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diff --git a/fs/unicode/utf8-norm.c b/fs/unicode/utf8-norm.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014 SGI.
+ * All rights reserved.
+ */
+
+#include "utf8n.h"
+
+int utf8version_is_supported(const struct unicode_map *um, unsigned int version)
+{
+ int i = um->tables->utf8agetab_size - 1;
+
+ while (i >= 0 && um->tables->utf8agetab[i] != 0) {
+ if (version == um->tables->utf8agetab[i])
+ return 1;
+ i--;
+ }
+ return 0;
+}
+
+/*
+ * UTF-8 valid ranges.
+ *
+ * The UTF-8 encoding spreads the bits of a 32bit word over several
+ * bytes. This table gives the ranges that can be held and how they'd
+ * be represented.
+ *
+ * 0x00000000 0x0000007F: 0xxxxxxx
+ * 0x00000000 0x000007FF: 110xxxxx 10xxxxxx
+ * 0x00000000 0x0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
+ * 0x00000000 0x001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ * 0x00000000 0x03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
+ * 0x00000000 0x7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
+ *
+ * There is an additional requirement on UTF-8, in that only the
+ * shortest representation of a 32bit value is to be used. A decoder
+ * must not decode sequences that do not satisfy this requirement.
+ * Thus the allowed ranges have a lower bound.
+ *
+ * 0x00000000 0x0000007F: 0xxxxxxx
+ * 0x00000080 0x000007FF: 110xxxxx 10xxxxxx
+ * 0x00000800 0x0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
+ * 0x00010000 0x001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ * 0x00200000 0x03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
+ * 0x04000000 0x7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
+ *
+ * Actual unicode characters are limited to the range 0x0 - 0x10FFFF,
+ * 17 planes of 65536 values. This limits the sequences actually seen
+ * even more, to just the following.
+ *
+ * 0 - 0x7F: 0 - 0x7F
+ * 0x80 - 0x7FF: 0xC2 0x80 - 0xDF 0xBF
+ * 0x800 - 0xFFFF: 0xE0 0xA0 0x80 - 0xEF 0xBF 0xBF
+ * 0x10000 - 0x10FFFF: 0xF0 0x90 0x80 0x80 - 0xF4 0x8F 0xBF 0xBF
+ *
+ * Within those ranges the surrogates 0xD800 - 0xDFFF are not allowed.
+ *
+ * Note that the longest sequence seen with valid usage is 4 bytes,
+ * the same a single UTF-32 character. This makes the UTF-8
+ * representation of Unicode strictly smaller than UTF-32.
+ *
+ * The shortest sequence requirement was introduced by:
+ * Corrigendum #1: UTF-8 Shortest Form
+ * It can be found here:
+ * http://www.unicode.org/versions/corrigendum1.html
+ *
+ */
+
+/*
+ * Return the number of bytes used by the current UTF-8 sequence.
+ * Assumes the input points to the first byte of a valid UTF-8
+ * sequence.
+ */
+static inline int utf8clen(const char *s)
+{
+ unsigned char c = *s;
+
+ return 1 + (c >= 0xC0) + (c >= 0xE0) + (c >= 0xF0);
+}
+
+/*
+ * Decode a 3-byte UTF-8 sequence.
+ */
+static unsigned int
+utf8decode3(const char *str)
+{
+ unsigned int uc;
+
+ uc = *str++ & 0x0F;
+ uc <<= 6;
+ uc |= *str++ & 0x3F;
+ uc <<= 6;
+ uc |= *str++ & 0x3F;
+
+ return uc;
+}
+
+/*
+ * Encode a 3-byte UTF-8 sequence.
+ */
+static int
+utf8encode3(char *str, unsigned int val)
+{
+ str[2] = (val & 0x3F) | 0x80;
+ val >>= 6;
+ str[1] = (val & 0x3F) | 0x80;
+ val >>= 6;
+ str[0] = val | 0xE0;
+
+ return 3;
+}
+
+/*
+ * utf8trie_t
+ *
+ * A compact binary tree, used to decode UTF-8 characters.
