[PATCH v15 00/23] Generic page walk and ptdump

[PATCH v15 00/23] Generic page walk and ptdump

[Steven Price]

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@arm.com/
 * 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

Changes since v13:
https://lore.kernel.org/lkml/20191024093716.49420-1-steven.price@arm.com/
 * 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@arm.com/
 * 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@arm.com/
 * Use "-1" as dummy depth parameter in patch 14.

Changes since v10:
https://lore.kernel.org/lkml/20190731154603.41797-1-steven.price@arm.com/
 * 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@arm.com/
 * 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@arm.com/
 * 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

-- 
2.20.1

[PATCH v15 01/23] mm: Add generic p?d_leaf() macros

[Steven Price]

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.

Signed-off-by: Steven Price <steven.price@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
 include/asm-generic/pgtable.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 818691846c90..7f9eced287b7 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1187,4 +1187,24 @@ static inline bool arch_has_pfn_modify_check(void)
 #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 */
-- 
2.20.1

[PATCH v15 02/23] arc: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information will be provided by the
p?d_leaf() functions/macros.

For arc, we only have two levels, so only pmd_leaf() is needed.

CC: Vineet Gupta <vgupta@synopsys.com>
CC: linux-snps-arc@lists.infradead.org
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arc/include/asm/pgtable.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h
index 7addd0301c51..b4a0cf27ac1c 100644
--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -274,6 +274,7 @@ static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
 #define pmd_none(x)			(!pmd_val(x))
 #define	pmd_bad(x)			((pmd_val(x) & ~PAGE_MASK))
 #define pmd_present(x)			(pmd_val(x))
+#define pmd_leaf(x)			(pmd_val(x) & _PAGE_HW_SZ)
 #define pmd_clear(xp)			do { pmd_val(*(xp)) = 0; } while (0)
 
 #define pte_page(pte)		pfn_to_page(pte_pfn(pte))
-- 
2.20.1

[PATCH v15 03/23] arm: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For arm pmd_large() already exists and does what we want. So simply
provide the generic pmd_leaf() name.

CC: Russell King <linux@armlinux.org.uk>
CC: linux-arm-kernel@lists.infradead.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm/include/asm/pgtable-2level.h | 1 +
 arch/arm/include/asm/pgtable-3level.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 51beec41d48c..0d3ea35c97fe 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -189,6 +189,7 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
 }
 
 #define pmd_large(pmd)		(pmd_val(pmd) & 2)
+#define pmd_leaf(pmd)		(pmd_val(pmd) & 2)
 #define pmd_bad(pmd)		(pmd_val(pmd) & 2)
 #define pmd_present(pmd)	(pmd_val(pmd))
 
diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 5b18295021a0..ad55ab068dbf 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -134,6 +134,7 @@
 #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
 						 PMD_TYPE_SECT)
 #define pmd_large(pmd)		pmd_sect(pmd)
+#define pmd_leaf(pmd)		pmd_sect(pmd)
 
 #define pud_clear(pudp)			\
 	do {				\
-- 
2.20.1

[PATCH v15 04/23] arm64: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information will be provided by the
p?d_leaf() functions/macros.

For arm64, we already have p?d_sect() macros which we can reuse for
p?d_leaf().

pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3
or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is
configured this way then architecturally it isn't allowed to have a
large page at this level, and any code using these page walking macros
is implicitly relying on the page size/number of levels being the same as
the kernel. So it is safe to reuse this for p?d_leaf() as it is an
architectural restriction.

CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/include/asm/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7576df00eb50..fe1da5010b18 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -462,6 +462,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 				 PMD_TYPE_TABLE)
 #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
 				 PMD_TYPE_SECT)
+#define pmd_leaf(pmd)		pmd_sect(pmd)
 
 #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3
 static inline bool pud_sect(pud_t pud) { return false; }
@@ -546,6 +547,7 @@ static inline void pte_unmap(pte_t *pte) { }
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!(pud_val(pud) & PUD_TABLE_BIT))
 #define pud_present(pud)	pte_present(pud_pte(pud))
+#define pud_leaf(pud)		pud_sect(pud)
 #define pud_valid(pud)		pte_valid(pud_pte(pud))
 
 static inline void set_pud(pud_t *pudp, pud_t pud)
-- 
2.20.1

[PATCH v15 05/23] mips: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

If _PAGE_HUGE is defined we can simply look for it. When not defined we
can be confident that there are no leaf pages in existence and fall back
on the generic implementation (added in a later patch) which returns 0.

CC: Ralf Baechle <ralf@linux-mips.org>
CC: Paul Burton <paul.burton@mips.com>
CC: James Hogan <jhogan@kernel.org>
CC: linux-mips@vger.kernel.org
Signed-off-by: Steven Price <steven.price@arm.com>
Acked-by: Paul Burton <paul.burton@mips.com>
---
 arch/mips/include/asm/pgtable.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index f85bd5b15f51..fff392ea80c7 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -639,6 +639,11 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#ifdef _PAGE_HUGE
+#define pmd_leaf(pmd)	((pmd_val(pmd) & _PAGE_HUGE) != 0)
+#define pud_leaf(pud)	((pud_val(pud) & _PAGE_HUGE) != 0)
+#endif
+
 #define gup_fast_permitted(start, end)	(!cpu_has_dc_aliases)
 
 #include <asm-generic/pgtable.h>
-- 
2.20.1

[PATCH v15 06/23] powerpc: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For powerpc pmd_large() already exists and does what we want, so hoist
it out of the CONFIG_TRANSPARENT_HUGEPAGE condition and implement the
other levels. Macros are used to provide the generic p?d_leaf() names.

CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: linuxppc-dev@lists.ozlabs.org
CC: kvm-ppc@vger.kernel.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index b01624e5c467..3dd7b6f5edd0 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -923,6 +923,12 @@ static inline int pud_present(pud_t pud)
 	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pud_leaf	pud_large
+static inline int pud_large(pud_t pud)
+{
+	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}
+
 extern struct page *pud_page(pud_t pud);
 extern struct page *pmd_page(pmd_t pmd);
 static inline pte_t pud_pte(pud_t pud)
@@ -966,6 +972,12 @@ static inline int pgd_present(pgd_t pgd)
 	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pgd_leaf	pgd_large
+static inline int pgd_large(pgd_t pgd)
+{
+	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PTE));
+}
+
 static inline pte_t pgd_pte(pgd_t pgd)
 {
 	return __pte_raw(pgd_raw(pgd));
@@ -1133,6 +1145,15 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
 	return pte_access_permitted(pmd_pte(pmd), write);
 }
 
+#define pmd_leaf	pmd_large
+/*
+ * returns true for pmd migration entries, THP, devmap, hugetlb
+ */
+static inline int pmd_large(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
 extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);
@@ -1159,15 +1180,6 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
 	return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
 }
 
-/*
- * returns true for pmd migration entries, THP, devmap, hugetlb
- * But compile time dependent on THP config
- */
-static inline int pmd_large(pmd_t pmd)
-{
-	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
 static inline pmd_t pmd_mknotpresent(pmd_t pmd)
 {
 	return __pmd(pmd_val(pmd) & ~_PAGE_PRESENT);
-- 
2.20.1

[PATCH v15 07/23] riscv: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For riscv a page is a leaf page when it has a read, write or execute bit
set on it.

CC: Palmer Dabbelt <palmer@sifive.com>
CC: Albert Ou <aou@eecs.berkeley.edu>
CC: linux-riscv@lists.infradead.org
Reviewed-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Zong Li <zong.li@sifive.com>
Acked-by: Paul Walmsley <paul.walmsley@sifive.com> # for arch/riscv
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/riscv/include/asm/pgtable-64.h | 7 +++++++
 arch/riscv/include/asm/pgtable.h    | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 74630989006d..4c4d2c65ba6c 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -43,6 +43,13 @@ static inline int pud_bad(pud_t pud)
 	return !pud_present(pud);
 }
 
+#define pud_leaf	pud_leaf
+static inline int pud_leaf(pud_t pud)
+{
+	return pud_present(pud) &&
+	       (pud_val(pud) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
+}
+
 static inline void set_pud(pud_t *pudp, pud_t pud)
 {
 	*pudp = pud;
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7255f2d8395b..3aa972dda75a 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -130,6 +130,13 @@ static inline int pmd_bad(pmd_t pmd)
 	return !pmd_present(pmd);
 }
 
+#define pmd_leaf	pmd_leaf
+static inline int pmd_leaf(pmd_t pmd)
+{
+	return pmd_present(pmd) &&
+	       (pmd_val(pmd) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
+}
+
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
-- 
2.20.1

[PATCH v15 08/23] s390: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For s390, pud_large() and pmd_large() are already implemented as static
inline functions. Add a macro to provide the p?d_leaf names for the
generic code to use.

CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: Vasily Gorbik <gor@linux.ibm.com>
CC: Christian Borntraeger <borntraeger@de.ibm.com>
CC: linux-s390@vger.kernel.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/s390/include/asm/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 36c578c0ff96..acab5a455490 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -675,6 +675,7 @@ static inline int pud_none(pud_t pud)
 	return pud_val(pud) == _REGION3_ENTRY_EMPTY;
 }
 
+#define pud_leaf	pud_large
 static inline int pud_large(pud_t pud)
 {
 	if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) != _REGION_ENTRY_TYPE_R3)
@@ -692,6 +693,7 @@ static inline unsigned long pud_pfn(pud_t pud)
 	return (pud_val(pud) & origin_mask) >> PAGE_SHIFT;
 }
 
+#define pmd_leaf	pmd_large
 static inline int pmd_large(pmd_t pmd)
 {
 	return (pmd_val(pmd) & _SEGMENT_ENTRY_LARGE) != 0;
-- 
2.20.1

[PATCH v15 09/23] sparc: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For sparc 64 bit, pmd_large() and pud_large() are already provided, so
add macros to provide the p?d_leaf names required by the generic code.

CC: "David S. Miller" <davem@davemloft.net>
CC: sparclinux@vger.kernel.org
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/sparc/include/asm/pgtable_64.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 6ae8016ef4ec..43206652eaf5 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -683,6 +683,7 @@ static inline unsigned long pte_special(pte_t pte)
 	return pte_val(pte) & _PAGE_SPECIAL;
 }
 
+#define pmd_leaf	pmd_large
 static inline unsigned long pmd_large(pmd_t pmd)
 {
 	pte_t pte = __pte(pmd_val(pmd));
@@ -867,6 +868,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 /* only used by the stubbed out hugetlb gup code, should never be called */
 #define pgd_page(pgd)			NULL
 
+#define pud_leaf	pud_large
 static inline unsigned long pud_large(pud_t pud)
 {
 	pte_t pte = __pte(pud_val(pud));
-- 
2.20.1

[PATCH v15 10/23] x86: mm: Add p?d_leaf() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For x86 we already have p?d_large() functions, so simply add macros to
provide the generic p?d_leaf() names for the generic code.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/include/asm/pgtable.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 0bc530c4eb13..6986a451619e 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -239,6 +239,7 @@ static inline unsigned long pgd_pfn(pgd_t pgd)
 	return (pgd_val(pgd) & PTE_PFN_MASK) >> PAGE_SHIFT;
 }
 
+#define p4d_leaf	p4d_large
 static inline int p4d_large(p4d_t p4d)
 {
 	/* No 512 GiB pages yet */
@@ -247,6 +248,7 @@ static inline int p4d_large(p4d_t p4d)
 
 #define pte_page(pte)	pfn_to_page(pte_pfn(pte))
 
+#define pmd_leaf	pmd_large
 static inline int pmd_large(pmd_t pte)
 {
 	return pmd_flags(pte) & _PAGE_PSE;
@@ -874,6 +876,7 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
 	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
 }
 
+#define pud_leaf	pud_large
 static inline int pud_large(pud_t pud)
 {
 	return (pud_val(pud) & (_PAGE_PSE | _PAGE_PRESENT)) ==
@@ -885,6 +888,7 @@ static inline int pud_bad(pud_t pud)
 	return (pud_flags(pud) & ~(_KERNPG_TABLE | _PAGE_USER)) != 0;
 }
 #else
+#define pud_leaf	pud_large
 static inline int pud_large(pud_t pud)
 {
 	return 0;
@@ -1233,6 +1237,7 @@ static inline bool pgdp_maps_userspace(void *__ptr)
 	return (((ptr & ~PAGE_MASK) / sizeof(pgd_t)) < PGD_KERNEL_START);
 }
 
+#define pgd_leaf	pgd_large
 static inline int pgd_large(pgd_t pgd) { return 0; }
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
-- 
2.20.1

[PATCH v15 11/23] mm: pagewalk: Add p4d_entry() and pgd_entry()

[Steven Price]

pgd_entry() and pud_entry() were removed by commit 0b1fbfe50006c410
("mm/pagewalk: remove pgd_entry() and pud_entry()") because there were
no users. We're about to add users so reintroduce them, along with
p4d_entry() as we now have 5 levels of tables.

Note that commit a00cc7d9dd93d66a ("mm, x86: add support for
PUD-sized transparent hugepages") already re-added pud_entry() but with
different semantics to the other callbacks. Since there have never
been upstream users of this, revert the semantics back to match the
other callbacks. This means pud_entry() is called for all entries, not
just transparent huge pages.

