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5ba9f198 | 1 | |
4767a9e7 | 2 | RFC: Common Trace Format (CTF) Proposal (pre-v1.7) |
5ba9f198 MD |
3 | |
4 | Mathieu Desnoyers, EfficiOS Inc. | |
5 | ||
6 | The goal of the present document is to propose a trace format that suits the | |
cc089c3a | 7 | needs of the embedded, telecom, high-performance and kernel communities. It is |
5ba9f198 | 8 | based on the Common Trace Format Requirements (v1.4) document. It is designed to |
cc089c3a | 9 | allow traces to be natively generated by the Linux kernel, Linux user-space |
6c7226e9 MD |
10 | applications written in C/C++, and hardware components. One major element of |
11 | CTF is the Trace Stream Description Language (TSDL) which flexibility | |
12 | enables description of various binary trace stream layouts. | |
cc089c3a MD |
13 | |
14 | The latest version of this document can be found at: | |
15 | ||
16 | git tree: git://git.efficios.com/ctf.git | |
17 | gitweb: http://git.efficios.com/?p=ctf.git | |
5ba9f198 MD |
18 | |
19 | A reference implementation of a library to read and write this trace format is | |
20 | being implemented within the BabelTrace project, a converter between trace | |
21 | formats. The development tree is available at: | |
22 | ||
23 | git tree: git://git.efficios.com/babeltrace.git | |
24 | gitweb: http://git.efficios.com/?p=babeltrace.git | |
25 | ||
26 | ||
27 | 1. Preliminary definitions | |
28 | ||
3bf79539 MD |
29 | - Event Trace: An ordered sequence of events. |
30 | - Event Stream: An ordered sequence of events, containing a subset of the | |
31 | trace event types. | |
32 | - Event Packet: A sequence of physically contiguous events within an event | |
33 | stream. | |
5ba9f198 MD |
34 | - Event: This is the basic entry in a trace. (aka: a trace record). |
35 | - An event identifier (ID) relates to the class (a type) of event within | |
3bf79539 MD |
36 | an event stream. |
37 | e.g. event: irq_entry. | |
5ba9f198 MD |
38 | - An event (or event record) relates to a specific instance of an event |
39 | class. | |
3bf79539 MD |
40 | e.g. event: irq_entry, at time X, on CPU Y |
41 | - Source Architecture: Architecture writing the trace. | |
42 | - Reader Architecture: Architecture reading the trace. | |
5ba9f198 MD |
43 | |
44 | ||
45 | 2. High-level representation of a trace | |
46 | ||
3bf79539 MD |
47 | A trace is divided into multiple event streams. Each event stream contains a |
48 | subset of the trace event types. | |
5ba9f198 | 49 | |
3bf79539 MD |
50 | The final output of the trace, after its generation and optional transport over |
51 | the network, is expected to be either on permanent or temporary storage in a | |
52 | virtual file system. Because each event stream is appended to while a trace is | |
53 | being recorded, each is associated with a separate file for output. Therefore, | |
54 | a stored trace can be represented as a directory containing one file per stream. | |
5ba9f198 | 55 | |
6672e9e1 MD |
56 | Meta-data description associated with the trace contains information on |
57 | trace event types expressed in the Trace Stream Description Language | |
58 | (TSDL). This language describes: | |
5ba9f198 MD |
59 | |
60 | - Trace version. | |
61 | - Types available. | |
6672e9e1 | 62 | - Per-trace event header description. |
3bf79539 | 63 | - Per-stream event header description. |
6672e9e1 | 64 | - Per-stream event context description. |
5ba9f198 | 65 | - Per-event |
3bf79539 | 66 | - Event type to stream mapping. |
5ba9f198 MD |
67 | - Event type to name mapping. |
68 | - Event type to ID mapping. | |
6672e9e1 | 69 | - Event context description. |
5ba9f198 MD |
70 | - Event fields description. |
71 | ||
72 | ||
3bf79539 | 73 | 3. Event stream |
5ba9f198 | 74 | |
6672e9e1 MD |
75 | An event stream can be divided into contiguous event packets of variable |
76 | size. These subdivisions have a variable size. An event packet can | |
77 | contain a certain amount of padding at the end. The stream header is | |
78 | repeated at the beginning of each event packet. The rationale for the | |
79 | event stream design choices is explained in Appendix B. Stream Header | |
80 | Rationale. | |
5ba9f198 | 81 | |
3bf79539 MD |
82 | The event stream header will therefore be referred to as the "event packet |
83 | header" throughout the rest of this document. | |
5ba9f198 MD |
84 | |
85 | ||
86 | 4. Types | |
87 | ||
1fad7a85 MD |
88 | Types are organized as type classes. Each type class belong to either of two |
89 | kind of types: basic types or compound types. | |
90 | ||
5ba9f198 MD |
91 | 4.1 Basic types |
92 | ||
1fad7a85 MD |
93 | A basic type is a scalar type, as described in this section. It includes |
94 | integers, GNU/C bitfields, enumerations, and floating point values. | |
5ba9f198 MD |
95 | |
96 | 4.1.1 Type inheritance | |
97 | ||
80fd2569 MD |
98 | Type specifications can be inherited to allow deriving types from a |
99 | type class. For example, see the uint32_t named type derived from the "integer" | |
100 | type class below ("Integers" section). Types have a precise binary | |
101 | representation in the trace. A type class has methods to read and write these | |
102 | types, but must be derived into a type to be usable in an event field. | |
5ba9f198 MD |
103 | |
104 | 4.1.2 Alignment | |
105 | ||
106 | We define "byte-packed" types as aligned on the byte size, namely 8-bit. | |
107 | We define "bit-packed" types as following on the next bit, as defined by the | |
370eae99 | 108 | "Integers" section. |
5ba9f198 | 109 | |
6672e9e1 MD |
110 | Each basic type must specify its alignment, in bits. Examples of |
111 | possible alignments are: bit-packed, byte-packed, or word-aligned. The | |
112 | choice depends on the architecture preference and compactness vs | |
113 | performance trade-offs of the implementation. Architectures providing | |
114 | fast unaligned write byte-packed basic types to save space, aligning | |
115 | each type on byte boundaries (8-bit). Architectures with slow unaligned | |
116 | writes align types on specific alignment values. If no specific | |
370eae99 MD |
117 | alignment is declared for a type, it is assumed to be bit-packed for |
118 | integers with size not multiple of 8 bits and for gcc bitfields. All | |
6672e9e1 MD |
119 | other types are byte-packed. It is however recommended to always specify |
120 | the alignment explicitly. | |
5ba9f198 | 121 | |
6672e9e1 | 122 | TSDL meta-data attribute representation of a specific alignment: |
5ba9f198 MD |
123 | |
124 | align = value; /* value in bits */ | |
125 | ||
126 | 4.1.3 Byte order | |
127 | ||
3bf79539 MD |
128 | By default, the native endianness of the source architecture the trace is used. |
129 | Byte order can be overridden for a basic type by specifying a "byte_order" | |
130 | attribute. Typical use-case is to specify the network byte order (big endian: | |
131 | "be") to save data captured from the network into the trace without conversion. | |
132 | If not specified, the byte order is native. | |
5ba9f198 | 133 | |
6672e9e1 | 134 | TSDL meta-data representation: |
5ba9f198 MD |
135 | |
136 | byte_order = native OR network OR be OR le; /* network and be are aliases */ | |
137 | ||
138 | 4.1.4 Size | |
139 | ||
140 | Type size, in bits, for integers and floats is that returned by "sizeof()" in C | |
141 | multiplied by CHAR_BIT. | |
142 | We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed | |
143 | to 8 bits for cross-endianness compatibility. | |
144 | ||
6672e9e1 | 145 | TSDL meta-data representation: |
5ba9f198 MD |
146 | |
147 | size = value; (value is in bits) | |
148 | ||
149 | 4.1.5 Integers | |
150 | ||
6672e9e1 MD |
151 | Signed integers are represented in two-complement. Integer alignment, |
