doc: convert printk-formats.txt to rst (b3ed2321) · Commits · 戴 / test

Documentation/00-INDEX

+0 −2

Original line number	Original line	Diff line number	Diff line
	@@ -346,8 +346,6 @@ prctl/
	- directory with info on the priveledge control subsystem		- directory with info on the priveledge control subsystem
	preempt-locking.txt		preempt-locking.txt
	- info on locking under a preemptive kernel.		- info on locking under a preemptive kernel.
	printk-formats.txt
	- how to get printk format specifiers right
	process/		process/
	- how to work with the mainline kernel development process.		- how to work with the mainline kernel development process.
	pps/		pps/

Documentation/core-api/index.rst

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -22,6 +22,7 @@ Core utilities
	flexible-arrays		flexible-arrays
	librs		librs
	genalloc		genalloc
			printk-formats

	Interfaces for kernel debugging		Interfaces for kernel debugging
	===============================		===============================

Documentation/printk-formats.txt→Documentation/core-api/printk-formats.rst

+118 −109

Original line number	Original line	Diff line number	Diff line
	@@ -5,6 +5,7 @@ How to get printk format specifiers right
	:Author: Randy Dunlap <rdunlap@infradead.org>		:Author: Randy Dunlap <rdunlap@infradead.org>
	:Author: Andrew Murray <amurray@mpc-data.co.uk>		:Author: Andrew Murray <amurray@mpc-data.co.uk>


	Integer types		Integer types
	=============		=============

	@@ -25,39 +26,45 @@ Integer types
	s64 %lld or %llx		s64 %lld or %llx
	u64 %llu 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``),		If <type> is dependent on a config option for its size (e.g., sector_t,
	use a format specifier of its largest possible type and explicitly cast to it.		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::		Example::

	printk("test: sector number/total blocks: %llu/%llu\n",		printk("test: sector number/total blocks: %llu/%llu\n",
	(unsigned long long)sector, (unsigned long long)blockcount);		(unsigned long long)sector, (unsigned long long)blockcount);

	Reminder: ``sizeof()`` result is of type ``size_t``.		Reminder: sizeof() returns type size_t.

	The kernel's printf does not support ``%n``. For obvious reasons, floating		The kernel's printf does not support %n. Floating point formats (%e, %f,
	point formats (``%e, %f, %g, %a``) are also not recognized. Use of any		%g, %a) are also not recognized, for obvious reasons. Use of any
	unsupported specifier or length qualifier results in a WARN and early		unsupported specifier or length qualifier results in a WARN and early
	return from vsnprintf.		return from vsnprintf().

	Raw pointer value SHOULD be printed with %p. The kernel supports
	the following extended format specifiers for pointer types:

	Pointer Types		Pointer types
	=============		=============

	Pointers printed without a specifier extension (i.e unadorned %p) are		A raw pointer value may be printed with %p which will hash the address
	hashed to give a unique identifier without leaking kernel addresses to user		before printing. The kernel also supports extended specifiers for printing
	space. On 64 bit machines the first 32 bits are zeroed. If you _really_		pointers of different types.
	want the address see %px below.
			Plain Pointers
			--------------

	::		::

	%p abcdef12 or 00000000abcdef12		%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		Symbols/Function Pointers
	=========================		-------------------------

	::		::

	@@ -69,6 +76,7 @@ Symbols/Function Pointers
	%ps versatile_init		%ps versatile_init
	%pB prev_fn_of_versatile_init+0x88/0x88		%pB prev_fn_of_versatile_init+0x88/0x88


	The ``F`` and ``f`` specifiers are for printing function pointers,		The ``F`` and ``f`` specifiers are for printing function pointers,
	for example, f->func, &gettimeofday. They have the same result as		for example, f->func, &gettimeofday. They have the same result as
	``S`` and ``s`` specifiers. But they do an extra conversion on		``S`` and ``s`` specifiers. But they do an extra conversion on
	@@ -77,14 +85,14 @@ are actually function descriptors.