Tested-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/pagewalk.h | 19 +++++++++++++------
 mm/pagewalk.c            | 27 ++++++++++++++++-----------
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index bddd9759bab9..12004b097eae 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -8,15 +8,15 @@ struct mm_walk;
 
 /**
  * mm_walk_ops - callbacks for walk_page_range
- * @pud_entry:		if set, called for each non-empty PUD (2nd-level) entry
- *			this handler should only handle pud_trans_huge() puds.
- *			the pmd_entry or pte_entry callbacks will be used for
- *			regular PUDs.
- * @pmd_entry:		if set, called for each non-empty PMD (3rd-level) entry
+ * @pgd_entry:		if set, called for each non-empty PGD (top-level) entry
+ * @p4d_entry:		if set, called for each non-empty P4D entry
+ * @pud_entry:		if set, called for each non-empty PUD entry
+ * @pmd_entry:		if set, called for each non-empty PMD entry
  *			this handler is required to be able to handle
  *			pmd_trans_huge() pmds.  They may simply choose to
  *			split_huge_page() instead of handling it explicitly.
- * @pte_entry:		if set, called for each non-empty PTE (4th-level) entry
+ * @pte_entry:		if set, called for each non-empty PTE (lowest-level)
+ *			entry
  * @pte_hole:		if set, called for each hole at all levels
  * @hugetlb_entry:	if set, called for each hugetlb entry
  * @test_walk:		caller specific callback function to determine whether
@@ -24,8 +24,15 @@ struct mm_walk;
  *			"do page table walk over the current vma", returning
  *			a negative value means "abort current page table walk
  *			right now" and returning 1 means "skip the current vma"
+ *
+ * p?d_entry callbacks are called even if those levels are folded on a
+ * particular architecture/configuration.
  */
 struct mm_walk_ops {
+	int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
+			 unsigned long next, struct mm_walk *walk);
+	int (*p4d_entry)(p4d_t *p4d, unsigned long addr,
+			 unsigned long next, struct mm_walk *walk);
 	int (*pud_entry)(pud_t *pud, unsigned long addr,
 			 unsigned long next, struct mm_walk *walk);
 	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d48c2a986ea3..fc4d98a3a5a0 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -93,15 +93,9 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 		}
 
 		if (ops->pud_entry) {
-			spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
-
-			if (ptl) {
-				err = ops->pud_entry(pud, addr, next, walk);
-				spin_unlock(ptl);
-				if (err)
-					break;
-				continue;
-			}
+			err = ops->pud_entry(pud, addr, next, walk);
+			if (err)
+				break;
 		}
 
 		split_huge_pud(walk->vma, pud, addr);
@@ -135,7 +129,12 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 				break;
 			continue;
 		}
-		if (ops->pmd_entry || ops->pte_entry)
+		if (ops->p4d_entry) {
+			err = ops->p4d_entry(p4d, addr, next, walk);
+			if (err)
+				break;
+		}
+		if (ops->pud_entry || ops->pmd_entry || ops->pte_entry)
 			err = walk_pud_range(p4d, addr, next, walk);
 		if (err)
 			break;
@@ -162,7 +161,13 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
 				break;
 			continue;
 		}
-		if (ops->pmd_entry || ops->pte_entry)
+		if (ops->pgd_entry) {
+			err = ops->pgd_entry(pgd, addr, next, walk);
+			if (err)
+				break;
+		}
+		if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry ||
+		    ops->pte_entry)
 			err = walk_p4d_range(pgd, addr, next, walk);
 		if (err)
 			break;
-- 
2.20.1

[PATCH v15 12/23] mm: pagewalk: Allow walking without vma

[Steven Price]

Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range
for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as
a hole, because it lacks a vma.

This means each arch has re-implemented page table walking when needed,
for example in the per-arch ptdump walker.

Remove the requirement to have a vma in the generic code and add a new
function walk_page_range_novma() which ignores the VMAs and simply walks
the page tables.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/pagewalk.h |  5 +++++
 mm/pagewalk.c            | 44 ++++++++++++++++++++++++++++++++--------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index 12004b097eae..ed2bb399fac2 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -53,6 +53,7 @@ struct mm_walk_ops {
  * @ops:	operation to call during the walk
  * @mm:		mm_struct representing the target process of page table walk
  * @vma:	vma currently walked (NULL if walking outside vmas)
+ * @no_vma:	walk ignoring vmas (vma will always be NULL)
  * @private:	private data for callbacks' usage
  *
  * (see the comment on walk_page_range() for more details)
@@ -61,12 +62,16 @@ struct mm_walk {
 	const struct mm_walk_ops *ops;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
+	bool no_vma;
 	void *private;
 };
 
 int walk_page_range(struct mm_struct *mm, unsigned long start,
 		unsigned long end, const struct mm_walk_ops *ops,
 		void *private);
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+			  unsigned long end, const struct mm_walk_ops *ops,
+			  void *private);
 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		void *private);
 
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index fc4d98a3a5a0..626e7fdb0508 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -38,7 +38,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	do {
 again:
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(*pmd) || !walk->vma) {
+		if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
 				err = ops->pte_hole(addr, next, walk);
 			if (err)
@@ -61,9 +61,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		if (!ops->pte_entry)
 			continue;
 
-		split_huge_pmd(walk->vma, pmd, addr);
-		if (pmd_trans_unstable(pmd))
-			goto again;
+		if (walk->vma) {
+			split_huge_pmd(walk->vma, pmd, addr);
+			if (pmd_trans_unstable(pmd))
+				goto again;
+		} else if (pmd_leaf(*pmd)) {
+			continue;
+		}
+
 		err = walk_pte_range(pmd, addr, next, walk);
 		if (err)
 			break;
@@ -84,7 +89,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 	do {
  again:
 		next = pud_addr_end(addr, end);
-		if (pud_none(*pud) || !walk->vma) {
+		if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
 				err = ops->pte_hole(addr, next, walk);
 			if (err)
@@ -98,9 +103,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 				break;
 		}
 
-		split_huge_pud(walk->vma, pud, addr);
-		if (pud_none(*pud))
-			goto again;
+		if (walk->vma) {
+			split_huge_pud(walk->vma, pud, addr);
+			if (pud_none(*pud))
+				goto again;
+		} else if (pud_leaf(*pud)) {
+			continue;
+		}
 
 		if (ops->pmd_entry || ops->pte_entry)
 			err = walk_pmd_range(pud, addr, next, walk);
@@ -358,6 +367,25 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 	return err;
 }
 
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+			  unsigned long end, const struct mm_walk_ops *ops,
+			  void *private)
+{
+	struct mm_walk walk = {
+		.ops		= ops,
+		.mm		= mm,
+		.private	= private,
+		.no_vma		= true
+	};
+
+	if (start >= end || !walk.mm)
+		return -EINVAL;
+
+	lockdep_assert_held(&walk.mm->mmap_sem);
+
+	return __walk_page_range(start, end, &walk);
+}
+
 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		void *private)
 {
-- 
2.20.1

[PATCH v15 13/23] mm: pagewalk: Add test_p?d callbacks

[Steven Price]

It is useful to be able to skip parts of the page table tree even when
walking without VMAs. Add test_p?d callbacks similar to test_walk but
which are called just before a table at that level is walked. If the
callback returns non-zero then the entire table is skipped.

Tested-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/pagewalk.h | 11 +++++++++++
 mm/pagewalk.c            | 24 ++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index ed2bb399fac2..fe61448c5900 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -24,6 +24,11 @@ struct mm_walk;
  *			"do page table walk over the current vma", returning
  *			a negative value means "abort current page table walk
  *			right now" and returning 1 means "skip the current vma"
+ * @test_pmd:		similar to test_walk(), but called for every pmd.
+ * @test_pud:		similar to test_walk(), but called for every pud.
+ * @test_p4d:		similar to test_walk(), but called for every p4d.
+ *			Returning 0 means walk this part of the page tables,
+ *			returning 1 means to skip this range.
  *
  * p?d_entry callbacks are called even if those levels are folded on a
  * particular architecture/configuration.
@@ -46,6 +51,12 @@ struct mm_walk_ops {
 			     struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
+	int (*test_pmd)(unsigned long addr, unsigned long next,
+			pmd_t *pmd_start, struct mm_walk *walk);
+	int (*test_pud)(unsigned long addr, unsigned long next,
+			pud_t *pud_start, struct mm_walk *walk);
+	int (*test_p4d)(unsigned long addr, unsigned long next,
+			p4d_t *p4d_start, struct mm_walk *walk);
 };
 
 /**
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 626e7fdb0508..4616281f5b69 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -34,6 +34,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
+	if (ops->test_pmd) {
+		err = ops->test_pmd(addr, end, pmd_offset(pud, 0UL), walk);
+		if (err < 0)
+			return err;
+		if (err > 0)
+			return 0;
+	}
+
 	pmd = pmd_offset(pud, addr);
 	do {
 again:
@@ -85,6 +93,14 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
+	if (ops->test_pud) {
+		err = ops->test_pud(addr, end, pud_offset(p4d, 0UL), walk);
+		if (err < 0)
+			return err;
+		if (err > 0)
+			return 0;
+	}
+
 	pud = pud_offset(p4d, addr);
 	do {
  again:
@@ -128,6 +144,14 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
+	if (ops->test_p4d) {
+		err = ops->test_p4d(addr, end, p4d_offset(pgd, 0UL), walk);
+		if (err < 0)
+			return err;
+		if (err > 0)
+			return 0;
+	}
+
 	p4d = p4d_offset(pgd, addr);
 	do {
 		next = p4d_addr_end(addr, end);
-- 
2.20.1

[PATCH v15 14/23] mm: pagewalk: Add 'depth' parameter to pte_hole

[Steven Price]

The pte_hole() callback is called at multiple levels of the page tables.
Code dumping the kernel page tables needs to know what at what depth
the missing entry is. Add this is an extra parameter to pte_hole().
When the depth isn't know (e.g. processing a vma) then -1 is passed.

The depth that is reported is the actual level where the entry is
missing (ignoring any folding that is in place), i.e. any levels where
PTRS_PER_P?D is set to 1 are ignored.

Note that depth starts at 0 for a PGD so that PUD/PMD/PTE retain their
natural numbers as levels 2/3/4.

Tested-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 fs/proc/task_mmu.c       |  4 ++--
 include/linux/pagewalk.h |  7 +++++--
 mm/hmm.c                 |  8 ++++----
 mm/migrate.c             |  5 +++--
 mm/mincore.c             |  1 +
 mm/pagewalk.c            | 31 +++++++++++++++++++++++++------
 6 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 9442631fd4af..3ba9ae83bff5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -505,7 +505,7 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
 
 #ifdef CONFIG_SHMEM
 static int smaps_pte_hole(unsigned long addr, unsigned long end,
-		struct mm_walk *walk)
+			  __always_unused int depth, struct mm_walk *walk)
 {
 	struct mem_size_stats *mss = walk->private;
 
@@ -1282,7 +1282,7 @@ static int add_to_pagemap(unsigned long addr, pagemap_entry_t *pme,
 }
 
 static int pagemap_pte_hole(unsigned long start, unsigned long end,
-				struct mm_walk *walk)
+			    __always_unused int depth, struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
 	unsigned long addr = start;
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index fe61448c5900..94c9ad171f1c 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -17,7 +17,10 @@ struct mm_walk;
  *			split_huge_page() instead of handling it explicitly.
  * @pte_entry:		if set, called for each non-empty PTE (lowest-level)
  *			entry
- * @pte_hole:		if set, called for each hole at all levels
+ * @pte_hole:		if set, called for each hole at all levels,
+ *			depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD
+ *			4:PTE. Any folded depths (where PTRS_PER_P?D is equal
+ *			to 1) are skipped.
  * @hugetlb_entry:	if set, called for each hugetlb entry
  * @test_walk:		caller specific callback function to determine whether
  *			we walk over the current vma or not. Returning 0 means
@@ -45,7 +48,7 @@ struct mm_walk_ops {
 	int (*pte_entry)(pte_t *pte, unsigned long addr,
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
-			struct mm_walk *walk);
+			int depth, struct mm_walk *walk);
 	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
 			     unsigned long addr, unsigned long next,
 			     struct mm_walk *walk);
diff --git a/mm/hmm.c b/mm/hmm.c
index 902f5fa6bf93..df3d531c8f2d 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -376,7 +376,7 @@ static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
 }
 
 static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
-			     struct mm_walk *walk)
+			     __always_unused int depth, struct mm_walk *walk)
 {
 	struct hmm_vma_walk *hmm_vma_walk = walk->private;
 	struct hmm_range *range = hmm_vma_walk->range;
@@ -564,7 +564,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 again:
 	pmd = READ_ONCE(*pmdp);
 	if (pmd_none(pmd))
-		return hmm_vma_walk_hole(start, end, walk);
+		return hmm_vma_walk_hole(start, end, -1, walk);
 
 	if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
 		bool fault, write_fault;
@@ -666,7 +666,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
 again:
 	pud = READ_ONCE(*pudp);
 	if (pud_none(pud))
-		return hmm_vma_walk_hole(start, end, walk);
+		return hmm_vma_walk_hole(start, end, -1, walk);
 
 	if (pud_huge(pud) && pud_devmap(pud)) {
 		unsigned long i, npages, pfn;
@@ -674,7 +674,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
 		bool fault, write_fault;
 
 		if (!pud_present(pud))
-			return hmm_vma_walk_hole(start, end, walk);
+			return hmm_vma_walk_hole(start, end, -1, walk);
 
 		i = (addr - range->start) >> PAGE_SHIFT;
 		npages = (end - addr) >> PAGE_SHIFT;
diff --git a/mm/migrate.c b/mm/migrate.c
index 4fe45d1428c8..435258df9a36 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2123,6 +2123,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 #ifdef CONFIG_DEVICE_PRIVATE
 static int migrate_vma_collect_hole(unsigned long start,
 				    unsigned long end,
+				    __always_unused int depth,
 				    struct mm_walk *walk)
 {
 	struct migrate_vma *migrate = walk->private;
@@ -2167,7 +2168,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 
 again:
 	if (pmd_none(*pmdp))
-		return migrate_vma_collect_hole(start, end, walk);
+		return migrate_vma_collect_hole(start, end, -1, walk);
 
 	if (pmd_trans_huge(*pmdp)) {
 		struct page *page;
@@ -2200,7 +2201,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 				return migrate_vma_collect_skip(start, end,
 								walk);
 			if (pmd_none(*pmdp))
-				return migrate_vma_collect_hole(start, end,
+				return migrate_vma_collect_hole(start, end, -1,
 								walk);
 		}
 	}
diff --git a/mm/mincore.c b/mm/mincore.c
index 49b6fa2f6aa1..0e6dd9948f1a 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -112,6 +112,7 @@ static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
 }
 
 static int mincore_unmapped_range(unsigned long addr, unsigned long end,
+				   __always_unused int depth,
 				   struct mm_walk *walk)
 {
 	walk->private += __mincore_unmapped_range(addr, end,
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 4616281f5b69..c7529dc4f82b 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -4,6 +4,22 @@
 #include <linux/sched.h>
 #include <linux/hugetlb.h>
 
+/*
+ * We want to know the real level where a entry is located ignoring any
+ * folding of levels which may be happening. For example if p4d is folded then
+ * a missing entry found at level 1 (p4d) is actually at level 0 (pgd).
+ */
+static int real_depth(int depth)
+{
+	if (depth == 3 && PTRS_PER_PMD == 1)
+		depth = 2;
+	if (depth == 2 && PTRS_PER_PUD == 1)
+		depth = 1;
+	if (depth == 1 && PTRS_PER_P4D == 1)
+		depth = 0;
+	return depth;
+}
+
 static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 			  struct mm_walk *walk)
 {
@@ -33,6 +49,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	unsigned long next;
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
+	int depth = real_depth(3);
 
 	if (ops->test_pmd) {
 		err = ops->test_pmd(addr, end, pmd_offset(pud, 0UL), walk);
@@ -48,7 +65,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		next = pmd_addr_end(addr, end);
 		if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
-				err = ops->pte_hole(addr, next, walk);
+				err = ops->pte_hole(addr, next, depth, walk);
 			if (err)
 				break;
 			continue;
@@ -92,6 +109,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 	unsigned long next;
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
+	int depth = real_depth(2);
 
 	if (ops->test_pud) {
 		err = ops->test_pud(addr, end, pud_offset(p4d, 0UL), walk);
@@ -107,7 +125,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 		next = pud_addr_end(addr, end);
 		if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
-				err = ops->pte_hole(addr, next, walk);
+				err = ops->pte_hole(addr, next, depth, walk);
 			if (err)
 				break;
 			continue;
@@ -143,6 +161,7 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 	unsigned long next;
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
+	int depth = real_depth(1);
 
 	if (ops->test_p4d) {
 		err = ops->test_p4d(addr, end, p4d_offset(pgd, 0UL), walk);
@@ -157,7 +176,7 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 		next = p4d_addr_end(addr, end);
 		if (p4d_none_or_clear_bad(p4d)) {
 			if (ops->pte_hole)
-				err = ops->pte_hole(addr, next, walk);
+				err = ops->pte_hole(addr, next, depth, walk);
 			if (err)
 				break;
 			continue;
@@ -189,7 +208,7 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd)) {
 			if (ops->pte_hole)
-				err = ops->pte_hole(addr, next, walk);
+				err = ops->pte_hole(addr, next, 0, walk);
 			if (err)
 				break;
 			continue;
@@ -236,7 +255,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		if (pte)
 			err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
 		else if (ops->pte_hole)
-			err = ops->pte_hole(addr, next, walk);
+			err = ops->pte_hole(addr, next, -1, walk);
 
 		if (err)
 			break;
@@ -280,7 +299,7 @@ static int walk_page_test(unsigned long start, unsigned long end,
 	if (vma->vm_flags & VM_PFNMAP) {
 		int err = 1;
 		if (ops->pte_hole)
-			err = ops->pte_hole(start, end, walk);
+			err = ops->pte_hole(start, end, -1, walk);
 		return err ? err : 1;
 	}
 	return 0;
-- 
2.20.1

[PATCH v15 15/23] x86: mm: Point to struct seq_file from struct pg_state

[Steven Price]

mm/dump_pagetables.c passes both struct seq_file and struct pg_state
down the chain of walk_*_level() functions to be passed to note_page().
Instead place the struct seq_file in struct pg_state and access it from
struct pg_state (which is private to this file) in note_page().