+ *
+ * Internal nodes are one byte for the node itself, and up to three
+ * bytes for an offset into the tree. The first byte contains the
+ * following information:
+ * NEXTBYTE - flag - advance to next byte if set
+ * BITNUM - 3 bit field - the bit number to tested
+ * OFFLEN - 2 bit field - number of bytes in the offset
+ * if offlen == 0 (non-branching node)
+ * RIGHTPATH - 1 bit field - set if the following node is for the
+ * right-hand path (tested bit is set)
+ * TRIENODE - 1 bit field - set if the following node is an internal
+ * node, otherwise it is a leaf node
+ * if offlen != 0 (branching node)
+ * LEFTNODE - 1 bit field - set if the left-hand node is internal
+ * RIGHTNODE - 1 bit field - set if the right-hand node is internal
+ *
+ * Due to the way utf8 works, there cannot be branching nodes with
+ * NEXTBYTE set, and moreover those nodes always have a righthand
+ * descendant.
+ */
+typedef const unsigned char utf8trie_t;
+#define BITNUM 0x07
+#define NEXTBYTE 0x08
+#define OFFLEN 0x30
+#define OFFLEN_SHIFT 4
+#define RIGHTPATH 0x40
+#define TRIENODE 0x80
+#define RIGHTNODE 0x40
+#define LEFTNODE 0x80
+
+/*
+ * utf8leaf_t
+ *
+ * The leaves of the trie are embedded in the trie, and so the same
+ * underlying datatype: unsigned char.
+ *
+ * leaf[0]: The unicode version, stored as a generation number that is
+ * an index into ->utf8agetab[]. With this we can filter code
+ * points based on the unicode version in which they were
+ * defined. The CCC of a non-defined code point is 0.
+ * leaf[1]: Canonical Combining Class. During normalization, we need
+ * to do a stable sort into ascending order of all characters
+ * with a non-zero CCC that occur between two characters with
+ * a CCC of 0, or at the begin or end of a string.
+ * The unicode standard guarantees that all CCC values are
+ * between 0 and 254 inclusive, which leaves 255 available as
+ * a special value.
+ * Code points with CCC 0 are known as stoppers.
+ * leaf[2]: Decomposition. If leaf[1] == 255, then leaf[2] is the
+ * start of a NUL-terminated string that is the decomposition
+ * of the character.
+ * The CCC of a decomposable character is the same as the CCC
+ * of the first character of its decomposition.
+ * Some characters decompose as the empty string: these are
+ * characters with the Default_Ignorable_Code_Point property.
+ * These do affect normalization, as they all have CCC 0.
+ *
+ * The decompositions in the trie have been fully expanded, with the
+ * exception of Hangul syllables, which are decomposed algorithmically.
+ *
+ * Casefolding, if applicable, is also done using decompositions.
+ *
+ * The trie is constructed in such a way that leaves exist for all
+ * UTF-8 sequences that match the criteria from the "UTF-8 valid
+ * ranges" comment above, and only for those sequences. Therefore a
+ * lookup in the trie can be used to validate the UTF-8 input.
+ */
+typedef const unsigned char utf8leaf_t;
+
+#define LEAF_GEN(LEAF) ((LEAF)[0])
+#define LEAF_CCC(LEAF) ((LEAF)[1])
+#define LEAF_STR(LEAF) ((const char *)((LEAF) + 2))
+
+#define MINCCC (0)
+#define MAXCCC (254)
+#define STOPPER (0)
+#define DECOMPOSE (255)
+
+/* Marker for hangul syllable decomposition. */
+#define HANGUL ((char)(255))
+/* Size of the synthesized leaf used for Hangul syllable decomposition. */
+#define UTF8HANGULLEAF (12)
+
+/*
+ * Hangul decomposition (algorithm from Section 3.12 of Unicode 6.3.0)
+ *
+ * AC00;<Hangul Syllable, First>;Lo;0;L;;;;;N;;;;;
+ * D7A3;<Hangul Syllable, Last>;Lo;0;L;;;;;N;;;;;
+ *
+ * SBase = 0xAC00
