Most architectures current have a debugfs file for dumping the kernel page tables. Currently each architecture has to implement custom functions for walking the page tables because the generic walk_page_range() function is unable to walk the page tables used by the kernel. 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). x86 and arm64 are then converted to make use of walk_page_range() removing the custom page 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. Since arm, powerpc, s390, sparc and x86 all have p?d_large macros lets standardise on that and implement those that are missing. Potentially future changes could unify the implementations of the debugfs walkers further, moving the common functionality into common code. This would require a common way of handling the effective permissions (currently implemented only for x86) along with a per-arch way of formatting the page table information for debugfs. One immediate benefit would be getting the KASAN speed up optimisation in arm64 (and other arches) which is currently only implemented for x86. Also available as a git tree: git://linux-arm.org/linux-sp.git walk_page_range/v8 Changes since v7: https://lore.kernel.org/lkml/20190328152104.23106-1-steven.price@xxxxxxx/T/ * Updated commit message in patch 2 to clarify that we rely on the page tables being walked to be the same page size/depth as the kernel's (since this confused me earlier today). Changes since v6: https://lore.kernel.org/lkml/20190326162624.20736-1-steven.price@xxxxxxx/T/ * Split the changes for powerpc. pmd_large() is now added in patch 4 patch, and pmd_is_leaf() removed in patch 5. Changes since v5: https://lore.kernel.org/lkml/20190321141953.31960-1-steven.price@xxxxxxx/T/ * Updated comment for struct mm_walk based on Mike Rapoport's suggestion Changes since v4: https://lore.kernel.org/lkml/20190306155031.4291-1-steven.price@xxxxxxx/T/ * Correctly force result to a boolean in p?d_large for powerpc. * Added Acked-bys * Rebased onto v5.1-rc1 Changes since v3: https://lore.kernel.org/lkml/20190227170608.27963-1-steven.price@xxxxxxx/T/ * Restored the generic macros, only implement p?d_large() for architectures that have support for large pages. This also means adding dummy #defines for architectures that define p?d_large as static inline to avoid picking up the generic macro. * Drop the 'depth' argument from pte_hole * Because we no longer have the depth for holes, we also drop support in x86 for showing missing pages in debugfs. See discussion below: https://lore.kernel.org/lkml/26df02dd-c54e-ea91-bdd1-0a4aad3a30ac@xxxxxxx/ * mips: only define p?d_large when _PAGE_HUGE is defined. Changes since v2: https://lore.kernel.org/lkml/20190221113502.54153-1-steven.price@xxxxxxx/T/ * Rather than attemping to provide generic macros, actually implement p?d_large() for each architecture. Changes since v1: https://lore.kernel.org/lkml/20190215170235.23360-1-steven.price@xxxxxxx/T/ * Added p4d_large() macro * Comments to explain p?d_large() macro semantics * Expanded comment for pte_hole() callback to explain mapping between depth and P?D * Handle folded page tables at all levels, so depth from pte_hole() ignores folding at any level (see real_depth() function in mm/pagewalk.c) Steven Price (20): arc: mm: Add p?d_large() definitions arm64: mm: Add p?d_large() definitions mips: mm: Add p?d_large() definitions powerpc: mm: Add p?d_large() definitions KVM: PPC: Book3S HV: Remove pmd_is_leaf() riscv: mm: Add p?d_large() definitions s390: mm: Add p?d_large() definitions sparc: mm: Add p?d_large() definitions x86: mm: Add p?d_large() definitions mm: Add generic p?d_large() macros mm: pagewalk: Add p4d_entry() and pgd_entry() mm: pagewalk: Allow walking without vma mm: pagewalk: Add test_p?d callbacks arm64: mm: Convert mm/dump.c to use walk_page_range() x86: mm: Don't display pages which aren't present in debugfs 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 x86: mm: Convert dump_pagetables to use walk_page_range arch/arc/include/asm/pgtable.h | 1 + arch/arm64/include/asm/pgtable.h | 2 + arch/arm64/mm/dump.c | 117 +++---- arch/mips/include/asm/pgtable-64.h | 8 + arch/powerpc/include/asm/book3s/64/pgtable.h | 30 +- arch/powerpc/kvm/book3s_64_mmu_radix.c | 12 +- 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/include/asm/pgtable.h | 10 +- arch/x86/mm/debug_pagetables.c | 8 +- arch/x86/mm/dump_pagetables.c | 347 ++++++++++--------- arch/x86/platform/efi/efi_32.c | 2 +- arch/x86/platform/efi/efi_64.c | 4 +- include/asm-generic/pgtable.h | 19 + include/linux/mm.h | 26 +- mm/pagewalk.c | 76 +++- 18 files changed, 407 insertions(+), 273 deletions(-) -- 2.20.1
