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Commit 31550a16 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Linus Torvalds
Browse files

vsprintf: add support of '%*ph[CDN]' 

There are many places in the kernel where the drivers print small buffers
as a hex string.  This patch adds a support of the variable width buffer
to print it as a hex string with a delimiter.  The idea came from Pavel
Roskin here: http://www.digipedia.pl/usenet/thread/18835/17449/



Sample output of
	pr_info("buf[%d:%d] %*phC\n", from, len, len, &buf[from]);
could be look like this:
	[ 0.726130] buf[51:8] e8:16:b6:ef:e3:74:45:6e
	[ 0.750736] buf[59:15] 31:81:b8:3f:35:49:06:ae:df:32:06:05:4a:af:55
	[ 0.757602] buf[17:5] ac:16:d5:2c:ef

Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3715c530

Documentation/printk-formats.txt

+10 −0
Original line number Diff line number Diff line
@@ -53,6 +53,16 @@ Struct Resources: 
	For printing struct resources. The 'R' and 'r' specifiers result in a

	printed resource with ('R') or without ('r') a decoded flags member.



Raw buffer as a hex string:

	%*ph	00 01 02  ...  3f

	%*phC	00:01:02: ... :3f

	%*phD	00-01-02- ... -3f

	%*phN	000102 ... 3f



	For printing a small buffers (up to 64 bytes long) as a hex string with

	certain separator. For the larger buffers consider to use

	print_hex_dump().



MAC/FDDI addresses:



	%pM	00:01:02:03:04:05

lib/vsprintf.c

+55 −0
Original line number Diff line number Diff line
@@ -654,6 +654,50 @@ char *resource_string(char *buf, char *end, struct resource *res, 
	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 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)
@@ -974,6 +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
@@ -1007,6 +1058,8 @@ 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) */
@@ -1296,6 +1349,8 @@ int format_decode(const char *fmt, struct printf_spec *spec) 
 * %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 **