Skip to content

Commit

Permalink
Documentation/mm: add descriptions for arch page table helpers
Browse files Browse the repository at this point in the history 
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.

[[email protected]: fold in Mike's patch for the rst document, fix typos in the rst document]
  Link: http://lkml.kernel.org/r/[email protected]

Suggested-by: Mike Rapoport <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Zi Yan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
  • Loading branch information
@torvalds
Anshuman Khandual authored and torvalds committed Aug 7, 2020
1 parent 6315df4 commit b1d0000
Show file tree
Hide file tree
Showing 2 changed files with 264 additions and 0 deletions.
258 changes: 258 additions & 0 deletions Documentation/vm/arch_pgtable_helpers.rst
View file
Original file line number Diff line number Diff line change
@@ -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/[email protected]/
6 changes: 6 additions & 0 deletions mm/debug_vm_pgtable.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)

/*
Expand Down

0 comments on commit b1d0000

Please sign in to comment.