/*
 *  linux/lib/vsprintf.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

/*
 * Fri Jul 13 2001 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 * - changed to provide snprintf and vsnprintf functions
 * So Feb  1 16:51:32 CET 2004 Juergen Quade <quade@hsnr.de>
 * - scnprintf and vscnprintf
 */

#include <stdarg.h>
#include <linux/build_bug.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/module.h>       /* for KSYM_SYMBOL_LEN */
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/math64.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/dcache.h>
#include <linux/cred.h>
#include <linux/rtc.h>
#include <linux/uuid.h>
#include <linux/of.h>
#include <net/addrconf.h>
#include <linux/siphash.h>
#include <linux/compiler.h>
#ifdef CONFIG_BLOCK
#include <linux/blkdev.h>
#endif

#include "../mm/internal.h"     /* For the trace_print_flags arrays */

#include <asm/page.h>           /* for PAGE_SIZE */
#include <asm/byteorder.h>      /* cpu_to_le16 */

#include <linux/string_helpers.h>
#include "kstrtox.h"

/**
 * simple_strtoull - convert a string to an unsigned long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtoull instead.
 */
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
        unsigned long long result;
        unsigned int rv;

        cp = _parse_integer_fixup_radix(cp, &base);
        rv = _parse_integer(cp, base, &result);
        /* FIXME */
        cp += (rv & ~KSTRTOX_OVERFLOW);

        if (endp)
                *endp = (char *)cp;

        return result;
}
EXPORT_SYMBOL(simple_strtoull);

/**
 * simple_strtoul - convert a string to an unsigned long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtoul instead.
 */
unsigned long simple_strtoul(const char *cp, char **endp, unsigned int base)
{
        return simple_strtoull(cp, endp, base);
}
EXPORT_SYMBOL(simple_strtoul);

/**
 * simple_strtol - convert a string to a signed long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtol instead.
 */
long simple_strtol(const char *cp, char **endp, unsigned int base)
{
        if (*cp == '-')
                return -simple_strtoul(cp + 1, endp, base);

        return simple_strtoul(cp, endp, base);
}
EXPORT_SYMBOL(simple_strtol);

/**
 * simple_strtoll - convert a string to a signed long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtoll instead.
 */
long long simple_strtoll(const char *cp, char **endp, unsigned int base)
{
        if (*cp == '-')
                return -simple_strtoull(cp + 1, endp, base);

        return simple_strtoull(cp, endp, base);
}
EXPORT_SYMBOL(simple_strtoll);

static noinline_for_stack
int skip_atoi(const char **s)
{
        int i = 0;

        do {
                i = i*10 + *((*s)++) - '0';
        } while (isdigit(**s));

        return i;
}

/*
 * Decimal conversion is by far the most typical, and is used for
 * /proc and /sys data. This directly impacts e.g. top performance
 * with many processes running. We optimize it for speed by emitting
 * two characters at a time, using a 200 byte lookup table. This
 * roughly halves the number of multiplications compared to computing
 * the digits one at a time. Implementation strongly inspired by the
 * previous version, which in turn used ideas described at
 * <http://www.cs.uiowa.edu/~jones/bcd/divide.html> (with permission
 * from the author, Douglas W. Jones).
 *
 * It turns out there is precisely one 26 bit fixed-point
 * approximation a of 64/100 for which x/100 == (x * (u64)a) >> 32
 * holds for all x in [0, 10^8-1], namely a = 0x28f5c29. The actual
 * range happens to be somewhat larger (x <= 1073741898), but that's
 * irrelevant for our purpose.
 *
 * For dividing a number in the range [10^4, 10^6-1] by 100, we still
 * need a 32x32->64 bit multiply, so we simply use the same constant.
 *
 * For dividing a number in the range [100, 10^4-1] by 100, there are
 * several options. The simplest is (x * 0x147b) >> 19, which is valid
 * for all x <= 43698.
 */

static const u16 decpair[100] = {
#define _(x) (__force u16) cpu_to_le16(((x % 10) | ((x / 10) << 8)) + 0x3030)
        _( 0), _( 1), _( 2), _( 3), _( 4), _( 5), _( 6), _( 7), _( 8), _( 9),
        _(10), _(11), _(12), _(13), _(14), _(15), _(16), _(17), _(18), _(19),
        _(20), _(21), _(22), _(23), _(24), _(25), _(26), _(27), _(28), _(29),
        _(30), _(31), _(32), _(33), _(34), _(35), _(36), _(37), _(38), _(39),
        _(40), _(41), _(42), _(43), _(44), _(45), _(46), _(47), _(48), _(49),
        _(50), _(51), _(52), _(53), _(54), _(55), _(56), _(57), _(58), _(59),
        _(60), _(61), _(62), _(63), _(64), _(65), _(66), _(67), _(68), _(69),
        _(70), _(71), _(72), _(73), _(74), _(75), _(76), _(77), _(78), _(79),
        _(80), _(81), _(82), _(83), _(84), _(85), _(86), _(87), _(88), _(89),
        _(90), _(91), _(92), _(93), _(94), _(95), _(96), _(97), _(98), _(99),
#undef _
};

/*
 * This will print a single '0' even if r == 0, since we would
 * immediately jump to out_r where two 0s would be written but only
 * one of them accounted for in buf. This is needed by ip4_string
 * below. All other callers pass a non-zero value of r.
*/
static noinline_for_stack
char *put_dec_trunc8(char *buf, unsigned r)
{
        unsigned q;

        /* 1 <= r < 10^8 */
        if (r < 100)
                goto out_r;

        /* 100 <= r < 10^8 */
        q = (r * (u64)0x28f5c29) >> 32;
        *((u16 *)buf) = decpair[r - 100*q];
        buf += 2;

        /* 1 <= q < 10^6 */
        if (q < 100)
                goto out_q;

        /*  100 <= q < 10^6 */
        r = (q * (u64)0x28f5c29) >> 32;
        *((u16 *)buf) = decpair[q - 100*r];
        buf += 2;

        /* 1 <= r < 10^4 */
        if (r < 100)
                goto out_r;

        /* 100 <= r < 10^4 */
        q = (r * 0x147b) >> 19;
        *((u16 *)buf) = decpair[r - 100*q];
        buf += 2;
out_q:
        /* 1 <= q < 100 */
        r = q;
out_r:
        /* 1 <= r < 100 */
        *((u16 *)buf) = decpair[r];
        buf += r < 10 ? 1 : 2;
        return buf;
}

#if BITS_PER_LONG == 64 && BITS_PER_LONG_LONG == 64
static noinline_for_stack
char *put_dec_full8(char *buf, unsigned r)
{
        unsigned q;

        /* 0 <= r < 10^8 */
        q = (r * (u64)0x28f5c29) >> 32;
        *((u16 *)buf) = decpair[r - 100*q];
        buf += 2;

        /* 0 <= q < 10^6 */
        r = (q * (u64)0x28f5c29) >> 32;
        *((u16 *)buf) = decpair[q - 100*r];
        buf += 2;

        /* 0 <= r < 10^4 */
        q = (r * 0x147b) >> 19;
        *((u16 *)buf) = decpair[r - 100*q];
        buf += 2;

        /* 0 <= q < 100 */
        *((u16 *)buf) = decpair[q];
        buf += 2;
        return buf;
}

static noinline_for_stack
char *put_dec(char *buf, unsigned long long n)
{
        if (n >= 100*1000*1000)
                buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
        /* 1 <= n <= 1.6e11 */
        if (n >= 100*1000*1000)
                buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
        /* 1 <= n < 1e8 */
        return put_dec_trunc8(buf, n);
}

#elif BITS_PER_LONG == 32 && BITS_PER_LONG_LONG == 64

static void
put_dec_full4(char *buf, unsigned r)
{
        unsigned q;

        /* 0 <= r < 10^4 */
        q = (r * 0x147b) >> 19;
        *((u16 *)buf) = decpair[r - 100*q];
        buf += 2;
        /* 0 <= q < 100 */
        *((u16 *)buf) = decpair[q];
}

/*
 * Call put_dec_full4 on x % 10000, return x / 10000.
 * The approximation x/10000 == (x * 0x346DC5D7) >> 43
 * holds for all x < 1,128,869,999.  The largest value this
 * helper will ever be asked to convert is 1,125,520,955.
 * (second call in the put_dec code, assuming n is all-ones).
 */
static noinline_for_stack
unsigned put_dec_helper4(char *buf, unsigned x)
{
        uint32_t q = (x * (uint64_t)0x346DC5D7) >> 43;

        put_dec_full4(buf, x - q * 10000);
        return q;
}

/* Based on code by Douglas W. Jones found at
 * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
 * (with permission from the author).
 * Performs no 64-bit division and hence should be fast on 32-bit machines.
 */
static
char *put_dec(char *buf, unsigned long long n)
{
        uint32_t d3, d2, d1, q, h;

        if (n < 100*1000*1000)
                return put_dec_trunc8(buf, n);

        d1  = ((uint32_t)n >> 16); /* implicit "& 0xffff" */
        h   = (n >> 32);
        d2  = (h      ) & 0xffff;
        d3  = (h >> 16); /* implicit "& 0xffff" */

        /* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
             = 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
        q   = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
        q = put_dec_helper4(buf, q);

        q += 7671 * d3 + 9496 * d2 + 6 * d1;
        q = put_dec_helper4(buf+4, q);

        q += 4749 * d3 + 42 * d2;
        q = put_dec_helper4(buf+8, q);

        q += 281 * d3;
        buf += 12;
        if (q)
                buf = put_dec_trunc8(buf, q);
        else while (buf[-1] == '0')
                --buf;

        return buf;
}

#endif

/*
 * Convert passed number to decimal string.
 * Returns the length of string.  On buffer overflow, returns 0.
 *
 * If speed is not important, use snprintf(). It's easy to read the code.
 */
int num_to_str(char *buf, int size, unsigned long long num, unsigned int width)
{
        /* put_dec requires 2-byte alignment of the buffer. */
        char tmp[sizeof(num) * 3] __aligned(2);
        int idx, len;

