diff options
Diffstat (limited to 'Documentation/s390')
| -rw-r--r-- | Documentation/s390/s390dbf.rst | 672 |
1 files changed, 1 insertions, 671 deletions
diff --git a/Documentation/s390/s390dbf.rst b/Documentation/s390/s390dbf.rst index ec2a1faa414b..d2595b548879 100644 --- a/Documentation/s390/s390dbf.rst +++ b/Documentation/s390/s390dbf.rst @@ -104,684 +104,14 @@ 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. ----------------------------------------------------------------------------- - Kernel Interfaces: ------------------ -:: - - debug_info_t *debug_register(char *name, int pages, int nr_areas, - int buf_size); - -Parameter: - name: - Name of debug log (e.g. used for debugfs entry) - pages: - Number of pages, which will be allocated per area - nr_areas: - Number of debug areas - buf_size: - Size of data area in each debug entry - -Return Value: - Handle for generated debug area - - NULL if register failed - -Description: Allocates memory for a debug log - Must not be called within an interrupt handler - ----------------------------------------------------------------------------- - -:: - - debug_info_t *debug_register_mode(char *name, int pages, int nr_areas, - int buf_size, mode_t mode, uid_t uid, - gid_t gid); - -Parameter: - name: - Name of debug log (e.g. used for debugfs entry) - pages: - Number of pages, which will be allocated per area - nr_areas: - Number of debug areas - buf_size: - Size of data area in each debug entry - mode: - File mode for debugfs files. E.g. S_IRWXUGO - uid: - User ID for debugfs files. Currently only 0 is - supported. - gid: - Group ID for debugfs files. Currently only 0 is - supported. - -Return Value: - Handle for generated debug area - - NULL if register failed - -Description: - Allocates memory for a debug log - Must not be called within an interrupt handler - ---------------------------------------------------------------------------- - -:: - - void debug_unregister (debug_info_t * id); - -Parameter: - id: - handle for debug log - -Return Value: - none - -Description: - frees memory for a debug log and removes all registered debug - views. - - Must not be called within an interrupt handler - ---------------------------------------------------------------------------- - -:: - - void debug_set_level (debug_info_t * id, int new_level); - -Parameter: id: handle for debug log - new_level: new debug level - -Return Value: - none - -Description: - Sets new actual debug level if new_level is valid. - ---------------------------------------------------------------------------- - -:: - - bool debug_level_enabled (debug_info_t * id, int level); - -Parameter: - id: - handle for debug log - level: - debug level - -Return Value: - True if level is less or equal to the current debug level. - -Description: - Returns true if debug events for the specified level would be - logged. Otherwise returns false. - ---------------------------------------------------------------------------- - -:: - - void debug_stop_all(void); - -Parameter: - none - -Return Value: - none - -Description: - stops the debug feature if stopping is allowed. Currently - used in case of a kernel oops. - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_event (debug_info_t* id, int level, void* data, - int length); - -Parameter: - id: - handle for debug log - level: - debug level - data: - pointer to data for debug entry - length: - length of data in bytes - -Return Value: - Address of written debug entry - -Description: - writes debug entry to active debug area (if level <= actual - debug level) - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_int_event (debug_info_t * id, int level, - unsigned int data); - debug_entry_t* debug_long_event(debug_info_t * id, int level, - unsigned long data); - -Parameter: - id: - handle for debug log - level: - debug level - data: - integer value for debug entry - -Return Value: - Address of written debug entry - -Description: - writes debug entry to active debug area (if level <= actual - debug level) - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_text_event (debug_info_t * id, int level, - const char* data); - -Parameter: - id: - handle for debug log - level: - debug level - data: - string for debug entry - -Return Value: - Address of written debug entry - -Description: - writes debug entry in ascii format to active debug area - (if level <= actual debug level) - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_sprintf_event (debug_info_t * id, int level, - char* string,...); - -Parameter: - id: - handle for debug log - level: - debug level - string: - format string for debug entry - ...: - varargs used as in sprintf() - -Return Value: Address of written debug entry - -Description: - writes debug entry with format string and varargs (longs) to - active debug area (if level $<=$ actual debug level). - floats and long long datatypes cannot be used as varargs. - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_exception (debug_info_t* id, int level, void* data, - int length); - -Parameter: - id: - handle for debug log - level: - debug level - data: - pointer to data for debug entry - length: - length of data in bytes - -Return Value: - Address of written debug entry - -Description: - writes debug entry to active debug area (if level <= actual - debug level) and switches to next debug area - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_int_exception (debug_info_t * id, int level, - unsigned int data); - debug_entry_t* debug_long_exception(debug_info_t * id, int level, - unsigned long data); - -Parameter: id: handle for debug log - level: debug level - data: integer value for debug entry - -Return Value: Address of written debug entry - -Description: writes debug entry to active debug area (if level <= actual - debug level) and switches to next debug area - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_text_exception (debug_info_t * id, int level, - const char* data); - -Parameter: id: handle for debug log - level: debug level - data: string for debug entry - -Return Value: Address of written debug entry - -Description: writes debug entry in ascii format to active debug area - (if level <= actual debug level) and switches to next debug - area - ---------------------------------------------------------------------------- - -:: - - debug_entry_t* debug_sprintf_exception (debug_info_t * id, int level, - char* string,...); - -Parameter: id: handle for debug log - level: debug level - string: format string for debug entry - ...: varargs used as in sprintf() - -Return Value: Address of written debug entry - -Description: writes debug entry with format string and varargs (longs) to - active debug area (if level $<=$ actual debug level) and - switches to next debug area. - floats and long long datatypes cannot be used as varargs. - ---------------------------------------------------------------------------- - -:: - - int debug_register_view (debug_info_t * id, struct debug_view *view); - -Parameter: id: handle for debug log - view: pointer to debug view struct - -Return Value: 0 : ok - < 0: Error - -Description: registers new debug view and creates debugfs dir entry - ---------------------------------------------------------------------------- - -:: - - int debug_unregister_view (debug_info_t * id, struct debug_view *view); - -Parameter: id: handle for debug log - view: pointer to debug view struct - -Return Value: 0 : ok - < 0: Error - -Description: unregisters debug view and removes debugfs dir entry - - +.. kernel-doc:: arch/s390/include/asm/debug.h Predefined views: ----------------- -extern struct debug_view debug_hex_ascii_view; - -extern struct debug_view debug_raw_view; - -extern struct debug_view debug_sprintf_view; - -Examples --------- - -:: - - /* - * hex_ascii- + raw-view Example - */ - - #include <linux/init.h> - #include <asm/debug.h> - - 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_text_event(debug_info, 4 , "one "); - debug_int_exception(debug_info, 4, 4711); - debug_event(debug_info, 3, &debug_info, 4); - - return 0; - } - - static void cleanup(void) - { - debug_unregister (debug_info); - } - - module_init(init); - module_exit(cleanup); - ---------------------------------------------------------------------------- - -:: - - /* - * sprintf-view Example - */ - - #include <linux/init.h> - #include <asm/debug.h> - - 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_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); - - return 0; - } - - static void cleanup(void) - { - debug_unregister (debug_info); - } - - module_init(init); - module_exit(cleanup); - -Debugfs Interface ------------------ -Views to the debug logs can be investigated through reading the corresponding -debugfs-files: - -Example:: - - > ls /sys/kernel/debug/s390dbf/dasd - flush hex_ascii level pages raw - > cat /sys/kernel/debug/s390dbf/dasd/hex_ascii | sort -k2,2 -s - 00 00974733272:680099 2 - 02 0006ad7e 07 ea 4a 90 | .... - 00 00974733272:682210 2 - 02 0006ade6 46 52 45 45 | FREE - 00 00974733272:682213 2 - 02 0006adf6 07 ea 4a 90 | .... - 00 00974733272:682281 1 * 02 0006ab08 41 4c 4c 43 | EXCP - 01 00974733272:682284 2 - 02 0006ab16 45 43 4b 44 | ECKD - 01 00974733272:682287 2 - 02 0006ab28 00 00 00 04 | .... - 01 00974733272:682289 2 - 02 0006ab3e 00 00 00 20 | ... - 01 00974733272:682297 2 - 02 0006ad7e 07 ea 4a 90 | .... - 01 00974733272:684384 2 - 00 0006ade6 46 52 45 45 | FREE - 01 00974733272:684388 2 - 00 0006adf6 07 ea 4a 90 | .... - -See section about predefined views for explanation of the above output! - -Changing the debug level ------------------------- - -Example:: - - - > cat /sys/kernel/debug/s390dbf/dasd/level - 3 - > echo "5" > /sys/kernel/debug/s390dbf/dasd/level - > cat /sys/kernel/debug/s390dbf/dasd/level - 5 - -Flushing debug areas --------------------- -Debug areas can be flushed with piping the number of the desired -area (0...n) to the debugfs file "flush". When using "-" all debug areas -are flushed. - -Examples: - -1. Flush debug area 0:: - - > echo "0" > /sys/kernel/debug/s390dbf/dasd/flush - -2. Flush all debug areas:: - - > echo "-" > /sys/kernel/debug/s390dbf/dasd/flush - -Changing the size of debug areas ------------------------------------- -It is possible the change the size of debug areas through piping -the number of pages to the debugfs file "pages". The resize request will -also flush the debug areas. - -Example: - -Define 4 pages for the debug areas of debug feature "dasd":: - - > echo "4" > /sys/kernel/debug/s390dbf/dasd/pages - -Stooping the debug feature --------------------------- -Example: - -1. Check if stopping is allowed:: - - > cat /proc/sys/s390dbf/debug_stoppable - -2. Stop debug feature:: - - > echo 0 > /proc/sys/s390dbf/debug_active - -lcrash 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 -to investigate the debug logs on a live system and with a memory dump after -a system crash. - -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 -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 -a global variable with the pointer to the debug-logs. Following -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 -order to see the debug entries well formatted. - - -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'). -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 -function would do. The sprintf event/exception functions write to the -debug entry a pointer to the format string (size = sizeof(long)) -and for each vararg a long value. So e.g. for a debug entry with a format -string plus two varargs one would need to allocate a (3 * sizeof(long)) -byte data area in the debug_register() function. - -IMPORTANT: - Using "%s" in sprintf event functions is dangerous. You can only - use "%s" in the sprintf event functions, if the memory for the passed string - is available as long as the debug feature exists. The reason behind this is - that due to performance considerations only a pointer to the string is stored - in the debug feature. If you log a string that is freed afterwards, you will - get an OOPS when inspecting the debug feature, because then the debug feature - will access the already freed memory. - -NOTE: - If using the sprintf view do NOT use other event/exception functions - than the sprintf-event and -exception functions. - -The format of the hex_ascii and sprintf view is as follows: - -- Number of area -- Timestamp (formatted as seconds and microseconds since 00:00:00 Coordinated - Universal Time (UTC), January 1, 1970) -- level of debug entry -- Exception flag (* = Exception) -- Cpu-Number of calling task -- Return Address to caller -- data field - -The format of the raw view is: - -- Header as described in debug.h -- 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): - -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:: - - struct debug_view { - char name[DEBUG_MAX_PROCF_LEN]; - debug_prolog_proc_t* prolog_proc; - debug_header_proc_t* header_proc; - debug_format_proc_t* format_proc; - debug_input_proc_t* input_proc; - void* private_data; - }; - -where:: - - typedef int (debug_header_proc_t) (debug_info_t* id, - struct debug_view* view, - int area, - debug_entry_t* entry, - char* out_buf); - - typedef int (debug_format_proc_t) (debug_info_t* id, - struct debug_view* view, char* out_buf, - const char* in_buf); - typedef int (debug_prolog_proc_t) (debug_info_t* id, - struct debug_view* view, - char* out_buf); - typedef int (debug_input_proc_t) (debug_info_t* id, - struct debug_view* view, - struct file* file, const char* user_buf, - size_t in_buf_size, loff_t* offset); - - -The "private_data" member can be used as pointer to view specific data. -It is not used by the debug feature itself. - -The output when reading a debugfs file is structured like this:: - - "prolog_proc output" - - "header_proc output 1" "format_proc output 1" - "header_proc output 2" "format_proc output 2" - "header_proc output 3" "format_proc output 3" - ... - -When a view is read from the debugfs, the Debug Feature calls the -'prolog_proc' once for writing the prolog. -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). - -For header_proc there can be used the default function -debug_dflt_header_fn() which is defined in debug.h. -and which produces the same header output as the predefined views. -E.g:: - - 00 00964419409:440761 2 - 00 88023ec - -In order to see how to use the callback functions check the implementation -of the default views! - -Example:: - - #include <asm/debug.h> - - #define UNKNOWNSTR "data: %08x" - - const char* messages[] = - {"This error...........\n", - "That error...........\n", - "Problem..............\n", - "Something went wrong.\n", - "Everything ok........\n", - NULL - }; - - static int debug_test_format_fn( - debug_info_t * id, struct debug_view *view, - char *out_buf, const char *in_buf - ) - { - int i, rc = 0; - - if(id->buf_size >= 4) { - int msg_nr = *((int*)in_buf); - 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; - } - - struct debug_view debug_test_view = { - "myview", /* name of view */ - NULL, /* no prolog */ - &debug_dflt_header_fn, /* default header for each entry */ - &debug_test_format_fn, /* our own format function */ - NULL, /* no input function */ - NULL /* no private data */ - }; - -test: -===== - :: debug_info_t *debug_info; |