152 | size, signedness and byte ordering are defined in the TSDL meta-data. | |
153 | Integers aligned on byte size (8-bit) and with length multiple of byte | |
154 | size (8-bit) correspond to the C99 standard integers. In addition, | |
155 | integers with alignment and/or size that are _not_ a multiple of the | |
156 | byte size are permitted; these correspond to the C99 standard bitfields, | |
157 | with the added specification that the CTF integer bitfields have a fixed | |
158 | binary representation. A MIT-licensed reference implementation of the | |
159 | CTF portable bitfields is available at: | |
5ba9f198 MD |
160 | |
161 | http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h | |
162 | ||
163 | Binary representation of integers: | |
164 | ||
165 | - On little and big endian: | |
166 | - Within a byte, high bits correspond to an integer high bits, and low bits | |
167 | correspond to low bits. | |
168 | - On little endian: | |
169 | - Integer across multiple bytes are placed from the less significant to the | |
170 | most significant. | |
171 | - Consecutive integers are placed from lower bits to higher bits (even within | |
172 | a byte). | |
173 | - On big endian: | |
174 | - Integer across multiple bytes are placed from the most significant to the | |
175 | less significant. | |
176 | - Consecutive integers are placed from higher bits to lower bits (even within | |
177 | a byte). | |
178 | ||
179 | This binary representation is derived from the bitfield implementation in GCC | |
180 | for little and big endian. However, contrary to what GCC does, integers can | |
6672e9e1 | 181 | cross units boundaries (no padding is required). Padding can be explicitly |
5ba9f198 MD |
182 | added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed. |
183 | ||
6672e9e1 | 184 | TSDL meta-data representation: |
5ba9f198 | 185 | |
80fd2569 | 186 | integer { |
5ba9f198 MD |
187 | signed = true OR false; /* default false */ |
188 | byte_order = native OR network OR be OR le; /* default native */ | |
189 | size = value; /* value in bits, no default */ | |
190 | align = value; /* value in bits */ | |
2152348f | 191 | } |
5ba9f198 | 192 | |
80fd2569 | 193 | Example of type inheritance (creation of a uint32_t named type): |
5ba9f198 | 194 | |
359894ac | 195 | typealias integer { |
9e4e34e9 | 196 | size = 32; |
5ba9f198 MD |
197 | signed = false; |
198 | align = 32; | |
38b8da21 | 199 | } := uint32_t; |
5ba9f198 | 200 | |
80fd2569 | 201 | Definition of a named 5-bit signed bitfield: |
5ba9f198 | 202 | |
359894ac | 203 | typealias integer { |
5ba9f198 MD |
204 | size = 5; |
205 | signed = true; | |
206 | align = 1; | |
38b8da21 | 207 | } := int5_t; |
5ba9f198 MD |
208 | |
209 | 4.1.6 GNU/C bitfields | |
210 | ||
211 | The GNU/C bitfields follow closely the integer representation, with a | |
212 | particularity on alignment: if a bitfield cannot fit in the current unit, the | |
80fd2569 MD |
213 | unit is padded and the bitfield starts at the following unit. The unit size is |
214 | defined by the size of the type "unit_type". | |
5ba9f198 | 215 | |
6672e9e1 | 216 | TSDL meta-data representation: |
80fd2569 MD |
217 | |
218 | unit_type name:size: | |
219 | ||
5ba9f198 MD |
220 | As an example, the following structure declared in C compiled by GCC: |
221 | ||
222 | struct example { | |
223 | short a:12; | |
224 | short b:5; | |
225 | }; | |
226 | ||
2152348f MD |
227 | The example structure is aligned on the largest element (short). The second |
228 | bitfield would be aligned on the next unit boundary, because it would not fit in | |
229 | the current unit. | |
5ba9f198 MD |
230 | |
231 | 4.1.7 Floating point | |
232 | ||
6672e9e1 | 233 | The floating point values byte ordering is defined in the TSDL meta-data. |
5ba9f198 MD |
234 | |
235 | Floating point values follow the IEEE 754-2008 standard interchange formats. | |
236 | Description of the floating point values include the exponent and mantissa size | |
237 | in bits. Some requirements are imposed on the floating point values: | |
238 | ||
239 | - FLT_RADIX must be 2. | |
240 | - mant_dig is the number of digits represented in the mantissa. It is specified | |
241 | by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and | |
242 | LDBL_MANT_DIG as defined by <float.h>. | |
243 | - exp_dig is the number of digits represented in the exponent. Given that | |
244 | mant_dig is one bit more than its actual size in bits (leading 1 is not | |
245 | needed) and also given that the sign bit always takes one bit, exp_dig can be | |
246 | specified as: | |
247 | ||
248 | - sizeof(float) * CHAR_BIT - FLT_MANT_DIG | |
249 | - sizeof(double) * CHAR_BIT - DBL_MANT_DIG | |
250 | - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG | |
251 | ||
6672e9e1 | 252 | TSDL meta-data representation: |
5ba9f198 | 253 | |
80fd2569 | 254 | floating_point { |
5ba9f198 MD |
255 | exp_dig = value; |
256 | mant_dig = value; | |
257 | byte_order = native OR network OR be OR le; | |
2152348f | 258 | } |
5ba9f198 MD |
259 | |
260 | Example of type inheritance: | |
261 | ||
359894ac | 262 | typealias floating_point { |
5ba9f198 MD |
263 | exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */ |
264 | mant_dig = 24; /* FLT_MANT_DIG */ | |
265 | byte_order = native; | |
38b8da21 | 266 | } := float; |
5ba9f198 MD |
267 | |
268 | TODO: define NaN, +inf, -inf behavior. | |
269 | ||
270 | 4.1.8 Enumerations | |
271 | ||
272 | Enumerations are a mapping between an integer type and a table of strings. The | |
273 | numerical representation of the enumeration follows the integer type specified | |
6672e9e1 MD |
274 | by the meta-data. The enumeration mapping table is detailed in the enumeration |
275 | description within the meta-data. The mapping table maps inclusive value | |
276 | ranges (or single values) to strings. Instead of being limited to simple | |
3bf79539 | 277 | "value -> string" mappings, these enumerations map |
80fd2569 | 278 | "[ start_value ... end_value ] -> string", which map inclusive ranges of |
3bf79539 MD |
279 | values to strings. An enumeration from the C language can be represented in |
280 | this format by having the same start_value and end_value for each element, which | |
281 | is in fact a range of size 1. This single-value range is supported without | |
4767a9e7 | 282 | repeating the start and end values with the value = string declaration. |
80fd2569 | 283 | |
a9b83695 | 284 | enum name : integer_type { |
359894ac | 285 | somestring = start_value1 ... end_value1, |
80fd2569 MD |
286 | "other string" = start_value2 ... end_value2, |
287 | yet_another_string, /* will be assigned to end_value2 + 1 */ | |
288 | "some other string" = value, | |
289 | ... | |
290 | }; | |
291 | ||
292 | If the values are omitted, the enumeration starts at 0 and increment of 1 for | |
293 | each entry: | |
294 | ||
a9b83695 | 295 | enum name : unsigned int { |
80fd2569 MD |
296 | ZERO, |
297 | ONE, | |
298 | TWO, | |
299 | TEN = 10, | |
300 | ELEVEN, | |
3bf79539 | 301 | }; |
5ba9f198 | 302 | |
80fd2569 | 303 | Overlapping ranges within a single enumeration are implementation defined. |
5ba9f198 | 304 | |
2152348f MD |
305 | A nameless enumeration can be declared as a field type or as part of a typedef: |
306 | ||
a9b83695 | 307 | enum : integer_type { |
2152348f MD |
308 | ... |
309 | } | |
310 | ||
c2742c56 MD |
311 | Enumerations omitting the container type ": integer_type" use the "int" |
312 | type (for compatibility with C99). The "int" type must be previously | |
313 | declared. E.g.: | |
314 | ||
315 | typealias integer { size = 32; align = 32; signed = true } := int; | |
316 | ||
317 | enum { | |
318 | ... | |
319 | } | |
320 | ||
1fad7a85 | 321 | |
5ba9f198 MD |
322 | 4.2 Compound types |
323 | ||
1fad7a85 MD |
