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 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * If TRACE_SYSTEM is defined, that will be the directory created
  * in the ftrace directory under /sys/kernel/tracing/events/<system>
  *
  * The define_trace.h below will also look for a file name of
  * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
  * In this case, it would look for sample-trace.h
  *
  * If the header name will be different than the system name
  * (as in this case), then you can override the header name that
  * define_trace.h will look up by defining TRACE_INCLUDE_FILE
  *
  * This file is called trace-events-sample.h but we want the system
  * to be called "sample-trace". Therefore we must define the name of this
  * file:
  *
  * #define TRACE_INCLUDE_FILE trace-events-sample
  *
  * As we do an the bottom of this file.
  *
  * Notice that TRACE_SYSTEM should be defined outside of #if
  * protection, just like TRACE_INCLUDE_FILE.
  */
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM sample-trace
 
 /*
  * TRACE_SYSTEM is expected to be a C valid variable (alpha-numeric
  * and underscore), although it may start with numbers. If for some
  * reason it is not, you need to add the following lines:
  */
 #undef TRACE_SYSTEM_VAR
 #define TRACE_SYSTEM_VAR sample_trace
 /*
  * But the above is only needed if TRACE_SYSTEM is not alpha-numeric
  * and underscored. By default, TRACE_SYSTEM_VAR will be equal to
  * TRACE_SYSTEM. As TRACE_SYSTEM_VAR must be alpha-numeric, if
  * TRACE_SYSTEM is not, then TRACE_SYSTEM_VAR must be defined with
  * only alpha-numeric and underscores.
  *
  * The TRACE_SYSTEM_VAR is only used internally and not visible to
  * user space.
  */
 
 /*
  * Notice that this file is not protected like a normal header.
  * We also must allow for rereading of this file. The
  *
  *  || defined(TRACE_HEADER_MULTI_READ)
  *
  * serves this purpose.
  */
 #if !defined(_TRACE_EVENT_SAMPLE_H) || defined(TRACE_HEADER_MULTI_READ)
 #define _TRACE_EVENT_SAMPLE_H
 
 /*
  * All trace headers should include tracepoint.h, until we finally
  * make it into a standard header.
  */
 #include <linux/tracepoint.h>
 
 /*
  * The TRACE_EVENT macro is broken up into 5 parts.
  *
  * name: name of the trace point. This is also how to enable the tracepoint.
  *   A function called trace_foo_bar() will be created.
  *
  * proto: the prototype of the function trace_foo_bar()
  *   Here it is trace_foo_bar(char *foo, int bar).
  *
  * args:  must match the arguments in the prototype.
  *    Here it is simply "foo, bar".
  *
  * struct:  This defines the way the data will be stored in the ring buffer.
  *          The items declared here become part of a special structure
  *          called "__entry", which can be used in the fast_assign part of the
  *          TRACE_EVENT macro.
  *
  *      Here are the currently defined types you can use:
  *
  *   __field : Is broken up into type and name. Where type can be any
  *         primitive type (integer, long or pointer).
  *
  *        __field(int, foo)
  *
  *        __entry->foo = 5;
  *
  *   __field_struct : This can be any static complex data type (struct, union
  *         but not an array). Be careful using complex types, as each
  *         event is limited in size, and copying large amounts of data
  *         into the ring buffer can slow things down.
  *
  *         __field_struct(struct bar, foo)
  *
  *         __entry->bar.x = y;
 
