1 files changed, 456 insertions, 0 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
new file mode 100644
index 000000000..44242268f
--- /dev/null
+++ b/include/linux/highmem.h
@@ -0,0 +1,456 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_HIGHMEM_H
+#define _LINUX_HIGHMEM_H
+
+#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 "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 it is significantly faster than kmap() for the higmem 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 higmem case it
+ * comes with restrictions about the pointer validity. Only use when really
+ * necessary.
+ *
+ * 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 int 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)
+{
+}
+#endif
+
+#ifndef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
+static inline void flush_kernel_vmap_range(void *vaddr, int size)
+{
+}
+static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
+{
+}
+#endif
+
+/* 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
+
+#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
+/**
+ * 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
+ *
+ * Returns: The allocated and zeroed HIGHMEM page
+ *
+ * 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
+ *
+ * An architecture may override this function by defining
+ * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE and providing their own
+ * implementation.
+ */
+static inline struct page *
+alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+				   unsigned long vaddr)
+{
+	struct page *page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
+
+	if (page)
+		clear_user_highpage(page, vaddr);
+
+	return page;
+}
+#endif
+
+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)
+{
+	u8 tag;
+
+	tag = page_kasan_tag(page);
+	page_kasan_tag_reset(page);
+	clear_highpage(page);
+	page_kasan_tag_set(page, tag);
+}
+
+#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
+
+static inline void tag_clear_highpage(struct page *page)
+{
+}
+
+#endif
+
+/*
+ * 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.
+ */
+#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)
+{
+	void *kaddr = kmap_local_page(page);
+	unsigned int i;
+
+	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 zero_user_segment(struct page *page,
+	unsigned start, unsigned end)
+{
+	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,
+	unsigned long vaddr, struct vm_area_struct *vma)
+{
+	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);
+}
+
+#endif
+
+#ifdef copy_mc_to_kernel
+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);
+
+	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;
+}
+#endif
+
+#ifndef __HAVE_ARCH_COPY_HIGHPAGE
+
+static inline void copy_highpage(struct page *to, struct page *from)
+{
+	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);
+}
+
+#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)
+{
+	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);
+}
+
+static inline void memset_page(struct page *page, size_t offset, int val,
+			       size_t len)
+{
+	char *addr = kmap_local_page(page);
+
+	VM_BUG_ON(offset + len > PAGE_SIZE);
+	memset(addr + offset, val, len);
+	kunmap_local(addr);
+}
+
+static inline void memcpy_from_page(char *to, struct page *page,
+				    size_t offset, size_t len)
+{
+	char *from = kmap_local_page(page);
+
+	VM_BUG_ON(offset + len > PAGE_SIZE);
+	memcpy(to, from + offset, len);
+	kunmap_local(from);
+}
+
+static inline void memcpy_to_page(struct page *page, size_t offset,
+				  const char *from, size_t len)
+{
+	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 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);
+}
+
+/**
+ * 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(&folio->page, start1, xend1, start2, xend2);
+}
+
+/**
+ * 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(&folio->page, start, xend, 0, 0);
+}
+
+/**
+ * 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)
+{
+	zero_user_segments(&folio->page, start, start + length, 0, 0);
+}
+
+#endif /* _LINUX_HIGHMEM_H */