On Mon, Aug 30, 2021 at 04:59:13PM -0700, Rick Edgecombe wrote:
> Change the page table allocation functions defined in pgalloc.h to use
> a cache of physically grouped pages. This will let the page tables be set
> with PKS permissions later.
>
> For userspace page tables, they are gathered up using mmu gather, and
> freed along with other types of pages in swap.c. Move setting/clearing of
> the PageTable page flag to the allocators so that swap can know to return
> this page to the cache of page tables, and not free it to the page
> allocator. Where it currently is, in the ctor/dtors, causes it to be
> cleared before the page gets to swap.
>
> Do not set PKS permissions on the page tables, because the page table
> setting functions cannot handle it yet. This will be done in later
> patches.
>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> ---
> arch/x86/include/asm/pgalloc.h | 6 ++-
> arch/x86/include/asm/pgtable.h | 6 +++
> arch/x86/mm/pgtable.c | 79 ++++++++++++++++++++++++++++++++++
> include/asm-generic/pgalloc.h | 44 ++++++++++++++-----
> include/linux/mm.h | 11 +++--
> mm/swap.c | 6 +++
> mm/swap_state.c | 5 +++
> 7 files changed, 142 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
> index c7ec5bb88334..1ff308ea76cd 100644
> --- a/arch/x86/include/asm/pgalloc.h
> +++ b/arch/x86/include/asm/pgalloc.h
> @@ -7,6 +7,10 @@
> #include <linux/pagemap.h>
>
> #define __HAVE_ARCH_PTE_ALLOC_ONE
> +#ifdef CONFIG_PKS_PG_TABLES
> +#define __HAVE_ARCH_FREE_TABLE
> +#define __HAVE_ARCH_ALLOC_TABLE
I think one define would suffice. If we'd ever have an architecture that
can implement only one of those, we update the ifdefery in
asm-generic/pgalloc.h
> +#endif
> #define __HAVE_ARCH_PGD_FREE
> #include <asm-generic/pgalloc.h>
>
> @@ -162,7 +166,7 @@ static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
> return;
>
> BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
> - free_page((unsigned long)p4d);
> + free_table(virt_to_page(p4d));
> }
>
> extern void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d);
...
> diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
> index 02932efad3ab..e576c19abc8c 100644
> --- a/include/asm-generic/pgalloc.h
> +++ b/include/asm-generic/pgalloc.h
> @@ -2,11 +2,26 @@
> #ifndef __ASM_GENERIC_PGALLOC_H
> #define __ASM_GENERIC_PGALLOC_H
>
> +#include <linux/mm.h>
> +
Why is this required?
> #ifdef CONFIG_MMU
>
> #define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO)
> #define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
>
> +#ifndef __HAVE_ARCH_ALLOC_TABLE
> +static inline struct page *alloc_table(gfp_t gfp)
> +{
> + return alloc_page(gfp);
> +}
> +#else /* __HAVE_ARCH_ALLOC_TABLE */
> +extern struct page *alloc_table(gfp_t gfp);
> +#endif /* __HAVE_ARCH_ALLOC_TABLE */
> +
> +#ifdef __HAVE_ARCH_FREE_TABLE
> +extern void free_table(struct page *);
> +#endif /* __HAVE_ARCH_FREE_TABLE */
> +
> /**
> * __pte_alloc_one_kernel - allocate a page for PTE-level kernel page table
> * @mm: the mm_struct of the current context
...
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c13c7af7cad3..ab63d5a201cb 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2327,6 +2327,13 @@ static inline bool ptlock_init(struct page *page) { return true; }
> static inline void ptlock_free(struct page *page) {}
> #endif /* USE_SPLIT_PTE_PTLOCKS */
>
> +#ifndef CONFIG_PKS_PG_TABLES
> +static inline void free_table(struct page *table_page)
> +{
> + __free_pages(table_page, 0);
> +}
> +#endif /* CONFIG_PKS_PG_TABLES */
> +
Can't this live in asm-generic/pgalloc.h?
Then you won't need to include linux/mm.h there.
> static inline void pgtable_init(void)
> {
> ptlock_cache_init();
> @@ -2337,7 +2344,6 @@ static inline bool pgtable_pte_page_ctor(struct page *page)
> {
> if (!ptlock_init(page))
> return false;
> - __SetPageTable(page);
This change is only valid when __HAVE_ARCH_ALLOC_TABLE is set.
> inc_lruvec_page_state(page, NR_PAGETABLE);
> return true;
> }
> @@ -2345,7 +2351,6 @@ static inline bool pgtable_pte_page_ctor(struct page *page)
> static inline void pgtable_pte_page_dtor(struct page *page)
> {
> ptlock_free(page);
> - __ClearPageTable(page);
> dec_lruvec_page_state(page, NR_PAGETABLE);
> }
>
--
Sincerely yours,
Mike.