	The ``S`` and ``s`` specifiers can be used for printing symbols		The ``S`` and ``s`` specifiers can be used for printing symbols
	from direct addresses, for example, __builtin_return_address(0),		from direct addresses, for example, __builtin_return_address(0),
	(void *)regs->ip. They result in the symbol name with (``S``) or		(void *)regs->ip. They result in the symbol name with (S) or
	without (``s``) offsets. If KALLSYMS are disabled then the symbol		without (s) offsets. If KALLSYMS are disabled then the symbol
	address is printed instead.		address is printed instead.

	The ``B`` specifier results in the symbol name with offsets and should be		The ``B`` specifier results in the symbol name with offsets and should be
	used when printing stack backtraces. The specifier takes into		used when printing stack backtraces. The specifier takes into
	consideration the effect of compiler optimisations which may occur		consideration the effect of compiler optimisations which may occur
	when tail-call``s are used and marked with the noreturn GCC attribute.		when tail-calls are used and marked with the noreturn GCC attribute.

	Examples::		Examples::

	@@ -97,33 +105,32 @@ Examples::
	printk(" %s%pB\n", (reliable ? "" : "? "), (void )stack);		printk(" %s%pB\n", (reliable ? "" : "? "), (void )stack);

	Kernel Pointers		Kernel Pointers
	===============		---------------

	::		::

	%pK 01234567 or 0123456789abcdef		%pK 01234567 or 0123456789abcdef

	For printing kernel pointers which should be hidden from unprivileged		For printing kernel pointers which should be hidden from unprivileged
	users. The behaviour of ``%pK`` depends on the ``kptr_restrict sysctl`` - see		users. The behaviour of %pK depends on the kptr_restrict sysctl - see
	Documentation/sysctl/kernel.txt for more details.		Documentation/sysctl/kernel.txt for more details.

	Unmodified Addresses		Unmodified Addresses
	====================		--------------------

	::		::

	%px 01234567 or 0123456789abcdef		%px 01234567 or 0123456789abcdef

	For printing pointers when you _really_ want to print the address. Please		For printing pointers when you really want to print the address. Please
	consider whether or not you are leaking sensitive information about the		consider whether or not you are leaking sensitive information about the
	Kernel layout in memory before printing pointers with %px. %px is		kernel memory layout before printing pointers with %px. %px is functionally
	functionally equivalent to %lx. %px is preferred to %lx because it is more		equivalent to %lx (or %lu). %px is preferred because it is more uniquely
	uniquely grep'able. If, in the future, we need to modify the way the Kernel		grep'able. If in the future we need to modify the way the kernel handles
	handles printing pointers it will be nice to be able to find the call		printing pointers we will be better equipped to find the call sites.
	sites.

	Struct Resources		Struct Resources
	================		----------------

	::		::

	@@ -133,32 +140,37 @@ Struct Resources
	[mem 0x0000000060000000-0x000000006fffffff pref]		[mem 0x0000000060000000-0x000000006fffffff pref]

	For printing struct resources. The ``R`` and ``r`` specifiers result in a		For printing struct resources. The ``R`` and ``r`` specifiers result in a
	printed resource with (``R``) or without (``r``) a decoded flags member.		printed resource with (R) or without (r) a decoded flags member.

	Passed by reference.		Passed by reference.

	Physical addresses types ``phys_addr_t``		Physical address types phys_addr_t
	========================================		----------------------------------

	::		::

	%pa[p] 0x01234567 or 0x0123456789abcdef		%pa[p] 0x01234567 or 0x0123456789abcdef

	For printing a ``phys_addr_t`` type (and its derivatives, such as		For printing a phys_addr_t type (and its derivatives, such as
	``resource_size_t``) which can vary based on build options, regardless of		resource_size_t) which can vary based on build options, regardless of the
	the width of the CPU data path. Passed by reference.		width of the CPU data path.

	DMA addresses types ``dma_addr_t``		Passed by reference.
	==================================
			DMA address types dma_addr_t
			----------------------------

	::		::

	%pad 0x01234567 or 0x0123456789abcdef		%pad 0x01234567 or 0x0123456789abcdef

	For printing a ``dma_addr_t`` type which can vary based on build options,		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.		regardless of the width of the CPU data path.

			Passed by reference.