324 | Compound are aggregation of type declarations. Compound types include |
325 | structures, variant, arrays, sequences, and strings. | |
326 | ||
5ba9f198 MD |
327 | 4.2.1 Structures |
328 | ||
329 | Structures are aligned on the largest alignment required by basic types | |
330 | contained within the structure. (This follows the ISO/C standard for structures) | |
331 | ||
6672e9e1 | 332 | TSDL meta-data representation of a named structure: |
5ba9f198 | 333 | |
80fd2569 MD |
334 | struct name { |
335 | field_type field_name; | |
336 | field_type field_name; | |
337 | ... | |
338 | }; | |
5ba9f198 MD |
339 | |
340 | Example: | |
341 | ||
80fd2569 MD |
342 | struct example { |
343 | integer { /* Nameless type */ | |
344 | size = 16; | |
345 | signed = true; | |
346 | align = 16; | |
347 | } first_field_name; | |
6672e9e1 | 348 | uint64_t second_field_name; /* Named type declared in the meta-data */ |
3bf79539 | 349 | }; |
5ba9f198 MD |
350 | |
351 | The fields are placed in a sequence next to each other. They each possess a | |
352 | field name, which is a unique identifier within the structure. | |
353 | ||
2152348f | 354 | A nameless structure can be declared as a field type or as part of a typedef: |
80fd2569 MD |
355 | |
356 | struct { | |
357 | ... | |
2152348f | 358 | } |
80fd2569 | 359 | |
77a98c82 | 360 | 4.2.2 Variants (Discriminated/Tagged Unions) |
fcba70d4 | 361 | |
fdf2bb05 MD |
362 | A CTF variant is a selection between different types. A CTF variant must |
363 | always be defined within the scope of a structure or within fields | |
364 | contained within a structure (defined recursively). A "tag" enumeration | |
365 | field must appear in either the same lexical scope, prior to the variant | |
366 | field (in field declaration order), in an uppermost lexical scope (see | |
6c7226e9 | 367 | Section 7.3.1), or in an uppermost dynamic scope (see Section 7.3.2). |
fdf2bb05 MD |
368 | The type selection is indicated by the mapping from the enumeration |
369 | value to the string used as variant type selector. The field to use as | |
370 | tag is specified by the "tag_field", specified between "< >" after the | |
371 | "variant" keyword for unnamed variants, and after "variant name" for | |
372 | named variants. | |
fcba70d4 MD |
373 | |
374 | The alignment of the variant is the alignment of the type as selected by the tag | |
375 | value for the specific instance of the variant. The alignment of the type | |
376 | containing the variant is independent of the variant alignment. The size of the | |
377 | variant is the size as selected by the tag value for the specific instance of | |
378 | the variant. | |
379 | ||
380 | A named variant declaration followed by its definition within a structure | |
381 | declaration: | |
382 | ||
383 | variant name { | |
384 | field_type sel1; | |
385 | field_type sel2; | |
386 | field_type sel3; | |
387 | ... | |
388 | }; | |
389 | ||
390 | struct { | |
a9b83695 | 391 | enum : integer_type { sel1, sel2, sel3, ... } tag_field; |
fcba70d4 MD |
392 | ... |
393 | variant name <tag_field> v; | |
394 | } | |
395 | ||
396 | An unnamed variant definition within a structure is expressed by the following | |
6672e9e1 | 397 | TSDL meta-data: |
fcba70d4 MD |
398 | |
399 | struct { | |
a9b83695 | 400 | enum : integer_type { sel1, sel2, sel3, ... } tag_field; |
fcba70d4 MD |
401 | ... |
402 | variant <tag_field> { | |
403 | field_type sel1; | |
404 | field_type sel2; | |
405 | field_type sel3; | |
406 | ... | |
407 | } v; | |
408 | } | |
409 | ||
410 | Example of a named variant within a sequence that refers to a single tag field: | |
411 | ||
412 | variant example { | |
413 | uint32_t a; | |
414 | uint64_t b; | |
415 | short c; | |
416 | }; | |
417 | ||
418 | struct { | |
a9b83695 | 419 | enum : uint2_t { a, b, c } choice; |
15850440 | 420 | variant example <choice> v[unsigned int]; |
fcba70d4 MD |
421 | } |
422 | ||
423 | Example of an unnamed variant: | |
424 | ||
425 | struct { | |
a9b83695 | 426 | enum : uint2_t { a, b, c, d } choice; |
fcba70d4 MD |
427 | /* Unrelated fields can be added between the variant and its tag */ |
428 | int32_t somevalue; | |
429 | variant <choice> { | |
430 | uint32_t a; | |
431 | uint64_t b; | |
432 | short c; | |
433 | struct { | |
434 | unsigned int field1; | |
435 | uint64_t field2; | |
436 | } d; | |
437 | } s; | |
438 | } | |
439 | ||
440 | Example of an unnamed variant within an array: | |
441 | ||
442 | struct { | |
a9b83695 | 443 | enum : uint2_t { a, b, c } choice; |
fcba70d4 MD |
444 | variant <choice> { |
445 | uint32_t a; | |
446 | uint64_t b; | |
447 | short c; | |
15850440 | 448 | } v[10]; |
fcba70d4 MD |
449 | } |
450 | ||
451 | Example of a variant type definition within a structure, where the defined type | |
452 | is then declared within an array of structures. This variant refers to a tag | |
453 | located in an upper lexical scope. This example clearly shows that a variant | |
454 | type definition referring to the tag "x" uses the closest preceding field from | |
455 | the lexical scope of the type definition. | |
456 | ||
457 | struct { | |
a9b83695 | 458 | enum : uint2_t { a, b, c, d } x; |
fcba70d4 MD |
459 | |
460 | typedef variant <x> { /* | |
461 | * "x" refers to the preceding "x" enumeration in the | |
462 | * lexical scope of the type definition. | |
463 | */ | |
464 | uint32_t a; | |
465 | uint64_t b; | |
466 | short c; | |
467 | } example_variant; | |
468 | ||
469 | struct { | |
a9b83695 | 470 | enum : int { x, y, z } x; /* This enumeration is not used by "v". */ |
fcba70d4 | 471 | example_variant v; /* |
a9b83695 | 472 | * "v" uses the "enum : uint2_t { a, b, c, d }" |
fcba70d4 MD |
473 | * tag. |
474 | */ | |
475 | } a[10]; | |
476 | } | |
477 | ||
478 | 4.2.3 Arrays | |
5ba9f198 | 479 | |
6672e9e1 MD |
480 | Arrays are fixed-length. Their length is declared in the type |
481 | declaration within the meta-data. They contain an array of "inner type" | |
482 | elements, which can refer to any type not containing the type of the | |
483 | array being declared (no circular dependency). The length is the number | |
484 | of elements in an array. | |
5ba9f198 | 485 | |
6672e9e1 | 486 | TSDL meta-data representation of a named array: |
80fd2569 MD |
487 | |
488 | typedef elem_type name[length]; | |
5ba9f198 | 489 | |
2152348f | 490 | A nameless array can be declared as a field type within a structure, e.g.: |
5ba9f198 | 491 | |
2152348f | 492 | uint8_t field_name[10]; |
80fd2569 | 493 | |
5ba9f198 | 494 | |
fcba70d4 | 495 | 4.2.4 Sequences |
5ba9f198 MD |
496 | |
497 | Sequences are dynamically-sized arrays. They start with an integer that specify | |
498 | the length of the sequence, followed by an array of "inner type" elements. | |
3bf79539 | 499 | The length is the number of elements in the sequence. |
5ba9f198 | 500 | |
6672e9e1 | 501 | TSDL meta-data representation for a named sequence: |
80fd2569 MD |
502 | |
503 | typedef elem_type name[length_type]; | |
504 | ||
505 | A nameless sequence can be declared as a field type, e.g.: | |
506 | ||
80fd2569 MD |
507 | long field_name[int]; |
508 | ||
509 | The length type follows the integer types specifications, and the sequence | |
5ba9f198 MD |
510 | elements follow the "array" specifications. |
511 | ||
fcba70d4 | 512 | 4.2.5 Strings |
5ba9f198 MD |
513 | |
514 | Strings are an array of bytes of variable size and are terminated by a '\0' | |
6672e9e1 MD |
515 | "NULL" character. Their encoding is described in the TSDL meta-data. In |
516 | absence of encoding attribute information, the default encoding is | |
517 | UTF-8. | |
5ba9f198 | 518 | |
6672e9e1 | 519 | TSDL meta-data representation of a named string type: |
80fd2569 | 520 | |
359894ac | 521 | typealias string { |
5ba9f198 | 522 | encoding = UTF8 OR ASCII; |
38b8da21 | 523 | } := name; |
