1 files changed, 357 insertions, 0 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h
new file mode 100644
index 000000000..87fc3d0dd
--- /dev/null
+++ b/include/linux/uio.h
@@ -0,0 +1,357 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *	Berkeley style UIO structures	-	Alan Cox 1994.
+ */
+#ifndef __LINUX_UIO_H
+#define __LINUX_UIO_H
+
+#include <linux/kernel.h>
+#include <linux/thread_info.h>
+#include <linux/mm_types.h>
+#include <uapi/linux/uio.h>
+
+struct page;
+struct pipe_inode_info;
+
+struct kvec {
+	void *iov_base; /* and that should *never* hold a userland pointer */
+	size_t iov_len;
+};
+
+enum iter_type {
+	/* iter types */
+	ITER_IOVEC,
+	ITER_KVEC,
+	ITER_BVEC,
+	ITER_PIPE,
+	ITER_XARRAY,
+	ITER_DISCARD,
+	ITER_UBUF,
+};
+
+#define ITER_SOURCE	1	// == WRITE
+#define ITER_DEST	0	// == READ
+
+struct iov_iter_state {
+	size_t iov_offset;
+	size_t count;
+	unsigned long nr_segs;
+};
+
+struct iov_iter {
+	u8 iter_type;
+	bool nofault;
+	bool data_source;
+	bool user_backed;
+	union {
+		size_t iov_offset;
+		int last_offset;
+	};
+	size_t count;
+	union {
+		const struct iovec *iov;
+		const struct kvec *kvec;
+		const struct bio_vec *bvec;
+		struct xarray *xarray;
+		struct pipe_inode_info *pipe;
+		void __user *ubuf;
+	};
+	union {
+		unsigned long nr_segs;
+		struct {
+			unsigned int head;
+			unsigned int start_head;
+		};
+		loff_t xarray_start;
+	};
+};
+
+static inline enum iter_type iov_iter_type(const struct iov_iter *i)
+{
+	return i->iter_type;
+}
+
+static inline void iov_iter_save_state(struct iov_iter *iter,
+				       struct iov_iter_state *state)
+{
+	state->iov_offset = iter->iov_offset;
+	state->count = iter->count;
+	state->nr_segs = iter->nr_segs;
+}
+
+static inline bool iter_is_ubuf(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_UBUF;
+}
+
+static inline bool iter_is_iovec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_IOVEC;
+}
+
+static inline bool iov_iter_is_kvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_KVEC;
+}
+
+static inline bool iov_iter_is_bvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_BVEC;
+}
+
+static inline bool iov_iter_is_pipe(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_PIPE;
+}
+
+static inline bool iov_iter_is_discard(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_DISCARD;
+}
+
+static inline bool iov_iter_is_xarray(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_XARRAY;
+}
+
+static inline unsigned char iov_iter_rw(const struct iov_iter *i)
+{
+	return i->data_source ? WRITE : READ;
+}
+
+static inline bool user_backed_iter(const struct iov_iter *i)
+{
+	return i->user_backed;
+}
+
+/*
+ * Total number of bytes covered by an iovec.
+ *
+ * NOTE that it is not safe to use this function until all the iovec's
+ * segment lengths have been validated.  Because the individual lengths can
+ * overflow a size_t when added together.
+ */
+static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
+{
+	unsigned long seg;
+	size_t ret = 0;
+
+	for (seg = 0; seg < nr_segs; seg++)
+		ret += iov[seg].iov_len;
+	return ret;
+}
+
+static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
+{
+	return (struct iovec) {
+		.iov_base = iter->iov->iov_base + iter->iov_offset,
+		.iov_len = min(iter->count,
+			       iter->iov->iov_len - iter->iov_offset),
+	};
+}
+
+size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
+				  size_t bytes, struct iov_iter *i);
+void iov_iter_advance(struct iov_iter *i, size_t bytes);
+void iov_iter_revert(struct iov_iter *i, size_t bytes);
+size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
+size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
+size_t iov_iter_single_seg_count(const struct iov_iter *i);
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i);
+size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i);
+
+size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
+size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
+size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
+
+static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
+		size_t bytes, struct iov_iter *i)
+{
+	return copy_page_to_iter(&folio->page, offset, bytes, i);
+}
+
+static __always_inline __must_check
+size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
+{
+	if (check_copy_size(addr, bytes, true))
+		return _copy_to_iter(addr, bytes, i);
+	return 0;
+}
+
+static __always_inline __must_check
+size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+	if (check_copy_size(addr, bytes, false))
+		return _copy_from_iter(addr, bytes, i);
+	return 0;
+}
+
+static __always_inline __must_check
+bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
+{
+	size_t copied = copy_from_iter(addr, bytes, i);
+	if (likely(copied == bytes))
+		return true;
+	iov_iter_revert(i, copied);
+	return false;
+}
+
+static __always_inline __must_check
+size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	if (check_copy_size(addr, bytes, false))
+		return _copy_from_iter_nocache(addr, bytes, i);
+	return 0;
+}
+
+static __always_inline __must_check
+bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	size_t copied = copy_from_iter_nocache(addr, bytes, i);
+	if (likely(copied == bytes))
+		return true;
+	iov_iter_revert(i, copied);
+	return false;
+}
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
+/*
+ * Note, users like pmem that depend on the stricter semantics of
+ * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
+ * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
+ * destination is flushed from the cache on return.
