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arm64: add batched versions of ptep_modify_prot_start/commit

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Override the generic definition of modify_prot_start_ptes() to use
get_and_clear_full_ptes().  This helper does a TLBI only for the starting
and ending contpte block of the range, whereas the current implementation
will call ptep_get_and_clear() for every contpte block, thus doing a TLBI
on every contpte block.  Therefore, we have a performance win.

The arm64 definition of pte_accessible() allows us to batch in the
errata specific case:

#define pte_accessible(mm, pte)	\
	(mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte))

All ptes are obviously present in the folio batch, and they are also valid.

Override the generic definition of modify_prot_commit_ptes() to simply use
set_ptes() to map the new ptes into the pagetable.

Link: https://lkml.kernel.org/r/20250718090244.21092-8-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dev Jain
2025-07-18 14:32:44 +05:30
committed by Andrew Morton
parent cac1db8c3a
commit 7efa1cd5f8
2 changed files with 33 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
arch/arm64/include/asm/pgtable.h
View File

@@ -1643,6 +1643,16 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t old_pte, pte_t new_pte);
#define modify_prot_start_ptes modify_prot_start_ptes
extern pte_t modify_prot_start_ptes(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
unsigned int nr);
#define modify_prot_commit_ptes modify_prot_commit_ptes
extern void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, pte_t old_pte, pte_t pte,
unsigned int nr);
#ifdef CONFIG_ARM64_CONTPTE
/*

28
arch/arm64/mm/mmu.c
View File

@@ -26,6 +26,7 @@
#include <linux/set_memory.h>
#include <linux/kfence.h>
#include <linux/pkeys.h>
#include <linux/mm_inline.h>
#include <asm/barrier.h>
#include <asm/cputype.h>
@@ -1524,24 +1525,41 @@ static int __init prevent_bootmem_remove_init(void)
early_initcall(prevent_bootmem_remove_init);
#endif
pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, unsigned int nr)
{
pte_t pte = get_and_clear_full_ptes(vma->vm_mm, addr, ptep, nr, /* full = */ 0);
if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) {
/*
* Break-before-make (BBM) is required for all user space mappings
* when the permission changes from executable to non-executable
* in cases where cpu is affected with errata #2645198.
*/
if (pte_user_exec(ptep_get(ptep)))
return ptep_clear_flush(vma, addr, ptep);
if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte))
__flush_tlb_range(vma, addr, nr * PAGE_SIZE,
PAGE_SIZE, true, 3);
}
return ptep_get_and_clear(vma->vm_mm, addr, ptep);
return pte;
}
pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
return modify_prot_start_ptes(vma, addr, ptep, 1);
}
void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, pte_t old_pte, pte_t pte,
unsigned int nr)
{
set_ptes(vma->vm_mm, addr, ptep, pte, nr);
}
void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
pte_t old_pte, pte_t pte)
{
set_pte_at(vma->vm_mm, addr, ptep, pte);
modify_prot_commit_ptes(vma, addr, ptep, old_pte, pte, 1);
}
/*