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/mm/dump_pagetables.c | 69 ++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ab67822fd2f4..4dc6f4df40af 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -36,6 +36,7 @@ struct pg_state {
 	bool to_dmesg;
 	bool check_wx;
 	unsigned long wx_pages;
+	struct seq_file *seq;
 };
 
 struct addr_marker {
@@ -265,11 +266,12 @@ static void note_wx(struct pg_state *st)
  * of PTE entries; the next one is different so we need to
  * print what we collected so far.
  */
-static void note_page(struct seq_file *m, struct pg_state *st,
-		      pgprot_t new_prot, pgprotval_t new_eff, int level)
+static void note_page(struct pg_state *st, pgprot_t new_prot,
+		      pgprotval_t new_eff, int level)
 {
 	pgprotval_t prot, cur, eff;
 	static const char units[] = "BKMGTPE";
+	struct seq_file *m = st->seq;
 
 	/*
 	 * If we have a "break" in the series, we need to flush the state that
@@ -354,8 +356,8 @@ static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
 	       ((prot1 | prot2) & _PAGE_NX);
 }
 
-static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
-			   pgprotval_t eff_in, unsigned long P)
+static void walk_pte_level(struct pg_state *st, pmd_t addr, pgprotval_t eff_in,
+			   unsigned long P)
 {
 	int i;
 	pte_t *pte;
@@ -366,7 +368,7 @@ static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
 		pte = pte_offset_map(&addr, st->current_address);
 		prot = pte_flags(*pte);
 		eff = effective_prot(eff_in, prot);
-		note_page(m, st, __pgprot(prot), eff, 5);
+		note_page(st, __pgprot(prot), eff, 5);
 		pte_unmap(pte);
 	}
 }
@@ -379,22 +381,20 @@ static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
  * us dozens of seconds (minutes for 5-level config) while checking for
  * W+X mapping or reading kernel_page_tables debugfs file.
  */
-static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
-				void *pt)
+static inline bool kasan_page_table(struct pg_state *st, void *pt)
 {
 	if (__pa(pt) == __pa(kasan_early_shadow_pmd) ||
 	    (pgtable_l5_enabled() &&
 			__pa(pt) == __pa(kasan_early_shadow_p4d)) ||
 	    __pa(pt) == __pa(kasan_early_shadow_pud)) {
 		pgprotval_t prot = pte_flags(kasan_early_shadow_pte[0]);
-		note_page(m, st, __pgprot(prot), 0, 5);
+		note_page(st, __pgprot(prot), 0, 5);
 		return true;
 	}
 	return false;
 }
 #else
-static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
-				void *pt)
+static inline bool kasan_page_table(struct pg_state *st, void *pt)
 {
 	return false;
 }
@@ -402,7 +402,7 @@ static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
 
 #if PTRS_PER_PMD > 1
 
-static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
+static void walk_pmd_level(struct pg_state *st, pud_t addr,
 			   pgprotval_t eff_in, unsigned long P)
 {
 	int i;
@@ -416,27 +416,27 @@ static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
 			prot = pmd_flags(*start);
 			eff = effective_prot(eff_in, prot);
 			if (pmd_large(*start) || !pmd_present(*start)) {
-				note_page(m, st, __pgprot(prot), eff, 4);
-			} else if (!kasan_page_table(m, st, pmd_start)) {
-				walk_pte_level(m, st, *start, eff,
+				note_page(st, __pgprot(prot), eff, 4);
+			} else if (!kasan_page_table(st, pmd_start)) {
+				walk_pte_level(st, *start, eff,
 					       P + i * PMD_LEVEL_MULT);
 			}
 		} else
-			note_page(m, st, __pgprot(0), 0, 4);
+			note_page(st, __pgprot(0), 0, 4);
 		start++;
 	}
 }
 
 #else
-#define walk_pmd_level(m,s,a,e,p) walk_pte_level(m,s,__pmd(pud_val(a)),e,p)
+#define walk_pmd_level(s,a,e,p) walk_pte_level(s,__pmd(pud_val(a)),e,p)
 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
 #define pud_none(a)  pmd_none(__pmd(pud_val(a)))
 #endif
 
 #if PTRS_PER_PUD > 1
 
-static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr,
-			   pgprotval_t eff_in, unsigned long P)
+static void walk_pud_level(struct pg_state *st, p4d_t addr, pgprotval_t eff_in,
+			   unsigned long P)
 {
 	int i;
 	pud_t *start, *pud_start;
@@ -450,33 +450,33 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr,
 			prot = pud_flags(*start);
 			eff = effective_prot(eff_in, prot);
 			if (pud_large(*start) || !pud_present(*start)) {
-				note_page(m, st, __pgprot(prot), eff, 3);
-			} else if (!kasan_page_table(m, st, pud_start)) {
-				walk_pmd_level(m, st, *start, eff,
+				note_page(st, __pgprot(prot), eff, 3);
+			} else if (!kasan_page_table(st, pud_start)) {
+				walk_pmd_level(st, *start, eff,
 					       P + i * PUD_LEVEL_MULT);
 			}
 		} else
-			note_page(m, st, __pgprot(0), 0, 3);
+			note_page(st, __pgprot(0), 0, 3);
 
 		start++;
 	}
 }
 
 #else
-#define walk_pud_level(m,s,a,e,p) walk_pmd_level(m,s,__pud(p4d_val(a)),e,p)
+#define walk_pud_level(s,a,e,p) walk_pmd_level(s,__pud(p4d_val(a)),e,p)
 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
 #define p4d_none(a)  pud_none(__pud(p4d_val(a)))
 #endif
 
-static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
-			   pgprotval_t eff_in, unsigned long P)
+static void walk_p4d_level(struct pg_state *st, pgd_t addr, pgprotval_t eff_in,
+			   unsigned long P)
 {
 	int i;
 	p4d_t *start, *p4d_start;
 	pgprotval_t prot, eff;
 
 	if (PTRS_PER_P4D == 1)
-		return walk_pud_level(m, st, __p4d(pgd_val(addr)), eff_in, P);
+		return walk_pud_level(st, __p4d(pgd_val(addr)), eff_in, P);
 
 	p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
 
@@ -486,13 +486,13 @@ static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
 			prot = p4d_flags(*start);
 			eff = effective_prot(eff_in, prot);
 			if (p4d_large(*start) || !p4d_present(*start)) {
-				note_page(m, st, __pgprot(prot), eff, 2);
-			} else if (!kasan_page_table(m, st, p4d_start)) {
-				walk_pud_level(m, st, *start, eff,
+				note_page(st, __pgprot(prot), eff, 2);
+			} else if (!kasan_page_table(st, p4d_start)) {
+				walk_pud_level(st, *start, eff,
 					       P + i * P4D_LEVEL_MULT);
 			}
 		} else
-			note_page(m, st, __pgprot(0), 0, 2);
+			note_page(st, __pgprot(0), 0, 2);
 
 		start++;
 	}
@@ -529,6 +529,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 	}
 
 	st.check_wx = checkwx;
+	st.seq = m;
 	if (checkwx)
 		st.wx_pages = 0;
 
@@ -542,13 +543,13 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 			eff = prot;
 #endif
 			if (pgd_large(*start) || !pgd_present(*start)) {
-				note_page(m, &st, __pgprot(prot), eff, 1);
+				note_page(&st, __pgprot(prot), eff, 1);
 			} else {
-				walk_p4d_level(m, &st, *start, eff,
+				walk_p4d_level(&st, *start, eff,
 					       i * PGD_LEVEL_MULT);
 			}
 		} else
-			note_page(m, &st, __pgprot(0), 0, 1);
+			note_page(&st, __pgprot(0), 0, 1);
 
 		cond_resched();
 		start++;
@@ -556,7 +557,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 
 	/* Flush out the last page */
 	st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
-	note_page(m, &st, __pgprot(0), 0, 0);
+	note_page(&st, __pgprot(0), 0, 0);
 	if (!checkwx)
 		return;
 	if (st.wx_pages)
-- 
2.20.1

[PATCH v15 16/23] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct

[Steven Price]

To enable x86 to use the generic walk_page_range() function, the
callers of ptdump_walk_pgd_level() need to pass an mm_struct rather
than the raw pgd_t pointer. Luckily since commit 7e904a91bf60
("efi: Use efi_mm in x86 as well as ARM") we now have an mm_struct
for EFI on x86.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/include/asm/pgtable.h | 2 +-
 arch/x86/mm/dump_pagetables.c  | 4 ++--
 arch/x86/platform/efi/efi_32.c | 2 +-
 arch/x86/platform/efi/efi_64.c | 4 ++--
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 6986a451619e..1a2b469f6e75 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -29,7 +29,7 @@
 extern pgd_t early_top_pgt[PTRS_PER_PGD];
 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd);
 
-void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);
+void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm);
 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user);
 void ptdump_walk_pgd_level_checkwx(void);
 void ptdump_walk_user_pgd_level_checkwx(void);
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 4dc6f4df40af..24fe76325b31 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -567,9 +567,9 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 		pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
 }
 
-void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
+void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
 {
-	ptdump_walk_pgd_level_core(m, pgd, false, true);
+	ptdump_walk_pgd_level_core(m, mm->pgd, false, true);
 }
 
 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 9959657127f4..1616074075c3 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -49,7 +49,7 @@ void efi_sync_low_kernel_mappings(void) {}
 void __init efi_dump_pagetable(void)
 {
 #ifdef CONFIG_EFI_PGT_DUMP
-	ptdump_walk_pgd_level(NULL, swapper_pg_dir);
+	ptdump_walk_pgd_level(NULL, &init_mm);
 #endif
 }
 
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 08ce8177c3af..3cb63cd369d6 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -614,9 +614,9 @@ void __init efi_dump_pagetable(void)
 {
 #ifdef CONFIG_EFI_PGT_DUMP
 	if (efi_enabled(EFI_OLD_MEMMAP))
-		ptdump_walk_pgd_level(NULL, swapper_pg_dir);
+		ptdump_walk_pgd_level(NULL, &init_mm);
 	else
-		ptdump_walk_pgd_level(NULL, efi_mm.pgd);
+		ptdump_walk_pgd_level(NULL, &efi_mm);
 #endif
 }
 
-- 
2.20.1

[PATCH v15 17/23] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct

[Steven Price]

To enable x86 to use the generic walk_page_range() function, the
callers of ptdump_walk_pgd_level_debugfs() need to pass in the mm_struct.

This means that ptdump_walk_pgd_level_core() is now always passed a
valid pgd, so drop the support for pgd==NULL.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/include/asm/pgtable.h |  3 ++-
 arch/x86/mm/debug_pagetables.c |  8 ++++----
 arch/x86/mm/dump_pagetables.c  | 14 ++++++--------
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 1a2b469f6e75..1b255987712e 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -30,7 +30,8 @@ extern pgd_t early_top_pgt[PTRS_PER_PGD];
 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd);
 
 void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm);
-void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user);
+void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
+				   bool user);
 void ptdump_walk_pgd_level_checkwx(void);
 void ptdump_walk_user_pgd_level_checkwx(void);
 
diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
index 39001a401eff..d0efec713c6c 100644
--- a/arch/x86/mm/debug_pagetables.c
+++ b/arch/x86/mm/debug_pagetables.c
@@ -7,7 +7,7 @@
 
 static int ptdump_show(struct seq_file *m, void *v)
 {
-	ptdump_walk_pgd_level_debugfs(m, NULL, false);
+	ptdump_walk_pgd_level_debugfs(m, &init_mm, false);
 	return 0;
 }
 
@@ -17,7 +17,7 @@ static int ptdump_curknl_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
-		ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, false);
+		ptdump_walk_pgd_level_debugfs(m, current->mm, false);
 		up_read(&current->mm->mmap_sem);
 	}
 	return 0;
@@ -30,7 +30,7 @@ static int ptdump_curusr_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
-		ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, true);
+		ptdump_walk_pgd_level_debugfs(m, current->mm, true);
 		up_read(&current->mm->mmap_sem);
 	}
 	return 0;
@@ -43,7 +43,7 @@ DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
 static int ptdump_efi_show(struct seq_file *m, void *v)
 {
 	if (efi_mm.pgd)
-		ptdump_walk_pgd_level_debugfs(m, efi_mm.pgd, false);
+		ptdump_walk_pgd_level_debugfs(m, &efi_mm, false);
 	return 0;
 }
 
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 24fe76325b31..2f5f32f21f81 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -518,16 +518,12 @@ static inline bool is_hypervisor_range(int idx)
 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 				       bool checkwx, bool dmesg)
 {
-	pgd_t *start = INIT_PGD;
+	pgd_t *start = pgd;
 	pgprotval_t prot, eff;
 	int i;
 	struct pg_state st = {};
 
-	if (pgd) {
-		start = pgd;
-		st.to_dmesg = dmesg;
-	}
-
+	st.to_dmesg = dmesg;
 	st.check_wx = checkwx;
 	st.seq = m;
 	if (checkwx)
@@ -572,8 +568,10 @@ void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
 	ptdump_walk_pgd_level_core(m, mm->pgd, false, true);
 }
 
-void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
+void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
+				   bool user)
 {
+	pgd_t *pgd = mm->pgd;
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 	if (user && boot_cpu_has(X86_FEATURE_PTI))
 		pgd = kernel_to_user_pgdp(pgd);
@@ -599,7 +597,7 @@ void ptdump_walk_user_pgd_level_checkwx(void)
 
 void ptdump_walk_pgd_level_checkwx(void)
 {
-	ptdump_walk_pgd_level_core(NULL, NULL, true, false);
+	ptdump_walk_pgd_level_core(NULL, INIT_PGD, true, false);
 }
 
 static int __init pt_dump_init(void)
-- 
2.20.1

[PATCH v15 18/23] x86: mm: Convert ptdump_walk_pgd_level_core() to take an mm_struct

[Steven Price]

An mm_struct is needed to enable x86 to use of the generic
walk_page_range() function.

