--- /dev/null
- %pS versatile_init+0x0/0x110
+=========================================
+How to get printk format specifiers right
+=========================================
+
+:Author: Randy Dunlap <rdunlap@infradead.org>
+:Author: Andrew Murray <amurray@mpc-data.co.uk>
+
+
+Integer types
+=============
+
+::
+
+ If variable is of Type, use printk format specifier:
+ ------------------------------------------------------------
+ int %d or %x
+ unsigned int %u or %x
+ long %ld or %lx
+ unsigned long %lu or %lx
+ long long %lld or %llx
+ unsigned long long %llu or %llx
+ size_t %zu or %zx
+ ssize_t %zd or %zx
+ s32 %d or %x
+ u32 %u or %x
+ s64 %lld or %llx
+ u64 %llu or %llx
+
+
+If <type> is dependent on a config option for its size (e.g., sector_t,
+blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
+format specifier of its largest possible type and explicitly cast to it.
+
+Example::
+
+ printk("test: sector number/total blocks: %llu/%llu\n",
+ (unsigned long long)sector, (unsigned long long)blockcount);
+
+Reminder: sizeof() returns type size_t.
+
+The kernel's printf does not support %n. Floating point formats (%e, %f,
+%g, %a) are also not recognized, for obvious reasons. Use of any
+unsupported specifier or length qualifier results in a WARN and early
+return from vsnprintf().
+
+Pointer types
+=============
+
+A raw pointer value may be printed with %p which will hash the address
+before printing. The kernel also supports extended specifiers for printing
+pointers of different types.
+
+Plain Pointers
+--------------
+
+::
+
+ %p abcdef12 or 00000000abcdef12
+
+Pointers printed without a specifier extension (i.e unadorned %p) are
+hashed to prevent leaking information about the kernel memory layout. This
+has the added benefit of providing a unique identifier. On 64-bit machines
+the first 32 bits are zeroed. If you *really* want the address see %px
+below.
+
+Symbols/Function Pointers
+-------------------------
+
+::
+
++ %pS versatile_init+0x0/0x110
++ %ps versatile_init
+ %pF versatile_init+0x0/0x110
+ %pf versatile_init
- %ps versatile_init
+ %pSR versatile_init+0x9/0x110
+ (with __builtin_extract_return_addr() translation)
- The ``F`` and ``f`` specifiers are for printing function pointers,
- for example, f->func, &gettimeofday. They have the same result as
- ``S`` and ``s`` specifiers. But they do an extra conversion on
- ia64, ppc64 and parisc64 architectures where the function pointers
- are actually function descriptors.
+ %pB prev_fn_of_versatile_init+0x88/0x88
+
+
- The ``S`` and ``s`` specifiers can be used for printing symbols
- from direct addresses, for example, __builtin_return_address(0),
- (void *)regs->ip. They result in the symbol name with (S) or
- without (s) offsets. If KALLSYMS are disabled then the symbol
- address is printed instead.
++The ``S`` and ``s`` specifiers are used for printing a pointer in symbolic
++format. They result in the symbol name with (S) or without (s)
++offsets. If KALLSYMS are disabled then the symbol address is printed instead.
+
- Examples::
-
- printk("Going to call: %pF\n", gettimeofday);
- printk("Going to call: %pF\n", p->func);
- printk("%s: called from %pS\n", __func__, (void *)_RET_IP_);
- printk("%s: called from %pS\n", __func__,
- (void *)__builtin_return_address(0));
- printk("Faulted at %pS\n", (void *)regs->ip);
- printk(" %s%pB\n", (reliable ? "" : "? "), (void *)*stack);
-
++Note, that the ``F`` and ``f`` specifiers are identical to ``S`` (``s``)
++and thus deprecated. We have ``F`` and ``f`` because on ia64, ppc64 and
++parisc64 function pointers are indirect and, in fact, are function
++descriptors, which require additional dereferencing before we can lookup
++the symbol. As of now, ``S`` and ``s`` perform dereferencing on those
++platforms (when needed), so ``F`` and ``f`` exist for compatibility
++reasons only.
+
+The ``B`` specifier results in the symbol name with offsets and should be
+used when printing stack backtraces. The specifier takes into
+consideration the effect of compiler optimisations which may occur
+when tail-calls are used and marked with the noreturn GCC attribute.
+
+Kernel Pointers
+---------------
+
+::
+
+ %pK 01234567 or 0123456789abcdef
+
+For printing kernel pointers which should be hidden from unprivileged
+users. The behaviour of %pK depends on the kptr_restrict sysctl - see
+Documentation/sysctl/kernel.txt for more details.
+
+Unmodified Addresses
+--------------------
+
+::
+
+ %px 01234567 or 0123456789abcdef
+
+For printing pointers when you *really* want to print the address. Please
+consider whether or not you are leaking sensitive information about the
+kernel memory layout before printing pointers with %px. %px is functionally
+equivalent to %lx (or %lu). %px is preferred because it is more uniquely
+grep'able. If in the future we need to modify the way the kernel handles
+printing pointers we will be better equipped to find the call sites.
