On 03.07.19 12:19, Steffen Maier wrote:
> Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxx>
Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> Documentation/s390/s390dbf.rst | 122 +++++++++++++++++++++++------------------
> 1 file changed, 68 insertions(+), 54 deletions(-)
>
> diff --git a/Documentation/s390/s390dbf.rst b/Documentation/s390/s390dbf.rst
> index be42892b159e..cdb36842b898 100644
> --- a/Documentation/s390/s390dbf.rst
> +++ b/Documentation/s390/s390dbf.rst
> @@ -23,7 +23,8 @@ The debug feature may also very useful for kernel and driver development.
> Design:
> -------
> Kernel components (e.g. device drivers) can register themselves at the debug
> -feature with the function call debug_register(). This function initializes a
> +feature with the function call :c:func:`debug_register()`.
> +This function initializes a
> debug log for the caller. For each debug log exists a number of debug areas
> where exactly one is active at one time. Each debug area consists of contiguous
> pages in memory. In the debug areas there are stored debug entries (log records)
> @@ -44,8 +45,9 @@ The debug areas themselves are also ordered in form of a ring buffer.
> When an exception is thrown in the last debug area, the following debug
> entries are then written again in the very first area.
>
> -There are three versions for the event- and exception-calls: One for
> -logging raw data, one for text and one for numbers.
> +There are four versions for the event- and exception-calls: One for
> +logging raw data, one for text, one for numbers (unsigned int and long),
> +and one for sprintf-like formatted strings.
>
> Each debug entry contains the following data:
>
> @@ -56,29 +58,29 @@ Each debug entry contains the following data:
> - Flag, if entry is an exception or not
>
> The debug logs can be inspected in a live system through entries in
> -the debugfs-filesystem. Under the toplevel directory "s390dbf" there is
> +the debugfs-filesystem. Under the toplevel directory "``s390dbf``" there is
> a directory for each registered component, which is named like the
> corresponding component. The debugfs normally should be mounted to
> -/sys/kernel/debug therefore the debug feature can be accessed under
> -/sys/kernel/debug/s390dbf.
> +``/sys/kernel/debug`` therefore the debug feature can be accessed under
> +``/sys/kernel/debug/s390dbf``.
>
> The content of the directories are files which represent different views
> to the debug log. Each component can decide which views should be
> -used through registering them with the function debug_register_view().
> +used through registering them with the function :c:func:`debug_register_view()`.
> Predefined views for hex/ascii, sprintf and raw binary data are provided.
> It is also possible to define other views. The content of
> a view can be inspected simply by reading the corresponding debugfs file.
>
> All debug logs have an actual debug level (range from 0 to 6).
> -The default level is 3. Event and Exception functions have a 'level'
> +The default level is 3. Event and Exception functions have a :c:data:`level`
> parameter. Only debug entries with a level that is lower or equal
> than the actual level are written to the log. This means, when
> writing events, high priority log entries should have a low level
> value whereas low priority entries should have a high one.
> The actual debug level can be changed with the help of the debugfs-filesystem
> -through writing a number string "x" to the 'level' debugfs file which is
> +through writing a number string "x" to the ``level`` debugfs file which is
> provided for every debug log. Debugging can be switched off completely
> -by using "-" on the 'level' debugfs file.
> +by using "-" on the ``level`` debugfs file.
>
> Example::
>
> @@ -86,21 +88,21 @@ Example::
>
> It is also possible to deactivate the debug feature globally for every
> debug log. You can change the behavior using 2 sysctl parameters in
> -/proc/sys/s390dbf:
> +``/proc/sys/s390dbf``:
>
> There are currently 2 possible triggers, which stop the debug feature
> -globally. The first possibility is to use the "debug_active" sysctl. If
> -set to 1 the debug feature is running. If "debug_active" is set to 0 the
> +globally. The first possibility is to use the ``debug_active`` sysctl. If
> +set to 1 the debug feature is running. If ``debug_active`` is set to 0 the
> debug feature is turned off.
>
> The second trigger which stops the debug feature is a kernel oops.
> That prevents the debug feature from overwriting debug information that
> happened before the oops. After an oops you can reactivate the debug feature
> -by piping 1 to /proc/sys/s390dbf/debug_active. Nevertheless, its not
> +by piping 1 to ``/proc/sys/s390dbf/debug_active``. Nevertheless, it's not
> suggested to use an oopsed kernel in a production environment.