5ba9f198 | 524 | |
80fd2569 MD |
525 | A nameless string type can be declared as a field type: |
526 | ||
527 | string field_name; /* Use default UTF8 encoding */ | |
5ba9f198 | 528 | |
3bf79539 MD |
529 | 5. Event Packet Header |
530 | ||
6672e9e1 MD |
531 | The event packet header consists of two parts: the "event packet header" |
532 | is the same for all streams of a trace. The second part, the "event | |
533 | packet context", is described on a per-stream basis. Both are described | |
534 | in the TSDL meta-data. The packets are aligned on architecture-page-sized | |
535 | addresses. | |
3bf79539 | 536 | |
6672e9e1 | 537 | Event packet header (all fields are optional, specified by TSDL meta-data): |
3bf79539 | 538 | |
6672e9e1 MD |
539 | - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a |
540 | CTF packet. This magic number is optional, but when present, it should | |
541 | come at the very beginning of the packet. | |
542 | - Trace UUID, used to ensure the event packet match the meta-data used. | |
543 | (note: we cannot use a meta-data checksum in every cases instead of a | |
544 | UUID because meta-data can be appended to while tracing is active) | |
545 | This field is optional. | |
546 | - Stream ID, used as reference to stream description in meta-data. | |
547 | This field is optional if there is only one stream description in the | |
548 | meta-data, but becomes required if there are more than one stream in | |
549 | the TSDL meta-data description. | |
3bf79539 | 550 | |
6672e9e1 | 551 | Event packet context (all fields are optional, specified by TSDL meta-data): |
3bf79539 MD |
552 | |
553 | - Event packet content size (in bytes). | |
554 | - Event packet size (in bytes, includes padding). | |
555 | - Event packet content checksum (optional). Checksum excludes the event packet | |
556 | header. | |
557 | - Per-stream event packet sequence count (to deal with UDP packet loss). The | |
558 | number of significant sequence counter bits should also be present, so | |
b11853af | 559 | wrap-arounds are dealt with correctly. |
6672e9e1 | 560 | - Time-stamp at the beginning and time-stamp at the end of the event packet. |
3bf79539 MD |
561 | Both timestamps are written in the packet header, but sampled respectively |
562 | while (or before) writing the first event and while (or after) writing the | |
563 | last event in the packet. The inclusive range between these timestamps should | |
564 | include all event timestamps assigned to events contained within the packet. | |
5ba9f198 | 565 | - Events discarded count |
3bf79539 MD |
566 | - Snapshot of a per-stream free-running counter, counting the number of |
567 | events discarded that were supposed to be written in the stream prior to | |
568 | the first event in the event packet. | |
5ba9f198 | 569 | * Note: producer-consumer buffer full condition should fill the current |
3bf79539 | 570 | event packet with padding so we know exactly where events have been |
5ba9f198 | 571 | discarded. |
3bf79539 MD |
572 | - Lossless compression scheme used for the event packet content. Applied |
573 | directly to raw data. New types of compression can be added in following | |
574 | versions of the format. | |
5ba9f198 MD |
575 | 0: no compression scheme |
576 | 1: bzip2 | |
577 | 2: gzip | |
3bf79539 MD |
578 | 3: xz |
579 | - Cypher used for the event packet content. Applied after compression. | |
5ba9f198 MD |
580 | 0: no encryption |
581 | 1: AES | |
3bf79539 | 582 | - Checksum scheme used for the event packet content. Applied after encryption. |
5ba9f198 MD |
583 | 0: no checksum |
584 | 1: md5 | |
585 | 2: sha1 | |
586 | 3: crc32 | |
587 | ||
6672e9e1 | 588 | 5.1 Event Packet Header Description |
3bf79539 | 589 | |
fc5425db | 590 | The event packet header layout is indicated by the trace packet.header |
6672e9e1 MD |
591 | field. Here is a recommended structure type for the packet header with |
592 | the fields typically expected (although these fields are each optional): | |
fc5425db | 593 | |
80fd2569 MD |
594 | struct event_packet_header { |
595 | uint32_t magic; | |
596 | uint8_t trace_uuid[16]; | |
3bf79539 | 597 | uint32_t stream_id; |
80fd2569 | 598 | }; |
5ba9f198 | 599 | |
fc5425db MD |
600 | trace { |
601 | ... | |
602 | packet.header := struct event_packet_header; | |
603 | }; | |
604 | ||
6672e9e1 MD |
605 | If the magic number is not present, tools such as "file" will have no |
606 | mean to discover the file type. | |
607 | ||
608 | If the trace_uuid is not present, no validation that the meta-data | |
37b39e47 MD |
609 | actually corresponds to the stream is performed. |
610 | ||
611 | If the stream_id packet header field is missing, the trace can only | |
612 | contain a single stream. Its "id" field can be left out, and its events | |
613 | don't need to declare a "stream_id" field. | |
614 | ||
615 | ||
3bf79539 MD |
616 | 5.2 Event Packet Context Description |
617 | ||
618 | Event packet context example. These are declared within the stream declaration | |
6672e9e1 | 619 | in the meta-data. All these fields are optional. If the packet size field is |
6a7c61df | 620 | missing, the whole stream only contains a single packet. If the content |
f6b81726 MD |
621 | size field is missing, the packet is filled (no padding). The content |
622 | and packet sizes include all headers. | |
3bf79539 MD |
623 | |
624 | An example event packet context type: | |
625 | ||
80fd2569 | 626 | struct event_packet_context { |
3bf79539 MD |
627 | uint64_t timestamp_begin; |
628 | uint64_t timestamp_end; | |
629 | uint32_t checksum; | |
630 | uint32_t stream_packet_count; | |
631 | uint32_t events_discarded; | |
632 | uint32_t cpu_id; | |
633 | uint32_t/uint16_t content_size; | |
634 | uint32_t/uint16_t packet_size; | |
635 | uint8_t stream_packet_count_bits; /* Significant counter bits */ | |
636 | uint8_t compression_scheme; | |
637 | uint8_t encryption_scheme; | |
3b0f8e4d | 638 | uint8_t checksum_scheme; |
3bf79539 | 639 | }; |
5ba9f198 | 640 | |
fcba70d4 | 641 | |
5ba9f198 MD |
642 | 6. Event Structure |
643 | ||
644 | The overall structure of an event is: | |
645 | ||
6672e9e1 MD |
646 | 1 - Stream Packet Context (as specified by the stream meta-data) |
647 | 2 - Event Header (as specified by the stream meta-data) | |
648 | 3 - Stream Event Context (as specified by the stream meta-data) | |
649 | 4 - Event Context (as specified by the event meta-data) | |
650 | 5 - Event Payload (as specified by the event meta-data) | |
5ba9f198 | 651 | |
fdf2bb05 | 652 | This structure defines an implicit dynamic scoping, where variants |
7d9d7e92 MD |
653 | located in inner structures (those with a higher number in the listing |
654 | above) can refer to the fields of outer structures (with lower number in | |
6c7226e9 | 655 | the listing above). See Section 7.3 TSDL Scopes for more detail. |
5ba9f198 | 656 | |
fdf2bb05 | 657 | 6.1 Event Header |
fcba70d4 | 658 | |
6672e9e1 | 659 | Event headers can be described within the meta-data. We hereby propose, as an |
fcba70d4 MD |
660 | example, two types of events headers. Type 1 accommodates streams with less than |
661 | 31 event IDs. Type 2 accommodates streams with 31 or more event IDs. | |
5ba9f198 | 662 | |
3bf79539 MD |
663 | One major factor can vary between streams: the number of event IDs assigned to |
664 | a stream. Luckily, this information tends to stay relatively constant (modulo | |
5ba9f198 | 665 | event registration while trace is being recorded), so we can specify different |
3bf79539 | 666 | representations for streams containing few event IDs and streams containing |
6672e9e1 MD |
667 | many event IDs, so we end up representing the event ID and time-stamp as |
668 | densely as possible in each case. | |
5ba9f198 | 669 | |
fcba70d4 MD |