  *   __array: There are three fields (type, name, size). The type is the
  *         type of elements in the array, the name is the name of the array.
  *         size is the number of items in the array (not the total size).
  *
  *         __array( char, foo, 10) is the same as saying: char foo[10];
  *
  *         Assigning arrays can be done like any array:
  *
  *         __entry->foo[0] = 'a';
  *
  *         memcpy(__entry->foo, bar, 10);
  *
  *   __dynamic_array: This is similar to array, but can vary its size from
  *         instance to instance of the tracepoint being called.
  *         Like __array, this too has three elements (type, name, size);
  *         type is the type of the element, name is the name of the array.
  *         The size is different than __array. It is not a static number,
  *         but the algorithm to figure out the length of the array for the
  *         specific instance of tracepoint. Again, size is the number of
  *         items in the array, not the total length in bytes.
  *
  *         __dynamic_array( int, foo, bar) is similar to: int foo[bar];
  *
  *         Note, unlike arrays, you must use the __get_dynamic_array() macro
  *         to access the array.
  *
  *         memcpy(__get_dynamic_array(foo), bar, 10);
  *
  *         Notice, that "__entry" is not needed here.
  *
  *   __string: This is a special kind of __dynamic_array. It expects to
  *         have a null terminated character array passed to it (it allows
  *         for NULL too, which would be converted into "(null)"). __string
  *         takes two parameter (name, src), where name is the name of
  *         the string saved, and src is the string to copy into the
  *         ring buffer.
  *
  *         __string(foo, bar)  is similar to:  strcpy(foo, bar)
  *
  *         To assign a string, use the helper macro __assign_str().
  *
  *         __assign_str(foo, bar);
  *
  *         In most cases, the __assign_str() macro will take the same
  *         parameters as the __string() macro had to declare the string.
  *
  *   __vstring: This is similar to __string() but instead of taking a
  *         dynamic length, it takes a variable list va_list 'va' variable.
  *         Some event callers already have a message from parameters saved
  *         in a va_list. Passing in the format and the va_list variable
  *         will save just enough on the ring buffer for that string.
  *         Note, the va variable used is a pointer to a va_list, not
  *         to the va_list directly.
  *
  *           (va_list *va)
  *
  *         __vstring(foo, fmt, va)  is similar to:  vsnprintf(foo, fmt, va)
  *
  *         To assign the string, use the helper macro __assign_vstr().
  *
  *         __assign_vstr(foo, fmt, va);
  *
  *         In most cases, the __assign_vstr() macro will take the same
  *         parameters as the __vstring() macro had to declare the string.
  *         Use __get_str() to retrieve the __vstring() just like it would for
  *         __string().
  *
  *   __string_len: This is a helper to a __dynamic_array, but it understands
  *     that the array has characters in it, and with the combined
  *         use of __assign_str_len(), it will allocate 'len' + 1 bytes
  *         in the ring buffer and add a '\0' to the string. This is
  *         useful if the string being saved has no terminating '\0' byte.
  *         It requires that the length of the string is known as it acts
  *         like a memcpy().
  *
  *         Declared with:
  *
  *         __string_len(foo, bar, len)
  *
  *         To assign this string, use the helper macro __assign_str_len().
  *
  *         __assign_str_len(foo, bar, len);
  *
  *         Then len + 1 is allocated to the ring buffer, and a nul terminating
  *         byte is added. This is similar to:
  *
  *         memcpy(__get_str(foo), bar, len);
  *         __get_str(foo)[len] = 0;
  *
  *        The advantage of using this over __dynamic_array, is that it
  *        takes care of allocating the extra byte on the ring buffer
  *        for the '\0' terminating byte, and __get_str(foo) can be used
  *        in the TP_printk().
  *
  *   __bitmask: This is another kind of __dynamic_array, but it expects
  *         an array of longs, and the number of bits to parse. It takes
  *         two parameters (name, nr_bits), where name is the name of the
  *         bitmask to save, and the nr_bits is the number of bits to record.
  *
  *         __bitmask(target_cpu, nr_cpumask_bits)
  *
  *         To assign a bitmask, use the __assign_bitmask() helper macro.
  *
  *         __assign_bitmask(target_cpus, cpumask_bits(bar), nr_cpumask_bits);
  *
  *
  * fast_assign: This is a C like function that is used to store the items
  *    into the ring buffer. A special variable called "__entry" will be the
  *    structure that points into the ring buffer and has the same fields as
  *    described by the struct part of TRACE_EVENT above.
  *
  * printk: This is a way to print out the data in pretty print. This is
  *    useful if the system crashes and you are logging via a serial line,
  *    the data can be printed to the console using this "printk" method.
  *    This is also used to print out the data from the trace files.
  *    Again, the __entry macro is used to access the data from the ring buffer.
  *
  *    Note, __dynamic_array, __string, and __bitmask require special helpers
  *       to access the data.
  *
  *      For __dynamic_array(int, foo, bar) use __get_dynamic_array(foo)
  *            Use __get_dynamic_array_len(foo) to get the length of the array
  *            saved. Note, __get_dynamic_array_len() returns the total allocated
  *            length of the dynamic array; __print_array() expects the second
  *            parameter to be the number of elements. To get that, the array length
  *            needs to be divided by the element size.
  *
  *      For __string(foo, bar) use __get_str(foo)
  *
  *      For __bitmask(target_cpus, nr_cpumask_bits) use __get_bitmask(target_cpus)
  *
  *
  * Note, that for both the assign and the printk, __entry is the handler
  * to the data structure in the ring buffer, and is defined by the
  * TP_STRUCT__entry.
  */
 