>
> If you want to disallow the deactivation of the debug feature, you can use
> -the "debug_stoppable" sysctl. If you set "debug_stoppable" to 0 the debug
> +the ``debug_stoppable`` sysctl. If you set ``debug_stoppable`` to 0 the debug
> feature cannot be stopped. If the debug feature is already stopped, it
> will stay deactivated.
>
> @@ -113,16 +115,18 @@ Kernel Interfaces:
> Predefined views:
> -----------------
>
> -extern struct debug_view debug_hex_ascii_view;
> +.. code-block:: c
>
> -extern struct debug_view debug_raw_view;
> + extern struct debug_view debug_hex_ascii_view;
>
> -extern struct debug_view debug_sprintf_view;
> + extern struct debug_view debug_raw_view;
> +
> + extern struct debug_view debug_sprintf_view;
>
> Examples
> --------
>
> -::
> +.. code-block:: c
>
> /*
> * hex_ascii- + raw-view Example
> @@ -131,15 +135,15 @@ Examples
> #include <linux/init.h>
> #include <asm/debug.h>
>
> - static debug_info_t* debug_info;
> + static debug_info_t *debug_info;
>
> static int init(void)
> {
> /* register 4 debug areas with one page each and 4 byte data field */
>
> - debug_info = debug_register ("test", 1, 4, 4 );
> - debug_register_view(debug_info,&debug_hex_ascii_view);
> - debug_register_view(debug_info,&debug_raw_view);
> + debug_info = debug_register("test", 1, 4, 4 );
> + debug_register_view(debug_info, &debug_hex_ascii_view);
> + debug_register_view(debug_info, &debug_raw_view);
>
> debug_text_event(debug_info, 4 , "one ");
> debug_int_exception(debug_info, 4, 4711);
> @@ -150,13 +154,13 @@ Examples
>
> static void cleanup(void)
> {
> - debug_unregister (debug_info);
> + debug_unregister(debug_info);
> }
>
> module_init(init);
> module_exit(cleanup);
>
> -::
> +.. code-block:: c
>
> /*
> * sprintf-view Example
> @@ -165,15 +169,15 @@ Examples
> #include <linux/init.h>
> #include <asm/debug.h>
>
> - static debug_info_t* debug_info;
> + static debug_info_t *debug_info;
>
> static int init(void)
> {
> /* register 4 debug areas with one page each and data field for */
> /* format string pointer + 2 varargs (= 3 * sizeof(long)) */
>
> - debug_info = debug_register ("test", 1, 4, sizeof(long) * 3);
> - debug_register_view(debug_info,&debug_sprintf_view);
> + debug_info = debug_register("test", 1, 4, sizeof(long) * 3);
> + debug_register_view(debug_info, &debug_sprintf_view);
>
> debug_sprintf_event(debug_info, 2 , "first event in %s:%i\n",__FILE__,__LINE__);
> debug_sprintf_exception(debug_info, 1, "pointer to debug info: %p\n",&debug_info);
> @@ -183,7 +187,7 @@ Examples
>
> static void cleanup(void)
> {
> - debug_unregister (debug_info);
> + debug_unregister(debug_info);
> }
>
> module_init(init);
> @@ -252,7 +256,7 @@ Define 4 pages for the debug areas of debug feature "dasd"::
>
> > echo "4" > /sys/kernel/debug/s390dbf/dasd/pages
>
> -Stooping the debug feature
> +Stopping the debug feature
> --------------------------
> Example:
>
> @@ -264,10 +268,11 @@ Example:
>
> > echo 0 > /proc/sys/s390dbf/debug_active
>
> -lcrash Interface
> +crash Interface
> ----------------
> -It is planned that the dump analysis tool lcrash gets an additional command
> -'s390dbf' to display all the debug logs. With this tool it will be possible
> +The ``crash`` tool since v5.1.0 has a built-in command
> +``s390dbf`` to display all the debug logs or export them to the file system.
> +With this tool it is possible
> to investigate the debug logs on a live system and with a memory dump after
> a system crash.
>
> @@ -276,8 +281,8 @@ Investigating raw memory
> One last possibility to investigate the debug logs at a live
> system and after a system crash is to look at the raw memory
> under VM or at the Service Element.
> -It is possible to find the anker of the debug-logs through
> -the 'debug_area_first' symbol in the System map. Then one has
> +It is possible to find the anchor of the debug-logs through
> +the ``debug_area_first`` symbol in the System map. Then one has
> to follow the correct pointers of the data-structures defined
> in debug.h and find the debug-areas in memory.
