[PATCH v1 07/16] arm64: hugetlb: Use ___set_ptes() and ___ptep_get_and_clear()

[Ryan Roberts <ryan.roberts@arm.com>]

Refactor the huge_pte helpers to use the new generic ___set_ptes() and
___ptep_get_and_clear() APIs.

This provides 2 benefits; First, when page_table_check=on, hugetlb is
now properly/fully checked. Previously only the first page of a hugetlb
folio was checked. Second, instead of having to call __set_ptes(nr=1)
for each pte in a loop, the whole contiguous batch can now be set in one
go, which enables some efficiencies and cleans up the code.

One detail to note is that huge_ptep_clear_flush() was previously
calling ptep_clear_flush() for a non-contiguous pte (i.e. a pud or pmd
block mapping). This has a couple of disadvantages; first
ptep_clear_flush() calls ptep_get_and_clear() which transparently
handles contpte. Given we only call for non-contiguous ptes, it would be
safe, but a waste of effort. It's preferable to go stright to the layer
below. However, more problematic is that ptep_get_and_clear() is for
PAGE_SIZE entries so it calls page_table_check_pte_clear() and would not
clear the whole hugetlb folio. So let's stop special-casing the non-cont
case and just rely on get_clear_contig_flush() to do the right thing for
non-cont entries.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 arch/arm64/mm/hugetlbpage.c | 50 ++++++++-----------------------------
 1 file changed, 11 insertions(+), 39 deletions(-)

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index e870d01d12ea..02afee31444e 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -166,12 +166,12 @@ static pte_t get_clear_contig(struct mm_struct *mm,
 	pte_t pte, tmp_pte;
 	bool present;
 
-	pte = __ptep_get_and_clear(mm, addr, ptep);
+	pte = ___ptep_get_and_clear(mm, ptep, pgsize);
 	present = pte_present(pte);
 	while (--ncontig) {
 		ptep++;
 		addr += pgsize;
-		tmp_pte = __ptep_get_and_clear(mm, addr, ptep);
+		tmp_pte = ___ptep_get_and_clear(mm, ptep, pgsize);
 		if (present) {
 			if (pte_dirty(tmp_pte))
 				pte = pte_mkdirty(pte);
@@ -215,7 +215,7 @@ static void clear_flush(struct mm_struct *mm,
 	unsigned long i, saddr = addr;
 
 	for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
-		__ptep_get_and_clear(mm, addr, ptep);
+		___ptep_get_and_clear(mm, ptep, pgsize);
 
 	__flush_hugetlb_tlb_range(&vma, saddr, addr, pgsize, true);
 }
@@ -226,32 +226,20 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 	size_t pgsize;
 	int i;
 	int ncontig;
-	unsigned long pfn, dpfn;
-	pgprot_t hugeprot;
 
 	ncontig = num_contig_ptes(sz, &pgsize);
 
 	if (!pte_present(pte)) {
 		for (i = 0; i < ncontig; i++, ptep++, addr += pgsize)
-			__set_ptes(mm, addr, ptep, pte, 1);
+			___set_ptes(mm, ptep, pte, 1, pgsize);
 		return;
 	}
 
-	if (!pte_cont(pte)) {
-		__set_ptes(mm, addr, ptep, pte, 1);
-		return;
-	}
-
-	pfn = pte_pfn(pte);
-	dpfn = pgsize >> PAGE_SHIFT;
-	hugeprot = pte_pgprot(pte);
-
 	/* Only need to "break" if transitioning valid -> valid. */
-	if (pte_valid(__ptep_get(ptep)))
+	if (pte_cont(pte) && pte_valid(__ptep_get(ptep)))
 		clear_flush(mm, addr, ptep, pgsize, ncontig);
 
-	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
+	___set_ptes(mm, ptep, pte, ncontig, pgsize);
 }
 
 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -441,11 +429,9 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 			       unsigned long addr, pte_t *ptep,
 			       pte_t pte, int dirty)
 {
-	int ncontig, i;
+	int ncontig;
 	size_t pgsize = 0;
-	unsigned long pfn = pte_pfn(pte), dpfn;
 	struct mm_struct *mm = vma->vm_mm;
-	pgprot_t hugeprot;
 	pte_t orig_pte;
 
 	VM_WARN_ON(!pte_present(pte));
@@ -454,7 +440,6 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 		return __ptep_set_access_flags(vma, addr, ptep, pte, dirty);
 
 	ncontig = find_num_contig(mm, addr, ptep, &pgsize);
-	dpfn = pgsize >> PAGE_SHIFT;
 
 	if (!__cont_access_flags_changed(ptep, pte, ncontig))
 		return 0;
@@ -469,19 +454,14 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 	if (pte_young(orig_pte))
 		pte = pte_mkyoung(pte);
 
-	hugeprot = pte_pgprot(pte);
-	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
-
+	___set_ptes(mm, ptep, pte, ncontig, pgsize);
 	return 1;
 }
 
 void huge_ptep_set_wrprotect(struct mm_struct *mm,
 			     unsigned long addr, pte_t *ptep)
 {
-	unsigned long pfn, dpfn;
-	pgprot_t hugeprot;
-	int ncontig, i;
+	int ncontig;
 	size_t pgsize;
 	pte_t pte;
 
@@ -494,16 +474,11 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
 	}
 
 	ncontig = find_num_contig(mm, addr, ptep, &pgsize);
-	dpfn = pgsize >> PAGE_SHIFT;
 
 	pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
 	pte = pte_wrprotect(pte);
 
-	hugeprot = pte_pgprot(pte);
-	pfn = pte_pfn(pte);
-
-	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
+	___set_ptes(mm, ptep, pte, ncontig, pgsize);
 }
 
 pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
@@ -517,10 +492,7 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
 	pte = __ptep_get(ptep);
 	VM_WARN_ON(!pte_present(pte));
 
-	if (!pte_cont(pte))
-		return ptep_clear_flush(vma, addr, ptep);
-
-	ncontig = find_num_contig(mm, addr, ptep, &pgsize);
+	ncontig = num_contig_ptes(page_size(pte_page(pte)), &pgsize);
 	return get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
 }
 
-- 
2.43.0