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-rw-r--r--lib/vsprintf.c386
1 files changed, 282 insertions, 104 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index abbabec9720..0e337541f00 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -112,106 +112,199 @@ int skip_atoi(const char **s)
/* 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
- * using code from
- * http://www.cs.uiowa.edu/~jones/bcd/decimal.html
- * (with permission from the author, Douglas W. Jones). */
+ * using ideas described at <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
+ * (with permission from the author, Douglas W. Jones).
+ */
-/* Formats correctly any integer in [0,99999].
- * Outputs from one to five digits depending on input.
- * On i386 gcc 4.1.2 -O2: ~250 bytes of code. */
+#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
+/* Formats correctly any integer in [0, 999999999] */
static noinline_for_stack
-char *put_dec_trunc(char *buf, unsigned q)
+char *put_dec_full9(char *buf, unsigned q)
{
- unsigned d3, d2, d1, d0;
- d1 = (q>>4) & 0xf;
- d2 = (q>>8) & 0xf;
- d3 = (q>>12);
-
- d0 = 6*(d3 + d2 + d1) + (q & 0xf);
- q = (d0 * 0xcd) >> 11;
- d0 = d0 - 10*q;
- *buf++ = d0 + '0'; /* least significant digit */
- d1 = q + 9*d3 + 5*d2 + d1;
- if (d1 != 0) {
- q = (d1 * 0xcd) >> 11;
- d1 = d1 - 10*q;
- *buf++ = d1 + '0'; /* next digit */
-
- d2 = q + 2*d2;
- if ((d2 != 0) || (d3 != 0)) {
- q = (d2 * 0xd) >> 7;
- d2 = d2 - 10*q;
- *buf++ = d2 + '0'; /* next digit */
-
- d3 = q + 4*d3;
- if (d3 != 0) {
- q = (d3 * 0xcd) >> 11;
- d3 = d3 - 10*q;
- *buf++ = d3 + '0'; /* next digit */
- if (q != 0)
- *buf++ = q + '0'; /* most sign. digit */
- }
- }
- }
+ unsigned r;
+ /*
+ * Possible ways to approx. divide by 10
+ * (x * 0x1999999a) >> 32 x < 1073741829 (multiply must be 64-bit)
+ * (x * 0xcccd) >> 19 x < 81920 (x < 262149 when 64-bit mul)
+ * (x * 0x6667) >> 18 x < 43699
+ * (x * 0x3334) >> 17 x < 16389
+ * (x * 0x199a) >> 16 x < 16389
+ * (x * 0x0ccd) >> 15 x < 16389
+ * (x * 0x0667) >> 14 x < 2739
+ * (x * 0x0334) >> 13 x < 1029
+ * (x * 0x019a) >> 12 x < 1029
+ * (x * 0x00cd) >> 11 x < 1029 shorter code than * 0x67 (on i386)
+ * (x * 0x0067) >> 10 x < 179
+ * (x * 0x0034) >> 9 x < 69 same
+ * (x * 0x001a) >> 8 x < 69 same
+ * (x * 0x000d) >> 7 x < 69 same, shortest code (on i386)
+ * (x * 0x0007) >> 6 x < 19
+ * See <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
+ */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 1 */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 2 */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 3 */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 4 */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 5 */
+ /* Now value is under 10000, can avoid 64-bit multiply */
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0'; /* 6 */
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0'; /* 7 */
+ q = (r * 0xcd) >> 11;
+ *buf++ = (r - 10 * q) + '0'; /* 8 */
+ *buf++ = q + '0'; /* 9 */
return buf;
}
-/* Same with if's removed. Always emits five digits */
+#endif
+
+/* Similar to above but do not pad with zeros.
+ * Code can be easily arranged to print 9 digits too, but our callers
+ * always call put_dec_full9() instead when the number has 9 decimal digits.
