[PATCH v2 05/34] mm: add utility functions for ptdesc

Vishal Moola (Oracle)
2023-05-01T19:28:57Z

Introduce utility functions setting the foundation for ptdescs. These
will also assist in the splitting out of ptdesc from struct page.

ptdesc_alloc() is defined to allocate new ptdesc pages as compound
pages. This is to standardize ptdescs by allowing for one allocation
and one free function, in contrast to 2 allocation and 2 free functions.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
include/asm-generic/tlb.h | 11 ++++++++++
include/linux/mm.h | 44 +++++++++++++++++++++++++++++++++++++++
include/linux/pgtable.h | 12 +++++++++++
3 files changed, 67 insertions(+)

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index b46617207c93..6bade9e0e799 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -481,6 +481,17 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
return tlb_remove_page_size(tlb, page, PAGE_SIZE);
}

+static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
+{
+ tlb_remove_table(tlb, pt);
+}
+
+/* Like tlb_remove_ptdesc, but for page-like page directories. */
+static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
+{
+ tlb_remove_page(tlb, ptdesc_page(pt));
+}
+
static inline void tlb_change_page_size(struct mmu_gather *tlb,
unsigned int page_size)
{
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b18848ae7e22..258f3b730359 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2744,6 +2744,45 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
}
#endif /* CONFIG_MMU */

+static inline struct ptdesc *virt_to_ptdesc(const void *x)
+{
+ return page_ptdesc(virt_to_head_page(x));
+}
+
+static inline void *ptdesc_to_virt(const struct ptdesc *pt)
+{
+ return page_to_virt(ptdesc_page(pt));
+}
+
+static inline void *ptdesc_address(const struct ptdesc *pt)
+{
+ return folio_address(ptdesc_folio(pt));
+}
+
+static inline bool ptdesc_is_reserved(struct ptdesc *pt)
+{
+ return folio_test_reserved(ptdesc_folio(pt));
+}
+
+static inline struct ptdesc *ptdesc_alloc(gfp_t gfp, unsigned int order)
+{
+ struct page *page = alloc_pages(gfp | __GFP_COMP, order);
+
+ return page_ptdesc(page);
+}
+
+static inline void ptdesc_free(struct ptdesc *pt)
+{
+ struct page *page = ptdesc_page(pt);
+
+ __free_pages(page, compound_order(page));
+}
+
+static inline void ptdesc_clear(void *x)
+{
+ clear_page(x);
+}
+
#if USE_SPLIT_PTE_PTLOCKS
#if ALLOC_SPLIT_PTLOCKS
void __init ptlock_cache_init(void);
@@ -2970,6 +3009,11 @@ static inline void mark_page_reserved(struct page *page)
adjust_managed_page_count(page, -1);
}

+static inline void free_reserved_ptdesc(struct ptdesc *pt)
+{
+ free_reserved_page(ptdesc_page(pt));
+}
+
/*
* Default method to free all the __init memory into the buddy system.
* The freed pages will be poisoned with pattern "poison" if it's within
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 5e0f51308724..b067ac10f3dd 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1041,6 +1041,18 @@ TABLE_MATCH(ptl, ptl);
#undef TABLE_MATCH
static_assert(sizeof(struct ptdesc) <= sizeof(struct page));

+#define ptdesc_page(pt) (_Generic((pt), \
+ const struct ptdesc *: (const struct page *)(pt), \
+ struct ptdesc *: (struct page *)(pt)))
+
+#define ptdesc_folio(pt) (_Generic((pt), \
+ const struct ptdesc *: (const struct folio *)(pt), \
+ struct ptdesc *: (struct folio *)(pt)))
+
+#define page_ptdesc(p) (_Generic((p), \
+ const struct page *: (const struct ptdesc *)(p), \
+ struct page *: (struct ptdesc *)(p)))
+
/*
* No-op macros that just return the current protection value. Defined here
* because these macros can be used even if CONFIG_MMU is not defined.