+++ /dev/null
-From f8b663bbfa30af5515e222fd74df20ea4e8393a2 Mon Sep 17 00:00:00 2001
-From: Yu Zhao <yuzhao@google.com>
-Date: Sat, 26 Sep 2020 21:17:18 -0600
-Subject: [PATCH 02/10] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG
-
-Some architectures support the accessed bit on non-leaf PMD entries,
-e.g., x86_64 sets the accessed bit on a non-leaf PMD entry when using
-it as part of linear address translation [1]. As an optimization, page
-table walkers who are interested in the accessed bit can skip the PTEs
-under a non-leaf PMD entry if the accessed bit is cleared on this PMD
-entry.
-
-Although an inline function may be preferable, this capability is
-added as a configuration option to look consistent when used with the
-existing macros.
-
-[1]: Intel 64 and IA-32 Architectures Software Developer's Manual
- Volume 3 (June 2021), section 4.8
-
-Signed-off-by: Yu Zhao <yuzhao@google.com>
-Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
-Change-Id: I1a17be3ae926f721f7b17ea1539e5c39e8c4f9a8
----
- arch/Kconfig | 9 +++++++++
- arch/x86/Kconfig | 1 +
- arch/x86/include/asm/pgtable.h | 3 ++-
- arch/x86/mm/pgtable.c | 5 ++++-
- include/linux/pgtable.h | 4 ++--
- 5 files changed, 18 insertions(+), 4 deletions(-)
-
---- a/arch/Kconfig
-+++ b/arch/Kconfig
-@@ -1295,6 +1295,15 @@ config ARCH_HAS_ELFCORE_COMPAT
- config ARCH_HAS_PARANOID_L1D_FLUSH
- bool
-
-+config ARCH_HAS_NONLEAF_PMD_YOUNG
-+ bool
-+ depends on PGTABLE_LEVELS > 2
-+ help
-+ Architectures that select this are able to set the accessed bit on
-+ non-leaf PMD entries in addition to leaf PTE entries where pages are
-+ mapped. For them, page table walkers that clear the accessed bit may
-+ stop at non-leaf PMD entries if they do not see the accessed bit.
-+
- source "kernel/gcov/Kconfig"
-
- source "scripts/gcc-plugins/Kconfig"
---- a/arch/x86/Kconfig
-+++ b/arch/x86/Kconfig
-@@ -84,6 +84,7 @@ config X86
- select ARCH_HAS_PMEM_API if X86_64
- select ARCH_HAS_PTE_DEVMAP if X86_64
- select ARCH_HAS_PTE_SPECIAL
-+ select ARCH_HAS_NONLEAF_PMD_YOUNG if X86_64
- select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
- select ARCH_HAS_COPY_MC if X86_64
- select ARCH_HAS_SET_MEMORY
---- a/arch/x86/include/asm/pgtable.h
-+++ b/arch/x86/include/asm/pgtable.h
-@@ -817,7 +817,8 @@ static inline unsigned long pmd_page_vad
-
- static inline int pmd_bad(pmd_t pmd)
- {
-- return (pmd_flags(pmd) & ~_PAGE_USER) != _KERNPG_TABLE;
-+ return (pmd_flags(pmd) & ~(_PAGE_USER | _PAGE_ACCESSED)) !=
-+ (_KERNPG_TABLE & ~_PAGE_ACCESSED);
- }
-
- static inline unsigned long pages_to_mb(unsigned long npg)
---- a/arch/x86/mm/pgtable.c
-+++ b/arch/x86/mm/pgtable.c
-@@ -550,7 +550,7 @@ int ptep_test_and_clear_young(struct vm_
- return ret;
- }
-
--#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)
- int pmdp_test_and_clear_young(struct vm_area_struct *vma,
- unsigned long addr, pmd_t *pmdp)
- {
-@@ -562,6 +562,9 @@ int pmdp_test_and_clear_young(struct vm_
-
- return ret;
- }
-+#endif
-+
-+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- int pudp_test_and_clear_young(struct vm_area_struct *vma,
- unsigned long addr, pud_t *pudp)
- {
---- a/include/linux/pgtable.h
-+++ b/include/linux/pgtable.h
-@@ -212,7 +212,7 @@ static inline int ptep_test_and_clear_yo
- #endif
-
- #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
--#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)
- static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
- unsigned long address,
- pmd_t *pmdp)
-@@ -233,7 +233,7 @@ static inline int pmdp_test_and_clear_yo
- BUILD_BUG();
- return 0;
- }
--#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */
- #endif
-
- #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
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