| Message ID | 1572240562-23630-1-git-send-email-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Paul Burton |
| Headers | show |
| Series | [V8] mm/debug: Add tests validating architecture page table helpers | expand |
> On Oct 28, 2019, at 1:29 AM, Anshuman Khandual <Anshuman.Khandual@arm.com> 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. This looks like a perfect candidate to streamline with the new kunit framework, no?
On 10/29/2019 04:01 PM, Qian Cai wrote: > > >> On Oct 28, 2019, at 1:29 AM, Anshuman Khandual <Anshuman.Khandual@arm.com> 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. > > This looks like a perfect candidate to streamline with the new kunit framework, no? I have not been following the kunit test framework. But being highly dependent on existing MM accessors (generic or platform) and very much page table modification centric, mm/ is the best place for this test IMHO. It is now also part of DEBUG_VM set of tests. Probably in future all existing MM tests (mm/ or lib/) might move to kunit framework but for now it should remain with DEBUG_VM set of tests.
On 10/28/2019 10:59 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> > --- > > 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@arrakis.emea.arm.com/ > > Needs to be applied on linux-next (next-20191025). > > Changes in V8: > > - 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() Hello Andrew, Just wondering if this version looks okay or is there anything else which still needs to be accommodated here first, before this test can be considered for merging ? Thank you. - Anshuman
On 10/28/2019 10:59 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> > --- > > 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@arrakis.emea.arm.com/ > > Needs to be applied on linux-next (next-20191025). > > Changes in V8: > > - 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 Hello Andrew, Just wondering if this version looks okay or is there anything else which still needs to be accommodated here first, before this test can be considered for merging ? Thank you. - Anshuman
On Mon, 28 Oct 2019 10:59:22 +0530 Anshuman Khandual <anshuman.khandual@arm.com> 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. I've prepared a couple of commits to our arch code to make this work on s390, they will go upstream in the next merge window. After that, we can add s390 to the supported architectures. We had some issues, e.g. because we do not report large entries as bad in pxd_bad(), do not check for folded page tables in pxd_free(), or assume that primitives like pmd_mkdirty() will only be called after pmd_mkhuge(). None of those should have any impact on current code, but your test module revealed that we do not behave like other architectures in some aspects, and it's good to find and fix such things to prevent possible future issues. Thanks a lot for the effort! Regards, Gerald
On 11/06/2019 01:06 AM, Gerald Schaefer wrote: > On Mon, 28 Oct 2019 10:59:22 +0530 > Anshuman Khandual <anshuman.khandual@arm.com> 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. > > I've prepared a couple of commits to our arch code to make this work on s390, > they will go upstream in the next merge window. After that, we can add s390 > to the supported architectures. Thats good. > > We had some issues, e.g. because we do not report large entries as bad in > pxd_bad(), do not check for folded page tables in pxd_free(), or assume > that primitives like pmd_mkdirty() will only be called after pmd_mkhuge(). > None of those should have any impact on current code, but your test module > revealed that we do not behave like other architectures in some aspects, > and it's good to find and fix such things to prevent possible future issues. Right and those s390 fixes are the testimony for the usefulness of this test. > > Thanks a lot for the effort! > > Regards, > Gerald > >
