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Documentation/mm: add descriptions for arch page table helpers

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This adds a specific description file for all arch page table helpers which
is in sync with the semantics being tested via CONFIG_DEBUG_VM_PGTABLE. All
future changes either to these descriptions here or the debug test should
always remain in sync.

[anshuman.khandual@arm.com: fold in Mike's patch for the rst document, fix typos in the rst document]
  Link: http://lkml.kernel.org/r/1594610587-4172-5-git-send-email-anshuman.khandual@arm.com

Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/1593996516-7186-5-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Anshuman Khandual 2020-08-06 23:19:28 -07:00 committed by Linus Torvalds
parent 6315df41af
commit b1d00007f2
2 changed files with 264 additions and 0 deletions
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258
Documentation/vm/arch_pgtable_helpers.rst Normal file
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@ -0,0 +1,258 @@
.. SPDX-License-Identifier: GPL-2.0
.. _arch_page_table_helpers:
===============================
Architecture Page Table Helpers
===============================
Generic MM expects architectures (with MMU) to provide helpers to create, access
and modify page table entries at various level for different memory functions.
These page table helpers need to conform to a common semantics across platforms.
Following tables describe the expected semantics which can also be tested during
boot via CONFIG_DEBUG_VM_PGTABLE option. All future changes in here or the debug
test need to be in sync.
======================
PTE Page Table Helpers
======================
+---------------------------+--------------------------------------------------+
| pte_same | Tests whether both PTE entries are the same |
+---------------------------+--------------------------------------------------+
| pte_bad | Tests a non-table mapped PTE |
+---------------------------+--------------------------------------------------+
| pte_present | Tests a valid mapped PTE |
+---------------------------+--------------------------------------------------+
| pte_young | Tests a young PTE |
+---------------------------+--------------------------------------------------+
| pte_dirty | Tests a dirty PTE |
+---------------------------+--------------------------------------------------+
| pte_write | Tests a writable PTE |
+---------------------------+--------------------------------------------------+
| pte_special | Tests a special PTE |
+---------------------------+--------------------------------------------------+
| pte_protnone | Tests a PROT_NONE PTE |
+---------------------------+--------------------------------------------------+
| pte_devmap | Tests a ZONE_DEVICE mapped PTE |
+---------------------------+--------------------------------------------------+
| pte_soft_dirty | Tests a soft dirty PTE |
+---------------------------+--------------------------------------------------+
| pte_swp_soft_dirty | Tests a soft dirty swapped PTE |
+---------------------------+--------------------------------------------------+
| pte_mkyoung | Creates a young PTE |
+---------------------------+--------------------------------------------------+
| pte_mkold | Creates an old PTE |
+---------------------------+--------------------------------------------------+
| pte_mkdirty | Creates a dirty PTE |
+---------------------------+--------------------------------------------------+
| pte_mkclean | Creates a clean PTE |
+---------------------------+--------------------------------------------------+
| pte_mkwrite | Creates a writable PTE |
+---------------------------+--------------------------------------------------+
| pte_mkwrprotect | Creates a write protected PTE |
+---------------------------+--------------------------------------------------+
| pte_mkspecial | Creates a special PTE |
+---------------------------+--------------------------------------------------+
| pte_mkdevmap | Creates a ZONE_DEVICE mapped PTE |
+---------------------------+--------------------------------------------------+
| pte_mksoft_dirty | Creates a soft dirty PTE |
+---------------------------+--------------------------------------------------+
| pte_clear_soft_dirty | Clears a soft dirty PTE |
+---------------------------+--------------------------------------------------+
| pte_swp_mksoft_dirty | Creates a soft dirty swapped PTE |
+---------------------------+--------------------------------------------------+
| pte_swp_clear_soft_dirty | Clears a soft dirty swapped PTE |
+---------------------------+--------------------------------------------------+
| pte_mknotpresent | Invalidates a mapped PTE |
+---------------------------+--------------------------------------------------+
| ptep_get_and_clear | Clears a PTE |
+---------------------------+--------------------------------------------------+
| ptep_get_and_clear_full | Clears a PTE |
+---------------------------+--------------------------------------------------+
| ptep_test_and_clear_young | Clears young from a PTE |