	Raw buffer as an escaped string		Raw buffer as an escaped string
	===============================		-------------------------------

	::		::

	@@ -168,8 +180,8 @@ For printing raw buffer as an escaped string. For the following buffer::

	1b 62 20 5c 43 07 22 90 0d 5d		1b 62 20 5c 43 07 22 90 0d 5d

	few examples show how the conversion would be done (the result string		A few examples show how the conversion would be done (excluding surrounding
	without surrounding quotes)::		quotes)::

	%*pE "\eb \C\a"\220\r]"		%*pE "\eb \C\a"\220\r]"
	%*pEhp "\x1bb \C\x07"\x90\x0d]"		%*pEhp "\x1bb \C\x07"\x90\x0d]"
	@@ -179,23 +191,23 @@ The conversion rules are applied according to an optional combination
	of flags (see :c:func:`string_escape_mem` kernel documentation for the		of flags (see :c:func:`string_escape_mem` kernel documentation for the
	details):		details):

	- ``a`` - ESCAPE_ANY		- a - ESCAPE_ANY
	- ``c`` - ESCAPE_SPECIAL		- c - ESCAPE_SPECIAL
	- ``h`` - ESCAPE_HEX		- h - ESCAPE_HEX
	- ``n`` - ESCAPE_NULL		- n - ESCAPE_NULL
	- ``o`` - ESCAPE_OCTAL		- o - ESCAPE_OCTAL
	- ``p`` - ESCAPE_NP		- p - ESCAPE_NP
	- ``s`` - ESCAPE_SPACE		- s - ESCAPE_SPACE

	By default ESCAPE_ANY_NP is used.		By default ESCAPE_ANY_NP is used.

	ESCAPE_ANY_NP is the sane choice for many cases, in particularly for		ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
	printing SSIDs.		printing SSIDs.

	If field width is omitted the 1 byte only will be escaped.		If field width is omitted then 1 byte only will be escaped.

	Raw buffer as a hex string		Raw buffer as a hex string
	==========================		--------------------------

	::		::

	@@ -204,12 +216,12 @@ Raw buffer as a hex string
	%*phD 00-01-02- ... -3f		%*phD 00-01-02- ... -3f
	%*phN 000102 ... 3f		%*phN 000102 ... 3f

	For printing a small buffers (up to 64 bytes long) as a hex string with		For printing small buffers (up to 64 bytes long) as a hex string with a
	certain separator. For the larger buffers consider to use		certain separator. For larger buffers consider using
	:c:func:`print_hex_dump`.		:c:func:`print_hex_dump`.

	MAC/FDDI addresses		MAC/FDDI addresses
	==================		------------------

	::		::

	@@ -220,11 +232,11 @@ MAC/FDDI addresses
	%pmR 050403020100		%pmR 050403020100

	For printing 6-byte MAC/FDDI addresses in hex notation. The ``M`` and ``m``		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		specifiers result in a printed address with (M) or without (m) byte
	separators. The default byte separator is the colon (``:``).		separators. The default byte separator is the colon (:).

	Where FDDI addresses are concerned the ``F`` specifier can be used after		Where FDDI addresses are concerned the ``F`` specifier can be used after
	the ``M`` specifier to use dash (``-``) separators instead of the default		the ``M`` specifier to use dash (-) separators instead of the default
	separator.		separator.

	For Bluetooth addresses the ``R`` specifier shall be used after the ``M``		For Bluetooth addresses the ``R`` specifier shall be used after the ``M``
	@@ -234,7 +246,7 @@ of Bluetooth addresses which are in the little endian order.
	Passed by reference.		Passed by reference.

	IPv4 addresses		IPv4 addresses
	==============		--------------

	::		::

	@@ -243,8 +255,8 @@ IPv4 addresses
	%p[Ii]4[hnbl]		%p[Ii]4[hnbl]

	For printing IPv4 dot-separated decimal addresses. The ``I4`` and ``i4``		For printing IPv4 dot-separated decimal addresses. The ``I4`` and ``i4``
	specifiers result in a printed address with (``i4``) or without (``I4``)		specifiers result in a printed address with (i4) or without (I4) leading
	leading zeros.		zeros.