        /* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
        if (num <= 9) {
                tmp[0] = '0' + num;
                len = 1;
        } else {
                len = put_dec(tmp, num) - tmp;
        }

        if (len > size || width > size)
                return 0;

        if (width > len) {
                width = width - len;
                for (idx = 0; idx < width; idx++)
                        buf[idx] = ' ';
        } else {
                width = 0;
        }

        for (idx = 0; idx < len; ++idx)
                buf[idx + width] = tmp[len - idx - 1];

        return len + width;
}

#define SIGN    1               /* unsigned/signed, must be 1 */
#define LEFT    2               /* left justified */
#define PLUS    4               /* show plus */
#define SPACE   8               /* space if plus */
#define ZEROPAD 16              /* pad with zero, must be 16 == '0' - ' ' */
#define SMALL   32              /* use lowercase in hex (must be 32 == 0x20) */
#define SPECIAL 64              /* prefix hex with "0x", octal with "0" */

enum format_type {
        FORMAT_TYPE_NONE, /* Just a string part */
        FORMAT_TYPE_WIDTH,
        FORMAT_TYPE_PRECISION,
        FORMAT_TYPE_CHAR,
        FORMAT_TYPE_STR,
        FORMAT_TYPE_PTR,
        FORMAT_TYPE_PERCENT_CHAR,
        FORMAT_TYPE_INVALID,
        FORMAT_TYPE_LONG_LONG,
        FORMAT_TYPE_ULONG,
        FORMAT_TYPE_LONG,
        FORMAT_TYPE_UBYTE,
        FORMAT_TYPE_BYTE,
        FORMAT_TYPE_USHORT,
        FORMAT_TYPE_SHORT,
        FORMAT_TYPE_UINT,
        FORMAT_TYPE_INT,
        FORMAT_TYPE_SIZE_T,
        FORMAT_TYPE_PTRDIFF
};

struct printf_spec {
        unsigned int    type:8;         /* format_type enum */
        signed int      field_width:24; /* width of output field */
        unsigned int    flags:8;        /* flags to number() */
        unsigned int    base:8;         /* number base, 8, 10 or 16 only */
        signed int      precision:16;   /* # of digits/chars */
} __packed;
static_assert(sizeof(struct printf_spec) == 8);

#define FIELD_WIDTH_MAX ((1 << 23) - 1)
#define PRECISION_MAX ((1 << 15) - 1)

static noinline_for_stack
char *number(char *buf, char *end, unsigned long long num,
             struct printf_spec spec)
{
        /* put_dec requires 2-byte alignment of the buffer. */
        char tmp[3 * sizeof(num)] __aligned(2);
        char sign;
        char locase;
        int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
        int i;
        bool is_zero = num == 0LL;
        int field_width = spec.field_width;
        int precision = spec.precision;

        /* locase = 0 or 0x20. ORing digits or letters with 'locase'
         * produces same digits or (maybe lowercased) letters */
        locase = (spec.flags & SMALL);
        if (spec.flags & LEFT)
                spec.flags &= ~ZEROPAD;
        sign = 0;
        if (spec.flags & SIGN) {
                if ((signed long long)num < 0) {
                        sign = '-';
                        num = -(signed long long)num;
                        field_width--;
                } else if (spec.flags & PLUS) {
                        sign = '+';
                        field_width--;
                } else if (spec.flags & SPACE) {
                        sign = ' ';
                        field_width--;
                }
        }
        if (need_pfx) {
                if (spec.base == 16)
                        field_width -= 2;
                else if (!is_zero)
                        field_width--;
        }

        /* generate full string in tmp[], in reverse order */
        i = 0;
        if (num < spec.base)
                tmp[i++] = hex_asc_upper[num] | locase;
        else if (spec.base != 10) { /* 8 or 16 */
                int mask = spec.base - 1;
                int shift = 3;

                if (spec.base == 16)
                        shift = 4;
                do {
                        tmp[i++] = (hex_asc_upper[((unsigned char)num) & mask] | locase);
                        num >>= shift;
                } while (num);
        } else { /* base 10 */
                i = put_dec(tmp, num) - tmp;
        }

        /* printing 100 using %2d gives "100", not "00" */
        if (i > precision)
                precision = i;
        /* leading space padding */
        field_width -= precision;
        if (!(spec.flags & (ZEROPAD | LEFT))) {
                while (--field_width >= 0) {
                        if (buf < end)
                                *buf = ' ';
                        ++buf;
                }
        }
        /* sign */
        if (sign) {
                if (buf < end)
                        *buf = sign;
                ++buf;
        }
        /* "0x" / "0" prefix */
        if (need_pfx) {
                if (spec.base == 16 || !is_zero) {
                        if (buf < end)
                                *buf = '0';
                        ++buf;
                }
                if (spec.base == 16) {
                        if (buf < end)
                                *buf = ('X' | locase);
                        ++buf;
                }
        }
        /* zero or space padding */
        if (!(spec.flags & LEFT)) {
                char c = ' ' + (spec.flags & ZEROPAD);
                BUILD_BUG_ON(' ' + ZEROPAD != '0');
                while (--field_width >= 0) {
                        if (buf < end)
                                *buf = c;
                        ++buf;
                }
        }
        /* hmm even more zero padding? */
        while (i <= --precision) {
                if (buf < end)
                        *buf = '0';
                ++buf;
        }
        /* actual digits of result */
        while (--i >= 0) {
                if (buf < end)
                        *buf = tmp[i];
                ++buf;
        }
        /* trailing space padding */
        while (--field_width >= 0) {
                if (buf < end)
                        *buf = ' ';
                ++buf;
        }

        return buf;
}

static noinline_for_stack
char *special_hex_number(char *buf, char *end, unsigned long long num, int size)
{
        struct printf_spec spec;

        spec.type = FORMAT_TYPE_PTR;
        spec.field_width = 2 + 2 * size;        /* 0x + hex */
        spec.flags = SPECIAL | SMALL | ZEROPAD;
        spec.base = 16;
        spec.precision = -1;

        return number(buf, end, num, spec);
}

static void move_right(char *buf, char *end, unsigned len, unsigned spaces)
{
        size_t size;
        if (buf >= end) /* nowhere to put anything */
                return;
        size = end - buf;
        if (size <= spaces) {
                memset(buf, ' ', size);
                return;
        }
        if (len) {
                if (len > size - spaces)
                        len = size - spaces;
                memmove(buf + spaces, buf, len);
        }
        memset(buf, ' ', spaces);
}

/*
 * Handle field width padding for a string.
 * @buf: current buffer position
 * @n: length of string
 * @end: end of output buffer
 * @spec: for field width and flags
 * Returns: new buffer position after padding.
 */
static noinline_for_stack
char *widen_string(char *buf, int n, char *end, struct printf_spec spec)
{
        unsigned spaces;

        if (likely(n >= spec.field_width))
                return buf;
        /* we want to pad the sucker */
        spaces = spec.field_width - n;
        if (!(spec.flags & LEFT)) {
                move_right(buf - n, end, n, spaces);
                return buf + spaces;
        }
        while (spaces--) {
                if (buf < end)
                        *buf = ' ';
                ++buf;
        }
        return buf;
}

static noinline_for_stack
char *string(char *buf, char *end, const char *s, struct printf_spec spec)
{
        int len = 0;
        size_t lim = spec.precision;

        if ((unsigned long)s < PAGE_SIZE)
                s = "(null)";

        while (lim--) {
                char c = *s++;
                if (!c)
                        break;
                if (buf < end)
                        *buf = c;
                ++buf;
                ++len;
        }
        return widen_string(buf, len, end, spec);
}

static noinline_for_stack
char *pointer_string(char *buf, char *end, const void *ptr,
                     struct printf_spec spec)
{
        spec.base = 16;
        spec.flags |= SMALL;
        if (spec.field_width == -1) {
                spec.field_width = 2 * sizeof(ptr);
                spec.flags |= ZEROPAD;
        }

        return number(buf, end, (unsigned long int)ptr, spec);
}

/* Make pointers available for printing early in the boot sequence. */
static int debug_boot_weak_hash __ro_after_init;

static int __init debug_boot_weak_hash_enable(char *str)
{
        debug_boot_weak_hash = 1;
        pr_info("debug_boot_weak_hash enabled\n");
        return 0;
}
early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable);

static DEFINE_STATIC_KEY_TRUE(not_filled_random_ptr_key);
static siphash_key_t ptr_key __read_mostly;

static void enable_ptr_key_workfn(struct work_struct *work)
{
        get_random_bytes(&ptr_key, sizeof(ptr_key));
        /* Needs to run from preemptible context */
        static_branch_disable(&not_filled_random_ptr_key);
}

static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);

static void fill_random_ptr_key(struct random_ready_callback *unused)
{
        /* This may be in an interrupt handler. */
        queue_work(system_unbound_wq, &enable_ptr_key_work);
}

static struct random_ready_callback random_ready = {
        .func = fill_random_ptr_key
};

static int __init initialize_ptr_random(void)
{
        int key_size = sizeof(ptr_key);
        int ret;

        /* Use hw RNG if available. */
        if (get_random_bytes_arch(&ptr_key, key_size) == key_size) {
                static_branch_disable(&not_filled_random_ptr_key);
                return 0;
        }

        ret = add_random_ready_callback(&random_ready);
        if (!ret) {
                return 0;
        } else if (ret == -EALREADY) {
                /* This is in preemptible context */
                enable_ptr_key_workfn(&enable_ptr_key_work);
                return 0;
        }

        return ret;
}
early_initcall(initialize_ptr_random);

/* Maps a pointer to a 32 bit unique identifier. */
static char *ptr_to_id(char *buf, char *end, const void *ptr,
                       struct printf_spec spec)
{
        const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
        unsigned long hashval;

        /* When debugging early boot use non-cryptographically secure hash. */
        if (unlikely(debug_boot_weak_hash)) {
                hashval = hash_long((unsigned long)ptr, 32);
                return pointer_string(buf, end, (const void *)hashval, spec);
        }

        if (static_branch_unlikely(&not_filled_random_ptr_key)) {
                spec.field_width = 2 * sizeof(ptr);
                /* string length must be less than default_width */
                return string(buf, end, str, spec);
        }

#ifdef CONFIG_64BIT
        hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
        /*
         * Mask off the first 32 bits, this makes explicit that we have
         * modified the address (and 32 bits is plenty for a unique ID).
         */
        hashval = hashval & 0xffffffff;
#else
        hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key);
#endif
        return pointer_string(buf, end, (const void *)hashval, spec);
}

static noinline_for_stack
char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,
                  const char *fmt)
{
        const char *array[4], *s;
        const struct dentry *p;
        int depth;
        int i, n;

        switch (fmt[1]) {
                case '2': case '3': case '4':
                        depth = fmt[1] - '0';
                        break;
                default:
                        depth = 1;
        }

        rcu_read_lock();
        for (i = 0; i < depth; i++, d = p) {
                p = READ_ONCE(d->d_parent);
                array[i] = READ_ONCE(d->d_name.name);
                if (p == d) {
                        if (i)
                                array[i] = "";
                        i++;
                        break;
                }
        }
        s = array[--i];
        for (n = 0; n != spec.precision; n++, buf++) {
                char c = *s++;
                if (!c) {
                        if (!i)
                                break;
                        c = '/';
                        s = array[--i];
                }
                if (buf < end)
                        *buf = c;
        }
        rcu_read_unlock();
        return widen_string(buf, n, end, spec);
}