On 10/28/2019 10:59 AM, Anshuman Khandual wrote: > + ----------------------- > + | 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 | > + | ppc32: | ok | > + | riscv: | TODO | > + | s390: | TODO | > + | sh: | TODO | > + | sparc: | TODO | > + | um: | TODO | > + | unicore32: | TODO | > + | x86: | ok | > + | xtensa: | TODO | > + ----------------------- While here, are there some volunteers to test this on any of the 'yet to be tested and supported' platforms ? - Anshuman
Le 06/11/2019 à 04:22, Anshuman Khandual a écrit : > > > On 10/28/2019 10:59 AM, Anshuman Khandual wrote: >> + ----------------------- >> + | 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 | >> + | ppc32: | ok | Note that ppc32 is a part of powerpc, not a standalone arch. Maybe something like the following would be more correct: | powerpc/32: | ok | | powerpc/64: | TODO | Christophe >> + | riscv: | TODO | >> + | s390: | TODO | >> + | sh: | TODO | >> + | sparc: | TODO | >> + | um: | TODO | >> + | unicore32: | TODO | >> + | x86: | ok | >> + | xtensa: | TODO | >> + ----------------------- > > While here, are there some volunteers to test this on any of the > 'yet to be tested and supported' platforms ? > > - Anshuman >
On 11/06/2019 12:11 PM, Christophe Leroy wrote: > > > Le 06/11/2019 à 04:22, Anshuman Khandual a écrit : >> >> >> On 10/28/2019 10:59 AM, Anshuman Khandual wrote: >>> + ----------------------- >>> + | 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 | >>> + | ppc32: | ok | > > Note that ppc32 is a part of powerpc, not a standalone arch. Right, I understand. But we are yet to hear about how this test came about on powerpc server platforms. Will update 'powerpc' arch listing above once we get some confirmation. May be once this works on all relevant powerpc platforms, we can just merge 'powerpc' and 'ppc32' entries here as just 'powerpc'. > > Maybe something like the following would be more correct: > | powerpc/32: | ok | > | powerpc/64: | TODO | > > Christophe > >>> + | riscv: | TODO | >>> + | s390: | TODO | >>> + | sh: | TODO | >>> + | sparc: | TODO | >>> + | um: | TODO | >>> + | unicore32: | TODO | >>> + | x86: | ok | >>> + | xtensa: | TODO | >>> + ----------------------- >> >> While here, are there some volunteers to test this on any of the >> 'yet to be tested and supported' platforms ? >> >> - Anshuman >> >
Anshuman Khandual <anshuman.khandual@arm.com> writes: > On 11/06/2019 12:11 PM, Christophe Leroy wrote: >> Le 06/11/2019 à 04:22, Anshuman Khandual a écrit : >>> On 10/28/2019 10:59 AM, Anshuman Khandual wrote: >>>> + ----------------------- >>>> + | 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 | >>>> + | ppc32: | ok | >> >> Note that ppc32 is a part of powerpc, not a standalone arch. > > Right, I understand. But we are yet to hear about how this test > came about on powerpc server platforms. Will update 'powerpc' > arch listing above once we get some confirmation. May be once > this works on all relevant powerpc platforms, we can just merge > 'powerpc' and 'ppc32' entries here as just 'powerpc'. On pseries: watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [swapper/0:1] Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty #152 NIP: c0000000010435a0 LR: c0000000010434b4 CTR: 0000000000000000 REGS: c00000003a403980 TRAP: 0901 Not tainted (5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty) MSR: 8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 44000222 XER: 00000000 CFAR: c0000000010435a8 IRQMASK: 0 GPR00: c0000000010434b4 c00000003a403c10 c000000001295000 05210001000000c0 GPR04: 8000000000000105 0000000000400dc0 000000003eb00000 0000000000000001 GPR08: 0000000000000000 ffffffffffffffff 0000000000000001 0000000000000100 GPR12: 0000000000000000 c0000000018f0000 NIP [c0000000010435a0] debug_vm_pgtable+0x43c/0x82c LR [c0000000010434b4] debug_vm_pgtable+0x350/0x82c Call Trace: [c00000003a403c10] [c00000000104346c] debug_vm_pgtable+0x308/0x82c (unreliable) [c00000003a403ce0] [c000000001004310] kernel_init_freeable+0x1d0/0x39c [c00000003a403db0] [c000000000010da0] kernel_init+0x24/0x174 [c00000003a403e20] [c00000000000bdc4] ret_from_kernel_thread+0x5c/0x78 Instruction dump: 7d075078 7ce74b78 7ce0f9ad 40c2fff0 38800000 7f83e378 4b02eee1 60000000 48000080 3920ffff 39400001 39000000 <7ea0f8a8> 7ea75039 40c2fff8 7ea74878 Looking at the asm I think it's stuck in hash__pte_update() waiting for H_PAGE_BUSY to clear, but not sure why. That's just using qemu TCG, instructions here if anyone wants to test it themselves :) https://github.com/linuxppc/wiki/wiki/Booting-with-Qemu If I boot with -cpu power9 (using Radix MMU), I get a plain old BUG: debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers ------------[ cut here ]------------ kernel BUG at arch/powerpc/mm/pgtable.c:274! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=32 NUMA pSeries Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty #152 NIP: c0000000000724e8 LR: c00000000104358c CTR: 0000000000000000 REGS: c00000003a483980 TRAP: 0700 Not tainted (5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty) MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 24000224 XER: 20000000 CFAR: c000000001043588 IRQMASK: 0 GPR00: c00000000104358c c00000003a483c10 c000000001295000 0000000000000009 GPR04: 0000000000000000 0000000000000005 0000000000000000 0000000000000009 GPR08: 0000000000000001 000000000000000e 0000000000000001 c00000003a5f0000 GPR12: 0000000000000000 c0000000018f0000 c000000000010d84 0000000000000000 GPR16: 0000000000000000 0000000000000000 c00000003a5f0000 8000000000000105 GPR20: c000000001003ab8 0000000000000015 0500613a00000080 0900603a00000080 GPR24: 09202e3a00000080 c00000000133bd90 c00000000133bd98 c00000000133bda0 GPR28: c00000003a5e0000 c00000003a600af8 c00000003a2e2d48 c00000003a6100a0 NIP [c0000000000724e8] assert_pte_locked+0x88/0x190 LR [c00000000104358c] debug_vm_pgtable+0x428/0x82c Call Trace: [c00000003a483c10] [c00000000104346c] debug_vm_pgtable+0x308/0x82c (unreliable) [c00000003a483ce0] [c000000001004310] kernel_init_freeable+0x1d0/0x39c [c00000003a483db0] [c000000000010da0] kernel_init+0x24/0x174 [c00000003a483e20] [c00000000000bdc4] ret_from_kernel_thread+0x5c/0x78 Instruction dump: 7d251a14 39070010 7d463030 7d084a14 38c6ffff 7c884436 7cc607b4 7d083038 79081f24 7ccb402a 7cc80074 7908d182 <0b080000> 78cb0022 54c8c03e 7d473830 ---[ end trace a694f1bc56529c0e ]--- cheers
On 11/07/2019 06:24 PM, Michael Ellerman wrote: > Anshuman Khandual <anshuman.khandual@arm.com> writes: >> On 11/06/2019 12:11 PM, Christophe Leroy wrote: >>> Le 06/11/2019 à 04:22, Anshuman Khandual a écrit : >>>> On 10/28/2019 10:59 AM, Anshuman Khandual wrote: >>>>> + ----------------------- >>>>> + | 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 | >>>>> + | ppc32: | ok | >>> >>> Note that ppc32 is a part of powerpc, not a standalone arch. >> >> Right, I understand. But we are yet to hear about how this test >> came about on powerpc server platforms. Will update 'powerpc' >> arch listing above once we get some confirmation. May be once >> this works on all relevant powerpc platforms, we can just merge >> 'powerpc' and 'ppc32' entries here as just 'powerpc'. > > On pseries: > > watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [swapper/0:1] > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty #152 > NIP: c0000000010435a0 LR: c0000000010434b4 CTR: 0000000000000000 > REGS: c00000003a403980 TRAP: 0901 Not tainted (5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty) > MSR: 8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 44000222 XER: 00000000 > CFAR: c0000000010435a8 IRQMASK: 0 > GPR00: c0000000010434b4 c00000003a403c10 c000000001295000 05210001000000c0 > GPR04: 8000000000000105 0000000000400dc0 000000003eb00000 0000000000000001 > GPR08: 0000000000000000 ffffffffffffffff 0000000000000001 0000000000000100 > GPR12: 0000000000000000 c0000000018f0000 > NIP [c0000000010435a0] debug_vm_pgtable+0x43c/0x82c > LR [c0000000010434b4] debug_vm_pgtable+0x350/0x82c > Call Trace: > [c00000003a403c10] [c00000000104346c] debug_vm_pgtable+0x308/0x82c (unreliable) > [c00000003a403ce0] [c000000001004310] kernel_init_freeable+0x1d0/0x39c > [c00000003a403db0] [c000000000010da0] kernel_init+0x24/0x174 > [c00000003a403e20] [c00000000000bdc4] ret_from_kernel_thread+0x5c/0x78 > Instruction dump: > 7d075078 