+ * LBase = 0x1100
+ * VBase = 0x1161
+ * TBase = 0x11A7
+ * LCount = 19
+ * VCount = 21
+ * TCount = 28
+ * NCount = 588 (VCount * TCount)
+ * SCount = 11172 (LCount * NCount)
+ *
+ * Decomposition:
+ * SIndex = s - SBase
+ *
+ * LV (Canonical/Full)
+ * LIndex = SIndex / NCount
+ * VIndex = (Sindex % NCount) / TCount
+ * LPart = LBase + LIndex
+ * VPart = VBase + VIndex
+ *
+ * LVT (Canonical)
+ * LVIndex = (SIndex / TCount) * TCount
+ * TIndex = (Sindex % TCount)
+ * LVPart = SBase + LVIndex
+ * TPart = TBase + TIndex
+ *
+ * LVT (Full)
+ * LIndex = SIndex / NCount
+ * VIndex = (Sindex % NCount) / TCount
+ * TIndex = (Sindex % TCount)
+ * LPart = LBase + LIndex
+ * VPart = VBase + VIndex
+ * if (TIndex == 0) {
+ * d = <LPart, VPart>
+ * } else {
+ * TPart = TBase + TIndex
+ * d = <LPart, TPart, VPart>
+ * }
+ */
+
+/* Constants */
+#define SB (0xAC00)
+#define LB (0x1100)
+#define VB (0x1161)
+#define TB (0x11A7)
+#define LC (19)
+#define VC (21)
+#define TC (28)
+#define NC (VC * TC)
+#define SC (LC * NC)
+
+/* Algorithmic decomposition of hangul syllable. */
+static utf8leaf_t *
+utf8hangul(const char *str, unsigned char *hangul)
+{
+ unsigned int si;
+ unsigned int li;
+ unsigned int vi;
+ unsigned int ti;
+ unsigned char *h;
+
+ /* Calculate the SI, LI, VI, and TI values. */
+ si = utf8decode3(str) - SB;
+ li = si / NC;
+ vi = (si % NC) / TC;
+ ti = si % TC;
+
+ /* Fill in base of leaf. */
+ h = hangul;
+ LEAF_GEN(h) = 2;
+ LEAF_CCC(h) = DECOMPOSE;
+ h += 2;
+
+ /* Add LPart, a 3-byte UTF-8 sequence. */
+ h += utf8encode3((char *)h, li + LB);
+
+ /* Add VPart, a 3-byte UTF-8 sequence. */
+ h += utf8encode3((char *)h, vi + VB);
+
+ /* Add TPart if required, also a 3-byte UTF-8 sequence. */
+ if (ti)
+ h += utf8encode3((char *)h, ti + TB);
+
+ /* Terminate string. */
+ h[0] = '\0';
+
+ return hangul;
+}
+
+/*
+ * Use trie to scan s, touching at most len bytes.
+ * Returns the leaf if one exists, NULL otherwise.
+ *
+ * A non-NULL return guarantees that the UTF-8 sequence starting at s
+ * is well-formed and corresponds to a known unicode code point. The
+ * shorthand for this will be "is valid UTF-8 unicode".
+ */
+static utf8leaf_t *utf8nlookup(const struct unicode_map *um,
+ enum utf8_normalization n, unsigned char *hangul, const char *s,
+ size_t len)
+{
+ utf8trie_t *trie = um->tables->utf8data + um->ntab[n]->offset;
+ int offlen;
+ int offset;
+ int mask;
+ int node;
+
+ if (len == 0)
+ return NULL;
+
+ node = 1;
+ while (node) {
+ offlen = (*trie & OFFLEN) >> OFFLEN_SHIFT;
+ if (*trie & NEXTBYTE) {
+ if (--len == 0)
+ return NULL;
+ s++;
+ }
+ mask = 1 << (*trie & BITNUM);
+ if (*s & mask) {
+ /* Right leg */
+ if (offlen) {
+ /* Right node at offset of trie */
+ node = (*trie & RIGHTNODE);
+ offset = trie[offlen];
+ while (--offlen) {
+ offset <<= 8;
+ offset |= trie[offlen];
+ }
+ trie += offset;
+ } else if (*trie & RIGHTPATH) {
+ /* Right node after this node */
+ node = (*trie & TRIENODE);
+ trie++;
+ } else {
+ /* No right node. */
+ return NULL;
+ }
+ } else {
+ /* Left leg */
+ if (offlen) {
+ /* Left node after this node. */
+ node = (*trie & LEFTNODE);
+ trie += offlen + 1;
+ } else if (*trie & RIGHTPATH) {
+ /* No left node. */
+ return NULL;
+ } else {
+ /* Left node after this node */
+ node = (*trie & TRIENODE);
+ trie++;
+ }
+ }
+ }
+ /*
+ * Hangul decomposition is done algorithmically. These are the
+ * codepoints >= 0xAC00 and <= 0xD7A3. Their UTF-8 encoding is
+ * always 3 bytes long, so s has been advanced twice, and the
+ * start of the sequence is at s-2.
