> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@xxxxxx> wrote: > > On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote: >> Many architectures current have a debugfs file for dumping the kernel >> page tables. Currently each architecture has to implement custom >> functions for this because the details of walking the page tables used >> by the kernel are different between architectures. >> >> This series extends the capabilities of walk_page_range() so that it can >> deal with the page tables of the kernel (which have no VMAs and can >> contain larger huge pages than exist for user space). A generic PTDUMP >> implementation is the implemented making use of the new functionality of >> walk_page_range() and finally arm64 and x86 are switch to using it, >> removing the custom table walkers. >> >> To enable a generic page table walker to walk the unusual mappings of >> the kernel we need to implement a set of functions which let us know >> when the walker has reached the leaf entry. After a suggestion from Will >> Deacon I've chosen the name p?d_leaf() as this (hopefully) describes >> the purpose (and is a new name so has no historic baggage). Some >> architectures have p?d_large macros but this is easily confused with >> "large pages". >> >> This series ends with a generic PTDUMP implemention for arm64 and x86. >> >> Mostly this is a clean up and there should be very little functional >> change. The exceptions are: >> >> * arm64 PTDUMP debugfs now displays pages which aren't present (patch 22). >> >> * arm64 has the ability to efficiently process KASAN pages (which >> previously only x86 implemented). This means that the combination of >> KASAN and DEBUG_WX is now useable. >> >> Also available as a git tree: >> git://linux-arm.org/linux-sp.git walk_page_range/v15 >> >> Changes since v14: >> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@xxxxxxx/ >> * Switch walk_page_range() into two functions, the existing >> walk_page_range() now still requires VMAs (and treats areas without a >> VMA as a 'hole'). The new walk_page_range_novma() ignores VMAs and >> will report the actual page table layout. This fixes the previous >> breakage of /proc/<pid>/pagemap >> * New patch at the end of the series which reduces the 'level' numbers >> by 1 to simplify the code slightly >> * Added tags > > Does this new version also take care of this boot crash seen with v14? Suppose > it is now breaking CONFIG_EFI_PGT_DUMP=y? The full config is, > > https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config > V15 is indeed DOA here. [ 10.957006][ T0] pid_max: default: 131072 minimum: 1024 [ 11.543186][ T0] ---[ User Space ]--- [ 11.547009][ T0] 0x0000000000000000-0x0000000000001000 4K RW x pte [ 11.556612][ T0] 0x0000000000001000-0x0000000000200000 2044K pte [ 11.557008][ T0] 0x0000000000200000-0x0000000004000000 62M pmd [ 11.567014][ T0] 0x0000000004000000-0x0000000004076000 472K pte [ 11.577033][ T0] 0x0000000004076000-0x0000000004200000 1576K pte [ 11.587013][ T0] 0x0000000004200000-0x0000000011000000 206M pmd [ 11.597023][ T0] 0x0000000011000000-0x0000000011100000 1M pte [ 11.607023][ T0] 0x0000000011100000-0x0000000011200000 1M pte [ 11.617006][ T0] 0x0000000011200000-0x0000000011800000 6M pmd [ 11.627068][ T0] ================================================================== [ 