diff options
Diffstat (limited to 'include/linux/highmem.h')
| -rw-r--r-- | include/linux/highmem.h | 399 |
1 files changed, 341 insertions, 58 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 39bb9b47fa9c..abc20f9810fd 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -6,6 +6,7 @@ #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> @@ -37,12 +38,12 @@ static inline void *kmap(struct page *page); /** * kunmap - Unmap the virtual address mapped by kmap() - * @addr: Virtual address to be unmapped + * @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); +static inline void kunmap(const struct page *page); /** * kmap_to_page - Get the page for a kmap'ed address @@ -60,11 +61,11 @@ static inline void kmap_flush_unused(void); /** * kmap_local_page - Map a page for temporary usage - * @page: Pointer to the page to be mapped + * @page: Pointer to the page to be mapped * * Returns: The virtual address of the mapping * - * Can be invoked from any context. + * 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 @@ -85,15 +86,14 @@ static inline void kmap_flush_unused(void); * virtual address of the direct mapping. Only real highmem pages are * temporarily mapped. * - * While it is significantly faster than kmap() for the higmem case it - * comes with restrictions about the pointer validity. Only use when really - * necessary. + * 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); +static inline void *kmap_local_page(const struct page *page); /** * kmap_local_folio - Map a page in this folio for temporary usage @@ -119,9 +119,8 @@ static inline void *kmap_local_page(struct page *page); * virtual address of the direct mapping. Only real highmem pages are * temporarily mapped. * - * While it is significantly faster than kmap() for the higmem case it - * comes with restrictions about the pointer validity. Only use when really - * necessary. + * 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 @@ -130,7 +129,7 @@ static inline void *kmap_local_page(struct page *page); * 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); +static inline void *kmap_local_folio(const struct folio *folio, size_t offset); /** * kmap_atomic - Atomically map a page for temporary usage - Deprecated! @@ -138,26 +137,49 @@ static inline void *kmap_local_folio(struct folio *folio, size_t offset); * * Returns: The virtual address of the mapping * - * Effectively a wrapper around kmap_local_page() which disables pagefaults - * and preemption. + * 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. - */ -static inline void *kmap_atomic(struct page *page); - -/** - * kunmap_atomic - Unmap the virtual address mapped by kmap_atomic() - * @addr: Virtual address to be unmapped * - * Counterpart to kmap_atomic(). + * 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); * - * Effectively a wrapper around kunmap_local() which additionally undoes - * the side effects of kmap_atomic(), i.e. reenabling pagefaults and - * preemption. + * // 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(const struct page *page); /* Highmem related interfaces for management code */ -static inline unsigned int nr_free_highpages(void); +static inline unsigned long nr_free_highpages(void); static inline unsigned long totalhigh_pages(void); #ifndef ARCH_HAS_FLUSH_ANON_PAGE @@ -185,29 +207,30 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr) } #endif -#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE +#ifndef vma_alloc_zeroed_movable_folio /** - * 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 + * 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 for a VMA that the caller knows will - * be able to migrate in the future using move_pages() or reclaimed + * 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. * - * An architecture may override this function by defining - * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE and providing their own - * implementation. + * Return: A folio containing one allocated and zeroed page or NULL if + * we are out of memory. */ -static inline struct page * -alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma, +static inline +struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, unsigned long vaddr) { - struct page *page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); + struct folio *folio; - if (page) - clear_user_highpage(page, vaddr); + folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); + if (folio && user_alloc_needs_zeroing()) + clear_user_highpage(&folio->page, vaddr); - return page; + return folio; } #endif @@ -218,10 +241,20 @@ static inline void clear_highpage(struct page *page) kunmap_local(kaddr); } -#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE +static inline void clear_highpage_kasan_tagged(struct page *page) +{ + void *kaddr = kmap_local_page(page); -static inline void tag_clear_highpage(struct page *page) + clear_page(kasan_reset_tag(kaddr)); + kunmap_local(kaddr); +} + +#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGES + +/* Return false to let people know we did not initialize the pages */ +static inline bool tag_clear_highpages(struct page *page, int numpages) { + return false; } #endif @@ -261,12 +294,6 @@ static inline void zero_user_segment(struct page *page, zero_user_segments(page, start, end, 0, 0); } -static inline void zero_user(struct page *page, - unsigned start, unsigned size) -{ - zero_user_segments(page, start, start + size, 0, 0); -} - #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE static inline void copy_user_highpage(struct page *to, struct page *from, @@ -277,6 +304,7 @@ static inline void copy_user_highpage(struct page *to, struct page *from, 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); } @@ -292,12 +320,73 @@ static inline void copy_highpage(struct page *to, struct page *from) 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); } #endif +#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; + + 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); + + if (ret) + memory_failure_queue(page_to_pfn(from), 0); + + return ret; +} + +static inline int copy_mc_highpage(struct page *to, struct page *from) +{ + unsigned long ret; + char *vfrom, *vto; + + 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 int copy_mc_highpage(struct page *to, struct page *from) +{ + copy_highpage(to, from); + return 0; +} +#endif + static inline void memcpy_page(struct page *dst_page, size_t dst_off, struct page *src_page, size_t src_off, size_t len) @@ -311,17 +400,31 @@ static inline void memcpy_page(struct page *dst_page, size_t dst_off, kunmap_local(dst); } -static inline void memmove_page(struct page *dst_page, size_t dst_off, - struct page *src_page, size_t src_off, - size_t len) +static inline void memcpy_folio(struct folio *dst_folio, size_t dst_off, + struct folio *src_folio, size_t src_off, size_t len) { - 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); - memmove(dst + dst_off, src + src_off, len); - kunmap_local(src); - kunmap_local(dst); + 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); } static inline void memset_page(struct page *page, size_t offset, int val, @@ -358,12 +461,178 @@ static inline void memcpy_to_page(struct page *page, size_t offset, static inline void memzero_page(struct page *page, size_t offset, size_t len) { char *addr = kmap_local_page(page); + + VM_BUG_ON(offset + len > PAGE_SIZE); memset(addr + offset, 0, len); flush_dcache_page(page); kunmap_local(addr); } /** + * 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. + */ +static inline void memcpy_from_folio(char *to, struct folio *folio, + size_t offset, size_t len) +{ + 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); +} + +/** + * 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 void memcpy_to_folio(struct folio *folio, size_t offset, + const char *from, size_t len) +{ + VM_BUG_ON(offset + len > folio_size(folio)); + + do { + char *to = 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(to); + + from += chunk; + offset += chunk; + len -= chunk; + } while (len > 0); + + flush_dcache_folio(folio); +} + +/** + * 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. + * + * 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 __must_check void *folio_zero_tail(struct folio *folio, + size_t offset, void *kaddr) +{ + 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; +} + +/** + * 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) +{ + 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); +} + +/** + * 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) +{ + size_t offset = offset_in_folio(folio, pos); + char *from = kmap_local_folio(folio, offset); + + 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); + + memcpy(to, from, len); + kunmap_local(from); + + return len; +} + +/** * folio_zero_segments() - Zero two byte ranges in a folio. * @folio: The folio to write to. * @start1: The first byte to zero. @@ -401,4 +670,18 @@ static inline void folio_zero_range(struct folio *folio, zero_user_segments(&folio->page, start, start + length, 0, 0); } +/** + * 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) +{ + kunmap_local(addr); + folio_put(folio); +} #endif /* _LINUX_HIGHMEM_H */ |