[PATCH v3 04/15] arm64/mm: set_ptes()/set_pte_at(): New layer to manage contig bit

Ryan Roberts
2023-12-04T10:55:14Z

Create a new layer for the in-table PTE manipulation APIs. For now, The
existing API is prefixed with double underscore to become the
arch-private API and the public API is just a simple wrapper that calls
the private API.

The public API implementation will subsequently be used to transparently
manipulate the contiguous bit where appropriate. But since there are
already some contig-aware users (e.g. hugetlb, kernel mapper), we must
first ensure those users use the private API directly so that the future
contig-bit manipulations in the public API do not interfere with those
existing uses.

set_pte_at() is a core macro that forwards to set_ptes() (with nr=1).
Instead of creating a __set_pte_at() internal macro, convert all arch
users to use set_ptes()/__set_ptes() directly, as appropriate. Callers
in hugetlb may benefit from calling __set_ptes() once for their whole
range rather than managing their own loop. This is left for future
improvement.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
arch/arm64/include/asm/pgtable.h | 10 +++++-----
arch/arm64/kernel/mte.c | 2 +-
arch/arm64/kvm/guest.c | 2 +-
arch/arm64/mm/fault.c | 2 +-
arch/arm64/mm/hugetlbpage.c | 10 +++++-----
5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 650d4f4bb6dc..323ec91add60 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -342,9 +342,9 @@ static inline void __sync_cache_and_tags(pte_t pte, unsigned int nr_pages)
mte_sync_tags(pte, nr_pages);
}

-static inline void set_ptes(struct mm_struct *mm,
- unsigned long __always_unused addr,
- pte_t *ptep, pte_t pte, unsigned int nr)
+static inline void __set_ptes(struct mm_struct *mm,
+ unsigned long __always_unused addr,
+ pte_t *ptep, pte_t pte, unsigned int nr)
{
page_table_check_ptes_set(mm, ptep, pte, nr);
__sync_cache_and_tags(pte, nr);
@@ -358,7 +358,6 @@ static inline void set_ptes(struct mm_struct *mm,
pte_val(pte) += PAGE_SIZE;
}
}
-#define set_ptes set_ptes

/*
* Huge pte definitions.
@@ -1067,7 +1066,7 @@ static inline void arch_swap_restore(swp_entry_t entry, struct folio *folio)
#endif /* CONFIG_ARM64_MTE */

/*
- * On AArch64, the cache coherency is handled via the set_pte_at() function.
+ * On AArch64, the cache coherency is handled via the __set_ptes() function.
*/
static inline void update_mmu_cache_range(struct vm_fault *vmf,
struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
@@ -1121,6 +1120,7 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
pte_t old_pte, pte_t new_pte);

#define set_pte __set_pte
+#define set_ptes __set_ptes

#endif /* !__ASSEMBLY__ */

diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index a41ef3213e1e..dcdcccd40891 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -67,7 +67,7 @@ int memcmp_pages(struct page *page1, struct page *page2)
/*
* If the page content is identical but at least one of the pages is
* tagged, return non-zero to avoid KSM merging. If only one of the
- * pages is tagged, set_pte_at() may zero or change the tags of the
+ * pages is tagged, __set_ptes() may zero or change the tags of the
* other page via mte_sync_tags().
*/
if (page_mte_tagged(page1) || page_mte_tagged(page2))
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index aaf1d4939739..629145fd3161 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -1072,7 +1072,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
} else {
/*
* Only locking to serialise with a concurrent
- * set_pte_at() in the VMM but still overriding the
+ * __set_ptes() in the VMM but still overriding the
* tags, hence ignoring the return value.
*/
try_page_mte_tagging(page);
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 460d799e1296..a287c1dea871 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -205,7 +205,7 @@ static void show_pte(unsigned long addr)
*
* It needs to cope with hardware update of the accessed/dirty state by other
* agents in the system and can safely skip the __sync_icache_dcache() call as,
- * like set_pte_at(), the PTE is never changed from no-exec to exec here.
+ * like __set_ptes(), the PTE is never changed from no-exec to exec here.
*
* Returns whether or not the PTE actually changed.
*/
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index f5aae342632c..741cb53672fd 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -254,12 +254,12 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,

if (!pte_present(pte)) {
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize)
- set_pte_at(mm, addr, ptep, pte);
+ __set_ptes(mm, addr, ptep, pte, 1);
return;
}

if (!pte_cont(pte)) {
- set_pte_at(mm, addr, ptep, pte);
+ __set_ptes(mm, addr, ptep, pte, 1);
return;
}

@@ -270,7 +270,7 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
clear_flush(mm, addr, ptep, pgsize, ncontig);

for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
- set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+ __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
}

pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -478,7 +478,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,

hugeprot = pte_pgprot(pte);
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
- set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+ __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);

return 1;
}
@@ -507,7 +507,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
pfn = pte_pfn(pte);

for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
- set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+ __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
}

pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
--
2.25.1