+ */
static noinline_for_stack
-char *put_dec_full(char *buf, unsigned q)
+char *put_dec_trunc8(char *buf, unsigned r)
{
- /* BTW, if q is in [0,9999], 8-bit ints will be enough, */
- /* but anyway, gcc produces better code with full-sized ints */
- unsigned d3, d2, d1, d0;
- d1 = (q>>4) & 0xf;
- d2 = (q>>8) & 0xf;
- d3 = (q>>12);
+ unsigned q;
+
+ /* Copy of previous function's body with added early returns */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 2 */
+ if (q == 0)
+ return buf;
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 3 */
+ if (r == 0)
+ return buf;
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 4 */
+ if (q == 0)
+ return buf;
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 5 */
+ if (r == 0)
+ return buf;
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0'; /* 6 */
+ if (q == 0)
+ return buf;
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0'; /* 7 */
+ if (r == 0)
+ return buf;
+ q = (r * 0xcd) >> 11;
+ *buf++ = (r - 10 * q) + '0'; /* 8 */
+ if (q == 0)
+ return buf;
+ *buf++ = q + '0'; /* 9 */
+ return buf;
+}
- /*
- * Possible ways to approx. divide by 10
- * gcc -O2 replaces multiply with shifts and adds
- * (x * 0xcd) >> 11: 11001101 - shorter code than * 0x67 (on i386)
- * (x * 0x67) >> 10: 1100111
- * (x * 0x34) >> 9: 110100 - same
- * (x * 0x1a) >> 8: 11010 - same
- * (x * 0x0d) >> 7: 1101 - same, shortest code (on i386)
- */
- d0 = 6*(d3 + d2 + d1) + (q & 0xf);
- q = (d0 * 0xcd) >> 11;
- d0 = d0 - 10*q;
- *buf++ = d0 + '0';
- d1 = q + 9*d3 + 5*d2 + d1;
- q = (d1 * 0xcd) >> 11;
- d1 = d1 - 10*q;
- *buf++ = d1 + '0';
-
- d2 = q + 2*d2;
- q = (d2 * 0xd) >> 7;
- d2 = d2 - 10*q;
- *buf++ = d2 + '0';
-
- d3 = q + 4*d3;
- q = (d3 * 0xcd) >> 11; /* - shorter code */
- /* q = (d3 * 0x67) >> 10; - would also work */
- d3 = d3 - 10*q;
- *buf++ = d3 + '0';
- *buf++ = q + '0';
+/* There are two algorithms to print larger numbers.
+ * One is generic: divide by 1000000000 and repeatedly print
+ * groups of (up to) 9 digits. It's conceptually simple,
+ * but requires a (unsigned long long) / 1000000000 division.
+ *
+ * Second algorithm splits 64-bit unsigned long long into 16-bit chunks,
+ * manipulates them cleverly and generates groups of 4 decimal digits.
+ * It so happens that it does NOT require long long division.
+ *
+ * If long is > 32 bits, division of 64-bit values is relatively easy,
+ * and we will use the first algorithm.
+ * If long long is > 64 bits (strange architecture with VERY large long long),
+ * second algorithm can't be used, and we again use the first one.
+ *
+ * Else (if long is 32 bits and long long is 64 bits) we use second one.
+ */
- return buf;
+#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
+
+/* First algorithm: generic */
+
+static
+char *put_dec(char *buf, unsigned long long n)
+{
+ if (n >= 100*1000*1000) {
+ while (n >= 1000*1000*1000)
+ buf = put_dec_full9(buf, do_div(n, 1000*1000*1000));
+ if (n >= 100*1000*1000)
+ return put_dec_full9(buf, n);
+ }
+ return put_dec_trunc8(buf, n);
}
-/* No inlining helps gcc to use registers better */
+
+#else
+
+/* Second algorithm: valid only for 64-bit long longs */
+
static noinline_for_stack
-char *put_dec(char *buf, unsigned long long num)
+char *put_dec_full4(char *buf, unsigned q)
{
- while (1) {
- unsigned rem;
- if (num < 100000)
- return put_dec_trunc(buf, num);
- rem = do_div(num, 100000);
- buf = put_dec_full(buf, rem);
- }
+ unsigned r;
+ r = (q * 0xcccd) >> 19;
+ *buf++ = (q - 10 * r) + '0';
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0';
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0';
+ *buf++ = r + '0';
+ return buf;
}
+/* 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" */
+
+ q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
+
+ buf = put_dec_full4(buf, q % 10000);
+ q = q / 10000;
+
+ d1 = q + 7671 * d3 + 9496 * d2 + 6 * d1;
+ buf = put_dec_full4(buf, d1 % 10000);
+ q = d1 / 10000;
+
+ d2 = q + 4749 * d3 + 42 * d2;
+ buf = put_dec_full4(buf, d2 % 10000);
+ q = d2 / 10000;
+
+ d3 = q + 281 * d3;
+ if (!d3)
+ goto done;
+ buf = put_dec_full4(buf, d3 % 10000);
+ q = d3 / 10000;
+ if (!q)
+ goto done;
+ buf = put_dec_full4(buf, q);
+ done:
+ while (buf[-1] == '0')
+ --buf;
+
+ return buf;
+}
+
+#endif
+
/*
* Convert passed number to decimal string.
* Returns the length of string. On buffer overflow, returns 0.
