Re: [PATCH v4 19/36] parisc: Implement the new page table range API

[Mike Rapoport <rppt@kernel.org>]

On Wed, Mar 15, 2023 at 05:14:27AM +0000, Matthew Wilcox (Oracle) wrote:
> Add set_ptes(), update_mmu_cache_range(), flush_dcache_folio()
> and flush_icache_pages().  Change the PG_arch_1 (aka PG_dcache_dirty) flag
> from being per-page to per-folio.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> Cc: Helge Deller <deller@gmx.de>
> Cc: linux-parisc@vger.kernel.org

Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>

> ---
>  arch/parisc/include/asm/cacheflush.h |  14 ++--
>  arch/parisc/include/asm/pgtable.h    |  37 ++++++----
>  arch/parisc/kernel/cache.c           | 101 +++++++++++++++++++--------
>  3 files changed, 103 insertions(+), 49 deletions(-)
> 
> diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
> index 0bdee6724132..2cdc0ea562d6 100644
> --- a/arch/parisc/include/asm/cacheflush.h
> +++ b/arch/parisc/include/asm/cacheflush.h
> @@ -43,16 +43,20 @@ void invalidate_kernel_vmap_range(void *vaddr, int size);
>  #define flush_cache_vmap(start, end)		flush_cache_all()
>  #define flush_cache_vunmap(start, end)		flush_cache_all()
>  
> +void flush_dcache_folio(struct folio *folio);
> +#define flush_dcache_folio flush_dcache_folio
>  #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
> -void flush_dcache_page(struct page *page);
> +static inline void flush_dcache_page(struct page *page)
> +{
> +	flush_dcache_folio(page_folio(page));
> +}
>  
>  #define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
>  #define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages)
>  
> -#define flush_icache_page(vma,page)	do { 		\
> -	flush_kernel_dcache_page_addr(page_address(page)); \
> -	flush_kernel_icache_page(page_address(page)); 	\
> -} while (0)
> +void flush_icache_pages(struct vm_area_struct *vma, struct page *page,
> +		unsigned int nr);
> +#define flush_icache_page(vma, page)	flush_icache_pages(vma, page, 1)
>  
>  #define flush_icache_range(s,e)		do { 		\
>  	flush_kernel_dcache_range_asm(s,e); 		\
> diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
> index e2950f5db7c9..ca6afe1980a5 100644
> --- a/arch/parisc/include/asm/pgtable.h
> +++ b/arch/parisc/include/asm/pgtable.h
> @@ -73,15 +73,6 @@ extern void __update_cache(pte_t pte);
>  		mb();				\
>  	} while(0)
>  
> -#define set_pte_at(mm, addr, pteptr, pteval)	\
> -	do {					\
> -		if (pte_present(pteval) &&	\
> -		    pte_user(pteval))		\
> -			__update_cache(pteval);	\
> -		*(pteptr) = (pteval);		\
> -		purge_tlb_entries(mm, addr);	\
> -	} while (0)
> -
>  #endif /* !__ASSEMBLY__ */
>  
>  #define pte_ERROR(e) \
> @@ -285,7 +276,7 @@ extern unsigned long *empty_zero_page;
>  #define pte_none(x)     (pte_val(x) == 0)
>  #define pte_present(x)	(pte_val(x) & _PAGE_PRESENT)
>  #define pte_user(x)	(pte_val(x) & _PAGE_USER)
> -#define pte_clear(mm, addr, xp)  set_pte_at(mm, addr, xp, __pte(0))
> +#define pte_clear(mm, addr, xp)  set_pte(xp, __pte(0))
>  
>  #define pmd_flag(x)	(pmd_val(x) & PxD_FLAG_MASK)
>  #define pmd_address(x)	((unsigned long)(pmd_val(x) &~ PxD_FLAG_MASK) << PxD_VALUE_SHIFT)
> @@ -391,11 +382,29 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
>  
>  extern void paging_init (void);
>  
> +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> +		pte_t *ptep, pte_t pte, unsigned int nr)
> +{
> +	if (pte_present(pte) && pte_user(pte))
> +		__update_cache(pte);
> +	for (;;) {
> +		*ptep = pte;
> +		purge_tlb_entries(mm, addr);
