1067964305
In order to avoid making code that deals with printing both, IPv4 and
IPv6 addresses, unnecessary complicated as for example ...
if (sa.sa_family == AF_INET6)
printk("... %pI6 ...", ..sin6_addr);
else
printk("... %pI4 ...", ..sin_addr.s_addr);
... it would be better to introduce a format specifier that can deal
with those kind of situations internally; just as we have a "struct
sockaddr" for generic mapping into "struct sockaddr_in" or "struct
sockaddr_in6" as e.g. done in "union sctp_addr". Then, we could
reduce the above statement into something like:
printk("... %pIS ..", &sockaddr);
In case our pointer is NULL, pointer() then deals with that already at
an earlier point in time internally. While we're at it, support for both
%piS/%pIS, where 'S' stands for sockaddr, comes (almost) for free.
Additionally to that, postfix specifiers 'p', 'f' and 's' are supported
as suggested and initially implemented in 2009 by Joe Perches [1].
Handling of those additional specifiers orientate on the initial RFC that
was proposed. Also we support IPv6 compressed format specified by 'c' and
various other IPv4 extensions as stated in the documentation part.
Likely, there are many other areas than just SCTP in the kernel to make
use of this extension as well.
[1] http://patchwork.ozlabs.org/patch/31480/
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
CC: Joe Perches <joe@perches.com>
CC: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
209 lines
7.0 KiB
Plaintext
209 lines
7.0 KiB
Plaintext
If variable is of Type, use printk format specifier:
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---------------------------------------------------------
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int %d or %x
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unsigned int %u or %x
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long %ld or %lx
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unsigned long %lu or %lx
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long long %lld or %llx
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unsigned long long %llu or %llx
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size_t %zu or %zx
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ssize_t %zd or %zx
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Raw pointer value SHOULD be printed with %p. The kernel supports
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the following extended format specifiers for pointer types:
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Symbols/Function Pointers:
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%pF versatile_init+0x0/0x110
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%pf versatile_init
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%pS versatile_init+0x0/0x110
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%pSR versatile_init+0x9/0x110
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(with __builtin_extract_return_addr() translation)
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%ps versatile_init
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%pB prev_fn_of_versatile_init+0x88/0x88
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For printing symbols and function pointers. The 'S' and 's' specifiers
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result in the symbol name with ('S') or without ('s') offsets. Where
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this is used on a kernel without KALLSYMS - the symbol address is
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printed instead.
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The 'B' specifier results in the symbol name with offsets and should be
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used when printing stack backtraces. The specifier takes into
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consideration the effect of compiler optimisations which may occur
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when tail-call's are used and marked with the noreturn GCC attribute.
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On ia64, ppc64 and parisc64 architectures function pointers are
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actually function descriptors which must first be resolved. The 'F' and
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'f' specifiers perform this resolution and then provide the same
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functionality as the 'S' and 's' specifiers.
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Kernel Pointers:
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%pK 0x01234567 or 0x0123456789abcdef
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For printing kernel pointers which should be hidden from unprivileged
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users. The behaviour of %pK depends on the kptr_restrict sysctl - see
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Documentation/sysctl/kernel.txt for more details.
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Struct Resources:
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%pr [mem 0x60000000-0x6fffffff flags 0x2200] or
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[mem 0x0000000060000000-0x000000006fffffff flags 0x2200]
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%pR [mem 0x60000000-0x6fffffff pref] or
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[mem 0x0000000060000000-0x000000006fffffff pref]
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For printing struct resources. The 'R' and 'r' specifiers result in a
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printed resource with ('R') or without ('r') a decoded flags member.
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Physical addresses:
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%pa 0x01234567 or 0x0123456789abcdef
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For printing a phys_addr_t type (and its derivatives, such as
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resource_size_t) which can vary based on build options, regardless of
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the width of the CPU data path. Passed by reference.
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Raw buffer as a hex string:
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%*ph 00 01 02 ... 3f
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%*phC 00:01:02: ... :3f
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%*phD 00-01-02- ... -3f
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%*phN 000102 ... 3f
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For printing a small buffers (up to 64 bytes long) as a hex string with
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certain separator. For the larger buffers consider to use
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print_hex_dump().