11.635087][ T0] BUG: KASAN: wild-memory-access in ptdump_pte_entry+0x39/0x60 [ 11.636992][ T0] Read of size 8 at addr 000f887fee5ff000 by task swapper/0/0 [ 11.636992][ T0] [ 11.636992][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc6-next-20191106+ #6 [ 11.636992][ T0] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019 [ 11.636992][ T0] Call Trace: [ 11.636992][ T0] dump_stack+0xa0/0xea [ 11.636992][ T0] __kasan_report.cold.7+0xb0/0xc0 [ 11.636992][ T0] ? note_page+0x6a9/0xa70 [ 11.636992][ T0] ? ptdump_pte_entry+0x39/0x60 [ 11.636992][ T0] ? ptdump_walk_pgd_level_core+0x1e0/0x1e0 [ 11.636992][ T0] kasan_report+0x12/0x20 [ 11.636992][ T0] __asan_load8+0x71/0xa0 [ 11.636992][ T0] ptdump_pte_entry+0x39/0x60 [ 11.636992][ T0] walk_pgd_range+0x9e5/0xdb0 [ 11.636992][ T0] __walk_page_range+0x206/0x230 [ 11.636992][ T0] walk_page_range_novma+0xc5/0x130 [ 11.636992][ T0] ? walk_page_range+0x220/0x220 [ 11.636992][ T0] ptdump_walk_pgd+0x76/0xd0 [ 11.636992][ T0] ptdump_walk_pgd_level_core+0x169/0x1e0 [ 11.636992][ T0] ? hugetlb_get_unmapped_area+0x5b0/0x5b0 [ 11.636992][ T0] ? trace_hardirqs_on+0x3a/0x160 [ 11.636992][ T0] ? ptdump_walk_pgd_level_core+0x1e0/0x1e0 [ 11.636992][ T0] ? efi_delete_dummy_variable+0xa9/0xd0 [ 11.636992][ T0] ? __enc_copy+0x90/0x90 [ 11.636992][ T0] ptdump_walk_pgd_level+0x15/0x20 [ 11.636992][ T0] efi_dump_pagetable+0x35/0x37 [ 11.636992][ T0] efi_enter_virtual_mode+0x72a/0x737 [ 11.636992][ T0] start_kernel+0x607/0x6a9 [ 11.636992][ T0] ? thread_stack_cache_init+0xb/0xb [ 11.636992][ T0] ? idt_setup_from_table+0xd9/0x130 [ 11.636992][ T0] x86_64_start_reservations+0x24/0x26 [ 11.636992][ T0] x86_64_start_kernel+0xf4/0xfb [ 11.636992][ T0] secondary_startup_64+0xb6/0xc0 [ 11.636992][ T0] ================================================================== [ 11.636992][ T0] Disabling lock debugging due to kernel taint [ 11.637009][ T0] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 11.645067][ T0] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G B 5.4.0-rc6-next-20191106+ #6 [ 11.646992][ T0] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019 [ 11.646992][ T0] RIP: 0010:ptdump_pte_entry+0x39/0x60 [ 11.646992][ T0] Code: 55 41 54 49 89 fc 48 8d 79 20 53 48 89 cb e8 8e 9d fa ff 48 8b 5b 20 48 89 df e8 82 9d fa ff 4c 89 e7 4c 8b 2b e8 77 9d fa ff <49> 8b 0c 24 4c 89 f6 48 89 df ba 04 00 00 00 e8 f3 8d 9b 00 31 c0 [ 11.646992][ T0] RSP: 0000:ffffffff8a2079f0 EFLAGS: 00010286 [ 11.646992][ T0] RAX: 0000000000000000 RBX: ffffffff8a207cf0 RCX: ffffffff88d74576 [ 11.646992][ T0] RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffffffff8a8f53d4 [ 11.646992][ T0] RBP: ffffffff8a207a10 R08: fffffbfff151c01a R09: fffffbfff151c01a [ 11.646992][ T0] R10: fffffbfff151c019 R11: ffffffff8a8e00cb R12: 000f887fee5ff000 [ 11.646992][ T0] R13: ffffffff88caf040 R14: 0000000011a00000 R15: ffffffff89cfdcc0 [ 11.646992][ T0] FS: 0000000000000000(0000) GS:ffff888843400000(0000) knlGS:0000000000000000 [ 11.646992][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 11.646992][ T0] CR2: ffff8890779ff000 CR3: 0000000c54a12000 CR4: 00000000000406b0 [ 11.646992][ T0] Call Trace: [ 11.646992][ T0] walk_pgd_range+0x9e5/0xdb0 [ 11.646992][ T0] __walk_page_range+0x206/0x230 [ 11.646992][ T0] walk_page_range_novma+0xc5/0x130 [ 11.646992][ T0] ? walk_page_range+0x220/0x220 [ 11.646992][ T0] ptdump_walk_pgd+0x76/0xd0 [ 11.646992][ T0] ptdump_walk_pgd_level_core+0x169/0x1e0 [ 11.646992][ T0] ? hugetlb_get_unmapped_area+0x5b0/0x5b0 [ 11.646992][ T0] ? trace_hardirqs_on+0x3a/0x160 [ 11.646992][ T0] ? ptdump_walk_pgd_level_core+0x1e0/0x1e0 [ 11.646992][ T0] ? efi_delete_dummy_variable+0xa9/0xd0 [ 11.646992][ T0] ? __enc_copy+0x90/0x90 [ 11.646992][ T0] ptdump_walk_pgd_level+0x15/0x20 [ 11.646992][ T0] efi_dump_pagetable+0x35/0x37 [ 11.646992][ T0] efi_enter_virtual_mode+0x72a/0x737 [ 11.646992][ T0] start_kernel+0x607/0x6a9 [ 11.646992][ T0] ? thread_stack_cache_init+0xb/0xb [ 11.646992][ T0] ? idt_setup_from_table+0xd9/0x130 [ 11.646992][ T0] x86_64_start_reservations+0x24/0x26 [ 11.646992][ T0] x86_64_start_kernel+0xf4/0xfb [ 11.646992][ T0] secondary_startup_64+0xb6/0xc0 [ 11.646992][ T0] Modules linked in: [ 11.647003][ T0] ---[ end trace 751e8882de194a93 ]--- [ 11.652355][ T0] RIP: 0010:ptdump_pte_entry+0x39/0x60 [ 11.657001][ T0] Code: 55 41 54 49 89 fc 48 8d 79 20 53 48 89 cb e8 8e 9d fa ff 48 8b 5b 20 48 89 df e8 82 9d fa ff 4c 89 e7 4c 8b 2b e8 77 9d fa ff <49> 8b 0c 24 4c 89 f6 48 89 df ba 04 00 00 00 e8 f3 8d 9b 00 31 c0 [ 11.666998][ T0] RSP: 0000:ffffffff8a2079f0 EFLAGS: 00010286 [ 11.672961][ T0] RAX: 0000000000000000 RBX: ffffffff8a207cf0 RCX: ffffffff88d74576 [ 11.676998][ T0] RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffffffff8a8f53d4 [ 11.686998][ T0] RBP: ffffffff8a207a10 R08: fffffbfff151c01a R09: fffffbfff151c01a [ 11.696998][ T0] R10: fffffbfff151c019 R11: ffffffff8a8e00cb R12: 000f887fee5ff000 [ 11.704882][ T0] R13: ffffffff88caf040 R14: 0000000011a00000 R15: ffffffff89cfdcc0 [ 11.706999][ T0] FS: 0000000000000000(0000) GS:ffff888843400000(0000) knlGS:0000000000000000 [ 11.716998][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 11.726998][ T0] CR2: ffff8890779ff000 CR3: 0000000c54a12000 CR4: 00000000000406b0 [ 11.736998][ T0] Kernel panic - not syncing: Fatal exception [ 11.743272][ T0] ---[ end Kernel panic - not syncing: Fatal exception ]--- >> >> Changes since v13: >> https://lore.kernel.org/lkml/20191024093716.49420-1-steven.price@xxxxxxx/ >> * Fixed typo in arc definition of pmd_leaf() spotted by the kbuild test >> robot >> * Added tags >> >> Changes since v12: >> https://lore.kernel.org/lkml/20191018101248.33727-1-steven.price@xxxxxxx/ >> * Correct code format in riscv pud_leaf()/pmd_leaf() >> * v12 may not have reached everyone because of mail server problems >> (which are now hopefully resolved!) >> >> Changes since v11: >> https://lore.kernel.org/lkml/20191007153822.16518-1-steven.price@xxxxxxx/ >> * Use "-1" as dummy depth parameter in patch 14. >> >> Changes since v10: >> https://lore.kernel.org/lkml/20190731154603.41797-1-steven.price@xxxxxxx/ >> * Rebased to v5.4-rc1 - mainly various updates to deal with the >> splitting out of ops from struct mm_walk. >> * Deal with PGD_LEVEL_MULT not always being constant on x86. >> >> Changes since v9: >> https://lore.kernel.org/lkml/20190722154210.42799-1-steven.price@xxxxxxx/ >> * Moved generic macros to first page in the series and explained the >> macro naming in the commit message. >> * mips: Moved macros to pgtable.h as they are now valid for both 32 and 64 >> bit >> * x86: Dropped patch which changed the debugfs output