#ifdef CONFIG_BLOCK
static noinline_for_stack
char *bdev_name(char *buf, char *end, struct block_device *bdev,
                struct printf_spec spec, const char *fmt)
{
        struct gendisk *hd = bdev->bd_disk;
        
        buf = string(buf, end, hd->disk_name, spec);
        if (bdev->bd_part->partno) {
                if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) {
                        if (buf < end)
                                *buf = 'p';
                        buf++;
                }
                buf = number(buf, end, bdev->bd_part->partno, spec);
        }
        return buf;
}
#endif

static noinline_for_stack
char *symbol_string(char *buf, char *end, void *ptr,
                    struct printf_spec spec, const char *fmt)
{
        unsigned long value;
#ifdef CONFIG_KALLSYMS
        char sym[KSYM_SYMBOL_LEN];
#endif

        if (fmt[1] == 'R')
                ptr = __builtin_extract_return_addr(ptr);
        value = (unsigned long)ptr;

#ifdef CONFIG_KALLSYMS
        if (*fmt == 'B')
                sprint_backtrace(sym, value);
        else if (*fmt != 'f' && *fmt != 's')
                sprint_symbol(sym, value);
        else
                sprint_symbol_no_offset(sym, value);

        return string(buf, end, sym, spec);
#else
        return special_hex_number(buf, end, value, sizeof(void *));
#endif
}

static const struct printf_spec default_str_spec = {
        .field_width = -1,
        .precision = -1,
};

static const struct printf_spec default_flag_spec = {
        .base = 16,
        .precision = -1,
        .flags = SPECIAL | SMALL,
};

static const struct printf_spec default_dec_spec = {
        .base = 10,
        .precision = -1,
};

static const struct printf_spec default_dec02_spec = {
        .base = 10,
        .field_width = 2,
        .precision = -1,
        .flags = ZEROPAD,
};

static const struct printf_spec default_dec04_spec = {
        .base = 10,
        .field_width = 4,
        .precision = -1,
        .flags = ZEROPAD,
};

static noinline_for_stack
char *resource_string(char *buf, char *end, struct resource *res,
                      struct printf_spec spec, const char *fmt)
{
#ifndef IO_RSRC_PRINTK_SIZE
#define IO_RSRC_PRINTK_SIZE     6
#endif

#ifndef MEM_RSRC_PRINTK_SIZE
#define MEM_RSRC_PRINTK_SIZE    10
#endif
        static const struct printf_spec io_spec = {
                .base = 16,
                .field_width = IO_RSRC_PRINTK_SIZE,
                .precision = -1,
                .flags = SPECIAL | SMALL | ZEROPAD,
        };
        static const struct printf_spec mem_spec = {
                .base = 16,
                .field_width = MEM_RSRC_PRINTK_SIZE,
                .precision = -1,
                .flags = SPECIAL | SMALL | ZEROPAD,
        };
        static const struct printf_spec bus_spec = {
                .base = 16,
                .field_width = 2,
                .precision = -1,
                .flags = SMALL | ZEROPAD,
        };
        static const struct printf_spec str_spec = {
                .field_width = -1,
                .precision = 10,
                .flags = LEFT,
        };

        /* 32-bit res (sizeof==4): 10 chars in dec, 10 in hex ("0x" + 8)
         * 64-bit res (sizeof==8): 20 chars in dec, 18 in hex ("0x" + 16) */
#define RSRC_BUF_SIZE           ((2 * sizeof(resource_size_t)) + 4)
#define FLAG_BUF_SIZE           (2 * sizeof(res->flags))
#define DECODED_BUF_SIZE        sizeof("[mem - 64bit pref window disabled]")
#define RAW_BUF_SIZE            sizeof("[mem - flags 0x]")
        char sym[max(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
                     2*RSRC_BUF_SIZE + FLAG_BUF_SIZE + RAW_BUF_SIZE)];

        char *p = sym, *pend = sym + sizeof(sym);
        int decode = (fmt[0] == 'R') ? 1 : 0;
        const struct printf_spec *specp;

        *p++ = '[';
        if (res->flags & IORESOURCE_IO) {
                p = string(p, pend, "io  ", str_spec);
                specp = &io_spec;
        } else if (res->flags & IORESOURCE_MEM) {
                p = string(p, pend, "mem ", str_spec);
                specp = &mem_spec;
        } else if (res->flags & IORESOURCE_IRQ) {
                p = string(p, pend, "irq ", str_spec);
                specp = &default_dec_spec;
        } else if (res->flags & IORESOURCE_DMA) {
                p = string(p, pend, "dma ", str_spec);
                specp = &default_dec_spec;
        } else if (res->flags & IORESOURCE_BUS) {
                p = string(p, pend, "bus ", str_spec);
                specp = &bus_spec;
        } else {
                p = string(p, pend, "??? ", str_spec);
                specp = &mem_spec;
                decode = 0;
        }
        if (decode && res->flags & IORESOURCE_UNSET) {
                p = string(p, pend, "size ", str_spec);
                p = number(p, pend, resource_size(res), *specp);
        } else {
                p = number(p, pend, res->start, *specp);
                if (res->start != res->end) {
                        *p++ = '-';
                        p = number(p, pend, res->end, *specp);
                }
        }
        if (decode) {
                if (res->flags & IORESOURCE_MEM_64)
                        p = string(p, pend, " 64bit", str_spec);
                if (res->flags & IORESOURCE_PREFETCH)
                        p = string(p, pend, " pref", str_spec);
                if (res->flags & IORESOURCE_WINDOW)
                        p = string(p, pend, " window", str_spec);
                if (res->flags & IORESOURCE_DISABLED)
                        p = string(p, pend, " disabled", str_spec);
        } else {
                p = string(p, pend, " flags ", str_spec);
                p = number(p, pend, res->flags, default_flag_spec);
        }
        *p++ = ']';
        *p = '\0';

        return string(buf, end, sym, spec);
}

static noinline_for_stack
char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
                 const char *fmt)
{
        int i, len = 1;         /* if we pass '%ph[CDN]', field width remains
                                   negative value, fallback to the default */
        char separator;

        if (spec.field_width == 0)
                /* nothing to print */
                return buf;

        if (ZERO_OR_NULL_PTR(addr))
                /* NULL pointer */
                return string(buf, end, NULL, spec);

        switch (fmt[1]) {
        case 'C':
                separator = ':';
                break;
        case 'D':
                separator = '-';
                break;
        case 'N':
                separator = 0;
                break;
        default:
                separator = ' ';
                break;
        }

        if (spec.field_width > 0)
                len = min_t(int, spec.field_width, 64);

        for (i = 0; i < len; ++i) {
                if (buf < end)
                        *buf = hex_asc_hi(addr[i]);
                ++buf;
                if (buf < end)
                        *buf = hex_asc_lo(addr[i]);
                ++buf;

                if (separator && i != len - 1) {
                        if (buf < end)
                                *buf = separator;
                        ++buf;
                }
        }

        return buf;
}

static noinline_for_stack
char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
                    struct printf_spec spec, const char *fmt)
{
        const int CHUNKSZ = 32;
        int nr_bits = max_t(int, spec.field_width, 0);
        int i, chunksz;
        bool first = true;

        /* reused to print numbers */

        spec = (struct printf_spec){ .flags = SMALL | ZEROPAD, .base = 16 };

        chunksz = nr_bits & (CHUNKSZ - 1);
        if (chunksz == 0)
                chunksz = CHUNKSZ;

        i = ALIGN(nr_bits, CHUNKSZ) - CHUNKSZ;
        for (; i >= 0; i -= CHUNKSZ) {
                u32 chunkmask, val;
                int word, bit;

                chunkmask = ((1ULL << chunksz) - 1);
                word = i / BITS_PER_LONG;
                bit = i % BITS_PER_LONG;
                val = (bitmap[word] >> bit) & chunkmask;

                if (!first) {
                        if (buf < end)
                                *buf = ',';
                        buf++;
                }
                first = false;

                spec.field_width = DIV_ROUND_UP(chunksz, 4);
                buf = number(buf, end, val, spec);

                chunksz = CHUNKSZ;
        }
        return buf;
}

static noinline_for_stack
char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap,
                         struct printf_spec spec, const char *fmt)
{
        int nr_bits = max_t(int, spec.field_width, 0);
        /* current bit is 'cur', most recently seen range is [rbot, rtop] */
        int cur, rbot, rtop;
        bool first = true;

        rbot = cur = find_first_bit(bitmap, nr_bits);
        while (cur < nr_bits) {
                rtop = cur;
                cur = find_next_bit(bitmap, nr_bits, cur + 1);
                if (cur < nr_bits && cur <= rtop + 1)
                        continue;

                if (!first) {
                        if (buf < end)
                                *buf = ',';
                        buf++;
                }
                first = false;

                buf = number(buf, end, rbot, default_dec_spec);
                if (rbot < rtop) {
                        if (buf < end)
                                *buf = '-';
                        buf++;

                        buf = number(buf, end, rtop, default_dec_spec);
                }

                rbot = cur;
        }
        return buf;
}

static noinline_for_stack
char *mac_address_string(char *buf, char *end, u8 *addr,
                         struct printf_spec spec, const char *fmt)
{
        char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
        char *p = mac_addr;
        int i;
        char separator;
        bool reversed = false;

        switch (fmt[1]) {
        case 'F':
                separator = '-';
                break;

        case 'R':
                reversed = true;
                /* fall through */

        default:
                separator = ':';
                break;
        }

        for (i = 0; i < 6; i++) {
                if (reversed)
                        p = hex_byte_pack(p, addr[5 - i]);
                else
                        p = hex_byte_pack(p, addr[i]);

                if (fmt[0] == 'M' && i != 5)
                        *p++ = separator;
        }
        *p = '\0';

        return string(buf, end, mac_addr, spec);
}

static noinline_for_stack
char *ip4_string(char *p, const u8 *addr, const char *fmt)
{
        int i;
        bool leading_zeros = (fmt[0] == 'i');
        int index;
        int step;

        switch (fmt[2]) {
        case 'h':
#ifdef __BIG_ENDIAN
                index = 0;
                step = 1;
#else
                index = 3;
                step = -1;
#endif
                break;
        case 'l':
                index = 3;
                step = -1;
                break;
        case 'n':
        case 'b':
        default:
                index = 0;
                step = 1;
                break;
        }
        for (i = 0; i < 4; i++) {
                char temp[4] __aligned(2);      /* hold each IP quad in reverse order */
                int digits = put_dec_trunc8(temp, addr[index]) - temp;
                if (leading_zeros) {
                        if (digits < 3)
                                *p++ = '0';
                        if (digits < 2)
                                *p++ = '0';
                }
                /* reverse the digits in the quad */
                while (digits--)
                        *p++ = temp[digits];
                if (i < 3)
                        *p++ = '.';
                index += step;
        }
        *p = '\0';

        return p;
}

static noinline_for_stack
char *ip6_compressed_string(char *p, const char *addr)
{
        int i, j, range;
        unsigned char zerolength[8];
        int longest = 1;
        int colonpos = -1;
        u16 word;
        u8 hi, lo;
        bool needcolon = false;
        bool useIPv4;
        struct in6_addr in6;

        memcpy(&in6, addr, sizeof(struct in6_addr));

        useIPv4 = ipv6_addr_v4mapped(&in6) || ipv6_addr_is_isatap(&in6);

        memset(zerolength, 0, sizeof(zerolength));

        if (useIPv4)
                range = 6;
        else
                range = 8;