670 | The header is extended in the rare occasions where the information cannot be |
671 | represented in the ranges available in the standard event header. They are also | |
3bf79539 MD |
672 | used in the rare occasions where the data required for a field could not be |
673 | collected: the flag corresponding to the missing field within the missing_fields | |
674 | array is then set to 1. | |
5ba9f198 | 675 | |
6672e9e1 MD |
676 | Types uintX_t represent an X-bit unsigned integer, as declared with |
677 | either: | |
5ba9f198 | 678 | |
6672e9e1 MD |
679 | typealias integer { size = X; align = X; signed = false } := uintX_t; |
680 | ||
681 | or | |
682 | ||
683 | typealias integer { size = X; align = 1; signed = false } := uintX_t; | |
5ba9f198 | 684 | |
fdf2bb05 | 685 | 6.1.1 Type 1 - Few event IDs |
5ba9f198 MD |
686 | |
687 | - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture | |
688 | preference). | |
5ba9f198 | 689 | - Native architecture byte ordering. |
fcba70d4 MD |
690 | - For "compact" selection |
691 | - Fixed size: 32 bits. | |
692 | - For "extended" selection | |
693 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 694 | |
80fd2569 | 695 | struct event_header_1 { |
fcba70d4 MD |
696 | /* |
697 | * id: range: 0 - 30. | |
698 | * id 31 is reserved to indicate an extended header. | |
699 | */ | |
a9b83695 | 700 | enum : uint5_t { compact = 0 ... 30, extended = 31 } id; |
fcba70d4 MD |
701 | variant <id> { |
702 | struct { | |
703 | uint27_t timestamp; | |
704 | } compact; | |
705 | struct { | |
706 | uint32_t id; /* 32-bit event IDs */ | |
707 | uint64_t timestamp; /* 64-bit timestamps */ | |
708 | } extended; | |
709 | } v; | |
5ba9f198 MD |
710 | }; |
711 | ||
5ba9f198 | 712 | |
fdf2bb05 | 713 | 6.1.2 Type 2 - Many event IDs |
5ba9f198 | 714 | |
fcba70d4 | 715 | - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture |
5ba9f198 | 716 | preference). |
5ba9f198 | 717 | - Native architecture byte ordering. |
fcba70d4 MD |
718 | - For "compact" selection |
719 | - Size depends on the architecture and variant alignment. | |
720 | - For "extended" selection | |
721 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 722 | |
80fd2569 | 723 | struct event_header_2 { |
fcba70d4 MD |
724 | /* |
725 | * id: range: 0 - 65534. | |
726 | * id 65535 is reserved to indicate an extended header. | |
727 | */ | |
a9b83695 | 728 | enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id; |
fcba70d4 MD |
729 | variant <id> { |
730 | struct { | |
731 | uint32_t timestamp; | |
732 | } compact; | |
733 | struct { | |
734 | uint32_t id; /* 32-bit event IDs */ | |
735 | uint64_t timestamp; /* 64-bit timestamps */ | |
736 | } extended; | |
737 | } v; | |
5ba9f198 MD |
738 | }; |
739 | ||
5ba9f198 MD |
740 | |
741 | 6.2 Event Context | |
742 | ||
6672e9e1 MD |
743 | The event context contains information relative to the current event. |
744 | The choice and meaning of this information is specified by the TSDL | |
745 | stream and event meta-data descriptions. The stream context is applied | |
746 | to all events within the stream. The stream context structure follows | |
747 | the event header. The event context is applied to specific events. Its | |
748 | structure follows the stream context structure. | |
5ba9f198 | 749 | |
fcba70d4 MD |
750 | An example of stream-level event context is to save the event payload size with |
751 | each event, or to save the current PID with each event. These are declared | |
6672e9e1 | 752 | within the stream declaration within the meta-data: |
5ba9f198 | 753 | |
fcba70d4 MD |
754 | stream { |
755 | ... | |
6672e9e1 | 756 | event.context := struct { |
80fd2569 MD |
757 | uint pid; |
758 | uint16_t payload_size; | |
6672e9e1 | 759 | }; |
fcba70d4 MD |
760 | }; |
761 | ||
762 | An example of event-specific event context is to declare a bitmap of missing | |
763 | fields, only appended after the stream event context if the extended event | |
764 | header is selected. NR_FIELDS is the number of fields within the event (a | |
765 | numeric value). | |
5ba9f198 | 766 | |
fcba70d4 MD |
767 | event { |
768 | context = struct { | |
769 | variant <id> { | |
770 | struct { } compact; | |
771 | struct { | |
772 | uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */ | |
773 | } extended; | |
774 | } v; | |
775 | }; | |
776 | ... | |
777 | } | |
5ba9f198 MD |
778 | |
779 | 6.3 Event Payload | |
780 | ||
781 | An event payload contains fields specific to a given event type. The fields | |
6672e9e1 | 782 | belonging to an event type are described in the event-specific meta-data |
5ba9f198 MD |
783 | within a structure type. |
784 | ||
785 | 6.3.1 Padding | |
786 | ||
787 | No padding at the end of the event payload. This differs from the ISO/C standard | |
788 | for structures, but follows the CTF standard for structures. In a trace, even | |
789 | though it makes sense to align the beginning of a structure, it really makes no | |
790 | sense to add padding at the end of the structure, because structures are usually | |
791 | not followed by a structure of the same type. | |
792 | ||
793 | This trick can be done by adding a zero-length "end" field at the end of the C | |
794 | structures, and by using the offset of this field rather than using sizeof() | |
3bf79539 | 795 | when calculating the size of a structure (see Appendix "A. Helper macros"). |
5ba9f198 MD |
796 | |
797 | 6.3.2 Alignment | |
798 | ||
799 | The event payload is aligned on the largest alignment required by types | |
800 | contained within the payload. (This follows the ISO/C standard for structures) | |
801 | ||
802 | ||
6c7226e9 MD |
803 | 7. Trace Stream Description Language (TSDL) |
804 | ||
805 | The Trace Stream Description Language (TSDL) allows expression of the | |
806 | binary trace streams layout in a C99-like Domain Specific Language | |
807 | (DSL). | |
808 | ||
809 | ||
6672e9e1 | 810 | 7.1 Meta-data |
6c7226e9 MD |
811 | |
812 | The trace stream layout description is located in the trace meta-data. | |
813 | The meta-data is itself located in a stream identified by its name: | |
814 | "metadata". | |
5ba9f198 | 815 | |
6672e9e1 MD |
816 | The meta-data description can be expressed in two different formats: |
817 | text-only and packet-based. The text-only description facilitates | |
818 | generation of meta-data and provides a convenient way to enter the | |
819 | meta-data information by hand. The packet-based meta-data provides the | |
820 | CTF stream packet facilities (checksumming, compression, encryption, | |
821 | network-readiness) for meta-data stream generated and transported by a | |
822 | tracer. | |
823 | ||
824 | The text-only meta-data file is a plain text TSDL description. | |
825 | ||
826 | The packet-based meta-data is made of "meta-data packets", which each | |
827 | start with a meta-data packet header. The packet-based meta-data | |
828 | description is detected by reading the magic number "0x75D11D57" at the | |
829 | beginning of the file. This magic number is also used to detect the | |
830 | endianness of the architecture by trying to read the CTF magic number | |
831 | and its counterpart in reversed endianness. The events within the | |
832 | meta-data stream have no event header nor event context. Each event only | |
833 | contains a "string" payload. Each meta-data packet start with a special | |
834 | packet header, specific to the meta-data stream, which contains, | |
835 | exactly: | |
836 | ||
837 | struct metadata_packet_header { | |
2daeaa3a | 838 | uint32_t magic; /* 0x75D11D57 */ |
6672e9e1 MD |
839 | uint8_t trace_uuid[16]; /* Unique Universal Identifier */ |
840 | uint32_t checksum; /* 0 if unused */ | |
841 | uint32_t content_size; /* in bits */ | |
842 | uint32_t packet_size; /* in bits */ | |
843 | uint8_t compression_scheme; /* 0 if unused */ | |
