The patch titled
Subject: mm: add generic p?d_leaf() macros
has been added to the -mm tree. Its filename is
mm-add-generic-pd_leaf-macros.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-generic-pd_leaf-macros.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-generic-pd_leaf-macros.patch
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------------------------------------------------------
From: Steven Price <steven.price@xxxxxxx>
Subject: mm: add generic p?d_leaf() macros
Patch seriss "Generic page walk and ptdump", v10.
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".
Mostly this is a clean up and there should be very little functional
change. The exceptions are:
* x86 PTDUMP debugfs output no longer display pages which aren't
present (patch 14).
* 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.
Exposing the pud/pgd levels of the page tables to walk_page_range() means
we may come across the exotic large mappings that come with large areas of
contiguous memory (such as the kernel's linear map).
For architectures that don't provide all p?d_leaf() macros, provide
generic do nothing default that are suitable where there cannot be leaf
pages at that level. Futher patches will add implementations for
individual architectures.
The name p?d_leaf() is chosen to minimize the confusion with existing uses
of "large" pages and "huge" pages which do not necessary mean that the
entry is a leaf (for example it may be a set of contiguous entries that
only take 1 TLB slot). For the purpose of walking the page tables we
don't need to know how it will be represented in the TLB, but we do need
to know for sure if it is a leaf of the tree.
Link: http://lkml.kernel.org/r/20190731154603.41797-2-steven.price@xxxxxxx
Signed-off-by: Steven Price <steven.price@xxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Mark Rutland <Mark.Rutland@xxxxxxx>
Cc: "Liang Kan" <kan.liang@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/pgtable.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
--- a/include/asm-generic/pgtable.h~mm-add-generic-pd_leaf-macros
+++ a/include/asm-generic/pgtable.h
@@ -1188,4 +1188,24 @@ static inline bool arch_has_pfn_modify_c
#define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED)
#endif
+/*
+ * p?d_leaf() - true if this entry is a final mapping to a physical address.
+ * This differs from p?d_huge() by the fact that they are always available (if
+ * the architecture supports large pages at the appropriate level) even
+ * if CONFIG_HUGETLB_PAGE is not defined.
+ * Only meaningful when called on a valid entry.
+ */
+#ifndef pgd_leaf
+#define pgd_leaf(x) 0
+#endif
+#ifndef p4d_leaf
+#define p4d_leaf(x) 0
+#endif
+#ifndef pud_leaf
+#define pud_leaf(x) 0
+#endif
+#ifndef pmd_leaf
+#define pmd_leaf(x) 0
+#endif
+
#endif /* _ASM_GENERIC_PGTABLE_H */
_
Patches currently in -mm which might be from steven.price@xxxxxxx are
mm-add-generic-pd_leaf-macros.patch
arc-mm-add-pd_leaf-definitions.patch
arm-mm-add-pd_leaf-definitions.patch
arm64-mm-add-pd_leaf-definitions.patch
mips-mm-add-pd_leaf-definitions.patch
powerpc-mm-add-pd_leaf-definitions.patch
riscv-mm-add-pd_leaf-definitions.patch
s390-mm-add-pd_leaf-definitions.patch
sparc-mm-add-pd_leaf-definitions.patch
x86-mm-add-pd_leaf-definitions.patch
mm-pagewalk-add-p4d_entry-and-pgd_entry.patch
mm-pagewalk-allow-walking-without-vma.patch
mm-pagewalk-add-test_pd-callbacks.patch
mm-pagewalk-add-depth-parameter-to-pte_hole.patch
x86-mm-point-to-struct-seq_file-from-struct-pg_state.patch
x86-mmefi-convert-ptdump_walk_pgd_level-to-take-a-mm_struct.patch
x86-mm-convert-ptdump_walk_pgd_level_debugfs-to-take-an-mm_struct.patch
x86-mm-convert-ptdump_walk_pgd_level_core-to-take-an-mm_struct.patch
mm-add-generic-ptdump.patch
x86-mm-convert-dump_pagetables-to-use-walk_page_range.patch
arm64-mm-convert-mm-dumpc-to-use-walk_page_range.patch
arm64-mm-display-non-present-entries-in-ptdump.patch