 /*
  * It is OK to have helper functions in the file, but they need to be protected
  * from being defined more than once. Remember, this file gets included more
  * than once.
  */
 #ifndef __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS
 #define __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS
 static inline int __length_of(const int *list)
 {
     int i;
 
     if (!list)
         return 0;
 
     for (i = 0; list[i]; i++)
         ;
     return i;
 }
 
 enum {
     TRACE_SAMPLE_FOO = 2,
     TRACE_SAMPLE_BAR = 4,
     TRACE_SAMPLE_ZOO = 8,
 };
 #endif
 
 /*
  * If enums are used in the TP_printk(), their names will be shown in
  * format files and not their values. This can cause problems with user
  * space programs that parse the format files to know how to translate
  * the raw binary trace output into human readable text.
  *
  * To help out user space programs, any enum that is used in the TP_printk()
  * should be defined by TRACE_DEFINE_ENUM() macro. All that is needed to
  * be done is to add this macro with the enum within it in the trace
  * header file, and it will be converted in the output.
  */
 
 TRACE_DEFINE_ENUM(TRACE_SAMPLE_FOO);
 TRACE_DEFINE_ENUM(TRACE_SAMPLE_BAR);
 TRACE_DEFINE_ENUM(TRACE_SAMPLE_ZOO);
 
 TRACE_EVENT(foo_bar,
 
     TP_PROTO(const char *foo, int bar, const int *lst,
          const char *string, const struct cpumask *mask,
          const char *fmt, va_list *va),
 
     TP_ARGS(foo, bar, lst, string, mask, fmt, va),
 
     TP_STRUCT__entry(
         __array(    char,   foo,    10      )
         __field(    int,    bar         )
         __dynamic_array(int,    list,   __length_of(lst))
         __string(   str,    string          )
         __bitmask(  cpus,   num_possible_cpus() )
         __vstring(  vstr,   fmt,    va      )
     ),
 
     TP_fast_assign(
         strlcpy(__entry->foo, foo, 10);
         __entry->bar    = bar;
         memcpy(__get_dynamic_array(list), lst,
                __length_of(lst) * sizeof(int));
         __assign_str(str, string);
         __assign_vstr(vstr, fmt, va);
         __assign_bitmask(cpus, cpumask_bits(mask), num_possible_cpus());
     ),
 
     TP_printk("foo %s %d %s %s %s %s (%s) %s", __entry->foo, __entry->bar,
 
 /*
  * Notice here the use of some helper functions. This includes:
  *
  *  __print_symbolic( variable, { value, "string" }, ... ),
  *
  *    The variable is tested against each value of the { } pair. If
  *    the variable matches one of the values, then it will print the
  *    string in that pair. If non are matched, it returns a string
  *    version of the number (if __entry->bar == 7 then "7" is returned).
  */
           __print_symbolic(__entry->bar,
                    { 0, "zero" },
                    { TRACE_SAMPLE_FOO, "TWO" },
                    { TRACE_SAMPLE_BAR, "FOUR" },
                    { TRACE_SAMPLE_ZOO, "EIGHT" },
                    { 10, "TEN" }
               ),
 
 /*
  *  __print_flags( variable, "delim", { value, "flag" }, ... ),
  *
  *    This is similar to __print_symbolic, except that it tests the bits
  *    of the value. If ((FLAG & variable) == FLAG) then the string is
  *    printed. If more than one flag matches, then each one that does is
  *    also printed with delim in between them.
  *    If not all bits are accounted for, then the not found bits will be
  *    added in hex format: 0x506 will show BIT2|BIT4|0x500
  */
           __print_flags(__entry->bar, "|",
                 { 1, "BIT1" },
                 { 2, "BIT2" },
                 { 4, "BIT3" },
                 { 8, "BIT4" }
               ),
 /*
  *  __print_array( array, len, element_size )
  *
  *    This prints out the array that is defined by __array in a nice format.
  */
           __print_array(__get_dynamic_array(list),
                 __get_dynamic_array_len(list) / sizeof(int),
                 sizeof(int)),
           __get_str(str), __get_bitmask(cpus), __get_str(vstr))
 );
 