        /* find position of longest 0 run */
        for (i = 0; i < range; i++) {
                for (j = i; j < range; j++) {
                        if (in6.s6_addr16[j] != 0)
                                break;
                        zerolength[i]++;
                }
        }
        for (i = 0; i < range; i++) {
                if (zerolength[i] > longest) {
                        longest = zerolength[i];
                        colonpos = i;
                }
        }
        if (longest == 1)               /* don't compress a single 0 */
                colonpos = -1;

        /* emit address */
        for (i = 0; i < range; i++) {
                if (i == colonpos) {
                        if (needcolon || i == 0)
                                *p++ = ':';
                        *p++ = ':';
                        needcolon = false;
                        i += longest - 1;
                        continue;
                }
                if (needcolon) {
                        *p++ = ':';
                        needcolon = false;
                }
                /* hex u16 without leading 0s */
                word = ntohs(in6.s6_addr16[i]);
                hi = word >> 8;
                lo = word & 0xff;
                if (hi) {
                        if (hi > 0x0f)
                                p = hex_byte_pack(p, hi);
                        else
                                *p++ = hex_asc_lo(hi);
                        p = hex_byte_pack(p, lo);
                }
                else if (lo > 0x0f)
                        p = hex_byte_pack(p, lo);
                else
                        *p++ = hex_asc_lo(lo);
                needcolon = true;
        }

        if (useIPv4) {
                if (needcolon)
                        *p++ = ':';
                p = ip4_string(p, &in6.s6_addr[12], "I4");
        }
        *p = '\0';

        return p;
}

static noinline_for_stack
char *ip6_string(char *p, const char *addr, const char *fmt)
{
        int i;

        for (i = 0; i < 8; i++) {
                p = hex_byte_pack(p, *addr++);
                p = hex_byte_pack(p, *addr++);
                if (fmt[0] == 'I' && i != 7)
                        *p++ = ':';
        }
        *p = '\0';

        return p;
}

static noinline_for_stack
char *ip6_addr_string(char *buf, char *end, const u8 *addr,
                      struct printf_spec spec, const char *fmt)
{
        char ip6_addr[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255")];

        if (fmt[0] == 'I' && fmt[2] == 'c')
                ip6_compressed_string(ip6_addr, addr);
        else
                ip6_string(ip6_addr, addr, fmt);

        return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string(char *buf, char *end, const u8 *addr,
                      struct printf_spec spec, const char *fmt)
{
        char ip4_addr[sizeof("255.255.255.255")];

        ip4_string(ip4_addr, addr, fmt);

        return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
                         struct printf_spec spec, const char *fmt)
{
        bool have_p = false, have_s = false, have_f = false, have_c = false;
        char ip6_addr[sizeof("[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255]") +
                      sizeof(":12345") + sizeof("/123456789") +
                      sizeof("%1234567890")];
        char *p = ip6_addr, *pend = ip6_addr + sizeof(ip6_addr);
        const u8 *addr = (const u8 *) &sa->sin6_addr;
        char fmt6[2] = { fmt[0], '6' };
        u8 off = 0;

        fmt++;
        while (isalpha(*++fmt)) {
                switch (*fmt) {
                case 'p':
                        have_p = true;
                        break;
                case 'f':
                        have_f = true;
                        break;
                case 's':
                        have_s = true;
                        break;
                case 'c':
                        have_c = true;
                        break;
                }
        }

        if (have_p || have_s || have_f) {
                *p = '[';
                off = 1;
        }

        if (fmt6[0] == 'I' && have_c)
                p = ip6_compressed_string(ip6_addr + off, addr);
        else
                p = ip6_string(ip6_addr + off, addr, fmt6);

        if (have_p || have_s || have_f)
                *p++ = ']';

        if (have_p) {
                *p++ = ':';
                p = number(p, pend, ntohs(sa->sin6_port), spec);
        }
        if (have_f) {
                *p++ = '/';
                p = number(p, pend, ntohl(sa->sin6_flowinfo &
                                          IPV6_FLOWINFO_MASK), spec);
        }
        if (have_s) {
                *p++ = '%';
                p = number(p, pend, sa->sin6_scope_id, spec);
        }
        *p = '\0';

        return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
                         struct printf_spec spec, const char *fmt)
{
        bool have_p = false;
        char *p, ip4_addr[sizeof("255.255.255.255") + sizeof(":12345")];
        char *pend = ip4_addr + sizeof(ip4_addr);
        const u8 *addr = (const u8 *) &sa->sin_addr.s_addr;
        char fmt4[3] = { fmt[0], '4', 0 };

        fmt++;
        while (isalpha(*++fmt)) {
                switch (*fmt) {
                case 'p':
                        have_p = true;
                        break;
                case 'h':
                case 'l':
                case 'n':
                case 'b':
                        fmt4[2] = *fmt;
                        break;
                }
        }

        p = ip4_string(ip4_addr, addr, fmt4);
        if (have_p) {
                *p++ = ':';
                p = number(p, pend, ntohs(sa->sin_port), spec);
        }
        *p = '\0';

        return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
                     const char *fmt)
{
        bool found = true;
        int count = 1;
        unsigned int flags = 0;
        int len;

        if (spec.field_width == 0)
                return buf;                             /* nothing to print */

        if (ZERO_OR_NULL_PTR(addr))
                return string(buf, end, NULL, spec);    /* NULL pointer */


        do {
                switch (fmt[count++]) {
                case 'a':
                        flags |= ESCAPE_ANY;
                        break;
                case 'c':
                        flags |= ESCAPE_SPECIAL;
                        break;
                case 'h':
                        flags |= ESCAPE_HEX;
                        break;
                case 'n':
                        flags |= ESCAPE_NULL;
                        break;
                case 'o':
                        flags |= ESCAPE_OCTAL;
                        break;
                case 'p':
                        flags |= ESCAPE_NP;
                        break;
                case 's':
                        flags |= ESCAPE_SPACE;
                        break;
                default:
                        found = false;
                        break;
                }
        } while (found);

        if (!flags)
                flags = ESCAPE_ANY_NP;

        len = spec.field_width < 0 ? 1 : spec.field_width;

        /*
         * string_escape_mem() writes as many characters as it can to
         * the given buffer, and returns the total size of the output
         * had the buffer been big enough.
         */
        buf += string_escape_mem(addr, len, buf, buf < end ? end - buf : 0, flags, NULL);

        return buf;
}

static noinline_for_stack
char *uuid_string(char *buf, char *end, const u8 *addr,
                  struct printf_spec spec, const char *fmt)
{
        char uuid[UUID_STRING_LEN + 1];
        char *p = uuid;
        int i;
        const u8 *index = uuid_index;
        bool uc = false;

        switch (*(++fmt)) {
        case 'L':
                uc = true;              /* fall-through */
        case 'l':
                index = guid_index;
                break;
        case 'B':
                uc = true;
                break;
        }

        for (i = 0; i < 16; i++) {
                if (uc)
                        p = hex_byte_pack_upper(p, addr[index[i]]);
                else
                        p = hex_byte_pack(p, addr[index[i]]);
                switch (i) {
                case 3:
                case 5:
                case 7:
                case 9:
                        *p++ = '-';
                        break;
                }
        }

        *p = 0;

        return string(buf, end, uuid, spec);
}

int kptr_restrict __read_mostly;

static noinline_for_stack
char *restricted_pointer(char *buf, char *end, const void *ptr,
                         struct printf_spec spec)
{
        switch (kptr_restrict) {
        case 0:
                /* Always print %pK values */
                break;
        case 1: {
                const struct cred *cred;

                /*
                 * kptr_restrict==1 cannot be used in IRQ context
                 * because its test for CAP_SYSLOG would be meaningless.
                 */
                if (in_irq() || in_serving_softirq() || in_nmi()) {
                        if (spec.field_width == -1)
                                spec.field_width = 2 * sizeof(ptr);
                        return string(buf, end, "pK-error", spec);
                }

                /*
                 * Only print the real pointer value if the current
                 * process has CAP_SYSLOG and is running with the
                 * same credentials it started with. This is because
                 * access to files is checked at open() time, but %pK
                 * checks permission at read() time. We don't want to
                 * leak pointer values if a binary opens a file using
                 * %pK and then elevates privileges before reading it.
                 */
                cred = current_cred();
                if (!has_capability_noaudit(current, CAP_SYSLOG) ||
                    !uid_eq(cred->euid, cred->uid) ||
                    !gid_eq(cred->egid, cred->gid))
                        ptr = NULL;
                break;
        }
        case 2:
        default:
                /* Always print 0's for %pK */
                ptr = NULL;
                break;
        }

        return pointer_string(buf, end, ptr, spec);
}

static noinline_for_stack
char *netdev_bits(char *buf, char *end, const void *addr,
                  struct printf_spec spec,  const char *fmt)
{
        unsigned long long num;
        int size;

        switch (fmt[1]) {
        case 'F':
                num = *(const netdev_features_t *)addr;
                size = sizeof(netdev_features_t);
                break;
        default:
                return ptr_to_id(buf, end, addr, spec);
        }

        return special_hex_number(buf, end, num, size);
}

static noinline_for_stack
char *address_val(char *buf, char *end, const void *addr, const char *fmt)
{
        unsigned long long num;
        int size;

        switch (fmt[1]) {
        case 'd':
                num = *(const dma_addr_t *)addr;
                size = sizeof(dma_addr_t);
                break;
        case 'p':
        default:
                num = *(const phys_addr_t *)addr;
                size = sizeof(phys_addr_t);
                break;
        }

        return special_hex_number(buf, end, num, size);
}

static noinline_for_stack
char *date_str(char *buf, char *end, const struct rtc_time *tm, bool r)
{
        int year = tm->tm_year + (r ? 0 : 1900);
        int mon = tm->tm_mon + (r ? 0 : 1);

        buf = number(buf, end, year, default_dec04_spec);
        if (buf < end)
                *buf = '-';
        buf++;

        buf = number(buf, end, mon, default_dec02_spec);
        if (buf < end)
                *buf = '-';
        buf++;

        return number(buf, end, tm->tm_mday, default_dec02_spec);
}

static noinline_for_stack
char *time_str(char *buf, char *end, const struct rtc_time *tm, bool r)
{
        buf = number(buf, end, tm->tm_hour, default_dec02_spec);
        if (buf < end)
                *buf = ':';
        buf++;

        buf = number(buf, end, tm->tm_min, default_dec02_spec);
        if (buf < end)
                *buf = ':';
        buf++;