+---------------------------+--------------------------------------------------+
| ptep_set_wrprotect | Converts into a write protected PTE |
+---------------------------+--------------------------------------------------+
| ptep_set_access_flags | Converts into a more permissive PTE |
+---------------------------+--------------------------------------------------+
======================
PMD Page Table Helpers
======================
+---------------------------+--------------------------------------------------+
| pmd_same | Tests whether both PMD entries are the same |
+---------------------------+--------------------------------------------------+
| pmd_bad | Tests a non-table mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_leaf | Tests a leaf mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_huge | Tests a HugeTLB mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_trans_huge | Tests a Transparent Huge Page (THP) at PMD |
+---------------------------+--------------------------------------------------+
| pmd_present | Tests a valid mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_young | Tests a young PMD |
+---------------------------+--------------------------------------------------+
| pmd_dirty | Tests a dirty PMD |
+---------------------------+--------------------------------------------------+
| pmd_write | Tests a writable PMD |
+---------------------------+--------------------------------------------------+
| pmd_special | Tests a special PMD |
+---------------------------+--------------------------------------------------+
| pmd_protnone | Tests a PROT_NONE PMD |
+---------------------------+--------------------------------------------------+
| pmd_devmap | Tests a ZONE_DEVICE mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_soft_dirty | Tests a soft dirty PMD |
+---------------------------+--------------------------------------------------+
| pmd_swp_soft_dirty | Tests a soft dirty swapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkyoung | Creates a young PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkold | Creates an old PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkdirty | Creates a dirty PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkclean | Creates a clean PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkwrite | Creates a writable PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkwrprotect | Creates a write protected PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkspecial | Creates a special PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkdevmap | Creates a ZONE_DEVICE mapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_mksoft_dirty | Creates a soft dirty PMD |
+---------------------------+--------------------------------------------------+
| pmd_clear_soft_dirty | Clears a soft dirty PMD |
+---------------------------+--------------------------------------------------+
| pmd_swp_mksoft_dirty | Creates a soft dirty swapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_swp_clear_soft_dirty | Clears a soft dirty swapped PMD |
+---------------------------+--------------------------------------------------+
| pmd_mkinvalid | Invalidates a mapped PMD [1] |
+---------------------------+--------------------------------------------------+
| pmd_set_huge | Creates a PMD huge mapping |
+---------------------------+--------------------------------------------------+
| pmd_clear_huge | Clears a PMD huge mapping |
+---------------------------+--------------------------------------------------+
| pmdp_get_and_clear | Clears a PMD |
+---------------------------+--------------------------------------------------+
| pmdp_get_and_clear_full | Clears a PMD |
+---------------------------+--------------------------------------------------+
| pmdp_test_and_clear_young | Clears young from a PMD |
+---------------------------+--------------------------------------------------+
| pmdp_set_wrprotect | Converts into a write protected PMD |
+---------------------------+--------------------------------------------------+
| pmdp_set_access_flags | Converts into a more permissive PMD |
+---------------------------+--------------------------------------------------+
======================
PUD Page Table Helpers
======================
+---------------------------+--------------------------------------------------+
| pud_same | Tests whether both PUD entries are the same |
+---------------------------+--------------------------------------------------+
| pud_bad | Tests a non-table mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_leaf | Tests a leaf mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_huge | Tests a HugeTLB mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_trans_huge | Tests a Transparent Huge Page (THP) at PUD |
+---------------------------+--------------------------------------------------+
| pud_present | Tests a valid mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_young | Tests a young PUD |
+---------------------------+--------------------------------------------------+
| pud_dirty | Tests a dirty PUD |
+---------------------------+--------------------------------------------------+
