@@ -136,7 +136,7 @@ pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
if (!pte_present(orig_pte) || !pte_cont(orig_pte))
return orig_pte;
- ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize);
+ ncontig = find_num_contig(mm, addr, ptep, &pgsize);
for (i = 0; i < ncontig; i++, ptep++) {
pte_t pte = __ptep_get(ptep);
@@ -445,16 +445,19 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
pgprot_t hugeprot;
pte_t orig_pte;
+ VM_WARN_ON(!pte_present(pte));
+
if (!pte_cont(pte))
return __ptep_set_access_flags(vma, addr, ptep, pte, dirty);
- ncontig = find_num_contig(mm, addr, ptep, &pgsize);
+ ncontig = num_contig_ptes(huge_page_size(hstate_vma(vma)), &pgsize);
dpfn = pgsize >> PAGE_SHIFT;
if (!__cont_access_flags_changed(ptep, pte, ncontig))
return 0;
orig_pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
+ VM_WARN_ON(!pte_present(orig_pte));
/* Make sure we don't lose the dirty or young state */
if (pte_dirty(orig_pte))
@@ -479,7 +482,10 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
size_t pgsize;
pte_t pte;
- if (!pte_cont(__ptep_get(ptep))) {
+ pte = __ptep_get(ptep);
+ VM_WARN_ON(!pte_present(pte));
+
+ if (!pte_cont(pte)) {
__ptep_set_wrprotect(mm, addr, ptep);
return;
}
@@ -503,11 +509,15 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;
size_t pgsize;
int ncontig;
+ pte_t pte;
+
+ pte = __ptep_get(ptep);
+ VM_WARN_ON(!pte_present(pte));
- if (!pte_cont(__ptep_get(ptep)))
+ if (!pte_cont(pte))
return ptep_clear_flush(vma, addr, ptep);
- ncontig = find_num_contig(mm, addr, ptep, &pgsize);
+ ncontig = num_contig_ptes(huge_page_size(hstate_vma(vma)), &pgsize);
return get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
}
Not all huge_pte helper APIs explicitly provide the size of the huge_pte. So the helpers have to depend on various methods to determine the size of the huge_pte. Some of these methods are dubious. Let's clean up the code to use preferred methods and retire the dubious ones. The options in order of preference: - If size is provided as parameter, use it together with num_contig_ptes(). This is explicit and works for both present and non-present ptes. - If vma is provided as a parameter, retrieve size via huge_page_size(hstate_vma(vma)) and use it together with num_contig_ptes(). This is explicit and works for both present and non-present ptes. - If the pte is present and contiguous, use find_num_contig() to walk the pgtable to find the level and infer the number of ptes from level. Only works for *present* ptes. - If the pte is present and not contiguous and you can infer from this that only 1 pte needs to be operated on. This is ok if you don't care about the absolute size, and just want to know the number of ptes. - NEVER rely on resolving the PFN of a present pte to a folio and getting the folio's size. This is fragile at best, because there is nothing to stop the core-mm from allocating a folio twice as big as the huge_pte then mapping it across 2 consecutive huge_ptes. Or just partially mapping it. Where we require that the pte is present, add warnings if not-present. Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> --- arch/arm64/mm/hugetlbpage.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)