 /*
  * There may be a case where a tracepoint should only be called if
  * some condition is set. Otherwise the tracepoint should not be called.
  * But to do something like:
  *
  *  if (cond)
  *     trace_foo();
  *
  * Would cause a little overhead when tracing is not enabled, and that
  * overhead, even if small, is not something we want. As tracepoints
  * use static branch (aka jump_labels), where no branch is taken to
  * skip the tracepoint when not enabled, and a jmp is placed to jump
  * to the tracepoint code when it is enabled, having a if statement
  * nullifies that optimization. It would be nice to place that
  * condition within the static branch. This is where TRACE_EVENT_CONDITION
  * comes in.
  *
  * TRACE_EVENT_CONDITION() is just like TRACE_EVENT, except it adds another
  * parameter just after args. Where TRACE_EVENT has:
  *
  * TRACE_EVENT(name, proto, args, struct, assign, printk)
  *
  * the CONDITION version has:
  *
  * TRACE_EVENT_CONDITION(name, proto, args, cond, struct, assign, printk)
  *
  * Everything is the same as TRACE_EVENT except for the new cond. Think
  * of the cond variable as:
  *
  *   if (cond)
  *      trace_foo_bar_with_cond();
  *
  * Except that the logic for the if branch is placed after the static branch.
  * That is, the if statement that processes the condition will not be
  * executed unless that traecpoint is enabled. Otherwise it still remains
  * a nop.
  */
 TRACE_EVENT_CONDITION(foo_bar_with_cond,
 
     TP_PROTO(const char *foo, int bar),
 
     TP_ARGS(foo, bar),
 
     TP_CONDITION(!(bar % 10)),
 
     TP_STRUCT__entry(
         __string(   foo,    foo     )
         __field(    int,    bar         )
     ),
 
     TP_fast_assign(
         __assign_str(foo, foo);
         __entry->bar    = bar;
     ),
 
     TP_printk("foo %s %d", __get_str(foo), __entry->bar)
 );
 
 int foo_bar_reg(void);
 void foo_bar_unreg(void);
 
 /*
  * Now in the case that some function needs to be called when the
  * tracepoint is enabled and/or when it is disabled, the
  * TRACE_EVENT_FN() serves this purpose. This is just like TRACE_EVENT()
  * but adds two more parameters at the end:
  *
  * TRACE_EVENT_FN( name, proto, args, struct, assign, printk, reg, unreg)
  *
  * reg and unreg are functions with the prototype of:
  *
  *    void reg(void)
  *
  * The reg function gets called before the tracepoint is enabled, and
  * the unreg function gets called after the tracepoint is disabled.
  *
  * Note, reg and unreg are allowed to be NULL. If you only need to
  * call a function before enabling, or after disabling, just set one
  * function and pass in NULL for the other parameter.
  */
 TRACE_EVENT_FN(foo_bar_with_fn,
 
     TP_PROTO(const char *foo, int bar),
 
     TP_ARGS(foo, bar),
 
     TP_STRUCT__entry(
         __string(   foo,    foo     )
         __field(    int,    bar     )
     ),
 
     TP_fast_assign(
         __assign_str(foo, foo);
         __entry->bar    = bar;
     ),
 
     TP_printk("foo %s %d", __get_str(foo), __entry->bar),
 
     foo_bar_reg, foo_bar_unreg
 );
 
 /*
  * Each TRACE_EVENT macro creates several helper functions to produce
  * the code to add the tracepoint, create the files in the trace
  * directory, hook it to perf, assign the values and to print out
  * the raw data from the ring buffer. To prevent too much bloat,
  * if there are more than one tracepoint that uses the same format
  * for the proto, args, struct, assign and printk, and only the name
  * is different, it is highly recommended to use the DECLARE_EVENT_CLASS
  *
  * DECLARE_EVENT_CLASS() macro creates most of the functions for the
  * tracepoint. Then DEFINE_EVENT() is use to hook a tracepoint to those
  * functions. This DEFINE_EVENT() is an instance of the class and can
  * be enabled and disabled separately from other events (either TRACE_EVENT
  * or other DEFINE_EVENT()s).
  *
  * Note, TRACE_EVENT() itself is simply defined as:
  *
  * #define TRACE_EVENT(name, proto, args, tstruct, assign, printk)  \
  *  DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, printk); \
  *  DEFINE_EVENT(name, name, proto, args)
  *
  * The DEFINE_EVENT() also can be declared with conditions and reg functions:
  *
  * DEFINE_EVENT_CONDITION(template, name, proto, args, cond);
  * DEFINE_EVENT_FN(template, name, proto, args, reg, unreg);
  */
 DECLARE_EVENT_CLASS(foo_template,
 
