On 24/06/22 11:06 pm, James Houghton wrote:
This adds it for architectures that use GENERAL_HUGETLB, including x86.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
include/linux/hugetlb.h | 2 ++
mm/hugetlb.c | 45 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index e7a6b944d0cc..605aa19d8572 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -258,6 +258,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz);
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz);
+int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
+ unsigned long addr, unsigned long sz, bool stop_at_none);
int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long *addr, pte_t *ptep);
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 557b0afdb503..3ec2a921ee6f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6981,6 +6981,51 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
return (pte_t *)pmd;
}
not strong feeling but this name looks confusing to me as it does
not only walk over page-tables but can also alloc.
+int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
+ unsigned long addr, unsigned long sz, bool stop_at_none)
+{
+ pte_t *ptep;
+
+ if (!hpte->ptep) {
+ pgd_t *pgd = pgd_offset(mm, addr);
+
+ if (!pgd)
+ return -ENOMEM;
+ ptep = (pte_t *)p4d_alloc(mm, pgd, addr);
+ if (!ptep)
+ return -ENOMEM;
+ hugetlb_pte_populate(hpte, ptep, P4D_SHIFT);
+ }
+
+ while (hugetlb_pte_size(hpte) > sz &&
+ !hugetlb_pte_present_leaf(hpte) &&
+ !(stop_at_none && hugetlb_pte_none(hpte))) {
Should this ordering of if-else condition be in reverse, i mean it will look
more natural and possibly less condition checks as we go from top to bottom.
+ if (hpte->shift == PMD_SHIFT) {
+ ptep = pte_alloc_map(mm, (pmd_t *)hpte->ptep, addr);
+ if (!ptep)
+ return -ENOMEM;
+ hpte->shift = PAGE_SHIFT;
+ hpte->ptep = ptep;
+ } else if (hpte->shift == PUD_SHIFT) {
+ ptep = (pte_t *)pmd_alloc(mm, (pud_t *)hpte->ptep,
+ addr);
+ if (!ptep)
+ return -ENOMEM;
+ hpte->shift = PMD_SHIFT;
+ hpte->ptep = ptep;
+ } else if (hpte->shift == P4D_SHIFT) {
+ ptep = (pte_t *)pud_alloc(mm, (p4d_t *)hpte->ptep,
+ addr);
+ if (!ptep)
+ return -ENOMEM;
+ hpte->shift = PUD_SHIFT;
+ hpte->ptep = ptep;
+ } else
+ BUG();
+ }
+ return 0;
+}
+
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
#ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