        return number(buf, end, tm->tm_sec, default_dec02_spec);
}

static noinline_for_stack
char *rtc_str(char *buf, char *end, const struct rtc_time *tm, const char *fmt)
{
        bool have_t = true, have_d = true;
        bool raw = false;
        int count = 2;

        switch (fmt[count]) {
        case 'd':
                have_t = false;
                count++;
                break;
        case 't':
                have_d = false;
                count++;
                break;
        }

        raw = fmt[count] == 'r';

        if (have_d)
                buf = date_str(buf, end, tm, raw);
        if (have_d && have_t) {
                /* Respect ISO 8601 */
                if (buf < end)
                        *buf = 'T';
                buf++;
        }
        if (have_t)
                buf = time_str(buf, end, tm, raw);

        return buf;
}

static noinline_for_stack
char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
                    const char *fmt)
{
        switch (fmt[1]) {
        case 'R':
                return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt);
        default:
                return ptr_to_id(buf, end, ptr, spec);
        }
}

static noinline_for_stack
char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
            const char *fmt)
{
        if (!IS_ENABLED(CONFIG_HAVE_CLK) || !clk)
                return string(buf, end, NULL, spec);

        switch (fmt[1]) {
        case 'n':
        default:
#ifdef CONFIG_COMMON_CLK
                return string(buf, end, __clk_get_name(clk), spec);
#else
                return ptr_to_id(buf, end, clk, spec);
#endif
        }
}

static
char *format_flags(char *buf, char *end, unsigned long flags,
                                        const struct trace_print_flags *names)
{
        unsigned long mask;

        for ( ; flags && names->name; names++) {
                mask = names->mask;
                if ((flags & mask) != mask)
                        continue;

                buf = string(buf, end, names->name, default_str_spec);

                flags &= ~mask;
                if (flags) {
                        if (buf < end)
                                *buf = '|';
                        buf++;
                }
        }

        if (flags)
                buf = number(buf, end, flags, default_flag_spec);

        return buf;
}

static noinline_for_stack
char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
{
        unsigned long flags;
        const struct trace_print_flags *names;

        switch (fmt[1]) {
        case 'p':
                flags = *(unsigned long *)flags_ptr;
                /* Remove zone id */
                flags &= (1UL << NR_PAGEFLAGS) - 1;
                names = pageflag_names;
                break;
        case 'v':
                flags = *(unsigned long *)flags_ptr;
                names = vmaflag_names;
                break;
        case 'g':
                flags = *(gfp_t *)flags_ptr;
                names = gfpflag_names;
                break;
        default:
                WARN_ONCE(1, "Unsupported flags modifier: %c\n", fmt[1]);
                return buf;
        }

        return format_flags(buf, end, flags, names);
}

static const char *device_node_name_for_depth(const struct device_node *np, int depth)
{
        for ( ; np && depth; depth--)
                np = np->parent;

        return kbasename(np->full_name);
}

static noinline_for_stack
char *device_node_gen_full_name(const struct device_node *np, char *buf, char *end)
{
        int depth;
        const struct device_node *parent = np->parent;

        /* special case for root node */
        if (!parent)
                return string(buf, end, "/", default_str_spec);

        for (depth = 0; parent->parent; depth++)
                parent = parent->parent;

        for ( ; depth >= 0; depth--) {
                buf = string(buf, end, "/", default_str_spec);
                buf = string(buf, end, device_node_name_for_depth(np, depth),
                             default_str_spec);
        }
        return buf;
}

static noinline_for_stack
char *device_node_string(char *buf, char *end, struct device_node *dn,
                         struct printf_spec spec, const char *fmt)
{
        char tbuf[sizeof("xxxx") + 1];
        const char *p;
        int ret;
        char *buf_start = buf;
        struct property *prop;
        bool has_mult, pass;
        static const struct printf_spec num_spec = {
                .flags = SMALL,
                .field_width = -1,
                .precision = -1,
                .base = 10,
        };

        struct printf_spec str_spec = spec;
        str_spec.field_width = -1;

        if (!IS_ENABLED(CONFIG_OF))
                return string(buf, end, "(!OF)", spec);

        if ((unsigned long)dn < PAGE_SIZE)
                return string(buf, end, "(null)", spec);

        /* simple case without anything any more format specifiers */
        fmt++;
        if (fmt[0] == '\0' || strcspn(fmt,"fnpPFcC") > 0)
                fmt = "f";

        for (pass = false; strspn(fmt,"fnpPFcC"); fmt++, pass = true) {
                int precision;
                if (pass) {
                        if (buf < end)
                                *buf = ':';
                        buf++;
                }

                switch (*fmt) {
                case 'f':       /* full_name */
                        buf = device_node_gen_full_name(dn, buf, end);
                        break;
                case 'n':       /* name */
                        p = kbasename(of_node_full_name(dn));
                        precision = str_spec.precision;
                        str_spec.precision = strchrnul(p, '@') - p;
                        buf = string(buf, end, p, str_spec);
                        str_spec.precision = precision;
                        break;
                case 'p':       /* phandle */
                        buf = number(buf, end, (unsigned int)dn->phandle, num_spec);
                        break;
                case 'P':       /* path-spec */
                        p = kbasename(of_node_full_name(dn));
                        if (!p[1])
                                p = "/";
                        buf = string(buf, end, p, str_spec);
                        break;
                case 'F':       /* flags */
                        tbuf[0] = of_node_check_flag(dn, OF_DYNAMIC) ? 'D' : '-';
                        tbuf[1] = of_node_check_flag(dn, OF_DETACHED) ? 'd' : '-';
                        tbuf[2] = of_node_check_flag(dn, OF_POPULATED) ? 'P' : '-';
                        tbuf[3] = of_node_check_flag(dn, OF_POPULATED_BUS) ? 'B' : '-';
                        tbuf[4] = 0;
                        buf = string(buf, end, tbuf, str_spec);
                        break;
                case 'c':       /* major compatible string */
                        ret = of_property_read_string(dn, "compatible", &p);
                        if (!ret)
                                buf = string(buf, end, p, str_spec);
                        break;
                case 'C':       /* full compatible string */
                        has_mult = false;
                        of_property_for_each_string(dn, "compatible", prop, p) {
                                if (has_mult)
                                        buf = string(buf, end, ",", str_spec);
                                buf = string(buf, end, "\"", str_spec);
                                buf = string(buf, end, p, str_spec);
                                buf = string(buf, end, "\"", str_spec);

                                has_mult = true;
                        }
                        break;
                default:
                        break;
                }
        }

        return widen_string(buf, buf - buf_start, end, spec);
}

/*
 * Show a '%p' thing.  A kernel extension is that the '%p' is followed
 * by an extra set of alphanumeric characters that are extended format
 * specifiers.
 *
 * Please update scripts/checkpatch.pl when adding/removing conversion
 * characters.  (Search for "check for vsprintf extension").
 *
 * Right now we handle:
 *
 * - 'S' For symbolic direct pointers (or function descriptors) with offset
 * - 's' For symbolic direct pointers (or function descriptors) without offset
 * - 'F' Same as 'S'
 * - 'f' Same as 's'
 * - '[FfSs]R' as above with __builtin_extract_return_addr() translation
 * - 'B' For backtraced symbolic direct pointers with offset
 * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
 * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
 * - 'b[l]' For a bitmap, the number of bits is determined by the field
 *       width which must be explicitly specified either as part of the
 *       format string '%32b[l]' or through '%*b[l]', [l] selects
 *       range-list format instead of hex format
 * - 'M' For a 6-byte MAC address, it prints the address in the
 *       usual colon-separated hex notation
 * - 'm' For a 6-byte MAC address, it prints the hex address without colons
 * - 'MF' For a 6-byte MAC FDDI address, it prints the address
 *       with a dash-separated hex notation
 * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth)
 * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
 *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
 *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - 'i' [46] for 'raw' IPv4/IPv6 addresses
 *       IPv6 omits the colons (01020304...0f)
 *       IPv4 uses dot-separated decimal with leading 0's (010.123.045.006)
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
 * - 'I[6S]c' for IPv6 addresses printed as specified by
 *       http://tools.ietf.org/html/rfc5952
 * - 'E[achnops]' For an escaped buffer, where rules are defined by combination
 *                of the following flags (see string_escape_mem() for the
 *                details):
 *                  a - ESCAPE_ANY
 *                  c - ESCAPE_SPECIAL
 *                  h - ESCAPE_HEX
 *                  n - ESCAPE_NULL
 *                  o - ESCAPE_OCTAL
 *                  p - ESCAPE_NP
 *                  s - ESCAPE_SPACE
 *                By default ESCAPE_ANY_NP is used.
 * - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form
 *       "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
 *       Options for %pU are:
 *         b big endian lower case hex (default)
 *         B big endian UPPER case hex
 *         l little endian lower case hex
 *         L little endian UPPER case hex
 *           big endian output byte order is:
 *             [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15]
 *           little endian output byte order is:
 *             [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15]
 * - 'V' For a struct va_format which contains a format string * and va_list *,
 *       call vsnprintf(->format, *->va_list).
 *       Implements a "recursive vsnprintf".
 *       Do not use this feature without some mechanism to verify the
 *       correctness of the format string and va_list arguments.
 * - 'K' For a kernel pointer that should be hidden from unprivileged users
 * - 'NF' For a netdev_features_t
 * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
 *            a certain separator (' ' by default):
 *              C colon
 *              D dash
 *              N no separator
 *            The maximum supported length is 64 bytes of the input. Consider
 *            to use print_hex_dump() for the larger input.
 * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives
 *           (default assumed to be phys_addr_t, passed by reference)
 * - 'd[234]' For a dentry name (optionally 2-4 last components)
 * - 'D[234]' Same as 'd' but for a struct file
 * - 'g' For block_device name (gendisk + partition number)
 * - 't[R][dt][r]' For time and date as represented:
 *      R    struct rtc_time
 * - 'C' For a clock, it prints the name (Common Clock Framework) or address
 *       (legacy clock framework) of the clock
 * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
 *        (legacy clock framework) of the clock
 * - 'G' For flags to be printed as a collection of symbolic strings that would
 *       construct the specific value. Supported flags given by option:
 *       p page flags (see struct page) given as pointer to unsigned long
 *       g gfp flags (GFP_* and __GFP_*) given as pointer to gfp_t
 *       v vma flags (VM_*) given as pointer to unsigned long
 * - 'OF[fnpPcCF]'  For a device tree object
 *                  Without any optional arguments prints the full_name
 *                  f device node full_name
 *                  n device node name
 *                  p device node phandle
 *                  P device node path spec (name + @unit)
 *                  F device node flags
 *                  c major compatible string
 *                  C full compatible string
 * - 'x' For printing the address. Equivalent to "%lx".
 *
 * ** When making changes please also update:
 *      Documentation/core-api/printk-formats.rst
 *
 * Note: The default behaviour (unadorned %p) is to hash the address,
 * rendering it useful as a unique identifier.
 */
static noinline_for_stack
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
              struct printf_spec spec)
{
        const int default_width = 2 * sizeof(void *);

        if (!ptr && *fmt != 'K' && *fmt != 'x') {
                /*
                 * Print (null) with the same width as a pointer so it makes
                 * tabular output look nice.
                 */
                if (spec.field_width == -1)
                        spec.field_width = default_width;
                return string(buf, end, "(null)", spec);
        }

        switch (*fmt) {
        case 'F':
        case 'f':
        case 'S':
        case 's':
                ptr = dereference_symbol_descriptor(ptr);
                /* Fallthrough */
        case 'B':
                return symbol_string(buf, end, ptr, spec, fmt);
        case 'R':
        case 'r':
                return resource_string(buf, end, ptr, spec, fmt);
        case 'h':
                return hex_string(buf, end, ptr, spec, fmt);
        case 'b':
                switch (fmt[1]) {
                case 'l':
                        return bitmap_list_string(buf, end, ptr, spec, fmt);
                default:
                        return bitmap_string(buf, end, ptr, spec, fmt);
                }
        case 'M':                       /* Colon separated: 00:01:02:03:04:05 */
        case 'm':                       /* Contiguous: 000102030405 */
                                        /* [mM]F (FDDI) */
                                        /* [mM]R (Reverse order; Bluetooth) */
                return mac_address_string(buf, end, ptr, spec, fmt);
        case 'I':                       /* Formatted IP supported
                                         * 4:   1.2.3.4
                                         * 6:   0001:0203:...:0708