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MAC/FDDI addresses:
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%pM 00:01:02:03:04:05
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%pMR 05:04:03:02:01:00
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%pMF 00-01-02-03-04-05
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%pm 000102030405
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%pmR 050403020100
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For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm'
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specifiers result in a printed address with ('M') or without ('m') byte
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separators. The default byte separator is the colon (':').
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Where FDDI addresses are concerned the 'F' specifier can be used after
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the 'M' specifier to use dash ('-') separators instead of the default
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separator.
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For Bluetooth addresses the 'R' specifier shall be used after the 'M'
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specifier to use reversed byte order suitable for visual interpretation
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of Bluetooth addresses which are in the little endian order.
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IPv4 addresses:
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%pI4 1.2.3.4
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%pi4 001.002.003.004
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%p[Ii][hnbl]
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For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4'
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specifiers result in a printed address with ('i4') or without ('I4')
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leading zeros.
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The additional 'h', 'n', 'b', and 'l' specifiers are used to specify
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host, network, big or little endian order addresses respectively. Where
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no specifier is provided the default network/big endian order is used.
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IPv6 addresses:
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%pI6 0001:0002:0003:0004:0005:0006:0007:0008
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%pi6 00010002000300040005000600070008
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%pI6c 1:2:3:4:5:6:7:8
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For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6'
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specifiers result in a printed address with ('I6') or without ('i6')
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colon-separators. Leading zeros are always used.
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The additional 'c' specifier can be used with the 'I' specifier to
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print a compressed IPv6 address as described by
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http://tools.ietf.org/html/rfc5952
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IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
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%pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008
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%piS 001.002.003.004 or 00010002000300040005000600070008
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%pISc 1.2.3.4 or 1:2:3:4:5:6:7:8
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%pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
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%p[Ii]S[pfschnbl]
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For printing an IP address without the need to distinguish whether it's
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of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr',
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specified through 'IS' or 'iS', can be passed to this format specifier.
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The additional 'p', 'f', and 's' specifiers are used to specify port
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(IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix,
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flowinfo a '/' and scope a '%', each followed by the actual value.
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In case of an IPv6 address the compressed IPv6 address as described by
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http://tools.ietf.org/html/rfc5952 is being used if the additional
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specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in
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case of additional specifiers 'p', 'f' or 's' as suggested by
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https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07
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In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l'
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specifiers can be used as well and are ignored in case of an IPv6
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address.
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Further examples:
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%pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789
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%pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890
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%pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789
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UUID/GUID addresses:
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%pUb 00010203-0405-0607-0809-0a0b0c0d0e0f
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%pUB 00010203-0405-0607-0809-0A0B0C0D0E0F
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%pUl 03020100-0504-0706-0809-0a0b0c0e0e0f
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%pUL 03020100-0504-0706-0809-0A0B0C0E0E0F
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For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L',
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'b' and 'B' specifiers are used to specify a little endian order in
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lower ('l') or upper case ('L') hex characters - and big endian order
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in lower ('b') or upper case ('B') hex characters.
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Where no additional specifiers are used the default little endian
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order with lower case hex characters will be printed.
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struct va_format:
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%pV
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For printing struct va_format structures. These contain a format string
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and va_list as follows:
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struct va_format {
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const char *fmt;
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va_list *va;
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};
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Do not use this feature without some mechanism to verify the
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correctness of the format string and va_list arguments.
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u64 SHOULD be printed with %llu/%llx, (unsigned long long):
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printk("%llu", (unsigned long long)u64_var);
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s64 SHOULD be printed with %lld/%llx, (long long):
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printk("%lld", (long long)s64_var);
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If <type> is dependent on a config option for its size (e.g., sector_t,
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blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
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format specifier of its largest possible type and explicitly cast to it.
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Example:
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printk("test: sector number/total blocks: %llu/%llu\n",
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(unsigned long long)sector, (unsigned long long)blockcount);
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Reminder: sizeof() result is of type size_t.
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Thank you for your cooperation and attention.
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By Randy Dunlap <rdunlap@infradead.org> and
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Andrew Murray <amurray@mpc-data.co.uk>
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