diff options
Diffstat (limited to 'include/linux/highmem.h')
| -rw-r--r-- | include/linux/highmem.h | 785 |
1 files changed, 567 insertions, 218 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 14e6202ce47f..e48d7f27b0b9 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -5,11 +5,182 @@ #include <linux/fs.h> #include <linux/kernel.h> #include <linux/bug.h> +#include <linux/cacheflush.h> +#include <linux/kmsan.h> #include <linux/mm.h> #include <linux/uaccess.h> #include <linux/hardirq.h> -#include <asm/cacheflush.h> +#include "highmem-internal.h" + +/** + * kmap - Map a page for long term usage + * @page: Pointer to the page to be mapped + * + * Returns: The virtual address of the mapping + * + * Can only be invoked from preemptible task context because on 32bit + * systems with CONFIG_HIGHMEM enabled this function might sleep. + * + * For systems with CONFIG_HIGHMEM=n and for pages in the low memory area + * this returns the virtual address of the direct kernel mapping. + * + * The returned virtual address is globally visible and valid up to the + * point where it is unmapped via kunmap(). The pointer can be handed to + * other contexts. + * + * For highmem pages on 32bit systems this can be slow as the mapping space + * is limited and protected by a global lock. In case that there is no + * mapping slot available the function blocks until a slot is released via + * kunmap(). + */ +static inline void *kmap(struct page *page); + +/** + * kunmap - Unmap the virtual address mapped by kmap() + * @page: Pointer to the page which was mapped by kmap() + * + * Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of + * pages in the low memory area. + */ +static inline void kunmap(struct page *page); + +/** + * kmap_to_page - Get the page for a kmap'ed address + * @addr: The address to look up + * + * Returns: The page which is mapped to @addr. + */ +static inline struct page *kmap_to_page(void *addr); + +/** + * kmap_flush_unused - Flush all unused kmap mappings in order to + * remove stray mappings + */ +static inline void kmap_flush_unused(void); + +/** + * kmap_local_page - Map a page for temporary usage + * @page: Pointer to the page to be mapped + * + * Returns: The virtual address of the mapping + * + * Can be invoked from any context, including interrupts. + * + * Requires careful handling when nesting multiple mappings because the map + * management is stack based. The unmap has to be in the reverse order of + * the map operation: + * + * addr1 = kmap_local_page(page1); + * addr2 = kmap_local_page(page2); + * ... + * kunmap_local(addr2); + * kunmap_local(addr1); + * + * Unmapping addr1 before addr2 is invalid and causes malfunction. + * + * Contrary to kmap() mappings the mapping is only valid in the context of + * the caller and cannot be handed to other contexts. + * + * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the + * virtual address of the direct mapping. Only real highmem pages are + * temporarily mapped. + * + * While kmap_local_page() is significantly faster than kmap() for the highmem + * case it comes with restrictions about the pointer validity. + * + * On HIGHMEM enabled systems mapping a highmem page has the side effect of + * disabling migration in order to keep the virtual address stable across + * preemption. No caller of kmap_local_page() can rely on this side effect. + */ +static inline void *kmap_local_page(struct page *page); + +/** + * kmap_local_folio - Map a page in this folio for temporary usage + * @folio: The folio containing the page. + * @offset: The byte offset within the folio which identifies the page. + * + * Requires careful handling when nesting multiple mappings because the map + * management is stack based. The unmap has to be in the reverse order of + * the map operation:: + * + * addr1 = kmap_local_folio(folio1, offset1); + * addr2 = kmap_local_folio(folio2, offset2); + * ... + * kunmap_local(addr2); + * kunmap_local(addr1); + * + * Unmapping