844 | uint8_t encryption_scheme; /* 0 if unused */ | |
845 | uint8_t checksum_scheme; /* 0 if unused */ | |
846 | }; | |
847 | ||
848 | The packet-based meta-data can be converted to a text-only meta-data by | |
849 | concatenating all the strings in contains. | |
4fafe1ad | 850 | |
6672e9e1 MD |
851 | In the textual representation of the meta-data, the text contained |
852 | within "/*" and "*/", as well as within "//" and end of line, are | |
853 | treated as comments. Boolean values can be represented as true, TRUE, | |
854 | or 1 for true, and false, FALSE, or 0 for false. Within the string-based | |
855 | meta-data description, the trace UUID is represented as a string of | |
856 | hexadecimal digits and dashes "-". In the event packet header, the trace | |
857 | UUID is represented as an array of bytes. | |
fcba70d4 | 858 | |
fdf2bb05 | 859 | |
6c7226e9 | 860 | 7.2 Declaration vs Definition |
fdf2bb05 MD |
861 | |
862 | A declaration associates a layout to a type, without specifying where | |
863 | this type is located in the event structure hierarchy (see Section 6). | |
864 | This therefore includes typedef, typealias, as well as all type | |
865 | specifiers. In certain circumstances (typedef, structure field and | |
866 | variant field), a declaration is followed by a declarator, which specify | |
867 | the newly defined type name (for typedef), or the field name (for | |
868 | declarations located within structure and variants). Array and sequence, | |
869 | declared with square brackets ("[" "]"), are part of the declarator, | |
a9b83695 | 870 | similarly to C99. The enumeration base type is specified by |
6c7226e9 | 871 | ": enum_base", which is part of the type specifier. The variant tag |
a9b83695 | 872 | name, specified between "<" ">", is also part of the type specifier. |
fdf2bb05 MD |
873 | |
874 | A definition associates a type to a location in the event structure | |
b9606a77 MD |
875 | hierarchy (see Section 6). This association is denoted by ":=", as shown |
876 | in Section 7.3. | |
fdf2bb05 MD |
877 | |
878 | ||
6c7226e9 | 879 | 7.3 TSDL Scopes |
fdf2bb05 | 880 | |
6c7226e9 MD |
881 | TSDL uses two different types of scoping: a lexical scope is used for |
882 | declarations and type definitions, and a dynamic scope is used for | |
883 | variants references to tag fields. | |
fdf2bb05 | 884 | |
6c7226e9 | 885 | 7.3.1 Lexical Scope |
fdf2bb05 | 886 | |
d285084f MD |
887 | Each of "trace", "stream", "event", "struct" and "variant" have their own |
888 | nestable declaration scope, within which types can be declared using "typedef" | |
fdf2bb05 | 889 | and "typealias". A root declaration scope also contains all declarations |
7d9d7e92 | 890 | located outside of any of the aforementioned declarations. An inner |
fdf2bb05 | 891 | declaration scope can refer to type declared within its container |
7d9d7e92 MD |
892 | lexical scope prior to the inner declaration scope. Redefinition of a |
893 | typedef or typealias is not valid, although hiding an upper scope | |
fdf2bb05 MD |
894 | typedef or typealias is allowed within a sub-scope. |
895 | ||
6c7226e9 | 896 | 7.3.2 Dynamic Scope |
fdf2bb05 | 897 | |
7d9d7e92 MD |
898 | A dynamic scope consists in the lexical scope augmented with the |
899 | implicit event structure definition hierarchy presented at Section 6. | |
900 | The dynamic scope is only used for variant tag definitions. It is used | |
901 | at definition time to look up the location of the tag field associated | |
902 | with a variant. | |
903 | ||
904 | Therefore, variants in lower levels in the dynamic scope (e.g. event | |
905 | context) can refer to a tag field located in upper levels (e.g. in the | |
906 | event header) by specifying, in this case, the associated tag with | |
907 | <header.field_name>. This allows, for instance, the event context to | |
908 | define a variant referring to the "id" field of the event header as | |
909 | selector. | |
fdf2bb05 MD |
910 | |
911 | The target dynamic scope must be specified explicitly when referring to | |
912 | a field outside of the local static scope. The dynamic scope prefixes | |
913 | are thus: | |
914 | ||
e0d9e2c7 | 915 | - Trace Packet Header: <trace.packet.header. >, |
7d9d7e92 MD |
916 | - Stream Packet Context: <stream.packet.context. >, |
917 | - Event Header: <stream.event.header. >, | |
918 | - Stream Event Context: <stream.event.context. >, | |
919 | - Event Context: <event.context. >, | |
920 | - Event Payload: <event.fields. >. | |
fdf2bb05 MD |
921 | |
922 | Multiple declarations of the same field name within a single scope is | |
923 | not valid. It is however valid to re-use the same field name in | |
924 | different scopes. There is no possible conflict, because the dynamic | |
925 | scope must be specified when a variant refers to a tag field located in | |
926 | a different dynamic scope. | |
927 | ||
457d8b0a MD |
928 | The information available in the dynamic scopes can be thought of as the |
929 | current tracing context. At trace production, information about the | |
930 | current context is saved into the specified scope field levels. At trace | |
931 | consumption, for each event, the current trace context is therefore | |
932 | readable by accessing the upper dynamic scopes. | |
933 | ||
fdf2bb05 | 934 | |
6c7226e9 | 935 | 7.4 TSDL Examples |
d285084f | 936 | |
6672e9e1 | 937 | The grammar representing the TSDL meta-data is presented in Appendix C. |
7df6b93a | 938 | TSDL Grammar. This section presents a rather lighter reading that |
6672e9e1 | 939 | consists in examples of TSDL meta-data, with template values. |
969f30c0 | 940 | |
350bb633 MD |
941 | The stream "id" can be left out if there is only one stream in the |
942 | trace. The event "id" field can be left out if there is only one event | |
943 | in a stream. | |
944 | ||
5ba9f198 | 945 | trace { |
fdf2bb05 | 946 | major = value; /* Trace format version */ |
5ba9f198 | 947 | minor = value; |
fdf2bb05 | 948 | uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */ |
58997e9e | 949 | byte_order = be OR le; /* Endianness (required) */ |
fc5425db MD |
950 | packet.header := struct { |
951 | uint32_t magic; | |
952 | uint8_t trace_uuid[16]; | |
953 | uint32_t stream_id; | |
954 | }; | |
3bf79539 | 955 | }; |
5ba9f198 | 956 | |
3bf79539 MD |
957 | stream { |
958 | id = stream_id; | |
fdf2bb05 | 959 | /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */ |
4fa992a5 MD |
960 | event.header := event_header_1 OR event_header_2; |
961 | event.context := struct { | |
77a98c82 | 962 | ... |
3bf79539 | 963 | }; |
4fa992a5 | 964 | packet.context := struct { |
77a98c82 | 965 | ... |
3bf79539 MD |
966 | }; |
967 | }; | |
5ba9f198 MD |
968 | |
969 | event { | |
3d13ef1a | 970 | name = event_name; |
3bf79539 | 971 | id = value; /* Numeric identifier within the stream */ |
67f02e24 | 972 | stream_id = stream_id; |
4fa992a5 | 973 | context := struct { |
fcba70d4 MD |
974 | ... |
975 | }; | |
4fa992a5 | 976 | fields := struct { |
80fd2569 MD |
977 | ... |
978 | }; | |
3bf79539 | 979 | }; |
5ba9f198 MD |
980 | |
981 | /* More detail on types in section 4. Types */ | |
982 | ||
3d13ef1a MD |
983 | /* |
984 | * Named types: | |
985 | * | |
4fa992a5 | 986 | * Type declarations behave similarly to the C standard. |
3d13ef1a MD |
987 | */ |
988 | ||
80af8ac6 | 989 | typedef aliased_type_specifiers new_type_declarators; |
2152348f | 990 | |
3d13ef1a | 991 | /* e.g.: typedef struct example new_type_name[10]; */ |
80fd2569 | 992 | |
4fa992a5 MD |
993 | /* |
994 | * typealias | |
995 | * | |
996 | * The "typealias" declaration can be used to give a name (including | |
80af8ac6 MD |
997 | * pointer declarator specifier) to a type. It should also be used to |
998 | * map basic C types (float, int, unsigned long, ...) to a CTF type. | |