+ */
+ if (LEAF_CCC(trie) == DECOMPOSE && LEAF_STR(trie)[0] == HANGUL)
+ trie = utf8hangul(s - 2, hangul);
+ return trie;
+}
+
+/*
+ * Use trie to scan s.
+ * Returns the leaf if one exists, NULL otherwise.
+ *
+ * Forwards to utf8nlookup().
+ */
+static utf8leaf_t *utf8lookup(const struct unicode_map *um,
+ enum utf8_normalization n, unsigned char *hangul, const char *s)
+{
+ return utf8nlookup(um, n, hangul, s, (size_t)-1);
+}
+
+/*
+ * Length of the normalization of s, touch at most len bytes.
+ * Return -1 if s is not valid UTF-8 unicode.
+ */
+ssize_t utf8nlen(const struct unicode_map *um, enum utf8_normalization n,
+ const char *s, size_t len)
+{
+ utf8leaf_t *leaf;
+ size_t ret = 0;
+ unsigned char hangul[UTF8HANGULLEAF];
+
+ while (len && *s) {
+ leaf = utf8nlookup(um, n, hangul, s, len);
+ if (!leaf)
+ return -1;
+ if (um->tables->utf8agetab[LEAF_GEN(leaf)] >
+ um->ntab[n]->maxage)
+ ret += utf8clen(s);
+ else if (LEAF_CCC(leaf) == DECOMPOSE)
+ ret += strlen(LEAF_STR(leaf));
+ else
+ ret += utf8clen(s);
+ len -= utf8clen(s);
+ s += utf8clen(s);
+ }
+ return ret;
+}
+
+/*
+ * Set up an utf8cursor for use by utf8byte().
+ *
+ * u8c : pointer to cursor.
+ * data : const struct utf8data to use for normalization.
+ * s : string.
+ * len : length of s.
+ *
+ * Returns -1 on error, 0 on success.
+ */
+int utf8ncursor(struct utf8cursor *u8c, const struct unicode_map *um,
+ enum utf8_normalization n, const char *s, size_t len)
+{
+ if (!s)
+ return -1;
+ u8c->um = um;
+ u8c->n = n;
+ u8c->s = s;
+ u8c->p = NULL;
+ u8c->ss = NULL;
+ u8c->sp = NULL;
+ u8c->len = len;
+ u8c->slen = 0;
+ u8c->ccc = STOPPER;
+ u8c->nccc = STOPPER;
+ /* Check we didn't clobber the maximum length. */
+ if (u8c->len != len)
+ return -1;
+ /* The first byte of s may not be an utf8 continuation. */
+ if (len > 0 && (*s & 0xC0) == 0x80)
+ return -1;
+ return 0;
+}
+
+/*
+ * Get one byte from the normalized form of the string described by u8c.
+ *
+ * Returns the byte cast to an unsigned char on succes, and -1 on failure.
+ *
+ * The cursor keeps track of the location in the string in u8c->s.
+ * When a character is decomposed, the current location is stored in
+ * u8c->p, and u8c->s is set to the start of the decomposition. Note
+ * that bytes from a decomposition do not count against u8c->len.
+ *
+ * Characters are emitted if they match the current CCC in u8c->ccc.
+ * Hitting end-of-string while u8c->ccc == STOPPER means we're done,
+ * and the function returns 0 in that case.
+ *
+ * Sorting by CCC is done by repeatedly scanning the string. The
+ * values of u8c->s and u8c->p are stored in u8c->ss and u8c->sp at
+ * the start of the scan. The first pass finds the lowest CCC to be
+ * emitted and stores it in u8c->nccc, the second pass emits the
+ * characters with this CCC and finds the next lowest CCC. This limits
+ * the number of passes to 1 + the number of different CCCs in the
+ * sequence being scanned.
+ *
+ * Therefore:
+ * u8c->p != NULL -> a decomposition is being scanned.
+ * u8c->ss != NULL -> this is a repeating scan.
+ * u8c->ccc == -1 -> this is the first scan of a repeating scan.