In the case of walking the user page tables (when
CONFIG_PAGE_TABLE_ISOLATION is enabled), it is necessary to create a
fake_mm structure because there isn't an mm_struct with a pointer
to the pgd of the user page tables. This fake_mm structure is
initialised with the minimum necessary for the generic page walk code.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/mm/dump_pagetables.c | 36 ++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 2f5f32f21f81..3632be89ec99 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -107,8 +107,6 @@ static struct addr_marker address_markers[] = {
 	[END_OF_SPACE_NR]	= { -1,			NULL }
 };
 
-#define INIT_PGD	((pgd_t *) &init_top_pgt)
-
 #else /* CONFIG_X86_64 */
 
 enum address_markers_idx {
@@ -143,8 +141,6 @@ static struct addr_marker address_markers[] = {
 	[END_OF_SPACE_NR]	= { -1,			NULL }
 };
 
-#define INIT_PGD	(swapper_pg_dir)
-
 #endif /* !CONFIG_X86_64 */
 
 /* Multipliers for offsets within the PTEs */
@@ -515,10 +511,10 @@ static inline bool is_hypervisor_range(int idx)
 #endif
 }
 
-static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
+static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm,
 				       bool checkwx, bool dmesg)
 {
-	pgd_t *start = pgd;
+	pgd_t *start = mm->pgd;
 	pgprotval_t prot, eff;
 	int i;
 	struct pg_state st = {};
@@ -565,39 +561,49 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 
 void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
 {
-	ptdump_walk_pgd_level_core(m, mm->pgd, false, true);
+	ptdump_walk_pgd_level_core(m, mm, false, true);
 }
 
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+static void ptdump_walk_pgd_level_user_core(struct seq_file *m,
+					    struct mm_struct *mm,
+					    bool checkwx, bool dmesg)
+{
+	struct mm_struct fake_mm = {
+		.pgd = kernel_to_user_pgdp(mm->pgd)
+	};
+	init_rwsem(&fake_mm.mmap_sem);
+	ptdump_walk_pgd_level_core(m, &fake_mm, checkwx, dmesg);
+}
+#endif
+
 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
 				   bool user)
 {
-	pgd_t *pgd = mm->pgd;
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 	if (user && boot_cpu_has(X86_FEATURE_PTI))
-		pgd = kernel_to_user_pgdp(pgd);
+		ptdump_walk_pgd_level_user_core(m, mm, false, false);
+	else
 #endif
-	ptdump_walk_pgd_level_core(m, pgd, false, false);
+		ptdump_walk_pgd_level_core(m, mm, false, false);
 }
 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
 
 void ptdump_walk_user_pgd_level_checkwx(void)
 {
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
-	pgd_t *pgd = INIT_PGD;
-
 	if (!(__supported_pte_mask & _PAGE_NX) ||
 	    !boot_cpu_has(X86_FEATURE_PTI))
 		return;
 
 	pr_info("x86/mm: Checking user space page tables\n");
-	pgd = kernel_to_user_pgdp(pgd);
-	ptdump_walk_pgd_level_core(NULL, pgd, true, false);
+	ptdump_walk_pgd_level_user_core(NULL, &init_mm, true, false);
 #endif
 }
 
 void ptdump_walk_pgd_level_checkwx(void)
 {
-	ptdump_walk_pgd_level_core(NULL, INIT_PGD, true, false);
+	ptdump_walk_pgd_level_core(NULL, &init_mm, true, false);
 }
 
 static int __init pt_dump_init(void)
-- 
2.20.1

[PATCH v15 19/23] mm: Add generic ptdump

[Steven Price]

Add a generic version of page table dumping that architectures can
opt-in to

Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/ptdump.h |  21 ++++++
 mm/Kconfig.debug       |  21 ++++++
 mm/Makefile            |   1 +
 mm/ptdump.c            | 151 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 194 insertions(+)
 create mode 100644 include/linux/ptdump.h
 create mode 100644 mm/ptdump.c

diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h
new file mode 100644
index 000000000000..a0fb8dd2be97
--- /dev/null
+++ b/include/linux/ptdump.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_PTDUMP_H
+#define _LINUX_PTDUMP_H
+
+#include <linux/mm_types.h>
+
+struct ptdump_range {
+	unsigned long start;
+	unsigned long end;
+};
+
+struct ptdump_state {
+	void (*note_page)(struct ptdump_state *st, unsigned long addr,
+			  int level, unsigned long val);
+	const struct ptdump_range *range;
+};
+
+void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm);
+
+#endif /* _LINUX_PTDUMP_H */
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 327b3ebf23bf..0271b22e063f 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -117,3 +117,24 @@ config DEBUG_RODATA_TEST
     depends on STRICT_KERNEL_RWX
     ---help---
       This option enables a testcase for the setting rodata read-only.
+
+config GENERIC_PTDUMP
+	bool
+
+config PTDUMP_CORE
+	bool
+
+config PTDUMP_DEBUGFS
+	bool "Export kernel pagetable layout to userspace via debugfs"
+	depends on DEBUG_KERNEL
+	depends on DEBUG_FS
+	depends on GENERIC_PTDUMP
+	select PTDUMP_CORE
+	help
+	  Say Y here if you want to show the kernel pagetable layout in a
+	  debugfs file. This information is only useful for kernel developers
+	  who are working in architecture specific areas of the kernel.
+	  It is probably not a good idea to enable this feature in a production
+	  kernel.
+
+	  If in doubt, say N.
diff --git a/mm/Makefile b/mm/Makefile
index d996846697ef..6e962007f186 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -107,3 +107,4 @@ obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o
 obj-$(CONFIG_ZONE_DEVICE) += memremap.o
 obj-$(CONFIG_HMM_MIRROR) += hmm.o
 obj-$(CONFIG_MEMFD_CREATE) += memfd.o
+obj-$(CONFIG_PTDUMP_CORE) += ptdump.o
diff --git a/mm/ptdump.c b/mm/ptdump.c
new file mode 100644
index 000000000000..79e63454f1f7
--- /dev/null
+++ b/mm/ptdump.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pagewalk.h>
+#include <linux/ptdump.h>
+#include <linux/kasan.h>
+
+static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
+			    unsigned long next, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+	pgd_t val = READ_ONCE(*pgd);
+
+	if (pgd_leaf(val))
+		st->note_page(st, addr, 1, pgd_val(val));
+
+	return 0;
+}
+
+static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
+			    unsigned long next, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+	p4d_t val = READ_ONCE(*p4d);
+
+	if (p4d_leaf(val))
+		st->note_page(st, addr, 2, p4d_val(val));
+
+	return 0;
+}
+
+static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
+			    unsigned long next, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+	pud_t val = READ_ONCE(*pud);
+
+	if (pud_leaf(val))
+		st->note_page(st, addr, 3, pud_val(val));
+
+	return 0;
+}
+
+static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
+			    unsigned long next, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+	pmd_t val = READ_ONCE(*pmd);
+
+	if (pmd_leaf(val))
+		st->note_page(st, addr, 4, pmd_val(val));
+
+	return 0;
+}
+
+static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
+			    unsigned long next, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+
+	st->note_page(st, addr, 5, pte_val(READ_ONCE(*pte)));
+
+	return 0;
+}
+
+#ifdef CONFIG_KASAN
+/*
+ * This is an optimization for KASAN=y case. Since all kasan page tables
+ * eventually point to the kasan_early_shadow_page we could call note_page()
+ * right away without walking through lower level page tables. This saves
+ * us dozens of seconds (minutes for 5-level config) while checking for
+ * W+X mapping or reading kernel_page_tables debugfs file.
+ */
+static inline int note_kasan_page_table(struct mm_walk *walk,
+					unsigned long addr)
+{
+	struct ptdump_state *st = walk->private;
+
+	st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0]));
+	return 1;
+}
+
+static int ptdump_test_p4d(unsigned long addr, unsigned long next,
+			   p4d_t *p4d, struct mm_walk *walk)
+{
+#if CONFIG_PGTABLE_LEVELS > 4
+	if (p4d == lm_alias(kasan_early_shadow_p4d))
+		return note_kasan_page_table(walk, addr);
+#endif
+	return 0;
+}
+
+static int ptdump_test_pud(unsigned long addr, unsigned long next,
+			   pud_t *pud, struct mm_walk *walk)
+{
+#if CONFIG_PGTABLE_LEVELS > 3
+	if (pud == lm_alias(kasan_early_shadow_pud))
+		return note_kasan_page_table(walk, addr);
+#endif
+	return 0;
+}
+
+static int ptdump_test_pmd(unsigned long addr, unsigned long next,
+			   pmd_t *pmd, struct mm_walk *walk)
+{
+#if CONFIG_PGTABLE_LEVELS > 2
+	if (pmd == lm_alias(kasan_early_shadow_pmd))
+		return note_kasan_page_table(walk, addr);
+#endif
+	return 0;
+}
+#endif /* CONFIG_KASAN */
+
+static int ptdump_hole(unsigned long addr, unsigned long next,
+		       int depth, struct mm_walk *walk)
+{
+	struct ptdump_state *st = walk->private;
+
+	st->note_page(st, addr, depth + 1, 0);
+
+	return 0;
+}
+
+const static struct mm_walk_ops ptdump_ops = {
+	.pgd_entry	= ptdump_pgd_entry,
+	.p4d_entry	= ptdump_p4d_entry,
+	.pud_entry	= ptdump_pud_entry,
+	.pmd_entry	= ptdump_pmd_entry,
+	.pte_entry	= ptdump_pte_entry,
+#ifdef CONFIG_KASAN
+	.test_p4d	= ptdump_test_p4d,
+	.test_pud	= ptdump_test_pud,
+	.test_pmd	= ptdump_test_pmd,
+#endif
+	.pte_hole	= ptdump_hole,
+};
+
+void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
+{
+	const struct ptdump_range *range = st->range;
+
+	down_read(&mm->mmap_sem);
+	while (range->start != range->end) {
+		walk_page_range_novma(mm, range->start, range->end,
+				      &ptdump_ops, st);
+		range++;
+	}
+	up_read(&mm->mmap_sem);
+
+	/* Flush out the last page */
+	st->note_page(st, 0, 0, 0);
+}
-- 
2.20.1

[PATCH v15 20/23] x86: mm: Convert dump_pagetables to use walk_page_range

[Steven Price]

Make use of the new functionality in walk_page_range to remove the
arch page walking code and use the generic code to walk the page tables.

The effective permissions are passed down the chain using new fields
in struct pg_state.

The KASAN optimisation is implemented by including test_p?d callbacks
which can decide to skip an entire tree of entries

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/x86/Kconfig              |   1 +
 arch/x86/Kconfig.debug        |  20 +--
 arch/x86/mm/Makefile          |   4 +-
 arch/x86/mm/dump_pagetables.c | 289 +++++++---------------------------
 4 files changed, 66 insertions(+), 248 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d6e1faa28c58..87acf08358e9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -120,6 +120,7 @@ config X86
 	select GENERIC_IRQ_RESERVATION_MODE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PENDING_IRQ		if SMP
+	select GENERIC_PTDUMP
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index bf9cd83de777..b0f8e06cf0b8 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -62,26 +62,10 @@ config EARLY_PRINTK_USB_XDBC
 config MCSAFE_TEST
 	def_bool n
 
-config X86_PTDUMP_CORE
-	def_bool n
-
-config X86_PTDUMP
-	tristate "Export kernel pagetable layout to userspace via debugfs"
-	depends on DEBUG_KERNEL
-	select DEBUG_FS
-	select X86_PTDUMP_CORE
-	---help---
-	  Say Y here if you want to show the kernel pagetable layout in a
-	  debugfs file. This information is only useful for kernel developers
-	  who are working in architecture specific areas of the kernel.
-	  It is probably not a good idea to enable this feature in a production
-	  kernel.
-	  If in doubt, say "N"
-
 config EFI_PGT_DUMP
 	bool "Dump the EFI pagetable"
 	depends on EFI
-	select X86_PTDUMP_CORE
+	select PTDUMP_CORE
 	---help---
 	  Enable this if you want to dump the EFI page table before
 	  enabling virtual mode. This can be used to debug miscellaneous
@@ -90,7 +74,7 @@ config EFI_PGT_DUMP
 
 config DEBUG_WX
 	bool "Warn on W+X mappings at boot"
-	select X86_PTDUMP_CORE
+	select PTDUMP_CORE
 	---help---
 	  Generate a warning if any W+X mappings are found at boot.
 