	The additional ``h``, ``n``, ``b``, and ``l`` specifiers are used to specify		The additional ``h``, ``n``, ``b``, and ``l`` specifiers are used to specify
	host, network, big or little endian order addresses respectively. Where		host, network, big or little endian order addresses respectively. Where
	@@ -253,7 +265,7 @@ no specifier is provided the default network/big endian order is used.
	Passed by reference.		Passed by reference.

	IPv6 addresses		IPv6 addresses
	==============		--------------

	::		::

	@@ -262,7 +274,7 @@ IPv6 addresses
	%pI6c 1:2:3:4:5:6:7:8		%pI6c 1:2:3:4:5:6:7:8

	For printing IPv6 network-order 16-bit hex addresses. The ``I6`` and ``i6``		For printing IPv6 network-order 16-bit hex addresses. The ``I6`` and ``i6``
	specifiers result in a printed address with (``I6``) or without (``i6``)		specifiers result in a printed address with (I6) or without (i6)
	colon-separators. Leading zeros are always used.		colon-separators. Leading zeros are always used.

	The additional ``c`` specifier can be used with the ``I`` specifier to		The additional ``c`` specifier can be used with the ``I`` specifier to
	@@ -272,7 +284,7 @@ http://tools.ietf.org/html/rfc5952
	Passed by reference.		Passed by reference.

	IPv4/IPv6 addresses (generic, with port, flowinfo, scope)		IPv4/IPv6 addresses (generic, with port, flowinfo, scope)
	=========================================================		---------------------------------------------------------

	::		::

	@@ -282,8 +294,8 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope)
	%pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345		%pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
	%p[Ii]S[pfschnbl]		%p[Ii]S[pfschnbl]

	For printing an IP address without the need to distinguish whether it``s		For printing an IP address without the need to distinguish whether it's of
	of type AF_INET or AF_INET6, a pointer to a valid ``struct sockaddr``,		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.		specified through ``IS`` or ``iS``, can be passed to this format specifier.

	The additional ``p``, ``f``, and ``s`` specifiers are used to specify port		The additional ``p``, ``f``, and ``s`` specifiers are used to specify port
	@@ -309,7 +321,7 @@ Further examples::
	%pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789		%pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789

	UUID/GUID addresses		UUID/GUID addresses
	===================		-------------------

	::		::

	@@ -318,33 +330,33 @@ UUID/GUID addresses
	%pUl 03020100-0504-0706-0809-0a0b0c0e0e0f		%pUl 03020100-0504-0706-0809-0a0b0c0e0e0f
	%pUL 03020100-0504-0706-0809-0A0B0C0E0E0F		%pUL 03020100-0504-0706-0809-0A0B0C0E0E0F

	For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L',		For printing 16-byte UUID/GUIDs addresses. The additional ``l``, ``L``,
	'b' and 'B' specifiers are used to specify a little endian order in		``b`` and ``B`` specifiers are used to specify a little endian order in
	lower ('l') or upper case ('L') hex characters - and big endian order		lower (l) or upper case (L) hex notation - and big endian order in lower (b)
	in lower ('b') or upper case ('B') hex characters.		or upper case (B) hex notation.

	Where no additional specifiers are used the default big endian		Where no additional specifiers are used the default big endian
	order with lower case hex characters will be printed.		order with lower case hex notation will be printed.

	Passed by reference.		Passed by reference.

	dentry names		dentry names
	============		------------

	::		::

	%pd{,2,3,4}		%pd{,2,3,4}
	%pD{,2,3,4}		%pD{,2,3,4}

	For printing dentry name; if we race with :c:func:`d_move`, the name might be		For printing dentry name; if we race with :c:func:`d_move`, the name might
	a mix of old and new ones, but it won't oops. ``%pd`` dentry is a safer		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		equivalent of %s dentry->d_name.name we used to use, %pd<n> prints ``n``
	``n`` last components. ``%pD`` does the same thing for struct file.		last components. %pD does the same thing for struct file.