> Normally modules which use the debug feature will also have
> @@ -286,7 +291,7 @@ this pointer it will also be possible to find the debug logs in
> memory.
>
> For this method it is recommended to use '16 * x + 4' byte (x = 0..n)
> -for the length of the data field in debug_register() in
> +for the length of the data field in :c:func:`debug_register()` in
> order to see the debug entries well formatted.
>
>
> @@ -295,7 +300,7 @@ Predefined Views
>
> There are three predefined views: hex_ascii, raw and sprintf.
> The hex_ascii view shows the data field in hex and ascii representation
> -(e.g. '45 43 4b 44 | ECKD').
> +(e.g. ``45 43 4b 44 | ECKD``).
> The raw view returns a bytestream as the debug areas are stored in memory.
>
> The sprintf view formats the debug entries in the same way as the sprintf
> @@ -335,18 +340,20 @@ The format of the raw view is:
> - datafield
>
> A typical line of the hex_ascii view will look like the following (first line
> -is only for explanation and will not be displayed when 'cating' the view):
> +is only for explanation and will not be displayed when 'cating' the view)::
>
> -area time level exception cpu caller data (hex + ascii)
> ---------------------------------------------------------------------------
> -00 00964419409:440690 1 - 00 88023fe
> + area time level exception cpu caller data (hex + ascii)
> + --------------------------------------------------------------------------
> + 00 00964419409:440690 1 - 00 88023fe
>
>
> Defining views
> --------------
>
> Views are specified with the 'debug_view' structure. There are defined
> -callback functions which are used for reading and writing the debugfs files::
> +callback functions which are used for reading and writing the debugfs files:
> +
> +.. code-block:: c
>
> struct debug_view {
> char name[DEBUG_MAX_PROCF_LEN];
> @@ -357,7 +364,9 @@ callback functions which are used for reading and writing the debugfs files::
> void* private_data;
> };
>
> -where::
> +where:
> +
> +.. code-block:: c
>
> typedef int (debug_header_proc_t) (debug_info_t* id,
> struct debug_view* view,
> @@ -395,10 +404,10 @@ Then 'header_proc' and 'format_proc' are called for each
> existing debug entry.
>
> The input_proc can be used to implement functionality when it is written to
> -the view (e.g. like with 'echo "0" > /sys/kernel/debug/s390dbf/dasd/level).
> +the view (e.g. like with ``echo "0" > /sys/kernel/debug/s390dbf/dasd/level``).
>
> For header_proc there can be used the default function
> -debug_dflt_header_fn() which is defined in debug.h.
> +:c:func:`debug_dflt_header_fn()` which is defined in debug.h.
> and which produces the same header output as the predefined views.
> E.g::
>
> @@ -407,7 +416,9 @@ E.g::
> In order to see how to use the callback functions check the implementation
> of the default views!
>
> -Example::
> +Example:
> +
> +.. code-block:: c
>
> #include <asm/debug.h>
>
> @@ -423,21 +434,20 @@ Example::
> };
>
> static int debug_test_format_fn(
> - debug_info_t * id, struct debug_view *view,
> + debug_info_t *id, struct debug_view *view,
> char *out_buf, const char *in_buf
> )
> {
> int i, rc = 0;
>
> - if(id->buf_size >= 4) {
> + if (id->buf_size >= 4) {
> int msg_nr = *((int*)in_buf);
> - if(msg_nr < sizeof(messages)/sizeof(char*) - 1)
> + if (msg_nr < sizeof(messages) / sizeof(char*) - 1)
> rc += sprintf(out_buf, "%s", messages[msg_nr]);
> else
> rc += sprintf(out_buf, UNKNOWNSTR, msg_nr);
> }
> - out:
> - return rc;
> + return rc;
> }
>
> struct debug_view debug_test_view = {
> @@ -452,13 +462,17 @@ Example::
> test:
> =====
>
> -::
> +.. code-block:: c
>
> debug_info_t *debug_info;
> + int i;
> ...
> - debug_info = debug_register ("test", 0, 4, 4 ));
> + debug_info = debug_register("test", 0, 4, 4);
> debug_register_view(debug_info, &debug_test_view);
> - for(i = 0; i < 10; i ++) debug_int_event(debug_info, 1, i);
> + for (i = 0; i < 10; i ++)
> + debug_int_event(debug_info, 1, i);
> +
> +::
>
> > cat /sys/kernel/debug/s390dbf/test/myview
> 00 00964419734:611402 1 - 00 88042ca This error...........
>