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 84373dc9b341..66cf0ea5c2be 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -28,8 +28,8 @@ obj-$(CONFIG_X86_PAT)		+= pat_rbtree.o
 obj-$(CONFIG_X86_32)		+= pgtable_32.o iomap_32.o
 
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
-obj-$(CONFIG_X86_PTDUMP_CORE)	+= dump_pagetables.o
-obj-$(CONFIG_X86_PTDUMP)	+= debug_pagetables.o
+obj-$(CONFIG_PTDUMP_CORE)	+= dump_pagetables.o
+obj-$(CONFIG_PTDUMP_DEBUGFS)	+= debug_pagetables.o
 
 obj-$(CONFIG_HIGHMEM)		+= highmem_32.o
 
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 3632be89ec99..77a1332c6cd4 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -16,6 +16,7 @@
 #include <linux/seq_file.h>
 #include <linux/highmem.h>
 #include <linux/pci.h>
+#include <linux/ptdump.h>
 
 #include <asm/e820/types.h>
 #include <asm/pgtable.h>
@@ -26,11 +27,12 @@
  * when a "break" in the continuity is found.
  */
 struct pg_state {
+	struct ptdump_state ptdump;
 	int level;
-	pgprot_t current_prot;
+	pgprotval_t current_prot;
 	pgprotval_t effective_prot;
+	pgprotval_t prot_levels[5];
 	unsigned long start_address;
-	unsigned long current_address;
 	const struct addr_marker *marker;
 	unsigned long lines;
 	bool to_dmesg;
@@ -171,9 +173,8 @@ static struct addr_marker address_markers[] = {
 /*
  * Print a readable form of a pgprot_t to the seq_file
  */
-static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
+static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
 {
-	pgprotval_t pr = pgprot_val(prot);
 	static const char * const level_name[] =
 		{ "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
 
@@ -220,24 +221,11 @@ static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
 	pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
 }
 
-/*
- * On 64 bits, sign-extend the 48 bit address to 64 bit
- */
-static unsigned long normalize_addr(unsigned long u)
-{
-	int shift;
-	if (!IS_ENABLED(CONFIG_X86_64))
-		return u;
-
-	shift = 64 - (__VIRTUAL_MASK_SHIFT + 1);
-	return (signed long)(u << shift) >> shift;
-}
-
-static void note_wx(struct pg_state *st)
+static void note_wx(struct pg_state *st, unsigned long addr)
 {
 	unsigned long npages;
 
-	npages = (st->current_address - st->start_address) / PAGE_SIZE;
+	npages = (addr - st->start_address) / PAGE_SIZE;
 
 #ifdef CONFIG_PCI_BIOS
 	/*
@@ -245,7 +233,7 @@ static void note_wx(struct pg_state *st)
 	 * Inform about it, but avoid the warning.
 	 */
 	if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
-	    st->current_address <= PAGE_OFFSET + BIOS_END) {
+	    addr <= PAGE_OFFSET + BIOS_END) {
 		pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
 		return;
 	}
@@ -257,25 +245,44 @@ static void note_wx(struct pg_state *st)
 		  (void *)st->start_address);
 }
 
+static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
+{
+	return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) |
+	       ((prot1 | prot2) & _PAGE_NX);
+}
+
 /*
  * This function gets called on a break in a continuous series
  * of PTE entries; the next one is different so we need to
  * print what we collected so far.
  */
-static void note_page(struct pg_state *st, pgprot_t new_prot,
-		      pgprotval_t new_eff, int level)
+static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
+		      unsigned long val)
 {
-	pgprotval_t prot, cur, eff;
+	struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
+	pgprotval_t new_prot, new_eff;
+	pgprotval_t cur, eff;
 	static const char units[] = "BKMGTPE";
 	struct seq_file *m = st->seq;
 
+	new_prot = val & PTE_FLAGS_MASK;
+
+	if (level > 1) {
+		new_eff = effective_prot(st->prot_levels[level - 2],
+					 new_prot);
+	} else {
+		new_eff = new_prot;
+	}
+
+	if (level > 0)
+		st->prot_levels[level - 1] = new_eff;
+
 	/*
 	 * If we have a "break" in the series, we need to flush the state that
 	 * we have now. "break" is either changing perms, levels or
 	 * address space marker.
 	 */
-	prot = pgprot_val(new_prot);
-	cur = pgprot_val(st->current_prot);
+	cur = st->current_prot;
 	eff = st->effective_prot;
 
 	if (!st->level) {
@@ -287,14 +294,14 @@ static void note_page(struct pg_state *st, pgprot_t new_prot,
 		st->lines = 0;
 		pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
 				   st->marker->name);
-	} else if (prot != cur || new_eff != eff || level != st->level ||
-		   st->current_address >= st->marker[1].start_address) {
+	} else if (new_prot != cur || new_eff != eff || level != st->level ||
+		   addr >= st->marker[1].start_address) {
 		const char *unit = units;
 		unsigned long delta;
 		int width = sizeof(unsigned long) * 2;
 
 		if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
-			note_wx(st);
+			note_wx(st, addr);
 
 		/*
 		 * Now print the actual finished series
@@ -304,9 +311,9 @@ static void note_page(struct pg_state *st, pgprot_t new_prot,
 			pt_dump_seq_printf(m, st->to_dmesg,
 					   "0x%0*lx-0x%0*lx   ",
 					   width, st->start_address,
-					   width, st->current_address);
+					   width, addr);
 
-			delta = st->current_address - st->start_address;
+			delta = addr - st->start_address;
 			while (!(delta & 1023) && unit[1]) {
 				delta >>= 10;
 				unit++;
@@ -323,7 +330,7 @@ static void note_page(struct pg_state *st, pgprot_t new_prot,
 		 * such as the start of vmalloc space etc.
 		 * This helps in the interpretation.
 		 */
-		if (st->current_address >= st->marker[1].start_address) {
+		if (addr >= st->marker[1].start_address) {
 			if (st->marker->max_lines &&
 			    st->lines > st->marker->max_lines) {
 				unsigned long nskip =
@@ -339,217 +346,43 @@ static void note_page(struct pg_state *st, pgprot_t new_prot,
 					   st->marker->name);
 		}
 
-		st->start_address = st->current_address;
+		st->start_address = addr;
 		st->current_prot = new_prot;
 		st->effective_prot = new_eff;
 		st->level = level;
 	}
 }
 
-static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
-{
-	return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) |
-	       ((prot1 | prot2) & _PAGE_NX);
-}
-
-static void walk_pte_level(struct pg_state *st, pmd_t addr, pgprotval_t eff_in,
-			   unsigned long P)
-{
-	int i;
-	pte_t *pte;
-	pgprotval_t prot, eff;
-
-	for (i = 0; i < PTRS_PER_PTE; i++) {
-		st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
-		pte = pte_offset_map(&addr, st->current_address);
-		prot = pte_flags(*pte);
-		eff = effective_prot(eff_in, prot);
-		note_page(st, __pgprot(prot), eff, 5);
-		pte_unmap(pte);
-	}
-}
-#ifdef CONFIG_KASAN
-
-/*
- * This is an optimization for KASAN=y case. Since all kasan page tables
- * eventually point to the kasan_early_shadow_page we could call note_page()
- * right away without walking through lower level page tables. This saves
- * us dozens of seconds (minutes for 5-level config) while checking for
- * W+X mapping or reading kernel_page_tables debugfs file.
- */
-static inline bool kasan_page_table(struct pg_state *st, void *pt)
-{
-	if (__pa(pt) == __pa(kasan_early_shadow_pmd) ||
-	    (pgtable_l5_enabled() &&
-			__pa(pt) == __pa(kasan_early_shadow_p4d)) ||
-	    __pa(pt) == __pa(kasan_early_shadow_pud)) {
-		pgprotval_t prot = pte_flags(kasan_early_shadow_pte[0]);
-		note_page(st, __pgprot(prot), 0, 5);
-		return true;
-	}
-	return false;
-}
-#else
-static inline bool kasan_page_table(struct pg_state *st, void *pt)
-{
-	return false;
-}
-#endif
-
-#if PTRS_PER_PMD > 1
-
-static void walk_pmd_level(struct pg_state *st, pud_t addr,
-			   pgprotval_t eff_in, unsigned long P)
-{
-	int i;
-	pmd_t *start, *pmd_start;
-	pgprotval_t prot, eff;
-
-	pmd_start = start = (pmd_t *)pud_page_vaddr(addr);
-	for (i = 0; i < PTRS_PER_PMD; i++) {
-		st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
-		if (!pmd_none(*start)) {
-			prot = pmd_flags(*start);
-			eff = effective_prot(eff_in, prot);
-			if (pmd_large(*start) || !pmd_present(*start)) {
-				note_page(st, __pgprot(prot), eff, 4);
-			} else if (!kasan_page_table(st, pmd_start)) {
-				walk_pte_level(st, *start, eff,
-					       P + i * PMD_LEVEL_MULT);
-			}
-		} else
-			note_page(st, __pgprot(0), 0, 4);
-		start++;
-	}
-}
-
-#else
-#define walk_pmd_level(s,a,e,p) walk_pte_level(s,__pmd(pud_val(a)),e,p)
-#define pud_large(a) pmd_large(__pmd(pud_val(a)))
-#define pud_none(a)  pmd_none(__pmd(pud_val(a)))
-#endif
-
-#if PTRS_PER_PUD > 1
-
-static void walk_pud_level(struct pg_state *st, p4d_t addr, pgprotval_t eff_in,
-			   unsigned long P)
-{
-	int i;
-	pud_t *start, *pud_start;
-	pgprotval_t prot, eff;
-
-	pud_start = start = (pud_t *)p4d_page_vaddr(addr);
-
-	for (i = 0; i < PTRS_PER_PUD; i++) {
-		st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
-		if (!pud_none(*start)) {
-			prot = pud_flags(*start);
-			eff = effective_prot(eff_in, prot);
-			if (pud_large(*start) || !pud_present(*start)) {
-				note_page(st, __pgprot(prot), eff, 3);
-			} else if (!kasan_page_table(st, pud_start)) {
-				walk_pmd_level(st, *start, eff,
-					       P + i * PUD_LEVEL_MULT);
-			}
-		} else
-			note_page(st, __pgprot(0), 0, 3);
-
-		start++;
-	}
-}
-
-#else
-#define walk_pud_level(s,a,e,p) walk_pmd_level(s,__pud(p4d_val(a)),e,p)
-#define p4d_large(a) pud_large(__pud(p4d_val(a)))
-#define p4d_none(a)  pud_none(__pud(p4d_val(a)))
-#endif
-
-static void walk_p4d_level(struct pg_state *st, pgd_t addr, pgprotval_t eff_in,
-			   unsigned long P)
+static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm,
+				       bool checkwx, bool dmesg)
 {
-	int i;
-	p4d_t *start, *p4d_start;
-	pgprotval_t prot, eff;
-
-	if (PTRS_PER_P4D == 1)
-		return walk_pud_level(st, __p4d(pgd_val(addr)), eff_in, P);
-
-	p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
-
-	for (i = 0; i < PTRS_PER_P4D; i++) {
-		st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
-		if (!p4d_none(*start)) {
-			prot = p4d_flags(*start);
-			eff = effective_prot(eff_in, prot);
-			if (p4d_large(*start) || !p4d_present(*start)) {
-				note_page(st, __pgprot(prot), eff, 2);
-			} else if (!kasan_page_table(st, p4d_start)) {
-				walk_pud_level(st, *start, eff,
-					       P + i * P4D_LEVEL_MULT);
-			}
-		} else
-			note_page(st, __pgprot(0), 0, 2);
-
-		start++;
-	}
-}
+	const struct ptdump_range ptdump_ranges[] = {
+#ifdef CONFIG_X86_64
 
-#define pgd_large(a) (pgtable_l5_enabled() ? pgd_large(a) : p4d_large(__p4d(pgd_val(a))))
-#define pgd_none(a)  (pgtable_l5_enabled() ? pgd_none(a) : p4d_none(__p4d(pgd_val(a))))
+#define normalize_addr_shift (64 - (__VIRTUAL_MASK_SHIFT + 1))
+#define normalize_addr(u) ((signed long)((u) << normalize_addr_shift) >> \
+			   normalize_addr_shift)
 
-static inline bool is_hypervisor_range(int idx)
-{
-#ifdef CONFIG_X86_64
-	/*
-	 * A hole in the beginning of kernel address space reserved
-	 * for a hypervisor.
-	 */
-	return	(idx >= pgd_index(GUARD_HOLE_BASE_ADDR)) &&
-		(idx <  pgd_index(GUARD_HOLE_END_ADDR));
+	{0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
+	{normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
 #else
-	return false;
+	{0, ~0UL},
 #endif
-}
+	{0, 0}
+};
 
-static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm,
-				       bool checkwx, bool dmesg)
-{
-	pgd_t *start = mm->pgd;
-	pgprotval_t prot, eff;
-	int i;
-	struct pg_state st = {};
-
-	st.to_dmesg = dmesg;
-	st.check_wx = checkwx;
-	st.seq = m;
-	if (checkwx)
-		st.wx_pages = 0;
-
-	for (i = 0; i < PTRS_PER_PGD; i++) {
-		st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
-		if (!pgd_none(*start) && !is_hypervisor_range(i)) {
-			prot = pgd_flags(*start);
-#ifdef CONFIG_X86_PAE
-			eff = _PAGE_USER | _PAGE_RW;
-#else
-			eff = prot;
-#endif
-			if (pgd_large(*start) || !pgd_present(*start)) {
-				note_page(&st, __pgprot(prot), eff, 1);
-			} else {
-				walk_p4d_level(&st, *start, eff,
-					       i * PGD_LEVEL_MULT);
-			}
-		} else
-			note_page(&st, __pgprot(0), 0, 1);
+	struct pg_state st = {
+		.ptdump = {
+			.note_page	= note_page,
+			.range		= ptdump_ranges
+		},
+		.to_dmesg	= dmesg,
+		.check_wx	= checkwx,
+		.seq		= m
+	};
 
-		cond_resched();
-		start++;
-	}
+	ptdump_walk_pgd(&st.ptdump, mm);
 
-	/* Flush out the last page */
-	st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
-	note_page(&st, __pgprot(0), 0, 0);
 	if (!checkwx)
 		return;
 	if (st.wx_pages)
-- 
2.20.1

[PATCH v15 21/23] arm64: mm: Convert mm/dump.c to use walk_page_range()

[Steven Price]

Now walk_page_range() can walk kernel page tables, we can switch the
arm64 ptdump code over to using it, simplifying the code.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/Kconfig                 |   1 +
 arch/arm64/Kconfig.debug           |  19 +----
 arch/arm64/include/asm/ptdump.h    |   8 +-
 arch/arm64/mm/Makefile             |   4 +-
 arch/arm64/mm/dump.c               | 117 ++++++++++-------------------
 arch/arm64/mm/mmu.c                |   4 +-
 arch/arm64/mm/ptdump_debugfs.c     |   2 +-
 drivers/firmware/efi/arm-runtime.c |   2 +-
 8 files changed, 50 insertions(+), 107 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 41a9b4257b72..0f6ad8dabd77 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -104,6 +104,7 @@ config ARM64
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
 	select GENERIC_PCI_IOMAP
+	select GENERIC_PTDUMP
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_STRNCPY_FROM_USER
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index cf09010d825f..1c906d932d6b 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -1,22 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-config ARM64_PTDUMP_CORE
-	def_bool n
-
-config ARM64_PTDUMP_DEBUGFS
-	bool "Export kernel pagetable layout to userspace via debugfs"
-	depends on DEBUG_KERNEL
-	select ARM64_PTDUMP_CORE
-	select DEBUG_FS
-        help
-	  Say Y here if you want to show the kernel pagetable layout in a
-	  debugfs file. This information is only useful for kernel developers
-	  who are working in architecture specific areas of the kernel.
-	  It is probably not a good idea to enable this feature in a production
-	  kernel.
-
-	  If in doubt, say N.
-
 config PID_IN_CONTEXTIDR
 	bool "Write the current PID to the CONTEXTIDR register"
 	help
@@ -42,7 +25,7 @@ config ARM64_RANDOMIZE_TEXT_OFFSET
 
 config DEBUG_WX
 	bool "Warn on W+X mappings at boot"
-	select ARM64_PTDUMP_CORE
+	select PTDUMP_CORE
 	---help---
 	  Generate a warning if any W+X mappings are found at boot.
 
diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
index 0b8e7269ec82..38187f74e089 100644
--- a/arch/arm64/include/asm/ptdump.h
+++ b/arch/arm64/include/asm/ptdump.h
@@ -5,7 +5,7 @@
 #ifndef __ASM_PTDUMP_H
 #define __ASM_PTDUMP_H
 
-#ifdef CONFIG_ARM64_PTDUMP_CORE
+#ifdef CONFIG_PTDUMP_CORE
 
 #include <linux/mm_types.h>
 #include <linux/seq_file.h>
@@ -21,15 +21,15 @@ struct ptdump_info {
 	unsigned long			base_addr;
 };
 
-void ptdump_walk_pgd(struct seq_file *s, struct ptdump_info *info);
-#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
+void ptdump_walk(struct seq_file *s, struct ptdump_info *info);
+#ifdef CONFIG_PTDUMP_DEBUGFS
 void ptdump_debugfs_register(struct ptdump_info *info, const char *name);
 #else
 static inline void ptdump_debugfs_register(struct ptdump_info *info,
 					   const char *name) { }
 #endif
 void ptdump_check_wx(void);
-#endif /* CONFIG_ARM64_PTDUMP_CORE */
+#endif /* CONFIG_PTDUMP_CORE */
 
 #ifdef CONFIG_DEBUG_WX
 #define debug_checkwx()	ptdump_check_wx()
diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 849c1df3d214..d91030f0ffee 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -4,8 +4,8 @@ obj-y				:= dma-mapping.o extable.o fault.o init.o \
 				   ioremap.o mmap.o pgd.o mmu.o \
 				   context.o proc.o pageattr.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
-obj-$(CONFIG_ARM64_PTDUMP_CORE)	+= dump.o
-obj-$(CONFIG_ARM64_PTDUMP_DEBUGFS)	+= ptdump_debugfs.o
+obj-$(CONFIG_PTDUMP_CORE)	+= dump.o
+obj-$(CONFIG_PTDUMP_DEBUGFS)	+= ptdump_debugfs.o
 obj-$(CONFIG_NUMA)		+= numa.o
 obj-$(CONFIG_DEBUG_VIRTUAL)	+= physaddr.o
 KASAN_SANITIZE_physaddr.o	+= n
diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 93f9f77582ae..9d9b740a86d2 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -15,6 +15,7 @@
 #include <linux/io.h>
 #include <linux/init.h>
 #include <linux/mm.h>
+#include <linux/ptdump.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 
@@ -75,10 +76,11 @@ static struct addr_marker address_markers[] = {
  * dumps out a description of the range.
  */
 struct pg_state {
+	struct ptdump_state ptdump;
 	struct seq_file *seq;
 	const struct addr_marker *marker;
 	unsigned long start_address;
-	unsigned level;
+	int level;
 	u64 current_prot;
 	bool check_wx;
 	unsigned long wx_pages;
@@ -178,6 +180,10 @@ static struct pg_level pg_level[] = {
 		.name	= "PGD",
 		.bits	= pte_bits,
 		.num	= ARRAY_SIZE(pte_bits),
+	}, { /* p4d */
+		.name	= "P4D",
+		.bits	= pte_bits,
+		.num	= ARRAY_SIZE(pte_bits),
 	}, { /* pud */
 		.name	= (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
 		.bits	= pte_bits,
@@ -240,11 +246,15 @@ static void note_prot_wx(struct pg_state *st, unsigned long addr)
 	st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 }
 
-static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
-				u64 val)
+static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
+		      unsigned long val)
 {
+	struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
 	static const char units[] = "KMGTPE";
-	u64 prot = val & pg_level[level].mask;
+	u64 prot = 0;
+
+	if (level >= 0)
+		prot = val & pg_level[level].mask;
 
 	if (!st->level) {
 		st->level = level;
@@ -292,85 +302,27 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 
 }
 
-static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start,
-		     unsigned long end)
-{
-	unsigned long addr = start;
-	pte_t *ptep = pte_offset_kernel(pmdp, start);
-
-	do {
-		note_page(st, addr, 4, READ_ONCE(pte_val(*ptep)));
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-}
-
-static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start,
-		     unsigned long end)
-{
-	unsigned long next, addr = start;
-	pmd_t *pmdp = pmd_offset(pudp, start);
-
-	do {
-		pmd_t pmd = READ_ONCE(*pmdp);
-		next = pmd_addr_end(addr, end);
-
-		if (pmd_none(pmd) || pmd_sect(pmd)) {
-			note_page(st, addr, 3, pmd_val(pmd));
-		} else {
-			BUG_ON(pmd_bad(pmd));
-			walk_pte(st, pmdp, addr, next);
-		}
-	} while (pmdp++, addr = next, addr != end);
-}
-
-static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start,
-		     unsigned long end)
+void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
 {
-	unsigned long next, addr = start;
-	pud_t *pudp = pud_offset(pgdp, start);
-
-	do {
-		pud_t pud = READ_ONCE(*pudp);
-		next = pud_addr_end(addr, end);
-
-		if (pud_none(pud) || pud_sect(pud)) {
-			note_page(st, addr, 2, pud_val(pud));
-		} else {
-			BUG_ON(pud_bad(pud));
-			walk_pmd(st, pudp, addr, next);
-		}
-	} while (pudp++, addr = next, addr != end);
-}
+	unsigned long end = ~0UL;
+	struct pg_state st;
 
-static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
-		     unsigned long start)
-{
-	unsigned long end = (start < TASK_SIZE_64) ? TASK_SIZE_64 : 0;
-	unsigned long next, addr = start;
-	pgd_t *pgdp = pgd_offset(mm, start);
-
-	do {
-		pgd_t pgd = READ_ONCE(*pgdp);
-		next = pgd_addr_end(addr, end);
-
-		if (pgd_none(pgd)) {
-			note_page(st, addr, 1, pgd_val(pgd));
-		} else {
-			BUG_ON(pgd_bad(pgd));
-			walk_pud(st, pgdp, addr, next);
-		}
-	} while (pgdp++, addr = next, addr != end);
-}
+	if (info->base_addr < TASK_SIZE_64)
+		end = TASK_SIZE_64;
 
-void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
-{
-	struct pg_state st = {
-		.seq = m,
+	st = (struct pg_state){
+		.seq = s,
 		.marker = info->markers,
+		.ptdump = {
+			.note_page = note_page,
+			.range = (struct ptdump_range[]){
+				{info->base_addr, end},
+				{0, 0}
+			}
+		}
 	};
 
-	walk_pgd(&st, info->mm, info->base_addr);
-
-	note_page(&st, 0, 0, 0);
+	ptdump_walk_pgd(&st.ptdump, info->mm);
 }
 
 static void ptdump_initialize(void)
@@ -398,10 +350,17 @@ void ptdump_check_wx(void)
 			{ -1, NULL},
 		},
 		.check_wx = true,
+		.ptdump = {
+			.note_page = note_page,
+			.range = (struct ptdump_range[]) {
+				{PAGE_OFFSET, ~0UL},
+				{0, 0}
+			}
+		}
 	};
 
-	walk_pgd(&st, &init_mm, PAGE_OFFSET);
-	note_page(&st, 0, 0, 0);
+	ptdump_walk_pgd(&st.ptdump, &init_mm);
+
 	if (st.wx_pages || st.uxn_pages)
 		pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
 			st.wx_pages, st.uxn_pages);
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 60c929f3683b..6f12951c8052 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -944,13 +944,13 @@ int __init arch_ioremap_pud_supported(void)
 	 * SW table walks can't handle removal of intermediate entries.
 	 */
 	return IS_ENABLED(CONFIG_ARM64_4K_PAGES) &&
-	       !IS_ENABLED(CONFIG_ARM64_PTDUMP_DEBUGFS);
+	       !IS_ENABLED(CONFIG_PTDUMP_DEBUGFS);
 }
 
 int __init arch_ioremap_pmd_supported(void)
 {
 	/* See arch_ioremap_pud_supported() */
-	return !IS_ENABLED(CONFIG_ARM64_PTDUMP_DEBUGFS);
+	return !IS_ENABLED(CONFIG_PTDUMP_DEBUGFS);
 }
 
 int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c
index 064163f25592..1f2eae3e988b 100644
--- a/arch/arm64/mm/ptdump_debugfs.c
+++ b/arch/arm64/mm/ptdump_debugfs.c
@@ -7,7 +7,7 @@
 static int ptdump_show(struct seq_file *m, void *v)
 {
 	struct ptdump_info *info = m->private;
-	ptdump_walk_pgd(m, info);
+	ptdump_walk(m, info);
 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(ptdump);
diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index e2ac5fa5531b..1283685f9c20 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -27,7 +27,7 @@
 
 extern u64 efi_system_table;
 
-#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
+#if defined(CONFIG_PTDUMP_DEBUGFS) && defined(CONFIG_ARM64)
 #include <asm/ptdump.h>
 
 static struct ptdump_info efi_ptdump_info = {
-- 
2.20.1

[PATCH v15 22/23] arm64: mm: Display non-present entries in ptdump

[Steven Price]

Previously the /sys/kernel/debug/kernel_page_tables file would only show
lines for entries present in the page tables. However it is useful to
also show non-present entries as this makes the size and level of the
holes more visible. This aligns the behaviour with x86 which also shows
holes.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/dump.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 9d9b740a86d2..3203dd8e6d0a 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -269,21 +269,22 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 		if (st->current_prot) {
 			note_prot_uxn(st, addr);
 			note_prot_wx(st, addr);
-			pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
+		}
+
+		pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
 				   st->start_address, addr);
 
-			delta = (addr - st->start_address) >> 10;
-			while (!(delta & 1023) && unit[1]) {
-				delta >>= 10;
-				unit++;
-			}
-			pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
-				   pg_level[st->level].name);
-			if (pg_level[st->level].bits)
-				dump_prot(st, pg_level[st->level].bits,
-					  pg_level[st->level].num);
-			pt_dump_seq_puts(st->seq, "\n");
+		delta = (addr - st->start_address) >> 10;
+		while (!(delta & 1023) && unit[1]) {
+			delta >>= 10;
+			unit++;
 		}
+		pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
+				   pg_level[st->level].name);
+		if (st->current_prot && pg_level[st->level].bits)
+			dump_prot(st, pg_level[st->level].bits,
+				  pg_level[st->level].num);
+		pt_dump_seq_puts(st->seq, "\n");
 
 		if (addr >= st->marker[1].start_address) {
 			st->marker++;
-- 
2.20.1

[PATCH v15 23/23] mm: ptdump: Reduce level numbers by 1 in note_page()

[Steven Price]

Rather than having to increment the 'depth' number by 1 in
ptdump_hole(), let's change the meaning of 'level' in note_page() since
that makes the code simplier.

Note that for x86, the level numbers were previously increased by 1 in
commit 45dcd2091363 ("x86/mm/dump_pagetables: Fix printout of p4d level")
and the comment "Bit 7 has a different meaning" was not updated, so this
change also makes the code match the comment again.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/dump.c          |  6 +++---
 arch/x86/mm/dump_pagetables.c | 19 ++++++++++---------
 include/linux/ptdump.h        |  1 +
 mm/ptdump.c                   | 16 ++++++++--------
 4 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 3203dd8e6d0a..4997ce244172 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -175,8 +175,7 @@ struct pg_level {
 };
 
 static struct pg_level pg_level[] = {
-	{
-	}, { /* pgd */
+	{ /* pgd */
 		.name	= "PGD",
 		.bits	= pte_bits,
 		.num	= ARRAY_SIZE(pte_bits),
@@ -256,7 +255,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 	if (level >= 0)
 		prot = val & pg_level[level].mask;
 
-	if (!st->level) {
+	if (st->level == -1) {
 		st->level = level;
 		st->current_prot = prot;
 		st->start_address = addr;
@@ -350,6 +349,7 @@ void ptdump_check_wx(void)
 			{ 0, NULL},
 			{ -1, NULL},
 		},
+		.level = -1,
 		.check_wx = true,
 		.ptdump = {
 			.note_page = note_page,
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 77a1332c6cd4..d3c28b3765fc 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -176,7 +176,7 @@ static struct addr_marker address_markers[] = {
 static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
 {
 	static const char * const level_name[] =
-		{ "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
+		{ "pgd", "p4d", "pud", "pmd", "pte" };
 
 	if (!(pr & _PAGE_PRESENT)) {
 		/* Not present */
@@ -200,12 +200,12 @@ static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg
 			pt_dump_cont_printf(m, dmsg, "    ");
 
 		/* Bit 7 has a different meaning on level 3 vs 4 */
-		if (level <= 4 && pr & _PAGE_PSE)
+		if (level <= 3 && pr & _PAGE_PSE)
 			pt_dump_cont_printf(m, dmsg, "PSE ");
 		else
 			pt_dump_cont_printf(m, dmsg, "    ");
-		if ((level == 5 && pr & _PAGE_PAT) ||
-		    ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
+		if ((level == 4 && pr & _PAGE_PAT) ||
+		    ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
 			pt_dump_cont_printf(m, dmsg, "PAT ");
 		else
 			pt_dump_cont_printf(m, dmsg, "    ");
@@ -267,15 +267,15 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 
 	new_prot = val & PTE_FLAGS_MASK;
 
-	if (level > 1) {
-		new_eff = effective_prot(st->prot_levels[level - 2],
+	if (level > 0) {
+		new_eff = effective_prot(st->prot_levels[level - 1],
 					 new_prot);
 	} else {
 		new_eff = new_prot;
 	}
 
-	if (level > 0)
-		st->prot_levels[level - 1] = new_eff;
+	if (level >= 0)
+		st->prot_levels[level] = new_eff;
 
 	/*
 	 * If we have a "break" in the series, we need to flush the state that
@@ -285,7 +285,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 	cur = st->current_prot;
 	eff = st->effective_prot;
 