> +		if (--nr == 0)
> +			break;
> +		ptep++;
> +		pte_val(pte) += 1 << PFN_PTE_SHIFT;
> +		addr += PAGE_SIZE;
> +	}
> +}
> +#define set_ptes set_ptes
> +
>  /* Used for deferring calls to flush_dcache_page() */
>  
>  #define PG_dcache_dirty         PG_arch_1
>  
> -#define update_mmu_cache(vms,addr,ptep) __update_cache(*ptep)
> +#define update_mmu_cache_range(vma, addr, ptep, nr) __update_cache(*ptep)
> +#define update_mmu_cache(vma, addr, ptep) __update_cache(*ptep)
>  
>  /*
>   * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
> @@ -450,7 +459,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned
>  	if (!pte_young(pte)) {
>  		return 0;
>  	}
> -	set_pte_at(vma->vm_mm, addr, ptep, pte_mkold(pte));
> +	set_pte(ptep, pte_mkold(pte));
>  	return 1;
>  }
>  
> @@ -460,14 +469,14 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
>  	pte_t old_pte;
>  
>  	old_pte = *ptep;
> -	set_pte_at(mm, addr, ptep, __pte(0));
> +	set_pte(ptep, __pte(0));
>  
>  	return old_pte;
>  }
>  
>  static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
>  {
> -	set_pte_at(mm, addr, ptep, pte_wrprotect(*ptep));
> +	set_pte(ptep, pte_wrprotect(*ptep));
>  }
>  
>  #define pte_same(A,B)	(pte_val(A) == pte_val(B))
> diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
> index 1d3b8bc8a623..ceaa268fc1a6 100644
> --- a/arch/parisc/kernel/cache.c
> +++ b/arch/parisc/kernel/cache.c
> @@ -92,11 +92,11 @@ static inline void flush_data_cache(void)
>  /* Kernel virtual address of pfn.  */
>  #define pfn_va(pfn)	__va(PFN_PHYS(pfn))
>  
> -void
> -__update_cache(pte_t pte)
> +void __update_cache(pte_t pte)
>  {
>  	unsigned long pfn = pte_pfn(pte);
> -	struct page *page;
> +	struct folio *folio;
> +	unsigned int nr;
>  
>  	/* We don't have pte special.  As a result, we can be called with
>  	   an invalid pfn and we don't need to flush the kernel dcache page.
> @@ -104,13 +104,17 @@ __update_cache(pte_t pte)
>  	if (!pfn_valid(pfn))
>  		return;
>  
> -	page = pfn_to_page(pfn);
> -	if (page_mapping_file(page) &&
> -	    test_bit(PG_dcache_dirty, &page->flags)) {
> -		flush_kernel_dcache_page_addr(pfn_va(pfn));
> -		clear_bit(PG_dcache_dirty, &page->flags);
> +	folio = page_folio(pfn_to_page(pfn));
> +	pfn = folio_pfn(folio);
> +	nr = folio_nr_pages(folio);
> +	if (folio_flush_mapping(folio) &&
> +	    test_bit(PG_dcache_dirty, &folio->flags)) {
> +		while (nr--)
> +			flush_kernel_dcache_page_addr(pfn_va(pfn + nr));
> +		clear_bit(PG_dcache_dirty, &folio->flags);
>  	} else if (parisc_requires_coherency())
> -		flush_kernel_dcache_page_addr(pfn_va(pfn));
> +		while (nr--)
> +			flush_kernel_dcache_page_addr(pfn_va(pfn + nr));
>  }
>  
>  void
> @@ -364,6 +368,20 @@ static void flush_user_cache_page(struct vm_area_struct *vma, unsigned long vmad
>  	preempt_enable();
>  }
>  
> +void flush_icache_pages(struct vm_area_struct *vma, struct page *page,
> +		unsigned int nr)
> +{
> +	void *kaddr = page_address(page);
> +
> +	for (;;) {
> +		flush_kernel_dcache_page_addr(kaddr);
> +		flush_kernel_icache_page(kaddr);
> +		if (--nr == 0)
> +			break;
> +		page += PAGE_SIZE;
> +	}
> +}
> +
>  static inline pte_t *get_ptep(struct mm_struct *mm, unsigned long addr)
>  {
>  	pte_t *ptep = NULL;
> @@ -392,26 +410,30 @@ static inline bool pte_needs_flush(pte_t pte)
>  		== (_PAGE_PRESENT | _PAGE_ACCESSED);
>  }
>  
> -void flush_dcache_page(struct page *page)
> +void flush_dcache_folio(struct folio *folio)
>  {
> -	struct address_space *mapping = page_mapping_file(page);