+
+Struct Resources
+----------------
+
+::
+
+ %pr [mem 0x60000000-0x6fffffff flags 0x2200] or
+ [mem 0x0000000060000000-0x000000006fffffff flags 0x2200]
+ %pR [mem 0x60000000-0x6fffffff pref] or
+ [mem 0x0000000060000000-0x000000006fffffff pref]
+
+For printing struct resources. The ``R`` and ``r`` specifiers result in a
+printed resource with (R) or without (r) a decoded flags member.
+
+Passed by reference.
+
+Physical address types phys_addr_t
+----------------------------------
+
+::
+
+ %pa[p] 0x01234567 or 0x0123456789abcdef
+
+For printing a phys_addr_t type (and its derivatives, such as
+resource_size_t) which can vary based on build options, regardless of the
+width of the CPU data path.
+
+Passed by reference.
+
+DMA address types dma_addr_t
+----------------------------
+
+::
+
+ %pad 0x01234567 or 0x0123456789abcdef
+
+For printing a dma_addr_t type which can vary based on build options,
+regardless of the width of the CPU data path.
+
+Passed by reference.
+
+Raw buffer as an escaped string
+-------------------------------
+
+::
+
+ %*pE[achnops]
+
+For printing raw buffer as an escaped string. For the following buffer::
+
+ 1b 62 20 5c 43 07 22 90 0d 5d
+
+A few examples show how the conversion would be done (excluding surrounding
+quotes)::
+
+ %*pE "\eb \C\a"\220\r]"
+ %*pEhp "\x1bb \C\x07"\x90\x0d]"
+ %*pEa "\e\142\040\\\103\a\042\220\r\135"
+
+The conversion rules are applied according to an optional combination
+of flags (see :c:func:`string_escape_mem` kernel documentation 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.
+
+ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
+printing SSIDs.
+
+If field width is omitted then 1 byte only will be escaped.
+
+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 small buffers (up to 64 bytes long) as a hex string with a
+certain separator. For larger buffers consider using
+:c:func:`print_hex_dump`.
+
+MAC/FDDI addresses
+------------------
+
+::
+
+ %pM 00:01:02:03:04:05
+ %pMR 05:04:03:02:01:00
+ %pMF 00-01-02-03-04-05
+ %pm 000102030405
+ %pmR 050403020100
+
+For printing 6-byte MAC/FDDI addresses in hex notation. The ``M`` and ``m``
+specifiers result in a printed address with (M) or without (m) byte
+separators. The default byte separator is the colon (:).
+
+Where FDDI addresses are concerned the ``F`` specifier can be used after
+the ``M`` specifier to use dash (-) separators instead of the default
+separator.
+
+For Bluetooth addresses the ``R`` specifier shall be used after the ``M``
+specifier to use reversed byte order suitable for visual interpretation
+of Bluetooth addresses which are in the little endian order.
+
+Passed by reference.
+
+IPv4 addresses
+--------------
+
+::
+
+ %pI4 1.2.3.4
+ %pi4 001.002.003.004
+ %p[Ii]4[hnbl]
+
+For printing IPv4 dot-separated decimal addresses. The ``I4`` and ``i4``
+specifiers result in a printed address with (i4) or without (I4) leading
+zeros.
+
+The additional ``h``, ``n``, ``b``, and ``l`` specifiers are used to specify
+host, network, big or little endian order addresses respectively. Where
+no specifier is provided the default network/big endian order is used.
+
+Passed by reference.
+
+IPv6 addresses
+--------------
+
+::
+
+ %pI6 0001:0002:0003:0004:0005:0006:0007:0008
+ %pi6 00010002000300040005000600070008
+ %pI6c 1:2:3:4:5:6:7:8
+
+For printing IPv6 network-order 16-bit hex addresses. The ``I6`` and ``i6``
+specifiers result in a printed address with (I6) or without (i6)
+colon-separators. Leading zeros are always used.
+
+The additional ``c`` specifier can be used with the ``I`` specifier to
+print a compressed IPv6 address as described by
+http://tools.ietf.org/html/rfc5952
+
+Passed by reference.
+
+IPv4/IPv6 addresses (generic, with port, flowinfo, scope)
+---------------------------------------------------------
+
+::
+
+ %pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008
+ %piS 001.002.003.004 or 00010002000300040005000600070008
+ %pISc 1.2.3.4 or 1:2:3:4:5:6:7:8
+ %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
+ %p[Ii]S[pfschnbl]
+
+For printing an IP address without the need to distinguish whether it's of
+type AF_INET or AF_INET6. A pointer to a valid struct sockaddr,
+specified through ``IS`` or ``iS``, can be passed to this format specifier.