addr1 before addr2 is invalid and causes malfunction. + * + * Contrary to kmap() mappings the mapping is only valid in the context of + * the caller and cannot be handed to other contexts. + * + * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the + * virtual address of the direct mapping. Only real highmem pages are + * temporarily mapped. + * + * While it is significantly faster than kmap() for the highmem case it + * comes with restrictions about the pointer validity. + * + * On HIGHMEM enabled systems mapping a highmem page has the side effect of + * disabling migration in order to keep the virtual address stable across + * preemption. No caller of kmap_local_folio() can rely on this side effect. + * + * Context: Can be invoked from any context. + * Return: The virtual address of @offset. + */ +static inline void *kmap_local_folio(struct folio *folio, size_t offset); + +/** + * kmap_atomic - Atomically map a page for temporary usage - Deprecated! + * @page: Pointer to the page to be mapped + * + * Returns: The virtual address of the mapping + * + * In fact a wrapper around kmap_local_page() which also disables pagefaults + * and, depending on PREEMPT_RT configuration, also CPU migration and + * preemption. Therefore users should not count on the latter two side effects. + * + * Mappings should always be released by kunmap_atomic(). + * + * Do not use in new code. Use kmap_local_page() instead. + * + * It is used in atomic context when code wants to access the contents of a + * page that might be allocated from high memory (see __GFP_HIGHMEM), for + * example a page in the pagecache. The API has two functions, and they + * can be used in a manner similar to the following:: + * + * // Find the page of interest. + * struct page *page = find_get_page(mapping, offset); + * + * // Gain access to the contents of that page. + * void *vaddr = kmap_atomic(page); + * + * // Do something to the contents of that page. + * memset(vaddr, 0, PAGE_SIZE); + * + * // Unmap that page. + * kunmap_atomic(vaddr); + * + * Note that the kunmap_atomic() call takes the result of the kmap_atomic() + * call, not the argument. + * + * If you need to map two pages because you want to copy from one page to + * another you need to keep the kmap_atomic calls strictly nested, like: + * + * vaddr1 = kmap_atomic(page1); + * vaddr2 = kmap_atomic(page2); + * + * memcpy(vaddr1, vaddr2, PAGE_SIZE); + * + * kunmap_atomic(vaddr2); + * kunmap_atomic(vaddr1); + */ +static inline void *kmap_atomic(struct page *page); + +/* Highmem related interfaces for management code */ +static inline unsigned long nr_free_highpages(void); +static inline unsigned long totalhigh_pages(void); #ifndef ARCH_HAS_FLUSH_ANON_PAGE static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr) @@ -17,10 +188,7 @@ static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page } #endif -#ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE -static inline void flush_kernel_dcache_page(struct page *page) -{ -} +#ifndef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE static inline void flush_kernel_vmap_range(void *vaddr, int size) { } @@ -29,320 +197,501 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size) } #endif -#include <asm/kmap_types.h> +/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */ +#ifndef clear_user_highpage +static inline void clear_user_highpage(struct page *page, unsigned long vaddr) +{ + void *addr = kmap_local_page(page); + clear_user_page(addr, vaddr, page); + kunmap_local(addr); +} +#endif -#ifdef CONFIG_HIGHMEM -extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot); -extern void kunmap_atomic_high(void *kvaddr); -#include <asm/highmem.h> +#ifndef vma_alloc_zeroed_movable_folio +/** + * vma_alloc_zeroed_movable_folio - Allocate a zeroed page for a VMA. + * @vma: The VMA the page is to be allocated for. + * @vaddr: The virtual address the page will be inserted into. + * + * This