> -	struct vm_area_struct *mpnt;
> -	unsigned long offset;
> +	struct address_space *mapping = folio_flush_mapping(folio);
> +	struct vm_area_struct *vma;
>  	unsigned long addr, old_addr = 0;
> +	void *kaddr;
>  	unsigned long count = 0;
> +	unsigned long i, nr;
>  	pgoff_t pgoff;
>  
>  	if (mapping && !mapping_mapped(mapping)) {
> -		set_bit(PG_dcache_dirty, &page->flags);
> +		set_bit(PG_dcache_dirty, &folio->flags);
>  		return;
>  	}
>  
> -	flush_kernel_dcache_page_addr(page_address(page));
> +	nr = folio_nr_pages(folio);
> +	kaddr = folio_address(folio);
> +	for (i = 0; i < nr; i++)
> +		flush_kernel_dcache_page_addr(kaddr + i * PAGE_SIZE);
>  
>  	if (!mapping)
>  		return;
>  
> -	pgoff = page->index;
> +	pgoff = folio->index;
>  
>  	/*
>  	 * We have carefully arranged in arch_get_unmapped_area() that
> @@ -421,15 +443,29 @@ void flush_dcache_page(struct page *page)
>  	 * on machines that support equivalent aliasing
>  	 */
>  	flush_dcache_mmap_lock(mapping);
> -	vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
> -		offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
> -		addr = mpnt->vm_start + offset;
> -		if (parisc_requires_coherency()) {
> -			pte_t *ptep;
> +	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff + nr - 1) {
> +		unsigned long offset = pgoff - vma->vm_pgoff;
> +		unsigned long pfn = folio_pfn(folio);
> +
> +		addr = vma->vm_start;
> +		nr = folio_nr_pages(folio);
> +		if (offset > -nr) {
> +			pfn -= offset;
> +			nr += offset;
> +		} else {
> +			addr += offset * PAGE_SIZE;
> +		}
> +		if (addr + nr * PAGE_SIZE > vma->vm_end)
> +			nr = (vma->vm_end - addr) / PAGE_SIZE;
>  
> -			ptep = get_ptep(mpnt->vm_mm, addr);
> -			if (ptep && pte_needs_flush(*ptep))
> -				flush_user_cache_page(mpnt, addr);
> +		if (parisc_requires_coherency()) {
> +			for (i = 0; i < nr; i++) {
> +				pte_t *ptep = get_ptep(vma->vm_mm,
> +							addr + i * PAGE_SIZE);
> +				if (ptep && pte_needs_flush(*ptep))
> +					flush_user_cache_page(vma,
> +							addr + i * PAGE_SIZE);
> +			}
>  		} else {
>  			/*
>  			 * The TLB is the engine of coherence on parisc:
> @@ -442,27 +478,32 @@ void flush_dcache_page(struct page *page)
>  			 * in (until the user or kernel specifically
>  			 * accesses it, of course)
>  			 */
> -			flush_tlb_page(mpnt, addr);
> +			for (i = 0; i < nr; i++)
> +				flush_tlb_page(vma, addr + i * PAGE_SIZE);
>  			if (old_addr == 0 || (old_addr & (SHM_COLOUR - 1))
>  					!= (addr & (SHM_COLOUR - 1))) {
> -				__flush_cache_page(mpnt, addr, page_to_phys(page));
> +				for (i = 0; i < nr; i++)
> +					__flush_cache_page(vma,
> +						addr + i * PAGE_SIZE,
> +						(pfn + i) * PAGE_SIZE);
>  				/*
>  				 * Software is allowed to have any number
>  				 * of private mappings to a page.
>  				 */
> -				if (!(mpnt->vm_flags & VM_SHARED))
> +				if (!(vma->vm_flags & VM_SHARED))
>  					continue;
>  				if (old_addr)
>  					pr_err("INEQUIVALENT ALIASES 0x%lx and 0x%lx in file %pD\n",
> -						old_addr, addr, mpnt->vm_file);
> -				old_addr = addr;
> +						old_addr, addr, vma->vm_file);
> +				if (nr == folio_nr_pages(folio))
> +					old_addr = addr;
>  			}
>  		}
>  		WARN_ON(++count == 4096);
>  	}
>  	flush_dcache_mmap_unlock(mapping);
>  }
> -EXPORT_SYMBOL(flush_dcache_page);
> +EXPORT_SYMBOL(flush_dcache_folio);
>  
>  /* Defined in arch/parisc/kernel/pacache.S */
>  EXPORT_SYMBOL(flush_kernel_dcache_range_asm);
> -- 
> 2.39.2
> 
> 

-- 
Sincerely yours,
Mike.