                                         * 6c:  1::708 or 1::1.2.3.4
                                         */
        case 'i':                       /* Contiguous:
                                         * 4:   001.002.003.004
                                         * 6:   000102...0f
                                         */
                switch (fmt[1]) {
                case '6':
                        return ip6_addr_string(buf, end, ptr, spec, fmt);
                case '4':
                        return ip4_addr_string(buf, end, ptr, spec, fmt);
                case 'S': {
                        const union {
                                struct sockaddr         raw;
                                struct sockaddr_in      v4;
                                struct sockaddr_in6     v6;
                        } *sa = ptr;

                        switch (sa->raw.sa_family) {
                        case AF_INET:
                                return ip4_addr_string_sa(buf, end, &sa->v4, spec, fmt);
                        case AF_INET6:
                                return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
                        default:
                                return string(buf, end, "(invalid address)", spec);
                        }}
                }
                break;
        case 'E':
                return escaped_string(buf, end, ptr, spec, fmt);
        case 'U':
                return uuid_string(buf, end, ptr, spec, fmt);
        case 'V':
                {
                        va_list va;

                        va_copy(va, *((struct va_format *)ptr)->va);
                        buf += vsnprintf(buf, end > buf ? end - buf : 0,
                                         ((struct va_format *)ptr)->fmt, va);
                        va_end(va);
                        return buf;
                }
        case 'K':
                if (!kptr_restrict)
                        break;
                return restricted_pointer(buf, end, ptr, spec);
        case 'N':
                return netdev_bits(buf, end, ptr, spec, fmt);
        case 'a':
                return address_val(buf, end, ptr, fmt);
        case 'd':
                return dentry_name(buf, end, ptr, spec, fmt);
        case 't':
                return time_and_date(buf, end, ptr, spec, fmt);
        case 'C':
                return clock(buf, end, ptr, spec, fmt);
        case 'D':
                return dentry_name(buf, end,
                                   ((const struct file *)ptr)->f_path.dentry,
                                   spec, fmt);
#ifdef CONFIG_BLOCK
        case 'g':
                return bdev_name(buf, end, ptr, spec, fmt);
#endif

        case 'G':
                return flags_string(buf, end, ptr, fmt);
        case 'O':
                switch (fmt[1]) {
                case 'F':
                        return device_node_string(buf, end, ptr, spec, fmt + 1);
                }
                break;
        case 'x':
                return pointer_string(buf, end, ptr, spec);
        }

        /* default is to _not_ leak addresses, hash before printing */
        return ptr_to_id(buf, end, ptr, spec);
}

/*
 * Helper function to decode printf style format.
 * Each call decode a token from the format and return the
 * number of characters read (or likely the delta where it wants
 * to go on the next call).
 * The decoded token is returned through the parameters
 *
 * 'h', 'l', or 'L' for integer fields
 * 'z' support added 23/7/1999 S.H.
 * 'z' changed to 'Z' --davidm 1/25/99
 * 'Z' changed to 'z' --adobriyan 2017-01-25
 * 't' added for ptrdiff_t
 *
 * @fmt: the format string
 * @type of the token returned
 * @flags: various flags such as +, -, # tokens..
 * @field_width: overwritten width
 * @base: base of the number (octal, hex, ...)
 * @precision: precision of a number
 * @qualifier: qualifier of a number (long, size_t, ...)
 */
static noinline_for_stack
int format_decode(const char *fmt, struct printf_spec *spec)
{
        const char *start = fmt;
        char qualifier;

        /* we finished early by reading the field width */
        if (spec->type == FORMAT_TYPE_WIDTH) {
                if (spec->field_width < 0) {
                        spec->field_width = -spec->field_width;
                        spec->flags |= LEFT;
                }
                spec->type = FORMAT_TYPE_NONE;
                goto precision;
        }

        /* we finished early by reading the precision */
        if (spec->type == FORMAT_TYPE_PRECISION) {
                if (spec->precision < 0)
                        spec->precision = 0;

                spec->type = FORMAT_TYPE_NONE;
                goto qualifier;
        }

        /* By default */
        spec->type = FORMAT_TYPE_NONE;

        for (; *fmt ; ++fmt) {
                if (*fmt == '%')
                        break;
        }

        /* Return the current non-format string */
        if (fmt != start || !*fmt)
                return fmt - start;

        /* Process flags */
        spec->flags = 0;

        while (1) { /* this also skips first '%' */
                bool found = true;

                ++fmt;

                switch (*fmt) {
                case '-': spec->flags |= LEFT;    break;
                case '+': spec->flags |= PLUS;    break;
                case ' ': spec->flags |= SPACE;   break;
                case '#': spec->flags |= SPECIAL; break;
                case '0': spec->flags |= ZEROPAD; break;
                default:  found = false;
                }

                if (!found)
                        break;
        }

        /* get field width */
        spec->field_width = -1;

        if (isdigit(*fmt))
                spec->field_width = skip_atoi(&fmt);
        else if (*fmt == '*') {
                /* it's the next argument */
                spec->type = FORMAT_TYPE_WIDTH;
                return ++fmt - start;
        }

precision:
        /* get the precision */
        spec->precision = -1;
        if (*fmt == '.') {
                ++fmt;
                if (isdigit(*fmt)) {
                        spec->precision = skip_atoi(&fmt);
                        if (spec->precision < 0)
                                spec->precision = 0;
                } else if (*fmt == '*') {
                        /* it's the next argument */
                        spec->type = FORMAT_TYPE_PRECISION;
                        return ++fmt - start;
                }
        }

qualifier:
        /* get the conversion qualifier */
        qualifier = 0;
        if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
            *fmt == 'z' || *fmt == 't') {
                qualifier = *fmt++;
                if (unlikely(qualifier == *fmt)) {
                        if (qualifier == 'l') {
                                qualifier = 'L';
                                ++fmt;
                        } else if (qualifier == 'h') {
                                qualifier = 'H';
                                ++fmt;
                        }
                }
        }

        /* default base */
        spec->base = 10;
        switch (*fmt) {
        case 'c':
                spec->type = FORMAT_TYPE_CHAR;
                return ++fmt - start;

        case 's':
                spec->type = FORMAT_TYPE_STR;
                return ++fmt - start;

        case 'p':
                spec->type = FORMAT_TYPE_PTR;
                return ++fmt - start;

        case '%':
                spec->type = FORMAT_TYPE_PERCENT_CHAR;
                return ++fmt - start;

        /* integer number formats - set up the flags and "break" */
        case 'o':
                spec->base = 8;
                break;

        case 'x':
                spec->flags |= SMALL;
                /* fall through */

        case 'X':
                spec->base = 16;
                break;

        case 'd':
        case 'i':
                spec->flags |= SIGN;
        case 'u':
                break;

        case 'n':
                /*
                 * Since %n poses a greater security risk than
                 * utility, treat it as any other invalid or
                 * unsupported format specifier.
                 */
                /* Fall-through */

        default:
                WARN_ONCE(1, "Please remove unsupported %%%c in format string\n", *fmt);
                spec->type = FORMAT_TYPE_INVALID;
                return fmt - start;
        }

        if (qualifier == 'L')
                spec->type = FORMAT_TYPE_LONG_LONG;
        else if (qualifier == 'l') {
                BUILD_BUG_ON(FORMAT_TYPE_ULONG + SIGN != FORMAT_TYPE_LONG);
                spec->type = FORMAT_TYPE_ULONG + (spec->flags & SIGN);
        } else if (qualifier == 'z') {
                spec->type = FORMAT_TYPE_SIZE_T;
        } else if (qualifier == 't') {
                spec->type = FORMAT_TYPE_PTRDIFF;
        } else if (qualifier == 'H') {
                BUILD_BUG_ON(FORMAT_TYPE_UBYTE + SIGN != FORMAT_TYPE_BYTE);
                spec->type = FORMAT_TYPE_UBYTE + (spec->flags & SIGN);
        } else if (qualifier == 'h') {
                BUILD_BUG_ON(FORMAT_TYPE_USHORT + SIGN != FORMAT_TYPE_SHORT);
                spec->type = FORMAT_TYPE_USHORT + (spec->flags & SIGN);
        } else {
                BUILD_BUG_ON(FORMAT_TYPE_UINT + SIGN != FORMAT_TYPE_INT);
                spec->type = FORMAT_TYPE_UINT + (spec->flags & SIGN);
        }

        return ++fmt - start;
}

static void
set_field_width(struct printf_spec *spec, int width)
{
        spec->field_width = width;
        if (WARN_ONCE(spec->field_width != width, "field width %d too large", width)) {
                spec->field_width = clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX);
        }
}

static void
set_precision(struct printf_spec *spec, int prec)
{
        spec->precision = prec;
        if (WARN_ONCE(spec->precision != prec, "precision %d too large", prec)) {
                spec->precision = clamp(prec, 0, PRECISION_MAX);
        }
}

/**
 * vsnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * This function generally follows C99 vsnprintf, but has some
 * extensions and a few limitations:
 *
 *  - ``%n`` is unsupported
 *  - ``%p*`` is handled by pointer()
 *
 * See pointer() or Documentation/core-api/printk-formats.rst for more
 * extensive description.
 *
 * **Please update the documentation in both places when making changes**
 *
 * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99. If you want to have the exact
 * number of characters written into @buf as return value
 * (not including the trailing '\0'), use vscnprintf(). If the
 * return is greater than or equal to @size, the resulting
 * string is truncated.
 *
 * If you're not already dealing with a va_list consider using snprintf().
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
        unsigned long long num;
        char *str, *end;
        struct printf_spec spec = {0};