     TP_PROTO(const char *foo, int bar),
 
     TP_ARGS(foo, bar),
 
     TP_STRUCT__entry(
         __string(   foo,    foo     )
         __field(    int,    bar     )
     ),
 
     TP_fast_assign(
         __assign_str(foo, foo);
         __entry->bar    = bar;
     ),
 
     TP_printk("foo %s %d", __get_str(foo), __entry->bar)
 );
 
 /*
  * Here's a better way for the previous samples (except, the first
  * example had more fields and could not be used here).
  */
 DEFINE_EVENT(foo_template, foo_with_template_simple,
     TP_PROTO(const char *foo, int bar),
     TP_ARGS(foo, bar));
 
 DEFINE_EVENT_CONDITION(foo_template, foo_with_template_cond,
     TP_PROTO(const char *foo, int bar),
     TP_ARGS(foo, bar),
     TP_CONDITION(!(bar % 8)));
 
 
 DEFINE_EVENT_FN(foo_template, foo_with_template_fn,
     TP_PROTO(const char *foo, int bar),
     TP_ARGS(foo, bar),
     foo_bar_reg, foo_bar_unreg);
 
 /*
  * Anytime two events share basically the same values and have
  * the same output, use the DECLARE_EVENT_CLASS() and DEFINE_EVENT()
  * when ever possible.
  */
 
 /*
  * If the event is similar to the DECLARE_EVENT_CLASS, but you need
  * to have a different output, then use DEFINE_EVENT_PRINT() which
  * lets you override the TP_printk() of the class.
  */
 
 DEFINE_EVENT_PRINT(foo_template, foo_with_template_print,
     TP_PROTO(const char *foo, int bar),
     TP_ARGS(foo, bar),
     TP_printk("bar %s %d", __get_str(foo), __entry->bar));
 
 /*
  * There are yet another __rel_loc dynamic data attribute. If you
  * use __rel_dynamic_array() and __rel_string() etc. macros, you
  * can use this attribute. There is no difference from the viewpoint
  * of functionality with/without 'rel' but the encoding is a bit
  * different. This is expected to be used with user-space event,
  * there is no reason that the kernel event use this, but only for
  * testing.
  */
 
 TRACE_EVENT(foo_rel_loc,
 
     TP_PROTO(const char *foo, int bar, unsigned long *mask),
 
     TP_ARGS(foo, bar, mask),
 
     TP_STRUCT__entry(
         __rel_string(   foo,    foo )
         __field(    int,    bar )
         __rel_bitmask(  bitmask,
             BITS_PER_BYTE * sizeof(unsigned long)   )
     ),
 
     TP_fast_assign(
         __assign_rel_str(foo, foo);
         __entry->bar = bar;
         __assign_rel_bitmask(bitmask, mask,
             BITS_PER_BYTE * sizeof(unsigned long));
     ),
 
     TP_printk("foo_rel_loc %s, %d, %s", __get_rel_str(foo), __entry->bar,
           __get_rel_bitmask(bitmask))
 );
 #endif
 
 /***** NOTICE! The #if protection ends here. *****/
 
 
 /*
  * There are several ways I could have done this. If I left out the
  * TRACE_INCLUDE_PATH, then it would default to the kernel source
  * include/trace/events directory.
  *
  * I could specify a path from the define_trace.h file back to this
  * file.
  *
  * #define TRACE_INCLUDE_PATH ../../samples/trace_events
  *
  * But the safest and easiest way to simply make it use the directory
  * that the file is in is to add in the Makefile:
  *
  * CFLAGS_trace-events-sample.o := -I$(src)
  *
  * This will make sure the current path is part of the include
  * structure for our file so that define_trace.h can find it.
  *
  * I could have made only the top level directory the include:
  *
  * CFLAGS_trace-events-sample.o := -I$(PWD)
  *
  * And then let the path to this directory be the TRACE_INCLUDE_PATH:
  *
  * #define TRACE_INCLUDE_PATH samples/trace_events
  *
  * But then if something defines "samples" or "trace_events" as a macro
  * then we could risk that being converted too, and give us an unexpected
  * result.
  */
 #undef TRACE_INCLUDE_PATH
 #undef TRACE_INCLUDE_FILE
 #define TRACE_INCLUDE_PATH .
 /*
  * TRACE_INCLUDE_FILE is not needed if the filename and TRACE_SYSTEM are equal
  */
 #define TRACE_INCLUDE_FILE trace-events-sample
 #include <trace/define_trace.h>

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