function will allocate a page suitable for inserting into this + * VMA at this virtual address. It may be allocated from highmem or + * the movable zone. An architecture may provide its own implementation. + * + * Return: A folio containing one allocated and zeroed page or NULL if + * we are out of memory. + */ +static inline +struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, + unsigned long vaddr) +{ + struct folio *folio; -#ifndef ARCH_HAS_KMAP_FLUSH_TLB -static inline void kmap_flush_tlb(unsigned long addr) { } -#endif + folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); + if (folio && user_alloc_needs_zeroing()) + clear_user_highpage(&folio->page, vaddr); -#ifndef kmap_prot -#define kmap_prot PAGE_KERNEL + return folio; +} #endif -void *kmap_high(struct page *page); -static inline void *kmap(struct page *page) +static inline void clear_highpage(struct page *page) +{ + void *kaddr = kmap_local_page(page); + clear_page(kaddr); + kunmap_local(kaddr); +} + +static inline void clear_highpage_kasan_tagged(struct page *page) { - void *addr; + void *kaddr = kmap_local_page(page); - might_sleep(); - if (!PageHighMem(page)) - addr = page_address(page); - else - addr = kmap_high(page); - kmap_flush_tlb((unsigned long)addr); - return addr; + clear_page(kasan_reset_tag(kaddr)); + kunmap_local(kaddr); } -void kunmap_high(struct page *page); +#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE -static inline void kunmap(struct page *page) +static inline void tag_clear_highpage(struct page *page) { - might_sleep(); - if (!PageHighMem(page)) - return; - kunmap_high(page); } +#endif + /* - * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because - * no global lock is needed and because the kmap code must perform a global TLB - * invalidation when the kmap pool wraps. - * - * However when holding an atomic kmap it is not legal to sleep, so atomic - * kmaps are appropriate for short, tight code paths only. - * - * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap - * gives a more generic (and caching) interface. But kmap_atomic can - * be used in IRQ contexts, so in some (very limited) cases we need - * it. + * If we pass in a base or tail page, we can zero up to PAGE_SIZE. + * If we pass in a head page, we can zero up to the size of the compound page. */ -static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) +#ifdef CONFIG_HIGHMEM +void zero_user_segments(struct page *page, unsigned start1, unsigned end1, + unsigned start2, unsigned end2); +#else +static inline void zero_user_segments(struct page *page, + unsigned start1, unsigned end1, + unsigned start2, unsigned end2) { - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - return kmap_atomic_high_prot(page, prot); -} -#define kmap_atomic(page) kmap_atomic_prot(page, kmap_prot) + void *kaddr = kmap_local_page(page); + unsigned int i; -/* declarations for linux/mm/highmem.c */ -unsigned int nr_free_highpages(void); -extern atomic_long_t _totalhigh_pages; -static inline unsigned long totalhigh_pages(void) -{ - return (unsigned long)atomic_long_read(&_totalhigh_pages); + BUG_ON(end1 > page_size(page) || end2 > page_size(page)); + + if (end1 > start1) + memset(kaddr + start1, 0, end1 - start1); + + if (end2 > start2) + memset(kaddr + start2, 0, end2 - start2); + + kunmap_local(kaddr); + for (i = 0; i < compound_nr(page); i++) + flush_dcache_page(page + i); } +#endif -static inline void totalhigh_pages_inc(void) +static inline void zero_user_segment(struct page *page, + unsigned start, unsigned end) { - atomic_long_inc(&_totalhigh_pages); + zero_user_segments(page, start, end, 0, 0); } -static inline void totalhigh_pages_dec(void) +static inline void zero_user(struct page *page, + unsigned start, unsigned size) { - atomic_long_dec(&_totalhigh_pages); + zero_user_segments(page, start, start + size, 0, 0); } -static inline void totalhigh_pages_add(long count) +#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE + +static inline void copy_user_highpage(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) { - atomic_long_add(count, &_totalhigh_pages); + char *vfrom, *vto; + + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + copy_user_page(vto, vfrom, vaddr, to); + kmsan_unpoison_memory(page_address(to), PAGE_SIZE); + kunmap_local(vto); + kunmap_local(vfrom); } -static inline void totalhigh_pages_set(long val) +#endif + +#ifndef __HAVE_ARCH_COPY_HIGHPAGE + +static inline void copy_highpage(struct page *to, struct page *from) { - atomic_long_set(&_totalhigh_pages, val); + char *vfrom, *vto; + + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + copy_page(vto, vfrom); + kmsan_copy_page_meta(to, from); + kunmap_local(vto); + kunmap_local(vfrom); } -void kmap_flush_unused(void); +#endif -struct page *kmap_to_page(void *addr); +#ifdef copy_mc_to_kernel +/* + * If architecture supports machine check exception handling, define the + * #MC versions of copy_user_highpage and copy_highpage. They copy a memory + * page with #MC in source page (@from) handled, and return the number + * of bytes not copied if there was a #MC, otherwise 0 for success. + */ +static inline int copy_mc_user_highpage(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) +{ + unsigned long ret; + char *vfrom, *vto; -#else /* CONFIG_HIGHMEM */ + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE); + if (!ret) + kmsan_unpoison_memory(page_address(to), PAGE_SIZE); + kunmap_local(vto); + kunmap_local(vfrom); -static inline unsigned int nr_free_highpages(void) { return 0; } + if (ret) + memory_failure_queue(page_to_pfn(from), 0); -static inline struct page *kmap_to_page(void *addr) -{ - return virt_to_page(addr); + return ret; } -static inline unsigned long totalhigh_pages(void) { return 0UL; } - -static inline void *kmap(struct page *page) +static inline int copy_mc_highpage(struct page *to, struct page *from) { - might_sleep(); - return page_address(page); -} + unsigned long ret; + char *vfrom, *vto; -static inline void kunmap_high(struct page *page) + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE); + if (!ret) + kmsan_copy_page_meta(to, from); + kunmap_local(vto); + kunmap_local(vfrom); + + if (ret) + memory_failure_queue(page_to_pfn(from), 0); + + return ret; +} +#else +static inline int copy_mc_user_highpage(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) { + copy_user_highpage(to, from, vaddr, vma); + return 0; } -static inline void kunmap(struct page *page) +static inline int copy_mc_highpage(struct page *to, struct page *from) { -#ifdef ARCH_HAS_FLUSH_ON_KUNMAP - kunmap_flush_on_unmap(page_address(page)); -#endif + copy_highpage(to, from); + return 0; } +#endif -static inline void *kmap_atomic(struct page *page) +static inline void memcpy_page(struct page *dst_page, size_t dst_off, + struct page *src_page, size_t src_off, + size_t len) { - preempt_disable(); - pagefault_disable(); - return page_address(page); + char *dst = kmap_local_page(dst_page); + char *src = kmap_local_page(src_page); + + VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE); + memcpy(dst + dst_off, src + src_off, len); + kunmap_local(src); + kunmap_local(dst); } -#define kmap_atomic_prot(page, prot) kmap_atomic(page) -static inline void kunmap_atomic_high(void *addr) +static inline void memcpy_folio(struct folio *dst_folio, size_t dst_off, + struct folio *src_folio, size_t src_off, size_t len) { - /* - * Mostly nothing to do in the CONFIG_HIGHMEM=n case as kunmap_atomic() - * handles re-enabling faults + preemption - */ -#ifdef ARCH_HAS_FLUSH_ON_KUNMAP - kunmap_flush_on_unmap(addr); -#endif + VM_BUG_ON(dst_off + len > folio_size(dst_folio)); + VM_BUG_ON(src_off + len > folio_size(src_folio)); + + do { + char *dst = kmap_local_folio(dst_folio, dst_off); + const char *src = kmap_local_folio(src_folio, src_off); + size_t chunk = len; + + if (folio_test_highmem(dst_folio) && + chunk > PAGE_SIZE - offset_in_page(dst_off)) + chunk = PAGE_SIZE - offset_in_page(dst_off); + if (folio_test_highmem(src_folio) && + chunk > PAGE_SIZE - offset_in_page(src_off)) + chunk = PAGE_SIZE - offset_in_page(src_off); + memcpy(dst, src, chunk); + kunmap_local(src); + kunmap_local(dst); + + dst_off += chunk; + src_off += chunk; + len -= chunk; + } while (len > 0); } -#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn)) - -#define kmap_flush_unused() do {} while(0) - -#endif /* CONFIG_HIGHMEM */ - -#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32) +static inline void memset_page(struct page *page, size_t offset, int val, + size_t len) +{ + char *addr = kmap_local_page(page); -DECLARE_PER_CPU(int, __kmap_atomic_idx); + VM_BUG_ON(offset + len > PAGE_SIZE); + memset(addr + offset, val, len); + kunmap_local(addr); +} -static inline int kmap_atomic_idx_push(void) +static inline void memcpy_from_page(char *to, struct page *page, + size_t offset, size_t len) { - int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1; + char *from = kmap_local_page(page); -#ifdef CONFIG_DEBUG_HIGHMEM - WARN_ON_ONCE(in_irq() && !irqs_disabled()); - BUG_ON(idx >= KM_TYPE_NR); -#endif - return idx; + VM_BUG_ON(offset + len > PAGE_SIZE); + memcpy(to, from + offset, len); + kunmap_local(from); } -static inline int kmap_atomic_idx(void) +static inline void memcpy_to_page(struct page *page, size_t offset, + const char *from, size_t len) { - return __this_cpu_read(__kmap_atomic_idx) - 1; + char *to = kmap_local_page(page); + + VM_BUG_ON(offset + len > PAGE_SIZE); + memcpy(to + offset, from, len); + flush_dcache_page(page); + kunmap_local(to); } -static inline void kmap_atomic_idx_pop(void) +static inline void memzero_page(struct page *page, size_t offset, size_t len) { -#ifdef CONFIG_DEBUG_HIGHMEM - int idx = __this_cpu_dec_return(__kmap_atomic_idx); + char *addr = kmap_local_page(page); - BUG_ON(idx < 0); -#else - __this_cpu_dec(__kmap_atomic_idx); -#endif + VM_BUG_ON(offset + len > PAGE_SIZE); + memset(addr + offset, 0, len); + flush_dcache_page(page); + kunmap_local(addr); } -#endif - -/* - * Prevent people trying to call kunmap_atomic() as if it were kunmap() - * kunmap_atomic() should get the return value of kmap_atomic, not the page. +/** + * memcpy_from_folio - Copy a range of bytes from a folio. + * @to: The memory to copy to. + * @folio: The folio to read from. + * @offset: The first byte in the folio to read. + * @len: The number of bytes to copy. */ -#define kunmap_atomic(addr) \ -do { \ - BUILD_BUG_ON(__same_type((addr), struct page *)); \ - kunmap_atomic_high(addr); \ - pagefault_enable(); \ - preempt_enable(); \ -} while (0) - - -/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */ -#ifndef clear_user_highpage -static inline void clear_user_highpage(struct page *page, unsigned long vaddr) +static inline void memcpy_from_folio(char *to, struct folio *folio, + size_t offset, size_t len) { - void *addr = kmap_atomic(page); - clear_user_page(addr, vaddr, page); - kunmap_atomic(addr); + VM_BUG_ON(offset + len > folio_size(folio)); + + do { + const char *from = kmap_local_folio(folio, offset); + size_t chunk = len; + + if (folio_test_partial_kmap(folio) && + chunk > PAGE_SIZE - offset_in_page(offset)) + chunk = PAGE_SIZE - offset_in_page(offset); + memcpy(to, from, chunk); + kunmap_local(from); + + to += chunk; + offset += chunk; + len -= chunk; + } while (len > 0); } -#endif -#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /** - * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags - * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE - * @vma: The VMA the page is to be allocated for - * @vaddr: The virtual address the page will be inserted into - * - * This function will allocate a page for a VMA but the caller is expected - * to specify via movableflags whether the page will be movable in the - * future or not - * - * An architecture may override this function by defining - * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own - * implementation. + * memcpy_to_folio - Copy a range of bytes to a folio. + * @folio: The folio to write to. + * @offset: The first byte in the folio to store to. + * @from: The memory to copy from. + * @len: The number of bytes to copy. */ -static inline struct page * -__alloc_zeroed_user_highpage(gfp_t movableflags, - struct vm_area_struct *vma, - unsigned long vaddr) +static inline void memcpy_to_folio(struct folio *folio, size_t offset, + const char *from, size_t len) { - struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags, - vma, vaddr); + VM_BUG_ON(offset + len > folio_size(folio)); - if (page) - clear_user_highpage(page, vaddr); + do { + char *to = kmap_local_folio(folio, offset); + size_t chunk = len; - return page; + if (folio_test_partial_kmap(folio) && + chunk > PAGE_SIZE - offset_in_page(offset)) + chunk = PAGE_SIZE - offset_in_page(offset); + memcpy(to, from, chunk); + kunmap_local(to); + + from += chunk; + offset += chunk; + len -= chunk; + } while (len > 0); + + flush_dcache_folio(folio); } -#endif /** - * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move - * @vma: The VMA the page is to be allocated for - * @vaddr: The virtual address the page will be inserted into + * folio_zero_tail - Zero the tail of a folio. + * @folio: The folio to zero. + * @offset: The byte offset in the folio to start zeroing at. + * @kaddr: The address the folio is currently mapped to. * - * This function will allocate a page for a VMA that the caller knows will - * be able to migrate in the future using move_pages() or reclaimed + * If you have already used kmap_local_folio() to map a folio, written + * some data to it and now need to zero the end of the folio (and flush + * the dcache), you can use this function. If you do not have the + * folio kmapped (eg the folio has been partially populated by DMA), + * use folio_zero_range() or folio_zero_segment() instead. + * + * Return: An address which can be passed to kunmap_local(). */ -static inline struct page * -alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma, - unsigned long vaddr) +static inline __must_check void *folio_zero_tail(struct folio *folio, + size_t offset, void *kaddr) { - return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr); + size_t len = folio_size(folio) - offset; + + if (folio_test_partial_kmap(folio)) { + size_t max = PAGE_SIZE - offset_in_page(offset); + + while (len > max) { + memset(kaddr, 0, max); + kunmap_local(kaddr); + len -= max; + offset += max; + max = PAGE_SIZE; + kaddr = kmap_local_folio(folio, offset); + } + } + + memset(kaddr, 0, len); + flush_dcache_folio(folio); + + return kaddr; } -static inline void clear_highpage(struct page *page) +/** + * folio_fill_tail - Copy some data to a folio and pad with zeroes. + * @folio: The destination folio. + * @offset: The offset into @folio at which to start copying. + * @from: The data to copy. + * @len: How many bytes of data to copy. + * + * This function is most useful for filesystems which support inline data. + * When they want to copy data from the inode into the page cache, this + * function does everything for them. It supports large folios even on + * HIGHMEM configurations. + */ +static inline void folio_fill_tail(struct folio *folio, size_t offset, + const char *from, size_t len) { - void *kaddr = kmap_atomic(page); - clear_page(kaddr); - kunmap_atomic(kaddr); + char *to = kmap_local_folio(folio, offset); + + VM_BUG_ON(offset + len > folio_size(folio)); + + if (folio_test_partial_kmap(folio)) { + size_t max = PAGE_SIZE - offset_in_page(offset); + + while (len > max) { + memcpy(to, from, max); + kunmap_local(to); + len -= max; + from += max; + offset += max; + max = PAGE_SIZE; + to = kmap_local_folio(folio, offset); + } + } + + memcpy(to, from, len); + to = folio_zero_tail(folio, offset + len, to + len); + kunmap_local(to); } -static inline void zero_user_segments(struct