        /* Reject out-of-range values early.  Large positive sizes are
           used for unknown buffer sizes. */
        if (WARN_ON_ONCE(size > INT_MAX))
                return 0;

        str = buf;
        end = buf + size;

        /* Make sure end is always >= buf */
        if (end < buf) {
                end = ((void *)-1);
                size = end - buf;
        }

        while (*fmt) {
                const char *old_fmt = fmt;
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE: {
                        int copy = read;
                        if (str < end) {
                                if (copy > end - str)
                                        copy = end - str;
                                memcpy(str, old_fmt, copy);
                        }
                        str += read;
                        break;
                }

                case FORMAT_TYPE_WIDTH:
                        set_field_width(&spec, va_arg(args, int));
                        break;

                case FORMAT_TYPE_PRECISION:
                        set_precision(&spec, va_arg(args, int));
                        break;

                case FORMAT_TYPE_CHAR: {
                        char c;

                        if (!(spec.flags & LEFT)) {
                                while (--spec.field_width > 0) {
                                        if (str < end)
                                                *str = ' ';
                                        ++str;

                                }
                        }
                        c = (unsigned char) va_arg(args, int);
                        if (str < end)
                                *str = c;
                        ++str;
                        while (--spec.field_width > 0) {
                                if (str < end)
                                        *str = ' ';
                                ++str;
                        }
                        break;
                }

                case FORMAT_TYPE_STR:
                        str = string(str, end, va_arg(args, char *), spec);
                        break;

                case FORMAT_TYPE_PTR:
                        str = pointer(fmt, str, end, va_arg(args, void *),
                                      spec);
                        while (isalnum(*fmt))
                                fmt++;
                        break;

                case FORMAT_TYPE_PERCENT_CHAR:
                        if (str < end)
                                *str = '%';
                        ++str;
                        break;

                case FORMAT_TYPE_INVALID:
                        /*
                         * Presumably the arguments passed gcc's type
                         * checking, but there is no safe or sane way
                         * for us to continue parsing the format and
                         * fetching from the va_list; the remaining
                         * specifiers and arguments would be out of
                         * sync.
                         */
                        goto out;

                default:
                        switch (spec.type) {
                        case FORMAT_TYPE_LONG_LONG:
                                num = va_arg(args, long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                                num = va_arg(args, unsigned long);
                                break;
                        case FORMAT_TYPE_LONG:
                                num = va_arg(args, long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                if (spec.flags & SIGN)
                                        num = va_arg(args, ssize_t);
                                else
                                        num = va_arg(args, size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                num = va_arg(args, ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                                num = (unsigned char) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_BYTE:
                                num = (signed char) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_USHORT:
                                num = (unsigned short) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_SHORT:
                                num = (short) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_INT:
                                num = (int) va_arg(args, int);
                                break;
                        default:
                                num = va_arg(args, unsigned int);
                        }

                        str = number(str, end, num, spec);
                }
        }

out:
        if (size > 0) {
                if (str < end)
                        *str = '\0';
                else
                        end[-1] = '\0';
        }

        /* the trailing null byte doesn't count towards the total */
        return str-buf;

}
EXPORT_SYMBOL(vsnprintf);

/**
 * vscnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The return value is the number of characters which have been written into
 * the @buf not including the trailing '\0'. If @size is == 0 the function
 * returns 0.
 *
 * If you're not already dealing with a va_list consider using scnprintf().
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
        int i;

        i = vsnprintf(buf, size, fmt, args);

        if (likely(i < size))
                return i;
        if (size != 0)
                return size - 1;
        return 0;
}
EXPORT_SYMBOL(vscnprintf);

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters which would be
 * generated for the given input, excluding the trailing null,
 * as per ISO C99.  If the return is greater than or equal to
 * @size, the resulting string is truncated.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int snprintf(char *buf, size_t size, const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        i = vsnprintf(buf, size, fmt, args);
        va_end(args);

        return i;
}
EXPORT_SYMBOL(snprintf);

/**
 * scnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters written into @buf not including
 * the trailing '\0'. If @size is == 0 the function returns 0.
 */

int scnprintf(char *buf, size_t size, const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        i = vscnprintf(buf, size, fmt, args);
        va_end(args);

        return i;
}
EXPORT_SYMBOL(scnprintf);

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use vsnprintf() or vscnprintf() in order to avoid
 * buffer overflows.
 *
 * If you're not already dealing with a va_list consider using sprintf().
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int vsprintf(char *buf, const char *fmt, va_list args)
{
        return vsnprintf(buf, INT_MAX, fmt, args);
}
EXPORT_SYMBOL(vsprintf);

/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use snprintf() or scnprintf() in order to avoid
 * buffer overflows.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int sprintf(char *buf, const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        i = vsnprintf(buf, INT_MAX, fmt, args);
        va_end(args);

        return i;
}
EXPORT_SYMBOL(sprintf);

#ifdef CONFIG_BINARY_PRINTF
/*
 * bprintf service:
 * vbin_printf() - VA arguments to binary data
 * bstr_printf() - Binary data to text string
 */

/**
 * vbin_printf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The format follows C99 vsnprintf, except %n is ignored, and its argument
 * is skipped.
 *
 * The return value is the number of words(32bits) which would be generated for
 * the given input.
 *
 * NOTE:
 * If the return value is greater than @size, the resulting bin_buf is NOT
 * valid for bstr_printf().
 */
int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
{
        struct printf_spec spec = {0};
        char *str, *end;
        int width;

        str = (char *)bin_buf;
        end = (char *)(bin_buf + size);

#define save_arg(type)                                                  \
({                                                                      \
        unsigned long long value;                                       \
        if (sizeof(type) == 8) {                                        \
                unsigned long long val8;                                \
                str = PTR_ALIGN(str, sizeof(u32));                      \
                val8 = va_arg(args, unsigned long long);                \
                if (str + sizeof(type) <= end) {                        \
                        *(u32 *)str = *(u32 *)&val8;                    \
                        *(u32 *)(str + 4) = *((u32 *)&val8 + 1);        \
                }                                                       \
                value = val8;                                           \
        } else {                                                        \
                unsigned int val4;                                      \
                str = PTR_ALIGN(str, sizeof(type));                     \
                val4 = va_arg(args, int);                               \
                if (str + sizeof(type) <= end)                          \
                        *(typeof(type) *)str = (type)(long)val4;        \
                value = (unsigned long long)val4;                       \
        }                                                               \
        str += sizeof(type);                                            \
        value;                                                          \
})

        while (*fmt) {
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE:
                case FORMAT_TYPE_PERCENT_CHAR:
                        break;
                case FORMAT_TYPE_INVALID:
                        goto out;

                case FORMAT_TYPE_WIDTH:
                case FORMAT_TYPE_PRECISION:
                        width = (int)save_arg(int);
                        /* Pointers may require the width */
                        if (*fmt == 'p')
                                set_field_width(&spec, width);
                        break;

                case FORMAT_TYPE_CHAR:
                        save_arg(char);
                        break;

                case FORMAT_TYPE_STR: {
                        const char *save_str = va_arg(args, char *);
                        size_t len;

                        if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE
                                        || (unsigned long)save_str < PAGE_SIZE)
                                save_str = "(null)";
                        len = strlen(save_str) + 1;
                        if (str + len < end)
                                memcpy(str, save_str, len);
                        str += len;
                        break;
                }

                case FORMAT_TYPE_PTR:
                        /* Dereferenced pointers must be done now */
                        switch (*fmt) {
                        /* Dereference of functions is still OK */
                        case 'S':
                        case 's':
                        case 'F':
                        case 'f':
                        case 'x':
                        case 'K':
                                save_arg(void *);
                                break;
                        default:
                                if (!isalnum(*fmt)) {
                                        save_arg(void *);
                                        break;
                                }
                                str = pointer(fmt, str, end, va_arg(args, void *),
                                              spec);
                                if (str + 1 < end)
                                        *str++ = '\0';
                                else
                                        end[-1] = '\0'; /* Must be nul terminated */
                        }
                        /* skip all alphanumeric pointer suffixes */
                        while (isalnum(*fmt))
                                fmt++;
                        break;

                default:
                        switch (spec.type) {

                        case FORMAT_TYPE_LONG_LONG:
                                save_arg(long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                        case FORMAT_TYPE_LONG:
                                save_arg(unsigned long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                save_arg(size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                save_arg(ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                        case FORMAT_TYPE_BYTE:
                                save_arg(char);
                                break;
                        case FORMAT_TYPE_USHORT:
                        case FORMAT_TYPE_SHORT:
                                save_arg(short);
                                break;
                        default:
                                save_arg(int);
                        }
                }
        }

out:
        return (u32 *)(PTR_ALIGN(str, sizeof(u32))) - bin_buf;
#undef save_arg
}
EXPORT_SYMBOL_GPL(vbin_printf);

/**
 * bstr_printf - Format a string from binary arguments and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @bin_buf: Binary arguments for the format string
 *
 * This function like C99 vsnprintf, but the difference is that vsnprintf gets
 * arguments from stack, and bstr_printf gets arguments from @bin_buf which is
 * a binary buffer that generated by vbin_printf.
 *
 * The format follows C99 vsnprintf, but has some extensions:
 *  see vsnprintf comment for details.
 *
 * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99. If you want to have the exact
 * number of characters written into @buf as return value
 * (not including the trailing '\0'), use vscnprintf(). If the
 * return is greater than or equal to @size, the resulting
 * string is truncated.
 */
int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
{
        struct printf_spec spec = {0};
        char *str, *end;
        const char *args = (const char *)bin_buf;

        if (WARN_ON_ONCE(size > INT_MAX))
                return 0;

        str = buf;
        end = buf + size;

#define get_arg(type)                                                   \
({                                                                      \
        typeof(type) value;                                             \
        if (sizeof(type) == 8) {                                        \
                args = PTR_ALIGN(args, sizeof(u32));                    \
                *(u32 *)&value = *(u32 *)args;                          \
                *((u32 *)&value + 1) = *(u32 *)(args + 4);              \
        } else {                                                        \
                args = PTR_ALIGN(args, sizeof(type));                   \
                value = *(typeof(type) *)args;                          \
        }                                                               \
        args += sizeof(type);                                           \
        value;                                                          \
})

        /* Make sure end is always >= buf */
        if (end < buf) {
                end = ((void *)-1);
                size = end - buf;
        }

        while (*fmt) {
                const char *old_fmt = fmt;
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE: {
                        int copy = read;
                        if (str < end) {
                                if (copy > end - str)
                                        copy = end - str;
                                memcpy(str, old_fmt, copy);
                        }
                        str += read;
                        break;
                }

                case FORMAT_TYPE_WIDTH:
                        set_field_width(&spec, get_arg(int));
                        break;

                case FORMAT_TYPE_PRECISION:
                        set_precision(&spec, get_arg(int));
                        break;

                case FORMAT_TYPE_CHAR: {
                        char c;