-	if (!st->level) {
+	if (st->level == -1) {
 		/* First entry */
 		st->current_prot = new_prot;
 		st->effective_prot = new_eff;
@@ -376,6 +376,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm,
 			.note_page	= note_page,
 			.range		= ptdump_ranges
 		},
+		.level = -1,
 		.to_dmesg	= dmesg,
 		.check_wx	= checkwx,
 		.seq		= m
diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h
index a0fb8dd2be97..b28f3f2acf90 100644
--- a/include/linux/ptdump.h
+++ b/include/linux/ptdump.h
@@ -11,6 +11,7 @@ struct ptdump_range {
 };
 
 struct ptdump_state {
+	/* level is 0:PGD to 4:PTE, or -1 if unknown */
 	void (*note_page)(struct ptdump_state *st, unsigned long addr,
 			  int level, unsigned long val);
 	const struct ptdump_range *range;
diff --git a/mm/ptdump.c b/mm/ptdump.c
index 79e63454f1f7..9987baede3f2 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -11,7 +11,7 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
 	pgd_t val = READ_ONCE(*pgd);
 
 	if (pgd_leaf(val))
-		st->note_page(st, addr, 1, pgd_val(val));
+		st->note_page(st, addr, 0, pgd_val(val));
 
 	return 0;
 }
@@ -23,7 +23,7 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
 	p4d_t val = READ_ONCE(*p4d);
 
 	if (p4d_leaf(val))
-		st->note_page(st, addr, 2, p4d_val(val));
+		st->note_page(st, addr, 1, p4d_val(val));
 
 	return 0;
 }
@@ -35,7 +35,7 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
 	pud_t val = READ_ONCE(*pud);
 
 	if (pud_leaf(val))
-		st->note_page(st, addr, 3, pud_val(val));
+		st->note_page(st, addr, 2, pud_val(val));
 
 	return 0;
 }
@@ -47,7 +47,7 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
 	pmd_t val = READ_ONCE(*pmd);
 
 	if (pmd_leaf(val))
-		st->note_page(st, addr, 4, pmd_val(val));
+		st->note_page(st, addr, 3, pmd_val(val));
 
 	return 0;
 }
@@ -57,7 +57,7 @@ static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, 5, pte_val(READ_ONCE(*pte)));
+	st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte)));
 
 	return 0;
 }
@@ -75,7 +75,7 @@ static inline int note_kasan_page_table(struct mm_walk *walk,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0]));
+	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));
 	return 1;
 }
 
@@ -115,7 +115,7 @@ static int ptdump_hole(unsigned long addr, unsigned long next,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, depth + 1, 0);
+	st->note_page(st, addr, depth, 0);
 
 	return 0;
 }
@@ -147,5 +147,5 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
 	up_read(&mm->mmap_sem);
 
 	/* Flush out the last page */
-	st->note_page(st, 0, 0, 0);
+	st->note_page(st, 0, -1, 0);
 }
-- 
2.20.1

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Qian Cai]

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@arm.com/
>  * 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

[   10.550313][    T0] Switched APIC routing to physical flat.
[   10.563899][    T0] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[   10.614633][    T0] clocksource: tsc-early: mask: 0xffffffffffffffff
max_cycles: 0x1fa6f481074, max_idle_ns: 440795311917 ns
[   10.625979][    T0] Calibrating delay loop (skipped), value calculated using
timer frequency.. 4391.73 BogoMIPS (lpj=21958690)
[   10.635990][    T0] pid_max: default: 131072 minimum: 1024
[   11.259736][    T0] ---[ User Space ]---
[   11.263737][    T0] 0x0000000000000000-
0x0000000000001000           4K     RW                     x  pte
[   11.266028][    T0] 0x0000000000001000-
0x0000000000200000        2044K                               pte
[   11.275992][    T0] 0x0000000000200000-
0x0000000004000000          62M                               pmd
[   11.285998][    T0] 0x0000000004000000-
0x0000000004076000         472K                               pte
[   11.296019][    T0] 0x0000000004076000-
0x0000000004200000        1576K                               pte
[   11.305997][    T0] 0x0000000004200000-
0x0000000011000000         206M                               pmd
[   11.316008][    T0] 0x0000000011000000-
0x0000000011100000           1M                               pte
[   11.326008][    T0] 0x0000000011100000-
0x0000000011200000           1M                               pte
[   11.335990][    T0] 0x0000000011200000-
0x0000000011800000           6M                               pmd
[   11.346054][    T0]
==================================================================
[   11.354074][    T0] BUG: KASAN: wild-memory-access in
ptdump_pte_entry+0x39/0x60
[   11.355975][    T0] Read of size 8 at addr 000f887fee5ff000 by task
swapper/0/0
[   11.355975][    T0] 
[   11.355975][    T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc5-mm1+
#1
[   11.355975][    T0] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385
Gen10, BIOS A40 07/10/2019
[   11.355975][    T0] Call Trace:
[   11.355975][    T0]  dump_stack+0xa0/0xea
[   11.355975][    T0]  __kasan_report.cold.7+0xb0/0xc0
[   11.355975][    T0]  ? note_page+0x7f8/0xa70
[   11.355975][    T0]  ? ptdump_pte_entry+0x39/0x60
[   11.355975][    T0]  ? ptdump_walk_pgd_level_core+0x1b0/0x1b0
[   11.355975][    T0]  kasan_report+0x12/0x20
[   11.355975][    T0]  __asan_load8+0x71/0xa0
[   11.355975][    T0]  ptdump_pte_entry+0x39/0x60
[   11.355975][    T0]  walk_pgd_range+0xb75/0xce0
[   11.355975][    T0]  __walk_page_range+0x206/0x230
[   11.355975][    T0]  ? vmacache_find+0x3a/0x170
[   11.355975][    T0]  walk_page_range+0x136/0x210
[   11.355975][    T0]  ? __walk_page_range+0x230/0x230
[   11.355975][    T0]  ? find_held_lock+0xca/0xf0
[   11.355975][    T0]  ptdump_walk_pgd+0x76/0xd0
[   11.355975][    T0]  ptdump_walk_pgd_level_core+0x13b/0x1b0
[   11.355975][    T0]  ? hugetlb_get_unmapped_area+0x5b0/0x5b0
[   11.355975][    T0]  ? trace_hardirqs_on+0x3a/0x160
[   11.355975][    T0]  ? ptdump_walk_pgd_level_core+0x1b0/0x1b0
[   11.355975][    T0]  ? efi_delete_dummy_variable+0xa9/0xd0
[   11.355975][    T0]  ? __enc_copy+0x90/0x90
[   11.355975][    T0]  ptdump_walk_pgd_level+0x15/0x20
[   11.355975][    T0]  efi_dump_pagetable+0x35/0x37
[   11.355975][    T0]  efi_enter_virtual_mode+0x72a/0x737
[   11.355975][    T0]  start_kernel+0x607/0x6a9
[   11.355975][    T0]  ? thread_stack_cache_init+0xb/0xb
[   11.355975][    T0]  ? idt_setup_from_table+0xd9/0x130
[   11.355975][    T0]  x86_64_start_reservations+0x24/0x26
[   11.355975][    T0]  x86_64_start_kernel+0xf4/0xfb
[   11.355975][    T0]  secondary_startup_64+0xb6/0xc0
[   11.355975][    T0]
==================================================================
[   11.355975][    T0] Disabling lock debugging due to kernel taint
[   11.355991][    T0] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
KASAN NOPTI
[   11.364049][    T0] CPU: 0 PID: 0 Comm: swapper/0 Tainted:
G    B             5.4.0-rc5-mm1+ #1
[   11.365975][    T0] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385
Gen10, BIOS A40 07/10/2019
[   11.365975][    T0] RIP: 0010:ptdump_pte_entry+0x39/0x60
[   11.365975][    T0] Code: 55 41 54 49 89 fc 48 8d 79 18 53 48 89 cb e8 5e 0e
fa ff 48 8b 5b 18 48 89 df e8 52 0e fa ff 4c 89 e7 4c 8b 2b e8 47 0e fa ff <49>
8b 0c 24 4c 89 f6 48 89 df ba 05 00 00 00 e8 03 1d 9b 00 31 c0
[   11.365975][    T0] RSP: 0000:ffffffffaf8079d0 EFLAGS: 00010282
[   11.365975][    T0] RAX: 0000000000000000 RBX: ffffffffaf807cf0 RCX:
ffffffffae374306
[   11.365975][    T0] RDX: 0000000000000007 RSI: dffffc0000000000 RDI:
ffffffffafef2bf4
[   11.365975][    T0] RBP: ffffffffaf8079f0 R08: fffffbfff5fdbb22 R09:
fffffbfff5fdbb22
[   11.365975][    T0] R10: fffffbfff5fdbb21 R11: ffffffffafedd90b R12:
000f887fee5ff000
[   11.365975][    T0] R13: ffffffffae2aee40 R14: 0000000011a00000 R15:
0000000011a01000
[   11.365975][    T0] FS:  0000000000000000(0000) GS:ffff888843400000(0000)
knlGS:0000000000000000
[   11.365975][    T0] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   11.365975][    T0] CR2: ffff8890779ff000 CR3: 0000000baf412000 CR4:
00000000000406b0
[   11.365975][    T0] Call Trace:
[   11.365975][    T0]  walk_pgd_range+0xb75/0xce0
[   11.365975][    T0]  __walk_page_range+0x206/0x230
[   11.365975][    T0]  ? vmacache_find+0x3a/0x170
[   11.365975][    T0]  walk_page_range+0x136/0x210
[   11.365975][    T0]  ? __walk_page_range+0x230/0x230
[   11.365975][    T0]  ? find_held_lock+0xca/0xf0
[   11.365975][    T0]  ptdump_walk_pgd+0x76/0xd0
[   11.365975][    T0]  ptdump_walk_pgd_level_core+0x13b/0x1b0
[   11.365975][    T0]  ? hugetlb_get_unmapped_area+0x5b0/0x5b0
[   11.365975][    T0]  ? trace_hardirqs_on+0x3a/0x160
[   11.365975][    T0]  ? ptdump_walk_pgd_level_core+0x1b0/0x1b0
[   11.365975][    T0]  ? efi_delete_dummy_variable+0xa9/0xd0
[   11.365975][    T0]  ? __enc_copy+0x90/0x90
[   11.365975][    T0]  ptdump_walk_pgd_level+0x15/0x20
[   11.365975][    T0]  efi_dump_pagetable+0x35/0x37
[   11.365975][    T0]  efi_enter_virtual_mode+0x72a/0x737
[   11.365975][    T0]  start_kernel+0x607/0x6a9
[   11.365975][    T0]  ? thread_stack_cache_init+0xb/0xb
[   11.365975][    T0]  ? idt_setup_from_table+0xd9/0x130
[   11.365975][    T0]  x86_64_start_reservations+0x24/0x26
[   11.365975][    T0]  x86_64_start_kernel+0xf4/0xfb
[   11.365975][    T0]  secondary_startup_64+0xb6/0xc0
[   11.365975][    T0] Modules linked in:
[   11.365988][    T0] ---[ end trace 8e90dc89e2468d55 ]---
[   11.375984][    T0] RIP: 0010:ptdump_pte_entry+0x39/0x60
[   11.381335][    T0] Code: 55 41 54 49 89 fc 48 8d 79 18 53 48 89 cb e8 5e 0e
fa ff 48 8b 5b 18 48 89 df e8 52 0e fa ff 4c 89 e7 4c 8b 2b e8 47 0e fa ff <49>
8b 0c 24 4c 89 f6 48 89 df ba 05 00 00 00 e8 03 1d 9b 00 31 c0
[   11.385982][    T0] RSP: 0000:ffffffffaf8079d0 EFLAGS: 00010282
[   11.395982][    T0] RAX: 0000000000000000 RBX: ffffffffaf807cf0 RCX:
ffffffffae374306
[   11.403864][    T0] RDX: 0000000000000007 RSI: dffffc0000000000 RDI:
ffffffffafef2bf4
[   11.405982][    T0] RBP: ffffffffaf8079f0 R08: fffffbfff5fdbb22 R09:
fffffbfff5fdbb22
[   11.415982][    T0] R10: fffffbfff5fdbb21 R11: ffffffffafedd90b R12:
000f887fee5ff000
[   11.425982][    T0] R13: ffffffffae2aee40 R14: 0000000011a00000 R15:
0000000011a01000
[   11.435982][    T0] FS:  0000000000000000(0000) GS:ffff888843400000(0000)
knlGS:0000000000000000
[   11.445982][    T0] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   11.452466][    T0] CR2: ffff8890779ff000 CR3: 0000000baf412000 CR4:
00000000000406b0
[   11.455981][    T0] Kernel panic - not syncing: Fatal exception
[   11.462246][    T0] ---[ end Kernel panic - not syncing: Fatal exception ]---

> 
> Changes since v13:
> https://lore.kernel.org/lkml/20191024093716.49420-1-steven.price@arm.com/
>  * 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@arm.com/
>  * 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@arm.com/
>  * Use "-1" as dummy depth parameter in patch 14.
> 
> Changes since v10:
> https://lore.kernel.org/lkml/20190731154603.41797-1-steven.price@arm.com/
>  * 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@arm.com/
>  * 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@arm.com/
>  * 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
> 

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Qian Cai]

> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> 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@arm.com/
>> * 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@arm.com/
>> * 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@arm.com/
>> * 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@arm.com/
>> * Use "-1" as dummy depth parameter in patch 14.
>> 
>> Changes since v10:
>> https://lore.kernel.org/lkml/20190731154603.41797-1-steven.price@arm.com/
>> * 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@arm.com/
>> * 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@arm.com/
>> * 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
>> 

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Steven Price]

On 06/11/2019 13:31, Qian Cai wrote:
> 
> 
>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
>>
>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
[...]
>>> Changes since v14:
>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@arm.com/
>>> * 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.

Thanks for finding this, it looks like EFI causes issues here. The below fixes
this for me (booting in QEMU).

Andrew: do you want me to send out the entire series again for this fix, or
can you squash this into mm-pagewalk-allow-walking-without-vma.patch?