7ce74b78 7ce0f9ad 40c2fff0 38800000 7f83e378 4b02eee1 60000000 > 48000080 3920ffff 39400001 39000000 <7ea0f8a8> 7ea75039 40c2fff8 7ea74878 > > Looking at the asm I think it's stuck in hash__pte_update() waiting for > H_PAGE_BUSY to clear, but not sure why. > > That's just using qemu TCG, instructions here if anyone wants to test it > themselves :) > > https://github.com/linuxppc/wiki/wiki/Booting-with-Qemu > > > If I boot with -cpu power9 (using Radix MMU), I get a plain old BUG: > > debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers > ------------[ cut here ]------------ > kernel BUG at arch/powerpc/mm/pgtable.c:274! > Oops: Exception in kernel mode, sig: 5 [#1] > LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=32 NUMA pSeries > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty #152 > NIP: c0000000000724e8 LR: c00000000104358c CTR: 0000000000000000 > REGS: c00000003a483980 TRAP: 0700 Not tainted (5.4.0-rc6-gcc-8.2.0-next-20191107-00001-g250339d6747b-dirty) > MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 24000224 XER: 20000000 > CFAR: c000000001043588 IRQMASK: 0 > GPR00: c00000000104358c c00000003a483c10 c000000001295000 0000000000000009 > GPR04: 0000000000000000 0000000000000005 0000000000000000 0000000000000009 > GPR08: 0000000000000001 000000000000000e 0000000000000001 c00000003a5f0000 > GPR12: 0000000000000000 c0000000018f0000 c000000000010d84 0000000000000000 > GPR16: 0000000000000000 0000000000000000 c00000003a5f0000 8000000000000105 > GPR20: c000000001003ab8 0000000000000015 0500613a00000080 0900603a00000080 > GPR24: 09202e3a00000080 c00000000133bd90 c00000000133bd98 c00000000133bda0 > GPR28: c00000003a5e0000 c00000003a600af8 c00000003a2e2d48 c00000003a6100a0 > NIP [c0000000000724e8] assert_pte_locked+0x88/0x190 > LR [c00000000104358c] debug_vm_pgtable+0x428/0x82c > Call Trace: > [c00000003a483c10] [c00000000104346c] debug_vm_pgtable+0x308/0x82c (unreliable) > [c00000003a483ce0] [c000000001004310] kernel_init_freeable+0x1d0/0x39c > [c00000003a483db0] [c000000000010da0] kernel_init+0x24/0x174 > [c00000003a483e20] [c00000000000bdc4] ret_from_kernel_thread+0x5c/0x78 > Instruction dump: > 7d251a14 39070010 7d463030 7d084a14 38c6ffff 7c884436 7cc607b4 7d083038 > 79081f24 7ccb402a 7cc80074 7908d182 <0b080000> 78cb0022 54c8c03e 7d473830 > ---[ end trace a694f1bc56529c0e ]--- Oops. Does not seem like a quick problem to fix :) Though assert_pte_locked() gets checked only when DEBUG_VM is enabled. Probably will have to keep this test disabled on powerpc for now. > > > cheers >
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..764397de9283 --- /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: | 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 | + | ppc32: | ok | + | 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 8f2544bdcbe6..5768d639d1d4 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/powerpc/Kconfig b/arch/powerpc/Kconfig index 4c4a0fcd1674..27c5aa438587 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/Kconfig b/arch/x86/Kconfig index 45699e458057..3b4f096c68cc 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 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/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 9cdcbc7c0b7b..9eb02e105162 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 91f6ebb30ef0..af8379ed53dc 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 b48f5e974ed7..187101961b13 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -664,6 +664,12 @@ 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 @@ -699,6 +705,21 @@ 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 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 d996846697ef..2f085b971d34 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 000000000000..621ac09e78b3 --- /dev/null +++ b/mm/debug_vm_pgtable.c @@ -0,0 +1,387 @@ +// 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) "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 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; + + 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); +}