	Passed by reference.		Passed by reference.

	block_device names		block_device names
	==================		------------------

	::		::

	@@ -353,7 +365,7 @@ block_device names
	For printing name of block_device pointers.		For printing name of block_device pointers.

	struct va_format		struct va_format
	================		----------------

	::		::

	@@ -375,31 +387,27 @@ correctness of the format string and va_list arguments.
	Passed by reference.		Passed by reference.

	kobjects		kobjects
	========		--------

	::		::

	%pO		%pOF[fnpPcCF]

	Base specifier for kobject based structs. Must be followed with
	character for specific type of kobject as listed below:

	Device tree nodes:		For printing kobject based structs (device nodes). Default behaviour is
			equivalent to %pOFf.

	%pOF[fnpPcCF]		- 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

	For printing device tree nodes. The optional arguments are:
	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
	Without any arguments prints full_name (same as %pOFf)
	The separator when using multiple arguments is ':'		The separator when using multiple arguments is ':'

	Examples:		Examples::

	%pOF /foo/bar@0 - Node full name		%pOF /foo/bar@0 - Node full name
	%pOFf /foo/bar@0 - Same as above		%pOFf /foo/bar@0 - Same as above
	@@ -414,9 +422,8 @@ kobjects

	Passed by reference.		Passed by reference.


	struct clk		struct clk
	==========		----------

	::		::

	@@ -424,14 +431,14 @@ struct clk
	%pCn pll1		%pCn pll1
	%pCr 1560000000		%pCr 1560000000

	For printing struct clk structures. ``%pC`` and ``%pCn`` print the name		For printing struct clk structures. %pC and %pCn print the name
	(Common Clock Framework) or address (legacy clock framework) of the		(Common Clock Framework) or address (legacy clock framework) of the
	structure; ``%pCr`` prints the current clock rate.		structure; %pCr prints the current clock rate.

	Passed by reference.		Passed by reference.

	bitmap and its derivatives such as cpumask and nodemask		bitmap and its derivatives such as cpumask and nodemask
	=======================================================		-------------------------------------------------------

	::		::

	@@ -439,13 +446,13 @@ bitmap and its derivatives such as cpumask and nodemask
	%*pbl 0,3-6,8-10		%*pbl 0,3-6,8-10

	For printing bitmap and its derivatives such as cpumask and nodemask,		For printing bitmap and its derivatives such as cpumask and nodemask,
	``%pb`` output the bitmap with field width as the number of bits and ``%pbl``		%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.		output the bitmap as range list with field width as the number of bits.

	Passed by reference.		Passed by reference.

	Flags bitfields such as page flags, gfp_flags		Flags bitfields such as page flags, gfp_flags
	=============================================		---------------------------------------------

	::		::

	@@ -459,14 +466,14 @@ character. Currently supported are [p]age flags, [v]ma_flags (both
	expect ``unsigned long ``) and [g]fp_flags (expects ``gfp_t ``). The flag		expect ``unsigned long ``) and [g]fp_flags (expects ``gfp_t ``). The flag
	names and print order depends on the particular type.		names and print order depends on the particular type.

	Note that this format should not be used directly in :c:func:`TP_printk()` part		Note that this format should not be used directly in the
	of a tracepoint. Instead, use the ``show_*_flags()`` functions from		:c:func:`TP_printk()` part of a tracepoint. Instead, use the show_*_flags()
	<trace/events/mmflags.h>.		functions from <trace/events/mmflags.h>.

	Passed by reference.		Passed by reference.

	Network device features		Network device features
	=======================		-----------------------

	::		::

	@@ -476,8 +483,10 @@ For printing netdev_features_t.

	Passed by reference.		Passed by reference.

	If you add other ``%p`` extensions, please extend lib/test_printf.c with		Thanks
	one or more test cases, if at all feasible.		======

			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.		Thank you for your cooperation and attention.

lib/vsprintf.c

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1834,7 +1834,8 @@ static char ptr_to_id(char buf, char end, void ptr, struct printf_spec spec)
	*		*
	* - 'x' For printing the address. Equivalent to "%lx".		* - 'x' For printing the address. Equivalent to "%lx".
	*		*
	* Please update also Documentation/printk-formats.txt when making changes		* ** When making changes please also update:
			* Documentation/core-api/printk-formats.rst
	*		*
	* Note: The difference between 'S' and 'F' is that on ia64 and ppc64		* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
	* function pointers are really function descriptors, which contain a		* function pointers are really function descriptors, which contain a

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