mirror of https://gitee.com/openkylin/linux.git
524 lines
17 KiB
C
524 lines
17 KiB
C
/*
|
|
* 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 teh 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 numebr 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 nul terminated character array passed to it (it allows
|
|
* for NULL too, which would be converted into "(null)"). __string
|
|
* takes two paramenter (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.
|
|
*
|
|
* __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),
|
|
|
|
TP_ARGS(foo, bar, lst, string, mask),
|
|
|
|
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() )
|
|
),
|
|
|
|
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_bitmask(cpus, cpumask_bits(mask), num_possible_cpus());
|
|
),
|
|
|
|
TP_printk("foo %s %d %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))
|
|
);
|
|
|
|
/*
|
|
* 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) \
|
|
* DEFINE_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
|
|
* exmaple 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));
|
|
|
|
#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>
|