page *page, - unsigned start1, unsigned end1, - unsigned start2, unsigned end2) +/** + * memcpy_from_file_folio - Copy some bytes from a file folio. + * @to: The destination buffer. + * @folio: The folio to copy from. + * @pos: The position in the file. + * @len: The maximum number of bytes to copy. + * + * Copy up to @len bytes from this folio. This may be limited by PAGE_SIZE + * if the folio comes from HIGHMEM, and by the size of the folio. + * + * Return: The number of bytes copied from the folio. + */ +static inline size_t memcpy_from_file_folio(char *to, struct folio *folio, + loff_t pos, size_t len) { - void *kaddr = kmap_atomic(page); + size_t offset = offset_in_folio(folio, pos); + char *from = kmap_local_folio(folio, offset); - BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE); + if (folio_test_partial_kmap(folio)) { + offset = offset_in_page(offset); + len = min_t(size_t, len, PAGE_SIZE - offset); + } else + len = min(len, folio_size(folio) - offset); - if (end1 > start1) - memset(kaddr + start1, 0, end1 - start1); + memcpy(to, from, len); + kunmap_local(from); - if (end2 > start2) - memset(kaddr + start2, 0, end2 - start2); - - kunmap_atomic(kaddr); - flush_dcache_page(page); + return len; } -static inline void zero_user_segment(struct page *page, - unsigned start, unsigned end) +/** + * folio_zero_segments() - Zero two byte ranges in a folio. + * @folio: The folio to write to. + * @start1: The first byte to zero. + * @xend1: One more than the last byte in the first range. + * @start2: The first byte to zero in the second range. + * @xend2: One more than the last byte in the second range. + */ +static inline void folio_zero_segments(struct folio *folio, + size_t start1, size_t xend1, size_t start2, size_t xend2) { - zero_user_segments(page, start, end, 0, 0); + zero_user_segments(&folio->page, start1, xend1, start2, xend2); } -static inline void zero_user(struct page *page, - unsigned start, unsigned size) +/** + * folio_zero_segment() - Zero a byte range in a folio. + * @folio: The folio to write to. + * @start: The first byte to zero. + * @xend: One more than the last byte to zero. + */ +static inline void folio_zero_segment(struct folio *folio, + size_t start, size_t xend) { - zero_user_segments(page, start, start + size, 0, 0); + zero_user_segments(&folio->page, start, xend, 0, 0); } -#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE - -static inline void copy_user_highpage(struct page *to, struct page *from, - unsigned long vaddr, struct vm_area_struct *vma) +/** + * folio_zero_range() - Zero a byte range in a folio. + * @folio: The folio to write to. + * @start: The first byte to zero. + * @length: The number of bytes to zero. + */ +static inline void folio_zero_range(struct folio *folio, + size_t start, size_t length) { - char *vfrom, *vto; - - vfrom = kmap_atomic(from); - vto = kmap_atomic(to); - copy_user_page(vto, vfrom, vaddr, to); - kunmap_atomic(vto); - kunmap_atomic(vfrom); + zero_user_segments(&folio->page, start, start + length, 0, 0); } -#endif - -#ifndef __HAVE_ARCH_COPY_HIGHPAGE - -static inline void copy_highpage(struct page *to, struct page *from) +/** + * folio_release_kmap - Unmap a folio and drop a refcount. + * @folio: The folio to release. + * @addr: The address previously returned by a call to kmap_local_folio(). + * + * It is common, eg in directory handling to kmap a folio. This function + * unmaps the folio and drops the refcount that was being held to keep the + * folio alive while we accessed it. + */ +static inline void folio_release_kmap(struct folio *folio, void *addr) { - char *vfrom, *vto; - - vfrom = kmap_atomic(from); - vto = kmap_atomic(to); - copy_page(vto, vfrom); - kunmap_atomic(vto); - kunmap_atomic(vfrom); + kunmap_local(addr); + folio_put(folio); } -#endif +static inline void unmap_and_put_page(struct page *page, void *addr) +{ + folio_release_kmap(page_folio(page), addr); +} #endif /* _LINUX_HIGHMEM_H */ |