Thanks,

Steve

---8<---
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index c7529dc4f82b..70dcaa23598f 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
  			split_huge_pmd(walk->vma, pmd, addr);
  			if (pmd_trans_unstable(pmd))
  				goto again;
-		} else if (pmd_leaf(*pmd)) {
+		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
  			continue;
  		}
  
@@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
  			split_huge_pud(walk->vma, pud, addr);
  			if (pud_none(*pud))
  				goto again;
-		} else if (pud_leaf(*pud)) {
+		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
  			continue;
  		}
  

Re: [PATCH v15 00/23] Generic page walk and ptdump

[David Hildenbrand]

On 06.11.19 16:05, Steven Price wrote:
> On 06/11/2019 13:31, Qian Cai wrote:
>>
>>
>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
>>>
>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
> [...]
>>>> Changes since v14:
>>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@arm.com/
>>>> * 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.
> 
> Thanks for finding this, it looks like EFI causes issues here. The below fixes
> this for me (booting in QEMU).
> 
> Andrew: do you want me to send out the entire series again for this fix, or
> can you squash this into mm-pagewalk-allow-walking-without-vma.patch?
> 
> Thanks,
> 
> Steve
> 
> ---8<---
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index c7529dc4f82b..70dcaa23598f 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>   			split_huge_pmd(walk->vma, pmd, addr);
>   			if (pmd_trans_unstable(pmd))
>   				goto again;
> -		} else if (pmd_leaf(*pmd)) {
> +		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
>   			continue;
>   		}
>   
> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>   			split_huge_pud(walk->vma, pud, addr);
>   			if (pud_none(*pud))
>   				goto again;
> -		} else if (pud_leaf(*pud)) {
> +		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
>   			continue;
>   		}
>   
> 

Even with this fix, booting for me under QEMU fails. See

https://lore.kernel.org/linux-mm/b7ce62f2-9a48-6e48-6685-003431e521aa@redhat.com/

-- 
Thanks,

David / dhildenb

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Qian Cai]

> On Dec 3, 2019, at 6:02 AM, David Hildenbrand <david@redhat.com> wrote:
> 
> On 06.11.19 16:05, Steven Price wrote:
>> On 06/11/2019 13:31, Qian Cai wrote:
>>> 
>>> 
>>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
>>>> 
>>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
>> [...]
>>>>> Changes since v14:
>>>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@arm.com/
>>>>> * 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.
>> 
>> Thanks for finding this, it looks like EFI causes issues here. The below fixes
>> this for me (booting in QEMU).
>> 
>> Andrew: do you want me to send out the entire series again for this fix, or
>> can you squash this into mm-pagewalk-allow-walking-without-vma.patch?
>> 
>> Thanks,
>> 
>> Steve
>> 
>> ---8<---
>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
>> index c7529dc4f82b..70dcaa23598f 100644
>> --- a/mm/pagewalk.c
>> +++ b/mm/pagewalk.c
>> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>>  			split_huge_pmd(walk->vma, pmd, addr);
>>  			if (pmd_trans_unstable(pmd))
>>  				goto again;
>> -		} else if (pmd_leaf(*pmd)) {
>> +		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
>>  			continue;
>>  		}
>> 
>> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>>  			split_huge_pud(walk->vma, pud, addr);
>>  			if (pud_none(*pud))
>>  				goto again;
>> -		} else if (pud_leaf(*pud)) {
>> +		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
>>  			continue;
>>  		}
>> 
>> 
> 
> Even with this fix, booting for me under QEMU fails. See
> 
> https://lore.kernel.org/linux-mm/b7ce62f2-9a48-6e48-6685-003431e521aa@redhat.com/
> 

Yes, for some reasons, this starts to crash on almost all arches here, so it might be worth
for Andrew to revert those in the meantime while allowing Steven to rework.

Re: [PATCH v15 00/23] Generic page walk and ptdump

[David Hildenbrand]

On 04.12.19 15:54, Qian Cai wrote:
> 
> 
>> On Dec 3, 2019, at 6:02 AM, David Hildenbrand <david@redhat.com> wrote:
>>
>> On 06.11.19 16:05, Steven Price wrote:
>>> On 06/11/2019 13:31, Qian Cai wrote:
>>>>
>>>>
>>>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
>>>>>
>>>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
>>> [...]
>>>>>> Changes since v14:
>>>>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@arm.com/
>>>>>> * 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.
>>>
>>> Thanks for finding this, it looks like EFI causes issues here. The below fixes
>>> this for me (booting in QEMU).
>>>
>>> Andrew: do you want me to send out the entire series again for this fix, or
>>> can you squash this into mm-pagewalk-allow-walking-without-vma.patch?
>>>
>>> Thanks,
>>>
>>> Steve
>>>
>>> ---8<---
>>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
>>> index c7529dc4f82b..70dcaa23598f 100644
>>> --- a/mm/pagewalk.c
>>> +++ b/mm/pagewalk.c
>>> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>>>  			split_huge_pmd(walk->vma, pmd, addr);
>>>  			if (pmd_trans_unstable(pmd))
>>>  				goto again;
>>> -		} else if (pmd_leaf(*pmd)) {
>>> +		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
>>>  			continue;
>>>  		}
>>>
>>> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>>>  			split_huge_pud(walk->vma, pud, addr);
>>>  			if (pud_none(*pud))
>>>  				goto again;
>>> -		} else if (pud_leaf(*pud)) {
>>> +		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
>>>  			continue;
>>>  		}
>>>
>>>
>>
>> Even with this fix, booting for me under QEMU fails. See
>>
>> https://lore.kernel.org/linux-mm/b7ce62f2-9a48-6e48-6685-003431e521aa@redhat.com/
>>
> 
> Yes, for some reasons, this starts to crash on almost all arches here, so it might be worth
> for Andrew to revert those in the meantime while allowing Steven to rework.

I agree, this produces too much noise.


-- 
Thanks,

David / dhildenb

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Steven Price]

On Wed, Dec 04, 2019 at 02:56:58PM +0000, David Hildenbrand wrote:
> On 04.12.19 15:54, Qian Cai wrote:
> > 
> > 
> >> On Dec 3, 2019, at 6:02 AM, David Hildenbrand <david@redhat.com> wrote:
> >>
> >> On 06.11.19 16:05, Steven Price wrote:
> >>> On 06/11/2019 13:31, Qian Cai wrote:
> >>>>
> >>>>
> >>>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
> >>>>>
> >>>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
> >>> [...]
> >>>>>> Changes since v14:
> >>>>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@arm.com/
> >>>>>> * 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.
> >>>
> >>> Thanks for finding this, it looks like EFI causes issues here. The below fixes
> >>> this for me (booting in QEMU).
> >>>
> >>> Andrew: do you want me to send out the entire series again for this fix, or
> >>> can you squash this into mm-pagewalk-allow-walking-without-vma.patch?
> >>>
> >>> Thanks,
> >>>
> >>> Steve
> >>>
> >>> ---8<---
> >>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> >>> index c7529dc4f82b..70dcaa23598f 100644
> >>> --- a/mm/pagewalk.c
> >>> +++ b/mm/pagewalk.c
> >>> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
> >>>  			split_huge_pmd(walk->vma, pmd, addr);
> >>>  			if (pmd_trans_unstable(pmd))
> >>>  				goto again;
> >>> -		} else if (pmd_leaf(*pmd)) {
> >>> +		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
> >>>  			continue;
> >>>  		}
> >>>
> >>> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
> >>>  			split_huge_pud(walk->vma, pud, addr);
> >>>  			if (pud_none(*pud))
> >>>  				goto again;
> >>> -		} else if (pud_leaf(*pud)) {
> >>> +		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
> >>>  			continue;
> >>>  		}
> >>>
> >>>
> >>
> >> Even with this fix, booting for me under QEMU fails. See
> >>
> >> https://lore.kernel.org/linux-mm/b7ce62f2-9a48-6e48-6685-003431e521aa@redhat.com/
> >>
> > 
> > Yes, for some reasons, this starts to crash on almost all arches here, so it might be worth
> > for Andrew to revert those in the meantime while allowing Steven to rework.
> 
> I agree, this produces too much noise.

I've bisected this problem and it's a merge conflict with:

ace88f1018b8 ("mm: pagewalk: Take the pagetable lock in walk_pte_range()")

Reverting that commit "fixes" the problem. That commit adds a call to
pte_offset_map_lock(), however that isn't necessarily safe when
considering an "unusual" mapping in the kernel. Combined with my patch
set this leads to the BUG when walking the kernel's page tables.

At this stage I think it's best if Andrew drops my series and I'll try
to rework it on top -rc1 fixing up this conflict and the other x86
32-bit issue that has cropped up.

Steve

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Thomas Hellstrom]

On 12/4/19 5:32 PM, Steven Price wrote:
> On Wed, Dec 04, 2019 at 02:56:58PM +0000, David Hildenbrand wrote:
>> On 04.12.19 15:54, Qian Cai wrote:
>>>
>>>> On Dec 3, 2019, at 6:02 AM, David Hildenbrand <david@redhat.com> wrote:
>>>>
>>>> On 06.11.19 16:05, Steven Price wrote:
>>>>> On 06/11/2019 13:31, Qian Cai wrote:
>>>>>>
>>>>>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@lca.pw> wrote:
>>>>>>>
>>>>>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote:
>>>>> [...]
>>>>>>>> Changes since v14:
>>>>>>>> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20191028135910.33253-1-steven.price%40arm.com%2F&amp;data=02%7C01%7Cthellstrom%40vmware.com%7C9f50ca595f81432eff5b08d778d7968a%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637110739727088799&amp;sdata=B3n6TFU7hluQyAXUOEaHBAGNC8mhscMfxSJi%2FrFr%2Flo%3D&amp;reserved=0
>>>>>>>> * 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://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fraw.githubusercontent.com%2Fcailca%2Flinux-mm%2Fmaster%2Fx86.config&amp;data=02%7C01%7Cthellstrom%40vmware.com%7C9f50ca595f81432eff5b08d778d7968a%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637110739727088799&amp;sdata=ymVh49kh7VL9yseRdkjSbTwRh%2B7yBXxhK7QMTUzwn4U%3D&amp;reserved=0
>>>>>>>
>>>>>> V15 is indeed DOA here.
>>>>> Thanks for finding this, it looks like EFI causes issues here. The below fixes
>>>>> this for me (booting in QEMU).
>>>>>
>>>>> Andrew: do you want me to send out the entire series again for this fix, or
>>>>> can you squash this into mm-pagewalk-allow-walking-without-vma.patch?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Steve
>>>>>
>>>>> ---8<---
>>>>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
>>>>> index c7529dc4f82b..70dcaa23598f 100644
>>>>> --- a/mm/pagewalk.c
>>>>> +++ b/mm/pagewalk.c
>>>>> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>>>>>  			split_huge_pmd(walk->vma, pmd, addr);
>>>>>  			if (pmd_trans_unstable(pmd))
>>>>>  				goto again;
>>>>> -		} else if (pmd_leaf(*pmd)) {
>>>>> +		} else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) {
>>>>>  			continue;
>>>>>  		}
>>>>>
>>>>> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>>>>>  			split_huge_pud(walk->vma, pud, addr);
>>>>>  			if (pud_none(*pud))
>>>>>  				goto again;
>>>>> -		} else if (pud_leaf(*pud)) {
>>>>> +		} else if (pud_leaf(*pud) || !pud_present(*pud)) {
>>>>>  			continue;
>>>>>  		}
>>>>>
>>>>>
>>>> Even with this fix, booting for me under QEMU fails. See
>>>>
>>>> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-mm%2Fb7ce62f2-9a48-6e48-6685-003431e521aa%40redhat.com%2F&amp;data=02%7C01%7Cthellstrom%40vmware.com%7C9f50ca595f81432eff5b08d778d7968a%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637110739727088799&amp;sdata=fRuLrmrzNEkU2MFzSVdyVyXyRoyZ95yZOYuy7aMSi7A%3D&amp;reserved=0
>>>>
>>> Yes, for some reasons, this starts to crash on almost all arches here, so it might be worth
>>> for Andrew to revert those in the meantime while allowing Steven to rework.
>> I agree, this produces too much noise.
> I've bisected this problem and it's a merge conflict with:
>
> ace88f1018b8 ("mm: pagewalk: Take the pagetable lock in walk_pte_range()")
>
> Reverting that commit "fixes" the problem. That commit adds a call to
> pte_offset_map_lock(), however that isn't necessarily safe when
> considering an "unusual" mapping in the kernel. Combined with my patch
> set this leads to the BUG when walking the kernel's page tables.
>
> At this stage I think it's best if Andrew drops my series and I'll try
> to rework it on top -rc1 fixing up this conflict and the other x86
> 32-bit issue that has cropped up.

Hi,

Unfortunately I wasn't aware of that conflict.

Perhaps something similar to this

https://elixir.bootlin.com/linux/v5.4/source/mm/memory.c#L2012

would fix at least this particular issue?

/Thomas




>
> Steve
>

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Qian Cai]

> On Dec 4, 2019, at 11:32 AM, Steven Price <Steven.Price@arm.com> wrote:
> 
> I've bisected this problem and it's a merge conflict with:
> 
> ace88f1018b8 ("mm: pagewalk: Take the pagetable lock in walk_pte_range()")

Sigh, how does that commit end up merging in the mainline without going through Andrew’s tree and missed all the linux-next testing? It was merged into the mainline Oct 4th?

> Reverting that commit "fixes" the problem. That commit adds a call to
> pte_offset_map_lock(), however that isn't necessarily safe when
> considering an "unusual" mapping in the kernel. Combined with my patch
> set this leads to the BUG when walking the kernel's page tables.
> 
> At this stage I think it's best if Andrew drops my series and I'll try
> to rework it on top -rc1 fixing up this conflict and the other x86
> 32-bit issue that has cropped up.

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Thomas Hellstrom]

On Thu, 2019-12-05 at 08:15 -0500, Qian Cai wrote:
> > On Dec 4, 2019, at 11:32 AM, Steven Price <Steven.Price@arm.com>
> > wrote:
> > 
> > I've bisected this problem and it's a merge conflict with:
> > 
> > ace88f1018b8 ("mm: pagewalk: Take the pagetable lock in
> > walk_pte_range()")
> 
> Sigh, how does that commit end up merging in the mainline without
> going through Andrew’s tree and missed all the linux-next testing? It
> was merged into the mainline Oct 4th?

It was acked by Andrew to be merged through a drm tree, since it was
part of a graphics driver functionality. It was preceded by a fairly
lenghty discussion on linux-mm / linux-kernel.

It was merged into drm-next on 19-11-28, I think that's when it
normally is seen by linux-next. Merged into mainline 19-11-30. Andrew's
tree got merged 19-12-05.

linux-next signaled a merge conflict from one of the patches in this
series (not this one) resolved manually with the akpm tree on 19-12-02.

Thomas

Re: [PATCH v15 00/23] Generic page walk and ptdump

[Qian Cai]

> On Dec 5, 2019, at 9:32 AM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
> 
> On Thu, 2019-12-05 at 08:15 -0500, Qian Cai wrote:
>>> On Dec 4, 2019, at 11:32 AM, Steven Price <Steven.Price@arm.com>
>>> wrote:
>>> 
>>> I've bisected this problem and it's a merge conflict with:
>>> 
>>> ace88f1018b8 ("mm: pagewalk: Take the pagetable lock in
>>> walk_pte_range()")
>> 
>> Sigh, how does that commit end up merging in the mainline without
>> going through Andrew’s tree and missed all the linux-next testing? It
>> was merged into the mainline Oct 4th?
> 
> It was acked by Andrew to be merged through a drm tree, since it was
> part of a graphics driver functionality. It was preceded by a fairly
> lenghty discussion on linux-mm / linux-kernel.
> 
> It was merged into drm-next on 19-11-28, I think that's when it
> normally is seen by linux-next. Merged into mainline 19-11-30. Andrew's
> tree got merged 19-12-05.

Ah, that was the problem. Merged into the mainline after only a day or two
showed up in the linux-next. There isn’t enough time for integration testing.

> 
> linux-next signaled a merge conflict from one of the patches in this
> series (not this one) resolved manually with the akpm tree on 19-12-02.
> 
> Thomas
> 
> 
> 
> 
> 
>