for x86, instead >> we have... >> * new patch adding 'depth' parameter to pte_hole. This is used to >> provide the necessary information to output lines for 'holes' in the >> debugfs files >> * new patch changing arm64 debugfs output to include holes to match x86 >> * generic ptdump KASAN handling has been simplified and now works with >> CONFIG_DEBUG_VIRTUAL. >> >> Changes since v8: >> https://lore.kernel.org/lkml/20190403141627.11664-1-steven.price@xxxxxxx/ >> * Rename from p?d_large() to p?d_leaf() >> * Dropped patches migrating arm64/x86 custom walkers to >> walk_page_range() in favour of adding a generic PTDUMP implementation >> and migrating arm64/x86 to that instead. >> * Rebased to v5.3-rc1 >> >> Steven Price (23): >> mm: Add generic p?d_leaf() macros >> arc: mm: Add p?d_leaf() definitions >> arm: mm: Add p?d_leaf() definitions >> arm64: mm: Add p?d_leaf() definitions >> mips: mm: Add p?d_leaf() definitions >> powerpc: mm: Add p?d_leaf() definitions >> riscv: mm: Add p?d_leaf() definitions >> s390: mm: Add p?d_leaf() definitions >> sparc: mm: Add p?d_leaf() definitions >> x86: mm: Add p?d_leaf() definitions >> mm: pagewalk: Add p4d_entry() and pgd_entry() >> mm: pagewalk: Allow walking without vma >> mm: pagewalk: Add test_p?d callbacks >> mm: pagewalk: Add 'depth' parameter to pte_hole >> x86: mm: Point to struct seq_file from struct pg_state >> x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct >> x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct >> x86: mm: Convert ptdump_walk_pgd_level_core() to take an mm_struct >> mm: Add generic ptdump >> x86: mm: Convert dump_pagetables to use walk_page_range >> arm64: mm: Convert mm/dump.c to use walk_page_range() >> arm64: mm: Display non-present entries in ptdump >> mm: ptdump: Reduce level numbers by 1 in note_page() >> >> arch/arc/include/asm/pgtable.h | 1 + >> arch/arm/include/asm/pgtable-2level.h | 1 + >> arch/arm/include/asm/pgtable-3level.h | 1 + >> arch/arm64/Kconfig | 1 + >> arch/arm64/Kconfig.debug | 19 +- >> arch/arm64/include/asm/pgtable.h | 2 + >> arch/arm64/include/asm/ptdump.h | 8 +- >> arch/arm64/mm/Makefile | 4 +- >> arch/arm64/mm/dump.c | 148 +++----- >> arch/arm64/mm/mmu.c | 4 +- >> arch/arm64/mm/ptdump_debugfs.c | 2 +- >> arch/mips/include/asm/pgtable.h | 5 + >> arch/powerpc/include/asm/book3s/64/pgtable.h | 30 +- >> arch/riscv/include/asm/pgtable-64.h | 7 + >> arch/riscv/include/asm/pgtable.h | 7 + >> arch/s390/include/asm/pgtable.h | 2 + >> arch/sparc/include/asm/pgtable_64.h | 2 + >> arch/x86/Kconfig | 1 + >> arch/x86/Kconfig.debug | 20 +- >> arch/x86/include/asm/pgtable.h | 10 +- >> arch/x86/mm/Makefile | 4 +- >> arch/x86/mm/debug_pagetables.c | 8 +- >> arch/x86/mm/dump_pagetables.c | 343 +++++-------------- >> arch/x86/platform/efi/efi_32.c | 2 +- >> arch/x86/platform/efi/efi_64.c | 4 +- >> drivers/firmware/efi/arm-runtime.c | 2 +- >> fs/proc/task_mmu.c | 4 +- >> include/asm-generic/pgtable.h | 20 ++ >> include/linux/pagewalk.h | 42 ++- >> include/linux/ptdump.h | 22 ++ >> mm/Kconfig.debug | 21 ++ >> mm/Makefile | 1 + >> mm/hmm.c | 8 +- >> mm/migrate.c | 5 +- >> mm/mincore.c | 1 + >> mm/pagewalk.c | 126 +++++-- >> mm/ptdump.c | 151 ++++++++ >> 37 files changed, 586 insertions(+), 453 deletions(-) >> create mode 100644 include/linux/ptdump.h >> create mode 100644 mm/ptdump.c >>