999 | * Typealias is a superset of "typedef": it also allows assignment of a | |
38b8da21 | 1000 | * simple variable identifier to a type. |
4fa992a5 MD |
1001 | */ |
1002 | ||
1003 | typealias type_class { | |
80fd2569 | 1004 | ... |
38b8da21 | 1005 | } := type_specifiers type_declarator; |
2152348f | 1006 | |
3d13ef1a MD |
1007 | /* |
1008 | * e.g.: | |
4fa992a5 | 1009 | * typealias integer { |
3d13ef1a MD |
1010 | * size = 32; |
1011 | * align = 32; | |
1012 | * signed = false; | |
38b8da21 | 1013 | * } := struct page *; |
359894ac MD |
1014 | * |
1015 | * typealias integer { | |
1016 | * size = 32; | |
1017 | * align = 32; | |
1018 | * signed = true; | |
38b8da21 | 1019 | * } := int; |
3d13ef1a | 1020 | */ |
80fd2569 MD |
1021 | |
1022 | struct name { | |
3bf79539 MD |
1023 | ... |
1024 | }; | |
5ba9f198 | 1025 | |
fcba70d4 MD |
1026 | variant name { |
1027 | ... | |
1028 | }; | |
1029 | ||
a9b83695 | 1030 | enum name : integer_type { |
3bf79539 MD |
1031 | ... |
1032 | }; | |
1033 | ||
2152348f | 1034 | |
4fa992a5 MD |
1035 | /* |
1036 | * Unnamed types, contained within compound type fields, typedef or typealias. | |
1037 | */ | |
2152348f | 1038 | |
80fd2569 MD |
1039 | struct { |
1040 | ... | |
2152348f | 1041 | } |
5ba9f198 | 1042 | |
fcba70d4 MD |
1043 | variant { |
1044 | ... | |
1045 | } | |
1046 | ||
a9b83695 | 1047 | enum : integer_type { |
80fd2569 | 1048 | ... |
2152348f MD |
1049 | } |
1050 | ||
1051 | typedef type new_type[length]; | |
3bf79539 | 1052 | |
2152348f MD |
1053 | struct { |
1054 | type field_name[length]; | |
1055 | } | |
1056 | ||
1057 | typedef type new_type[length_type]; | |
1058 | ||
1059 | struct { | |
1060 | type field_name[length_type]; | |
1061 | } | |
1062 | ||
1063 | integer { | |
80fd2569 | 1064 | ... |
2152348f | 1065 | } |
3bf79539 | 1066 | |
2152348f | 1067 | floating_point { |
80fd2569 | 1068 | ... |
2152348f MD |
1069 | } |
1070 | ||
1071 | struct { | |
1072 | integer_type field_name:size; /* GNU/C bitfield */ | |
1073 | } | |
1074 | ||
1075 | struct { | |
1076 | string field_name; | |
1077 | } | |
3bf79539 | 1078 | |
fcba70d4 | 1079 | |
3bf79539 | 1080 | A. Helper macros |
5ba9f198 MD |
1081 | |
1082 | The two following macros keep track of the size of a GNU/C structure without | |
1083 | padding at the end by placing HEADER_END as the last field. A one byte end field | |
1084 | is used for C90 compatibility (C99 flexible arrays could be used here). Note | |
1085 | that this does not affect the effective structure size, which should always be | |
1086 | calculated with the header_sizeof() helper. | |
1087 | ||
1088 | #define HEADER_END char end_field | |
1089 | #define header_sizeof(type) offsetof(typeof(type), end_field) | |
3bf79539 MD |
1090 | |
1091 | ||
1092 | B. Stream Header Rationale | |
1093 | ||
1094 | An event stream is divided in contiguous event packets of variable size. These | |
1095 | subdivisions allow the trace analyzer to perform a fast binary search by time | |
1096 | within the stream (typically requiring to index only the event packet headers) | |
1097 | without reading the whole stream. These subdivisions have a variable size to | |
1098 | eliminate the need to transfer the event packet padding when partially filled | |
1099 | event packets must be sent when streaming a trace for live viewing/analysis. | |
1100 | An event packet can contain a certain amount of padding at the end. Dividing | |
1101 | streams into event packets is also useful for network streaming over UDP and | |
1102 | flight recorder mode tracing (a whole event packet can be swapped out of the | |
1103 | buffer atomically for reading). | |
1104 | ||
1105 | The stream header is repeated at the beginning of each event packet to allow | |
1106 | flexibility in terms of: | |
1107 | ||
1108 | - streaming support, | |
1109 | - allowing arbitrary buffers to be discarded without making the trace | |
1110 | unreadable, | |
1111 | - allow UDP packet loss handling by either dealing with missing event packet | |
1112 | or asking for re-transmission. | |
1113 | - transparently support flight recorder mode, | |
1114 | - transparently support crash dump. | |
1115 | ||
6c7226e9 MD |
1116 | |
1117 | C. TSDL Grammar | |
fcba70d4 | 1118 | |
4fa992a5 | 1119 | /* |
6c7226e9 | 1120 | * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar. |
4fa992a5 MD |
1121 | * |
1122 | * Inspired from the C99 grammar: | |
1123 | * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A) | |
6c7226e9 MD |
1124 | * and c++1x grammar (draft) |
1125 | * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A) | |
4fa992a5 MD |
1126 | * |
1127 | * Specialized for CTF needs by including only constant and declarations from | |
1128 | * C99 (excluding function declarations), and by adding support for variants, | |
6c7226e9 MD |
1129 | * sequences and CTF-specific specifiers. Enumeration container types |
1130 | * semantic is inspired from c++1x enum-base. | |
4fa992a5 MD |
1131 | */ |
1132 | ||
1133 | 1) Lexical grammar | |
1134 | ||
1135 | 1.1) Lexical elements | |
1136 | ||
1137 | token: | |
1138 | keyword | |
1139 | identifier | |
1140 | constant | |
1141 | string-literal | |
1142 | punctuator | |
1143 | ||
1144 | 1.2) Keywords | |
1145 | ||
1146 | keyword: is one of | |
1147 | ||
1148 | const | |
1149 | char | |
1150 | double | |
1151 | enum | |
1152 | event | |
1153 | floating_point | |
1154 | float | |
1155 | integer | |
1156 | int | |
1157 | long | |
1158 | short | |
1159 | signed | |
1160 | stream | |
1161 | string | |
1162 | struct | |
1163 | trace | |
3e1e1a78 | 1164 | typealias |
4fa992a5 MD |
1165 | typedef |
1166 | unsigned | |
1167 | variant | |
1168 | void | |
1169 | _Bool | |
1170 | _Complex | |
1171 | _Imaginary | |
1172 | ||
1173 | ||
1174 | 1.3) Identifiers | |
1175 | ||
1176 | identifier: | |
1177 | identifier-nondigit | |
1178 | identifier identifier-nondigit | |
1179 | identifier digit | |
1180 | ||
1181 | identifier-nondigit: | |
1182 | nondigit | |
1183 | universal-character-name | |
1184 | any other implementation-defined characters | |
1185 | ||
1186 | nondigit: | |
1187 | _ | |
1188 | [a-zA-Z] /* regular expression */ | |
1189 | ||
1190 | digit: | |
1191 | [0-9] /* regular expression */ | |
1192 | ||
1193 | 1.4) Universal character names | |
1194 | ||
1195 | universal-character-name: | |
1196 | \u hex-quad | |
1197 | \U hex-quad hex-quad | |
1198 | ||
1199 | hex-quad: | |
1200 | hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit | |
1201 | ||
1202 | 1.5) Constants | |
1203 | ||
1204 | constant: | |
1205 | integer-constant | |
1206 | enumeration-constant | |
1207 | character-constant | |
1208 | ||
1209 | integer-constant: | |
1210 | decimal-constant integer-suffix-opt | |
1211 | octal-constant integer-suffix-opt | |
1212 | hexadecimal-constant integer-suffix-opt | |
1213 | ||
1214 | decimal-constant: | |
1215 | nonzero-digit | |
1216 | decimal-constant digit | |
1217 | ||
1218 | octal-constant: | |
1219 | 0 | |
1220 | octal-constant octal-digit | |
1221 | ||
1222 | hexadecimal-constant: | |
1223 | hexadecimal-prefix hexadecimal-digit | |
1224 | hexadecimal-constant hexadecimal-digit | |
1225 | ||
1226 | hexadecimal-prefix: | |
1227 | 0x | |
1228 | 0X | |
1229 | ||
1230 | nonzero-digit: | |
1231 | [1-9] | |
1232 | ||
1233 | integer-suffix: | |
1234 | unsigned-suffix long-suffix-opt | |
1235 | unsigned-suffix long-long-suffix | |
1236 | long-suffix unsigned-suffix-opt | |
1237 | long-long-suffix unsigned-suffix-opt | |
1238 | ||
1239 | unsigned-suffix: | |
1240 | u | |
1241 | U | |
1242 | ||
1243 | long-suffix: | |
1244 | l | |
1245 | L | |
1246 | ||
1247 | long-long-suffix: | |
1248 | ll | |
1249 | LL | |
1250 | ||
4fa992a5 MD |
1251 | enumeration-constant: |
1252 | identifier | |
1253 | string-literal | |
