Commit eed9a328 authored Sep 18, 2022 by Yu Zhao Committed by Andrew Morton Sep 26, 2022

mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG

Some architectures support the accessed bit in non-leaf PMD entries, e.g.,
x86 sets the accessed bit in a non-leaf PMD entry when using it as part of
linear address translation [1].  Page table walkers that clear the
accessed bit may use this capability to reduce their search space.

Note that:
1. Although an inline function is preferable, this capability is added
   as a configuration option for consistency with the existing macros.
2. Due to the little interest in other varieties, this capability was
   only tested on Intel and AMD CPUs.

Thanks to the following developers for their efforts [2][3].
  Randy Dunlap <rdunlap@infradead.org>
  Stephen Rothwell <sfr@canb.auug.org.au>

[1]: Intel 64 and IA-32 Architectures Software Developer's Manual
     Volume 3 (June 2021), section 4.8
[2] https://lore.kernel.org/r/bfdcc7c8-922f-61a9-aa15-7e7250f04af7@infradead.org/
[3] https://lore.kernel.org/r/20220413151513.5a0d7a7e@canb.auug.org.au/

Link: https://lkml.kernel.org/r/20220918080010.2920238-3-yuzhao@google.com


Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Larabel <Michael@MichaelLarabel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent e1fd09e3

arch/Kconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -1415,6 +1415,14 @@ config DYNAMIC_SIGFRAME
		config HAVE_ARCH_NODE_DEV_GROUP
		bool

		config ARCH_HAS_NONLEAF_PMD_YOUNG
		bool
		help
		Architectures that select this option are capable of setting the
		accessed bit in non-leaf PMD entries when using them as part of linear
		address translations. Page table walkers that clear the accessed bit
		may use this capability to reduce their search space.

		source "kernel/gcov/Kconfig"

		source "scripts/gcc-plugins/Kconfig"

arch/x86/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -85,6 +85,7 @@ 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 PGTABLE_LEVELS > 2
		select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
		select ARCH_HAS_COPY_MC if X86_64
		select ARCH_HAS_SET_MEMORY

arch/x86/include/asm/pgtable.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -815,7 +815,8 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)

		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)

arch/x86/mm/pgtable.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -550,7 +550,7 @@ int ptep_test_and_clear_young(struct vm_area_struct *vma,
		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_area_struct *vma,

		return ret;
		}
		#endif

		#ifdef CONFIG_TRANSPARENT_HUGEPAGE
		int pudp_test_and_clear_young(struct vm_area_struct *vma,
		unsigned long addr, pud_t *pudp)
		{

include/linux/pgtable.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -213,7 +213,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
		#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)
		@@ -234,7 +234,7 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
		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