On Thu, May 25, 2023 at 2:10 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
On Mon, May 01, 2023 at 12:28:00PM -0700, Vishal Moola (Oracle) wrote: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@xxxxxxxxx> --- 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));Do we ever use compound pages for page tables?
Mips and s390 crst tables use multi-order (but not compound) pages. The ptdesc api *should* change that, but until all the allocation/free paths are changed it may cause problems. Thanks for catching that, I'll change it in v3.
+} + +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)); +}The ptdesc_{alloc,free} API does not sound right to me. The name ptdesc_alloc() implies the allocation of the ptdesc itself, rather than allocation of page table page. The same goes for free.
I'm not sure I see the difference. Could you elaborate?
+ +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. -- 2.39.2-- Sincerely yours, Mike.