1254 | ||
1255 | character-constant: | |
1256 | ' c-char-sequence ' | |
1257 | L' c-char-sequence ' | |
1258 | ||
1259 | c-char-sequence: | |
1260 | c-char | |
1261 | c-char-sequence c-char | |
1262 | ||
1263 | c-char: | |
1264 | any member of source charset except single-quote ('), backslash | |
1265 | (\), or new-line character. | |
1266 | escape-sequence | |
1267 | ||
1268 | escape-sequence: | |
1269 | simple-escape-sequence | |
1270 | octal-escape-sequence | |
1271 | hexadecimal-escape-sequence | |
1272 | universal-character-name | |
1273 | ||
1274 | simple-escape-sequence: one of | |
1275 | \' \" \? \\ \a \b \f \n \r \t \v | |
1276 | ||
1277 | octal-escape-sequence: | |
1278 | \ octal-digit | |
1279 | \ octal-digit octal-digit | |
1280 | \ octal-digit octal-digit octal-digit | |
1281 | ||
1282 | hexadecimal-escape-sequence: | |
1283 | \x hexadecimal-digit | |
1284 | hexadecimal-escape-sequence hexadecimal-digit | |
1285 | ||
1286 | 1.6) String literals | |
1287 | ||
1288 | string-literal: | |
1289 | " s-char-sequence-opt " | |
1290 | L" s-char-sequence-opt " | |
1291 | ||
1292 | s-char-sequence: | |
1293 | s-char | |
1294 | s-char-sequence s-char | |
1295 | ||
1296 | s-char: | |
1297 | any member of source charset except double-quote ("), backslash | |
1298 | (\), or new-line character. | |
1299 | escape-sequence | |
1300 | ||
1301 | 1.7) Punctuators | |
1302 | ||
1303 | punctuator: one of | |
1304 | [ ] ( ) { } . -> * + - < > : ; ... = , | |
1305 | ||
1306 | ||
1307 | 2) Phrase structure grammar | |
1308 | ||
1309 | primary-expression: | |
1310 | identifier | |
1311 | constant | |
1312 | string-literal | |
1313 | ( unary-expression ) | |
1314 | ||
1315 | postfix-expression: | |
1316 | primary-expression | |
1317 | postfix-expression [ unary-expression ] | |
1318 | postfix-expression . identifier | |
1319 | postfix-expressoin -> identifier | |
1320 | ||
1321 | unary-expression: | |
1322 | postfix-expression | |
1323 | unary-operator postfix-expression | |
1324 | ||
1325 | unary-operator: one of | |
1326 | + - | |
1327 | ||
4fa992a5 MD |
1328 | assignment-operator: |
1329 | = | |
1330 | ||
b9606a77 MD |
1331 | type-assignment-operator: |
1332 | := | |
1333 | ||
4fa992a5 MD |
1334 | constant-expression: |
1335 | unary-expression | |
1336 | ||
1337 | constant-expression-range: | |
1338 | constant-expression ... constant-expression | |
1339 | ||
1340 | 2.2) Declarations: | |
1341 | ||
1342 | declaration: | |
689e04b4 | 1343 | declaration-specifiers declarator-list-opt ; |
4fa992a5 MD |
1344 | ctf-specifier ; |
1345 | ||
1346 | declaration-specifiers: | |
689e04b4 | 1347 | storage-class-specifier declaration-specifiers-opt |
4fa992a5 MD |
1348 | type-specifier declaration-specifiers-opt |
1349 | type-qualifier declaration-specifiers-opt | |
1350 | ||
1351 | declarator-list: | |
1352 | declarator | |
1353 | declarator-list , declarator | |
1354 | ||
d285084f MD |
1355 | abstract-declarator-list: |
1356 | abstract-declarator | |
1357 | abstract-declarator-list , abstract-declarator | |
1358 | ||
4fa992a5 MD |
1359 | storage-class-specifier: |
1360 | typedef | |
1361 | ||
1362 | type-specifier: | |
1363 | void | |
1364 | char | |
1365 | short | |
1366 | int | |
1367 | long | |
1368 | float | |
1369 | double | |
1370 | signed | |
1371 | unsigned | |
1372 | _Bool | |
1373 | _Complex | |
cfdd51ec | 1374 | _Imaginary |
9dfcfc0f MD |
1375 | struct-specifier |
1376 | variant-specifier | |
4fa992a5 MD |
1377 | enum-specifier |
1378 | typedef-name | |
1379 | ctf-type-specifier | |
1380 | ||
1381 | struct-specifier: | |
3b0f8e4d | 1382 | struct identifier-opt { struct-or-variant-declaration-list-opt } |
4fa992a5 MD |
1383 | struct identifier |
1384 | ||
1385 | struct-or-variant-declaration-list: | |
1386 | struct-or-variant-declaration | |
1387 | struct-or-variant-declaration-list struct-or-variant-declaration | |
1388 | ||
1389 | struct-or-variant-declaration: | |
1390 | specifier-qualifier-list struct-or-variant-declarator-list ; | |
550aca33 | 1391 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ; |
38b8da21 MD |
1392 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ; |
1393 | typealias declaration-specifiers abstract-declarator-list := declarator-list ; | |
4fa992a5 MD |
1394 | |
1395 | specifier-qualifier-list: | |
1396 | type-specifier specifier-qualifier-list-opt | |
1397 | type-qualifier specifier-qualifier-list-opt | |
1398 | ||
1399 | struct-or-variant-declarator-list: | |
1400 | struct-or-variant-declarator | |
1401 | struct-or-variant-declarator-list , struct-or-variant-declarator | |
1402 | ||
1403 | struct-or-variant-declarator: | |
1404 | declarator | |
1405 | declarator-opt : constant-expression | |
1406 | ||
1407 | variant-specifier: | |
1408 | variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list } | |
1409 | variant identifier variant-tag | |
1410 | ||
1411 | variant-tag: | |
1412 | < identifier > | |
1413 | ||
1414 | enum-specifier: | |
1415 | enum identifier-opt { enumerator-list } | |
1416 | enum identifier-opt { enumerator-list , } | |
1417 | enum identifier | |
a9b83695 MD |
1418 | enum identifier-opt : declaration-specifiers { enumerator-list } |
1419 | enum identifier-opt : declaration-specifiers { enumerator-list , } | |
4fa992a5 MD |
1420 | |
1421 | enumerator-list: | |
1422 | enumerator | |
1423 | enumerator-list , enumerator | |
1424 | ||
1425 | enumerator: | |
1426 | enumeration-constant | |
1427 | enumeration-constant = constant-expression | |
1428 | enumeration-constant = constant-expression-range | |
1429 | ||
1430 | type-qualifier: | |
1431 | const | |
1432 | ||
1433 | declarator: | |
1434 | pointer-opt direct-declarator | |
1435 | ||
1436 | direct-declarator: | |
1437 | identifier | |
1438 | ( declarator ) | |
1439 | direct-declarator [ type-specifier ] | |
1440 | direct-declarator [ constant-expression ] | |
1441 | ||
d285084f MD |
1442 | abstract-declarator: |
1443 | pointer-opt direct-abstract-declarator | |
1444 | ||
1445 | direct-abstract-declarator: | |
1446 | identifier-opt | |
1447 | ( abstract-declarator ) | |
1448 | direct-abstract-declarator [ type-specifier ] | |
1449 | direct-abstract-declarator [ constant-expression ] | |
1450 | direct-abstract-declarator [ ] | |
1451 | ||
4fa992a5 | 1452 | pointer: |
3b0f8e4d MD |
1453 | * type-qualifier-list-opt |
1454 | * type-qualifier-list-opt pointer | |
4fa992a5 MD |
1455 | |
1456 | type-qualifier-list: | |
1457 | type-qualifier | |
1458 | type-qualifier-list type-qualifier | |
1459 | ||
4fa992a5 MD |
1460 | typedef-name: |
1461 | identifier | |
1462 | ||
1463 | 2.3) CTF-specific declarations | |
1464 | ||
1465 | ctf-specifier: | |
1466 | event { ctf-assignment-expression-list-opt } | |
1467 | stream { ctf-assignment-expression-list-opt } | |
1468 | trace { ctf-assignment-expression-list-opt } | |
38b8da21 MD |
1469 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ; |
1470 | typealias declaration-specifiers abstract-declarator-list := declarator-list ; | |
4fa992a5 MD |
1471 | |
1472 | ctf-type-specifier: | |
1473 | floating_point { ctf-assignment-expression-list-opt } | |
1474 | integer { ctf-assignment-expression-list-opt } | |
1475 | string { ctf-assignment-expression-list-opt } | |
1476 | ||
1477 | ctf-assignment-expression-list: | |
1478 | ctf-assignment-expression | |
1479 | ctf-assignment-expression-list ; ctf-assignment-expression | |
1480 | ||
1481 | ctf-assignment-expression: | |
1482 | unary-expression assignment-operator unary-expression | |
1483 | unary-expression type-assignment-operator type-specifier | |
550aca33 | 1484 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list |
38b8da21 MD |
1485 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list |
1486 | typealias declaration-specifiers abstract-declarator-list := declarator-list |