| pud_write | Tests a writable PUD |
+---------------------------+--------------------------------------------------+
| pud_devmap | Tests a ZONE_DEVICE mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_mkyoung | Creates a young PUD |
+---------------------------+--------------------------------------------------+
| pud_mkold | Creates an old PUD |
+---------------------------+--------------------------------------------------+
| pud_mkdirty | Creates a dirty PUD |
+---------------------------+--------------------------------------------------+
| pud_mkclean | Creates a clean PUD |
+---------------------------+--------------------------------------------------+
| pud_mkwrite | Creates a writable PUD |
+---------------------------+--------------------------------------------------+
| pud_mkwrprotect | Creates a write protected PUD |
+---------------------------+--------------------------------------------------+
| pud_mkdevmap | Creates a ZONE_DEVICE mapped PUD |
+---------------------------+--------------------------------------------------+
| pud_mkinvalid | Invalidates a mapped PUD [1] |
+---------------------------+--------------------------------------------------+
| pud_set_huge | Creates a PUD huge mapping |
+---------------------------+--------------------------------------------------+
| pud_clear_huge | Clears a PUD huge mapping |
+---------------------------+--------------------------------------------------+
| pudp_get_and_clear | Clears a PUD |
+---------------------------+--------------------------------------------------+
| pudp_get_and_clear_full | Clears a PUD |
+---------------------------+--------------------------------------------------+
| pudp_test_and_clear_young | Clears young from a PUD |
+---------------------------+--------------------------------------------------+
| pudp_set_wrprotect | Converts into a write protected PUD |
+---------------------------+--------------------------------------------------+
| pudp_set_access_flags | Converts into a more permissive PUD |
+---------------------------+--------------------------------------------------+
==========================
HugeTLB Page Table Helpers
==========================
+---------------------------+--------------------------------------------------+
| pte_huge | Tests a HugeTLB |
+---------------------------+--------------------------------------------------+
| pte_mkhuge | Creates a HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_pte_dirty | Tests a dirty HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_pte_write | Tests a writable HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_pte_mkdirty | Creates a dirty HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_pte_mkwrite | Creates a writable HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_pte_mkwrprotect | Creates a write protected HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_ptep_get_and_clear | Clears a HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_ptep_set_wrprotect | Converts into a write protected HugeTLB |
+---------------------------+--------------------------------------------------+
| huge_ptep_set_access_flags | Converts into a more permissive HugeTLB |
+---------------------------+--------------------------------------------------+
========================
SWAP Page Table Helpers
========================
+---------------------------+--------------------------------------------------+
| __pte_to_swp_entry | Creates a swapped entry (arch) from a mapped PTE |
+---------------------------+--------------------------------------------------+
| __swp_to_pte_entry | Creates a mapped PTE from a swapped entry (arch) |
+---------------------------+--------------------------------------------------+
| __pmd_to_swp_entry | Creates a swapped entry (arch) from a mapped PMD |
+---------------------------+--------------------------------------------------+
| __swp_to_pmd_entry | Creates a mapped PMD from a swapped entry (arch) |
+---------------------------+--------------------------------------------------+
| is_migration_entry | Tests a migration (read or write) swapped entry |
+---------------------------+--------------------------------------------------+
| is_write_migration_entry | Tests a write migration swapped entry |
+---------------------------+--------------------------------------------------+
| make_migration_entry_read | Converts into read migration swapped entry |
+---------------------------+--------------------------------------------------+
| make_migration_entry | Creates a migration swapped entry (read or write)|
+---------------------------+--------------------------------------------------+
[1] https://lore.kernel.org/linux-mm/20181017020930.GN30832@redhat.com/

6
mm/debug_vm_pgtable.c
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@ -31,6 +31,12 @@
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
/*
* Please refer Documentation/vm/arch_pgtable_helpers.rst for the semantics
* expectations that are being validated here. All future changes in here
* or the documentation need to be in sync.
*/
#define VMFLAGS (VM_READ|VM_WRITE|VM_EXEC)
/*