPS > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 0b30e884e088..aaf8ba415145 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_PREP_COHERENT > select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 497b7d0b2d7e..8d5ae14c5d4c 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -116,6 +116,7 @@ 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/s390/Kconfig b/arch/s390/Kconfig > index 8abe77536d9d..af284dbb07e7 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -59,6 +59,7 @@ config KASAN_SHADOW_OFFSET > config S390 > def_bool y > select ARCH_BINFMT_ELF_STATE > + select ARCH_HAS_DEBUG_VM_PGTABLE > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index beea77046f9b..df8a19e52e82 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 if !X86_PAE > 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 0b6c4042942a..fb0e76d254b3 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/linux/mmdebug.h b/include/linux/mmdebug.h > index 2ad72d2c8cc5..5339aa14b749 100644 > --- a/include/linux/mmdebug.h > +++ b/include/linux/mmdebug.h > @@ -64,4 +64,9 @@ void dump_mm(const struct mm_struct *mm); > #define VM_BUG_ON_PGFLAGS(cond, page) BUILD_BUG_ON_INVALID(cond) > #endif > > +#ifdef CONFIG_DEBUG_VM_PGTABLE > +void debug_vm_pgtable(void); > +#else > +static inline void debug_vm_pgtable(void) { } > +#endif > #endif > diff --git a/init/main.c b/init/main.c > index cc0ee4873419..adf37e8b1d69 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -94,6 +94,7 @@ > #include <linux/rodata_test.h> > #include <linux/jump_label.h> > #include <linux/mem_encrypt.h> > +#include <linux/mmdebug.h> > > #include <asm/io.h> > #include <asm/bugs.h> > @@ -1323,6 +1324,7 @@ static int __ref kernel_init(void *unused) > kernel_init_freeable(); > /* need to finish all async __init code before freeing the memory */ > async_synchronize_full(); > + debug_vm_pgtable(); > ftrace_free_init_mem(); > free_initmem(); > mark_readonly(); > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 69def4a9df00..1b5bd9f7c967 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -653,6 +653,12 @@ config SCHED_STACK_END_CHECK > data corruption or a sporadic crash at a later stage once the region > is examined. The runtime overhead introduced is minimal. > > +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 > bool "Debug VM" > depends on DEBUG_KERNEL > @@ -688,6 +694,26 @@ config DEBUG_VM_PGFLAGS > > If unsure, say N. > > +config DEBUG_VM_PGTABLE > + bool "Debug arch page table for semantics compliance" > + depends on MMU > + depends on !IA64 && !ARM > + depends on ARCH_HAS_DEBUG_VM_PGTABLE || EXPERT > + default n if !ARCH_HAS_DEBUG_VM_PGTABLE > + default y if DEBUG_VM > + 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. Platforms will have to opt in for > + this through ARCH_HAS_DEBUG_VM_PGTABLE. Although it can also be > + enabled through EXPERT without requiring code change. This test > + is disabled on IA64 and ARM platforms where it fails to build. > + > + If unsure, say N. > + > config ARCH_HAS_DEBUG_VIRTUAL > bool > > diff --git a/mm/Makefile b/mm/Makefile > index 272e66039e70..b0692e6a4b58 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -87,6 +87,7 @@ 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 000000000000..70bf8ed8fd51 > --- /dev/null > +++ b/mm/debug_vm_pgtable.c > @@ -0,0 +1,389 @@ > +// 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@xxxxxxx> > + */ > +#define pr_fmt(fmt) "debug_vm_pgtable: %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 4 bits are used to identify given page table > + * entry type. But these bits might affect the ability to clear entries with > + * pxx_clear() because of how dynamic page table folding works on s390. So > + * while loading up the entries do not change the lower 4 bits. It does not > + * have affect any other platform. > + */ > +#define S390_MASK_BITS 4 > +#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS) > +#define RANDOM_NZVALUE GENMASK(7, 0) > + > +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_mkold(pte)))); > + WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte)))); > + WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte)))); > + WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte)))); > + WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte)))); > + WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte)))); > +} > + > +#ifdef CONFIG_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_mkold(pmd)))); > + WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd)))); > + WARN_ON(!pmd_write(pmd_mkwrite(pmd_wrprotect(pmd)))); > + WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd)))); > + WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd)))); > + WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(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))); > +} > + > +#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_mkold(pud)))); > + WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud)))); > + WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud)))); > + WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud)))); > + > + if (mm_pmd_folded(mm)) > + 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 > +#else > +static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { } > +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 __PAGETABLE_PUD_FOLDED > +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 __PAGETABLE_P4D_FOLDED > +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; > + > + 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; > + > + pr_info("Validating architecture page table helpers\n"); > + 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. > + */ > + 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; > + WARN_ON(!pfn_valid(pte_aligned)); > + > + 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); > +}
