Thread (43 messages) 43 messages, 4 authors, 2023-04-20

[PATCH 04/33] mm: add utility functions for ptdesc

From: Vishal Moola (Oracle) <hidden>
Date: 2023-04-17 20:52:56
Also in: kvm, linux-arch, linux-m68k, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, linux-um, linuxppc-dev, loongarch, sparclinux, xen-devel
Subsystem: generic include/asm header files, memory management - core, mmu gather and tlb invalidation, the rest · Maintainers: Arnd Bergmann, Andrew Morton, David Hildenbrand, Will Deacon, "Aneesh Kumar K.V", Nick Piggin, Peter Zijlstra, Linus Torvalds

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) <redacted>
---
 include/asm-generic/tlb.h | 11 ++++++++++
 include/linux/mm.h        | 44 +++++++++++++++++++++++++++++++++++++++
 include/linux/pgtable.h   | 13 ++++++++++++
 3 files changed, 68 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..ec3cbe2fa665 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(struct ptdesc *pt)
+{
+	return page_to_virt(ptdesc_page(pt));
+}
+
+static inline void *ptdesc_address(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 7cc6ea057ee9..7cd803aa38eb 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -97,6 +97,19 @@ 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)))
+
+static inline struct ptdesc *page_ptdesc(struct page *page)
+{
+	return (struct ptdesc *)page;
+}
+
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
  *
-- 
2.39.2


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