+ */
+size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
+#else
+#define _copy_from_iter_flushcache _copy_from_iter_nocache
+#endif
+
+#ifdef CONFIG_ARCH_HAS_COPY_MC
+size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
+#else
+#define _copy_mc_to_iter _copy_to_iter
+#endif
+
+size_t iov_iter_zero(size_t bytes, struct iov_iter *);
+bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
+			unsigned len_mask);
+unsigned long iov_iter_alignment(const struct iov_iter *i);
+unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
+void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
+			unsigned long nr_segs, size_t count);
+void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
+			unsigned long nr_segs, size_t count);
+void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
+			unsigned long nr_segs, size_t count);
+void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
+			size_t count);
+void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
+void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
+		     loff_t start, size_t count);
+ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
+			size_t maxsize, unsigned maxpages, size_t *start);
+ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
+			size_t maxsize, size_t *start);
+int iov_iter_npages(const struct iov_iter *i, int maxpages);
+void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
+
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
+
+static inline size_t iov_iter_count(const struct iov_iter *i)
+{
+	return i->count;
+}
+
+/*
+ * Cap the iov_iter by given limit; note that the second argument is
+ * *not* the new size - it's upper limit for such.  Passing it a value
+ * greater than the amount of data in iov_iter is fine - it'll just do
+ * nothing in that case.
+ */
+static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
+{
+	/*
+	 * count doesn't have to fit in size_t - comparison extends both
+	 * operands to u64 here and any value that would be truncated by
+	 * conversion in assignement is by definition greater than all
+	 * values of size_t, including old i->count.
+	 */
+	if (i->count > count)
+		i->count = count;
+}
+
+/*
+ * reexpand a previously truncated iterator; count must be no more than how much
+ * we had shrunk it.
+ */
+static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
+{
+	i->count = count;
+}
+
+static inline int
+iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
+{
+	size_t shorted = 0;
+	int npages;
+
+	if (iov_iter_count(i) > max_bytes) {
+		shorted = iov_iter_count(i) - max_bytes;
+		iov_iter_truncate(i, max_bytes);
+	}
+	npages = iov_iter_npages(i, maxpages);
+	if (shorted)
+		iov_iter_reexpand(i, iov_iter_count(i) + shorted);
+
+	return npages;
+}
+
+struct csum_state {
+	__wsum csum;
+	size_t off;
+};
+
+size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
+size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
+
+static __always_inline __must_check
+bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
+				  __wsum *csum, struct iov_iter *i)
+{
+	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
+	if (likely(copied == bytes))
+		return true;
+	iov_iter_revert(i, copied);
+	return false;
+}
+size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
+		struct iov_iter *i);
+
+struct iovec *iovec_from_user(const struct iovec __user *uvector,
+		unsigned long nr_segs, unsigned long fast_segs,
+		struct iovec *fast_iov, bool compat);
+ssize_t import_iovec(int type, const struct iovec __user *uvec,
+		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
+		 struct iov_iter *i);
+ssize_t __import_iovec(int type, const struct iovec __user *uvec,
+		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
+		 struct iov_iter *i, bool compat);
+int import_single_range(int type, void __user *buf, size_t len,
+		 struct iovec *iov, struct iov_iter *i);
+
+static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
+			void __user *buf, size_t count)
+{
+	WARN_ON(direction & ~(READ | WRITE));
+	*i = (struct iov_iter) {
+		.iter_type = ITER_UBUF,
+		.user_backed = true,
+		.data_source = direction,
+		.ubuf = buf,
+		.count = count
+	};
+}
+
+#endif