@@ -220,16 +313,22 @@ char *put_dec(char *buf, unsigned long long num)
*/
int num_to_str(char *buf, int size, unsigned long long num)
{
- char tmp[21]; /* Enough for 2^64 in decimal */
+ char tmp[sizeof(num) * 3];
int idx, len;
- len = put_dec(tmp, num) - tmp;
+ /* 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)
return 0;
for (idx = 0; idx < len; ++idx)
buf[idx] = tmp[len - idx - 1];
- return len;
+ return len;
}
#define ZEROPAD 1 /* pad with zero */
@@ -284,6 +383,7 @@ char *number(char *buf, char *end, unsigned long long num,
char locase;
int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
int i;
+ bool is_zero = num == 0LL;
/* locase = 0 or 0x20. ORing digits or letters with 'locase'
* produces same digits or (maybe lowercased) letters */
@@ -305,15 +405,16 @@ char *number(char *buf, char *end, unsigned long long num,
}
}
if (need_pfx) {
- spec.field_width--;
if (spec.base == 16)
+ spec.field_width -= 2;
+ else if (!is_zero)
spec.field_width--;
}
/* generate full string in tmp[], in reverse order */
i = 0;
- if (num == 0)
- tmp[i++] = '0';
+ if (num < spec.base)
+ tmp[i++] = digits[num] | locase;
/* Generic code, for any base:
else do {
tmp[i++] = (digits[do_div(num,base)] | locase);
@@ -353,9 +454,11 @@ char *number(char *buf, char *end, unsigned long long num,
}
/* "0x" / "0" prefix */
if (need_pfx) {
- if (buf < end)
- *buf = '0';
- ++buf;
+ if (spec.base == 16 || !is_zero) {
+ if (buf < end)
+ *buf = '0';
+ ++buf;
+ }
if (spec.base == 16) {
if (buf < end)
*buf = ('X' | locase);
@@ -436,7 +539,7 @@ char *symbol_string(char *buf, char *end, void *ptr,
else if (ext != 'f' && ext != 's')
sprint_symbol(sym, value);
else
- kallsyms_lookup(value, NULL, NULL, NULL, sym);
+ sprint_symbol_no_offset(sym, value);
return string(buf, end, sym, spec);
#else
@@ -552,6 +655,50 @@ char *resource_string(char *buf, char *end, struct resource *res,
}
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 witdh 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 && buf < end - 1; i++) {
+ buf = hex_byte_pack(buf, addr[i]);
+
+ if (buf < end && separator && i != len - 1)
+ *buf++ = separator;
+ }
+
+ return buf;
+}
+
+static noinline_for_stack
char *mac_address_string(char *buf, char *end, u8 *addr,
struct printf_spec spec, const char *fmt)
{
@@ -559,15 +706,28 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
char *p = mac_addr;
int i;
char separator;
+ bool reversed = false;
- if (fmt[1] == 'F') { /* FDDI canonical format */
+ switch (fmt[1]) {
+ case 'F':
separator = '-';
- } else {
+ break;
+
+ case 'R':
+ reversed = true;
+ /* fall through */
+
+ default:
separator = ':';
+ break;
}
for (i = 0; i < 6; i++) {
- p = hex_byte_pack(p, addr[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;
}
@@ -607,7 +767,7 @@ char *ip4_string(char *p, const u8 *addr, const char *fmt)
}
for (i = 0; i < 4; i++) {
char temp[3]; /* hold each IP quad in reverse order */
- int digits = put_dec_trunc(temp, addr[index]) - temp;
+ int digits = put_dec_trunc8(temp, addr[index]) - temp;
if (leading_zeros) {
if (digits < 3)
*p++ = '0';
@@ -830,6 +990,7 @@ int kptr_restrict __read_mostly;
* - '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
@@ -857,6 +1018,13 @@ int kptr_restrict __read_mostly;
* 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.
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
@@ -866,13 +1034,15 @@ static noinline_for_stack
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
struct printf_spec spec)
{
+ int default_width = 2 * sizeof(void *) + (spec.flags & SPECIAL ? 2 : 0);
+
if (!ptr && *fmt != 'K') {
/*
* Print (null) with the same width as a pointer so it makes
* tabular output look nice.
*/
if (spec.field_width == -1)
- spec.field_width = 2 * sizeof(void *);
+ spec.field_width = default_width;
return string(buf, end, "(null)", spec);
}
@@ -888,9 +1058,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
case 'R':
case 'r':
return resource_string(buf, end, ptr, spec, fmt);
+ case 'h':
+ return hex_string(buf, end, ptr, spec, fmt);
case 'M': /* Colon separated: 00:01:02:03:04:05 */
case 'm': /* Contiguous: 000102030405 */
- /* [mM]F (FDDI, bit reversed) */
+ /* [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
@@ -925,9 +1098,10 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
* %pK cannot be used in IRQ context because its test
* for CAP_SYSLOG would be meaningless.
*/
- if (in_irq() || in_serving_softirq() || in_nmi()) {
+ if (kptr_restrict && (in_irq() || in_serving_softirq() ||
+ in_nmi())) {
if (spec.field_width == -1)
- spec.field_width = 2 * sizeof(void *);
+ spec.field_width = default_width;
return string(buf, end, "pK-error", spec);
}
if (!((kptr_restrict == 0) ||
@@ -944,7 +1118,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
- spec.field_width = 2 * sizeof(void *);
+ spec.field_width = default_width;
spec.flags |= ZEROPAD;
}
spec.base = 16;
@@ -1175,8 +1349,12 @@ qualifier:
* %pI6c print an IPv6 address as specified by RFC 5952
* %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
* case.
+ * %*ph[CDN] a variable-length hex string with a separator (supports up to 64
+ * bytes of the input)
* %n is ignored
*
+ * ** Please update Documentation/printk-formats.txt 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
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-04-13 01:08:14 +0000