Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 644 insertions, 0 deletions

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
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+=========================================
+How to get printk format specifiers right
+=========================================
+
+.. _printk-specifiers:
+
+: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:
+	------------------------------------------------------------
+		char			%d or %x
+		unsigned char		%u or %x
+		short int		%d or %x
+		unsigned short int	%u or %x
+		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
+		s8			%d or %x
+		u8			%u or %x
+		s16			%d or %x
+		u16			%u or %x
+		s32			%d or %x
+		u32			%u or %x
+		s64			%lld or %llx
+		u64			%llu or %llx
+
+
+If <type> is architecture-dependent for its size (e.g., cycles_t, tcflag_t) or
+is dependent on a config option for its size (e.g., blk_status_t), use a format
+specifier of its largest possible type and explicitly cast to it.
+
+Example::
+
+	printk("test: latency: %llu cycles\n", (unsigned long long)time);
+
+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.
+
+Some of the extended specifiers print the data on the given address instead
+of printing the address itself. In this case, the following error messages
+might be printed instead of the unreachable information::
+
+	(null)	 data on plain NULL address
+	(efault) data on invalid address
+	(einval) invalid data on a valid address
+
+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. The kernel will print ``(ptrval)`` until it
+gathers enough entropy.
+
+When possible, use specialised modifiers such as %pS or %pB (described below)
+to avoid the need of providing an unhashed address that has to be interpreted
+post-hoc. If not possible, and the aim of printing the address is to provide
+more information for debugging, use %p and boot the kernel with the
+``no_hash_pointers`` parameter during debugging, which will print all %p
+addresses unmodified. If you *really* always want the unmodified address, see
+%px below.
+
+If (and only if) you are printing addresses as a content of a virtual file in
+e.g. procfs or sysfs (using e.g. seq_printf(), not printk()) read by a
+userspace process, use the %pK modifier described below instead of %p or %px.
+
+Error Pointers
+--------------
+
+::
+
+	%pe	-ENOSPC
+
+For printing error pointers (i.e. a pointer for which IS_ERR() is true)
+as a symbolic error name. Error values for which no symbolic name is
+known are printed in decimal, while a non-ERR_PTR passed as the
+argument to %pe gets treated as ordinary %p.
+
+Symbols/Function Pointers
+-------------------------
+
+::
+
+	%pS	versatile_init+0x0/0x110
+	%ps	versatile_init
+	%pSR	versatile_init+0x9/0x110
+		(with __builtin_extract_return_addr() translation)
+	%pB	prev_fn_of_versatile_init+0x88/0x88
+
+
+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.
+
+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.
+
+If the pointer is within a module, the module name and optionally build ID is
+printed after the symbol name with an extra ``b`` appended to the end of the
+specifier.
+
+::
+
+	%pS	versatile_init+0x0/0x110 [module_name]
+	%pSb	versatile_init+0x0/0x110 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e]
+	%pSRb	versatile_init+0x9/0x110 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e]
+		(with __builtin_extract_return_addr() translation)
+	%pBb	prev_fn_of_versatile_init+0x88/0x88 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e]
+
+Probed Pointers from BPF / tracing
+----------------------------------
+
+::
+
+	%pks	kernel string
+	%pus	user string
+
+The ``k`` and ``u`` specifiers are used for printing prior probed memory from
+either kernel memory (k) or user memory (u). The subsequent ``s`` specifier
+results in printing a string. For direct use in regular vsnprintf() the (k)
+and (u) annotation is ignored, however, when used out of BPF's bpf_trace_printk(),
+for example, it reads the memory it is pointing to without faulting.
+
+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/admin-guide/sysctl/kernel.rst for more details.
+
+This modifier is *only* intended when producing content of a file read by
+userspace from e.g. procfs or sysfs, not for dmesg. Please refer to the
+section about %p above for discussion about how to manage hashing pointers
+in printk().
+
+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.
+
+Before using %px, consider if using %p is sufficient together with enabling the
+``no_hash_pointers`` kernel parameter during debugging sessions (see the %p
+description above). One valid scenario for %px might be printing information
+immediately before a panic, which prevents any sensitive information to be
+exploited anyway, and with %px there would be no need to reproduce the panic
+with no_hash_pointers.
+
+Pointer Differences
+-------------------
+
+::
+
+	%td	2560
+	%tx	a00
+
+For printing the pointer differences, use the %t modifier for ptrdiff_t.
+
+Example::
+
+	printk("test: difference between pointers: %td\n", ptr2 - ptr1);
+
+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
+https://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
+https://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.
+
+Device tree nodes
+-----------------
+
+::
+
+	%pOF[fnpPcCF]
+
+
+For printing device tree node structures. 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.
+
+Fwnode handles
+--------------
+
+::
+
+	%pfw[fP]
+
+For printing information on fwnode handles. The default is to print the full
+node name, including the path. The modifiers are functionally equivalent to
+%pOF above.
+
+	- f - full name of the node, including the path
+	- P - the name of the node including an address (if there is one)
+
+Examples (ACPI)::
+
+	%pfwf	\_SB.PCI0.CIO2.port@1.endpoint@0	- Full node name
+	%pfwP	endpoint@0				- Node name
+
+Examples (OF)::
+
+	%pfwf	/ocp@68000000/i2c@48072000/camera@10/port/endpoint - Full name
+	%pfwP	endpoint				- Node name
+
+Time and date
+-------------
+
+::
+
+	%pt[RT]			YYYY-mm-ddTHH:MM:SS
+	%pt[RT]s		YYYY-mm-dd HH:MM:SS
+	%pt[RT]d		YYYY-mm-dd
+	%pt[RT]t		HH:MM:SS
+	%pt[RT][dt][r][s]
+
+For printing date and time as represented by::
+
+	R  struct rtc_time structure
+	T  time64_t type
+
+in human readable format.
+
+By default year will be incremented by 1900 and month by 1.
+Use %pt[RT]r (raw) to suppress this behaviour.
+
+The %pt[RT]s (space) will override ISO 8601 separator by using ' ' (space)
+instead of 'T' (Capital T) between date and time. It won't have any effect
+when date or time is omitted.
+
+Passed by reference.
+
+struct clk
+----------
+
+::
+
+	%pC	pll1
+	%pCn	pll1
+
+For printing struct clk structures. %pC and %pCn print the name of the clock
+(Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
+
+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.
+
+The field width is passed by value, the bitmap is passed by reference.
+Helper macros cpumask_pr_args() and nodemask_pr_args() are available to ease
+printing cpumask and nodemask.
+
+Flags bitfields such as page flags, gfp_flags
+---------------------------------------------
+
+::
+
+	%pGp	0x17ffffc0002036(referenced|uptodate|lru|active|private|node=0|zone=2|lastcpupid=0x1fffff)
+	%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.
+
+V4L2 and DRM FourCC code (pixel format)
+---------------------------------------
+
+::
+
+	%p4cc
+
+Print a FourCC code used by V4L2 or DRM, including format endianness and
+its numerical value as hexadecimal.
+
+Passed by reference.
+
+Examples::
+
+	%p4cc	BG12 little-endian (0x32314742)
+	%p4cc	Y10  little-endian (0x20303159)
+	%p4cc	NV12 big-endian (0xb231564e)
+
+Rust
+----
+
+::
+
+	%pA
+
+Only intended to be used from Rust code to format ``core::fmt::Arguments``.
+Do *not* use it from C.
+
+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.