After high-granularity mapping, page table entries for HugeTLB pages can
be of any size/type. (For example, we can have a 1G page mapped with a
mix of PMDs and PTEs.) This struct is to help keep track of a HugeTLB
PTE after we have done a page table walk.
Without this, we'd have to pass around the "size" of the PTE everywhere.
We effectively did this before; it could be fetched from the hstate,
which we pass around pretty much everywhere.
hugetlb_pte_present_leaf is included here as a helper function that will
be used frequently later on.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
include/linux/hugetlb.h | 72 +++++++++++++++++++++++++++++++++++++++++
mm/hugetlb.c | 29 +++++++++++++++++
2 files changed, 101 insertions(+)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 3f098363cd6e..bf441d8a1b52 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -38,6 +38,54 @@ typedef struct { unsigned long pd; } hugepd_t;
*/
#define __NR_USED_SUBPAGE 3
+enum hugetlb_level {
+ HUGETLB_LEVEL_PTE = 1,
+ /*
+ * We always include PMD, PUD, and P4D in this enum definition so that,
+ * when logged as an integer, we can easily tell which level it is.
+ */
+ HUGETLB_LEVEL_PMD,
+ HUGETLB_LEVEL_PUD,
+ HUGETLB_LEVEL_P4D,
+ HUGETLB_LEVEL_PGD,
+};
+
+struct hugetlb_pte {
+ pte_t *ptep;
+ unsigned int shift;
+ enum hugetlb_level level;
+ spinlock_t *ptl;
+};
+
+static inline
+void __hugetlb_pte_populate(struct hugetlb_pte *hpte, pte_t *ptep,
+ unsigned int shift, enum hugetlb_level level,
+ spinlock_t *ptl)
+{
+ /*
+ * If 'shift' indicates that this PTE is contiguous, then @ptep must
+ * be the first pte of the contiguous bunch.
+ */
+ hpte->ptl = ptl;
+ hpte->ptep = ptep;
+ hpte->shift = shift;
+ hpte->level = level;
+}
+
+static inline
+unsigned long hugetlb_pte_size(const struct hugetlb_pte *hpte)
+{
+ return 1UL << hpte->shift;
+}
+
+static inline
+unsigned long hugetlb_pte_mask(const struct hugetlb_pte *hpte)
+{
+ return ~(hugetlb_pte_size(hpte) - 1);
+}
+
+bool hugetlb_pte_present_leaf(const struct hugetlb_pte *hpte, pte_t pte);
+
struct hugepage_subpool {
spinlock_t lock;
long count;
@@ -1232,6 +1280,30 @@ static inline spinlock_t *huge_pte_lock(struct hstate *h,
return ptl;
}
+static inline
+spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
+{
+ return hpte->ptl;
+}
+
+static inline
+spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
+{
+ spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
+
+ spin_lock(ptl);
+ return ptl;
+}
+
+static inline
+void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
+ pte_t *ptep, unsigned int shift,
+ enum hugetlb_level level)
+{
+ __hugetlb_pte_populate(hpte, ptep, shift, level,
+ huge_pte_lockptr(shift, mm, ptep));
+}
+
#if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_CMA)
extern void __init hugetlb_cma_reserve(int order);
#else
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4db38dc79d0e..2d83a2c359a2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1266,6 +1266,35 @@ static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
return false;
}
+bool hugetlb_pte_present_leaf(const struct hugetlb_pte *hpte, pte_t pte)
+{
+ pgd_t pgd;
+ p4d_t p4d;
+ pud_t pud;
+ pmd_t pmd;
+
+ switch (hpte->level) {
+ case HUGETLB_LEVEL_PGD:
+ pgd = __pgd(pte_val(pte));
+ return pgd_present(pgd) && pgd_leaf(pgd);
+ case HUGETLB_LEVEL_P4D:
+ p4d = __p4d(pte_val(pte));
+ return p4d_present(p4d) && p4d_leaf(p4d);
+ case HUGETLB_LEVEL_PUD:
+ pud = __pud(pte_val(pte));
+ return pud_present(pud) && pud_leaf(pud);
+ case HUGETLB_LEVEL_PMD:
+ pmd = __pmd(pte_val(pte));
+ return pmd_present(pmd) && pmd_leaf(pmd);
+ case HUGETLB_LEVEL_PTE:
+ return pte_present(pte);
+ default:
+ WARN_ON_ONCE(1);
+ return false;
+ }
+}
+
+
static void enqueue_hugetlb_folio(struct hstate *h, struct folio *folio)
{
int nid = folio_nid(folio);
--
2.39.0.314.g84b9a713c41-goog