+ */
+int utf8byte(struct utf8cursor *u8c)
+{
+ utf8leaf_t *leaf;
+ int ccc;
+
+ for (;;) {
+ /* Check for the end of a decomposed character. */
+ if (u8c->p && *u8c->s == '\0') {
+ u8c->s = u8c->p;
+ u8c->p = NULL;
+ }
+
+ /* Check for end-of-string. */
+ if (!u8c->p && (u8c->len == 0 || *u8c->s == '\0')) {
+ /* There is no next byte. */
+ if (u8c->ccc == STOPPER)
+ return 0;
+ /* End-of-string during a scan counts as a stopper. */
+ ccc = STOPPER;
+ goto ccc_mismatch;
+ } else if ((*u8c->s & 0xC0) == 0x80) {
+ /* This is a continuation of the current character. */
+ if (!u8c->p)
+ u8c->len--;
+ return (unsigned char)*u8c->s++;
+ }
+
+ /* Look up the data for the current character. */
+ if (u8c->p) {
+ leaf = utf8lookup(u8c->um, u8c->n, u8c->hangul, u8c->s);
+ } else {
+ leaf = utf8nlookup(u8c->um, u8c->n, u8c->hangul,
+ u8c->s, u8c->len);
+ }
+
+ /* No leaf found implies that the input is a binary blob. */
+ if (!leaf)
+ return -1;
+
+ ccc = LEAF_CCC(leaf);
+ /* Characters that are too new have CCC 0. */
+ if (u8c->um->tables->utf8agetab[LEAF_GEN(leaf)] >
+ u8c->um->ntab[u8c->n]->maxage) {
+ ccc = STOPPER;
+ } else if (ccc == DECOMPOSE) {
+ u8c->len -= utf8clen(u8c->s);
+ u8c->p = u8c->s + utf8clen(u8c->s);
+ u8c->s = LEAF_STR(leaf);
+ /* Empty decomposition implies CCC 0. */
+ if (*u8c->s == '\0') {
+ if (u8c->ccc == STOPPER)
+ continue;
+ ccc = STOPPER;
+ goto ccc_mismatch;
+ }
+
+ leaf = utf8lookup(u8c->um, u8c->n, u8c->hangul, u8c->s);
+ if (!leaf)
+ return -1;
+ ccc = LEAF_CCC(leaf);
+ }
+
+ /*
+ * If this is not a stopper, then see if it updates
+ * the next canonical class to be emitted.
+ */
+ if (ccc != STOPPER && u8c->ccc < ccc && ccc < u8c->nccc)
+ u8c->nccc = ccc;
+
+ /*
+ * Return the current byte if this is the current
+ * combining class.
+ */
+ if (ccc == u8c->ccc) {
+ if (!u8c->p)
+ u8c->len--;
+ return (unsigned char)*u8c->s++;
+ }
+
+ /* Current combining class mismatch. */
+ccc_mismatch:
+ if (u8c->nccc == STOPPER) {
+ /*
+ * Scan forward for the first canonical class
+ * to be emitted. Save the position from
+ * which to restart.
+ */
+ u8c->ccc = MINCCC - 1;
+ u8c->nccc = ccc;
+ u8c->sp = u8c->p;
+ u8c->ss = u8c->s;
+ u8c->slen = u8c->len;
+ if (!u8c->p)
+ u8c->len -= utf8clen(u8c->s);
+ u8c->s += utf8clen(u8c->s);
+ } else if (ccc != STOPPER) {
+ /* Not a stopper, and not the ccc we're emitting. */
+ if (!u8c->p)
+ u8c->len -= utf8clen(u8c->s);
+ u8c->s += utf8clen(u8c->s);
+ } else if (u8c->nccc != MAXCCC + 1) {
+ /* At a stopper, restart for next ccc. */
+ u8c->ccc = u8c->nccc;
+ u8c->nccc = MAXCCC + 1;
+ u8c->s = u8c->ss;
+ u8c->p = u8c->sp;
+ u8c->len = u8c->slen;
+ } else {
+ /* All done, proceed from here. */
+ u8c->ccc = STOPPER;
+ u8c->nccc = STOPPER;
+ u8c->sp = NULL;
+ u8c->ss = NULL;
+ u8c->slen = 0;
+ }
+ }
+}
+
+#ifdef CONFIG_UNICODE_NORMALIZATION_SELFTEST_MODULE
+EXPORT_SYMBOL_GPL(utf8version_is_supported);
+EXPORT_SYMBOL_GPL(utf8nlen);
+EXPORT_SYMBOL_GPL(utf8ncursor);
+EXPORT_SYMBOL_GPL(utf8byte);
+#endif
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