+
+The additional ``p``, ``f``, and ``s`` specifiers are used to specify port
+(IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ``:`` prefix,
+flowinfo a ``/`` and scope a ``%``, each followed by the actual value.
+
+In case of an IPv6 address the compressed IPv6 address as described by
+http://tools.ietf.org/html/rfc5952 is being used if the additional
+specifier ``c`` is given. The IPv6 address is surrounded by ``[``, ``]`` in
+case of additional specifiers ``p``, ``f`` or ``s`` as suggested by
+https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07
+
+In case of IPv4 addresses, the additional ``h``, ``n``, ``b``, and ``l``
+specifiers can be used as well and are ignored in case of an IPv6
+address.
+
+Passed by reference.
+
+Further examples::
+
+ %pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789
+ %pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890
+ %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789
+
+UUID/GUID addresses
+-------------------
+
+::
+
+ %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f
+ %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F
+ %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f
+ %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F
+
+For printing 16-byte UUID/GUIDs addresses. The additional ``l``, ``L``,
+``b`` and ``B`` specifiers are used to specify a little endian order in
+lower (l) or upper case (L) hex notation - and big endian order in lower (b)
+or upper case (B) hex notation.
+
+Where no additional specifiers are used the default big endian
+order with lower case hex notation will be printed.
+
+Passed by reference.
+
+dentry names
+------------
+
+::
+
+ %pd{,2,3,4}
+ %pD{,2,3,4}
+
+For printing dentry name; if we race with :c:func:`d_move`, the name might
+be a mix of old and new ones, but it won't oops. %pd dentry is a safer
+equivalent of %s dentry->d_name.name we used to use, %pd<n> prints ``n``
+last components. %pD does the same thing for struct file.
+
+Passed by reference.
+
+block_device names
+------------------
+
+::
+
+ %pg sda, sda1 or loop0p1
+
+For printing name of block_device pointers.
+
+struct va_format
+----------------
+
+::
+
+ %pV
+
+For printing struct va_format structures. These contain a format string
+and va_list as follows::
+
+ struct va_format {
+ const char *fmt;
+ va_list *va;
+ };
+
+Implements a "recursive vsnprintf".
+
+Do not use this feature without some mechanism to verify the
+correctness of the format string and va_list arguments.
+
+Passed by reference.
+
+kobjects
+--------
+
+::
+
+ %pOF[fnpPcCF]
+
+
+For printing kobject based structs (device nodes). Default behaviour is
+equivalent to %pOFf.
+
+ - 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
+
+The separator when using multiple arguments is ':'
+
+Examples::
+
+ %pOF /foo/bar@0 - Node full name
+ %pOFf /foo/bar@0 - Same as above
+ %pOFfp /foo/bar@0:10 - Node full name + phandle
+ %pOFfcF /foo/bar@0:foo,device:--P- - Node full name +
+ major compatible string +
+ node flags
+ D - dynamic
+ d - detached
+ P - Populated
+ B - Populated bus
+
+Passed by reference.
+
+struct clk
+----------
+
+::
+
+ %pC pll1
+ %pCn pll1
+ %pCr 1560000000
+
+For printing struct clk structures. %pC and %pCn print the name
+(Common Clock Framework) or address (legacy clock framework) of the
+structure; %pCr prints the current clock rate.
+
+Passed by reference.
+
+bitmap and its derivatives such as cpumask and nodemask
+-------------------------------------------------------
+
+::
+
+ %*pb 0779
+ %*pbl 0,3-6,8-10
+
+For printing bitmap and its derivatives such as cpumask and nodemask,
+%*pb outputs the bitmap with field width as the number of bits and %*pbl
+output the bitmap as range list with field width as the number of bits.
+
+Passed by reference.
+
+Flags bitfields such as page flags, gfp_flags
+---------------------------------------------
+
+::
+
+ %pGp referenced|uptodate|lru|active|private
+ %pGg GFP_USER|GFP_DMA32|GFP_NOWARN
+ %pGv read|exec|mayread|maywrite|mayexec|denywrite
+
+For printing flags bitfields as a collection of symbolic constants that
+would construct the value. The type of flags is given by the third
+character. Currently supported are [p]age flags, [v]ma_flags (both
+expect ``unsigned long *``) and [g]fp_flags (expects ``gfp_t *``). The flag
+names and print order depends on the particular type.
+
+Note that this format should not be used directly in the
+:c:func:`TP_printk()` part of a tracepoint. Instead, use the show_*_flags()
+functions from <trace/events/mmflags.h>.
+
+Passed by reference.
+
+Network device features
+-----------------------
+
+::
+
+ %pNF 0x000000000000c000
+
+For printing netdev_features_t.
+
+Passed by reference.
+
+Thanks
+======
+
+If you add other %p extensions, please extend <lib/test_printf.c> with
+one or more test cases, if at all feasible.
+
+Thank you for your cooperation and attention.
projects / linux-2.6-microblaze.git / commitdiff