                        if (!(spec.flags & LEFT)) {
                                while (--spec.field_width > 0) {
                                        if (str < end)
                                                *str = ' ';
                                        ++str;
                                }
                        }
                        c = (unsigned char) get_arg(char);
                        if (str < end)
                                *str = c;
                        ++str;
                        while (--spec.field_width > 0) {
                                if (str < end)
                                        *str = ' ';
                                ++str;
                        }
                        break;
                }

                case FORMAT_TYPE_STR: {
                        const char *str_arg = args;
                        args += strlen(str_arg) + 1;
                        str = string(str, end, (char *)str_arg, spec);
                        break;
                }

                case FORMAT_TYPE_PTR: {
                        bool process = false;
                        int copy, len;
                        /* Non function dereferences were already done */
                        switch (*fmt) {
                        case 'S':
                        case 's':
                        case 'F':
                        case 'f':
                        case 'x':
                        case 'K':
                                process = true;
                                break;
                        default:
                                if (!isalnum(*fmt)) {
                                        process = true;
                                        break;
                                }
                                /* Pointer dereference was already processed */
                                if (str < end) {
                                        len = copy = strlen(args);
                                        if (copy > end - str)
                                                copy = end - str;
                                        memcpy(str, args, copy);
                                        str += len;
                                        args += len + 1;
                                }
                        }
                        if (process)
                                str = pointer(fmt, str, end, get_arg(void *), spec);

                        while (isalnum(*fmt))
                                fmt++;
                        break;
                }

                case FORMAT_TYPE_PERCENT_CHAR:
                        if (str < end)
                                *str = '%';
                        ++str;
                        break;

                case FORMAT_TYPE_INVALID:
                        goto out;

                default: {
                        unsigned long long num;

                        switch (spec.type) {

                        case FORMAT_TYPE_LONG_LONG:
                                num = get_arg(long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                        case FORMAT_TYPE_LONG:
                                num = get_arg(unsigned long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                num = get_arg(size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                num = get_arg(ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                                num = get_arg(unsigned char);
                                break;
                        case FORMAT_TYPE_BYTE:
                                num = get_arg(signed char);
                                break;
                        case FORMAT_TYPE_USHORT:
                                num = get_arg(unsigned short);
                                break;
                        case FORMAT_TYPE_SHORT:
                                num = get_arg(short);
                                break;
                        case FORMAT_TYPE_UINT:
                                num = get_arg(unsigned int);
                                break;
                        default:
                                num = get_arg(int);
                        }

                        str = number(str, end, num, spec);
                } /* default: */
                } /* switch(spec.type) */
        } /* while(*fmt) */

out:
        if (size > 0) {
                if (str < end)
                        *str = '\0';
                else
                        end[-1] = '\0';
        }

#undef get_arg

        /* the trailing null byte doesn't count towards the total */
        return str - buf;
}
EXPORT_SYMBOL_GPL(bstr_printf);

/**
 * bprintf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of words(u32) written
 * into @bin_buf.
 */
int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...)
{
        va_list args;
        int ret;

        va_start(args, fmt);
        ret = vbin_printf(bin_buf, size, fmt, args);
        va_end(args);

        return ret;
}
EXPORT_SYMBOL_GPL(bprintf);

#endif /* CONFIG_BINARY_PRINTF */

/**
 * vsscanf - Unformat a buffer into a list of arguments
 * @buf:        input buffer
 * @fmt:        format of buffer
 * @args:       arguments
 */
int vsscanf(const char *buf, const char *fmt, va_list args)
{
        const char *str = buf;
        char *next;
        char digit;
        int num = 0;
        u8 qualifier;
        unsigned int base;
        union {
                long long s;
                unsigned long long u;
        } val;
        s16 field_width;
        bool is_sign;

        while (*fmt) {
                /* skip any white space in format */
                /* white space in format matchs any amount of
                 * white space, including none, in the input.
                 */
                if (isspace(*fmt)) {
                        fmt = skip_spaces(++fmt);
                        str = skip_spaces(str);
                }

                /* anything that is not a conversion must match exactly */
                if (*fmt != '%' && *fmt) {
                        if (*fmt++ != *str++)
                                break;
                        continue;
                }

                if (!*fmt)
                        break;
                ++fmt;

                /* skip this conversion.
                 * advance both strings to next white space
                 */
                if (*fmt == '*') {
                        if (!*str)
                                break;
                        while (!isspace(*fmt) && *fmt != '%' && *fmt) {
                                /* '%*[' not yet supported, invalid format */
                                if (*fmt == '[')
                                        return num;
                                fmt++;
                        }
                        while (!isspace(*str) && *str)
                                str++;
                        continue;
                }

                /* get field width */
                field_width = -1;
                if (isdigit(*fmt)) {
                        field_width = skip_atoi(&fmt);
                        if (field_width <= 0)
                                break;
                }

                /* get conversion qualifier */
                qualifier = -1;
                if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
                    *fmt == 'z') {
                        qualifier = *fmt++;
                        if (unlikely(qualifier == *fmt)) {
                                if (qualifier == 'h') {
                                        qualifier = 'H';
                                        fmt++;
                                } else if (qualifier == 'l') {
                                        qualifier = 'L';
                                        fmt++;
                                }
                        }
                }

                if (!*fmt)
                        break;

                if (*fmt == 'n') {
                        /* return number of characters read so far */
                        *va_arg(args, int *) = str - buf;
                        ++fmt;
                        continue;
                }

                if (!*str)
                        break;

                base = 10;
                is_sign = false;

                switch (*fmt++) {
                case 'c':
                {
                        char *s = (char *)va_arg(args, char*);
                        if (field_width == -1)
                                field_width = 1;
                        do {
                                *s++ = *str++;
                        } while (--field_width > 0 && *str);
                        num++;
                }
                continue;
                case 's':
                {
                        char *s = (char *)va_arg(args, char *);
                        if (field_width == -1)
                                field_width = SHRT_MAX;
                        /* first, skip leading white space in buffer */
                        str = skip_spaces(str);

                        /* now copy until next white space */
                        while (*str && !isspace(*str) && field_width--)
                                *s++ = *str++;
                        *s = '\0';
                        num++;
                }
                continue;
                /*
                 * Warning: This implementation of the '[' conversion specifier
                 * deviates from its glibc counterpart in the following ways:
                 * (1) It does NOT support ranges i.e. '-' is NOT a special
                 *     character
                 * (2) It cannot match the closing bracket ']' itself
                 * (3) A field width is required
                 * (4) '%*[' (discard matching input) is currently not supported
                 *
                 * Example usage:
                 * ret = sscanf("00:0a:95","%2[^:]:%2[^:]:%2[^:]",
                 *              buf1, buf2, buf3);
                 * if (ret < 3)
                 *    // etc..
                 */
                case '[':
                {
                        char *s = (char *)va_arg(args, char *);
                        DECLARE_BITMAP(set, 256) = {0};
                        unsigned int len = 0;
                        bool negate = (*fmt == '^');

                        /* field width is required */
                        if (field_width == -1)
                                return num;

                        if (negate)
                                ++fmt;

                        for ( ; *fmt && *fmt != ']'; ++fmt, ++len)
                                set_bit((u8)*fmt, set);

                        /* no ']' or no character set found */
                        if (!*fmt || !len)
                                return num;
                        ++fmt;

                        if (negate) {
                                bitmap_complement(set, set, 256);
                                /* exclude null '\0' byte */
                                clear_bit(0, set);
                        }

                        /* match must be non-empty */
                        if (!test_bit((u8)*str, set))
                                return num;

                        while (test_bit((u8)*str, set) && field_width--)
                                *s++ = *str++;
                        *s = '\0';
                        ++num;
                }
                continue;
                case 'o':
                        base = 8;
                        break;
                case 'x':
                case 'X':
                        base = 16;
                        break;
                case 'i':
                        base = 0;
                        /* fall through */
                case 'd':
                        is_sign = true;
                        /* fall through */
                case 'u':
                        break;
                case '%':
                        /* looking for '%' in str */
                        if (*str++ != '%')
                                return num;
                        continue;
                default:
                        /* invalid format; stop here */
                        return num;
                }

                /* have some sort of integer conversion.
                 * first, skip white space in buffer.
                 */
                str = skip_spaces(str);

                digit = *str;
                if (is_sign && digit == '-')
                        digit = *(str + 1);

                if (!digit
                    || (base == 16 && !isxdigit(digit))
                    || (base == 10 && !isdigit(digit))
                    || (base == 8 && (!isdigit(digit) || digit > '7'))
                    || (base == 0 && !isdigit(digit)))
                        break;

                if (is_sign)
                        val.s = qualifier != 'L' ?
                                simple_strtol(str, &next, base) :
                                simple_strtoll(str, &next, base);
                else
                        val.u = qualifier != 'L' ?
                                simple_strtoul(str, &next, base) :
                                simple_strtoull(str, &next, base);

                if (field_width > 0 && next - str > field_width) {
                        if (base == 0)
                                _parse_integer_fixup_radix(str, &base);
                        while (next - str > field_width) {
                                if (is_sign)
                                        val.s = div_s64(val.s, base);
                                else
                                        val.u = div_u64(val.u, base);
                                --next;
                        }
                }

                switch (qualifier) {
                case 'H':       /* that's 'hh' in format */
                        if (is_sign)
                                *va_arg(args, signed char *) = val.s;
                        else
                                *va_arg(args, unsigned char *) = val.u;
                        break;
                case 'h':
                        if (is_sign)
                                *va_arg(args, short *) = val.s;
                        else
                                *va_arg(args, unsigned short *) = val.u;
                        break;
                case 'l':
                        if (is_sign)
                                *va_arg(args, long *) = val.s;
                        else
                                *va_arg(args, unsigned long *) = val.u;
                        break;
                case 'L':
                        if (is_sign)
                                *va_arg(args, long long *) = val.s;
                        else
                                *va_arg(args, unsigned long long *) = val.u;
                        break;
                case 'z':
                        *va_arg(args, size_t *) = val.u;
                        break;
                default:
                        if (is_sign)
                                *va_arg(args, int *) = val.s;
                        else
                                *va_arg(args, unsigned int *) = val.u;
                        break;
                }
                num++;

                if (!next)
                        break;
                str = next;
        }

        return num;
}
EXPORT_SYMBOL(vsscanf);

/**
 * sscanf - Unformat a buffer into a list of arguments
 * @buf:        input buffer
 * @fmt:        formatting of buffer
 * @...:        resulting arguments
 */
int sscanf(const char *buf, const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        i = vsscanf(buf, fmt, args);
        va_end(args);

        return i;
}
EXPORT_SYMBOL(sscanf);