Commit | Line | Data |
---|---|---|
3cd046f1 | 1 | #!/usr/bin/env python3 |
56a092c8 QM |
2 | # SPDX-License-Identifier: GPL-2.0-only |
3 | # | |
748c7c82 | 4 | # Copyright (C) 2018-2019 Netronome Systems, Inc. |
923a932c | 5 | # Copyright (C) 2021 Isovalent, Inc. |
56a092c8 QM |
6 | |
7 | # In case user attempts to run with Python 2. | |
8 | from __future__ import print_function | |
9 | ||
10 | import argparse | |
11 | import re | |
12 | import sys, os | |
fd0a38f9 QM |
13 | import subprocess |
14 | ||
92ec1cc3 | 15 | helpersDocStart = 'Start of BPF helper function descriptions:' |
56a092c8 QM |
16 | |
17 | class NoHelperFound(BaseException): | |
18 | pass | |
19 | ||
a67882a2 JS |
20 | class NoSyscallCommandFound(BaseException): |
21 | pass | |
22 | ||
56a092c8 QM |
23 | class ParsingError(BaseException): |
24 | def __init__(self, line='<line not provided>', reader=None): | |
25 | if reader: | |
26 | BaseException.__init__(self, | |
27 | 'Error at file offset %d, parsing line: %s' % | |
28 | (reader.tell(), line)) | |
29 | else: | |
30 | BaseException.__init__(self, 'Error parsing line: %s' % line) | |
31 | ||
a67882a2 JS |
32 | |
33 | class APIElement(object): | |
56a092c8 | 34 | """ |
a67882a2 JS |
35 | An object representing the description of an aspect of the eBPF API. |
36 | @proto: prototype of the API symbol | |
37 | @desc: textual description of the symbol | |
38 | @ret: (optional) description of any associated return value | |
56a092c8 QM |
39 | """ |
40 | def __init__(self, proto='', desc='', ret=''): | |
41 | self.proto = proto | |
42 | self.desc = desc | |
43 | self.ret = ret | |
44 | ||
a67882a2 JS |
45 | |
46 | class Helper(APIElement): | |
47 | """ | |
48 | An object representing the description of an eBPF helper function. | |
49 | @proto: function prototype of the helper function | |
50 | @desc: textual description of the helper function | |
51 | @ret: description of the return value of the helper function | |
52 | """ | |
0a0d55ef EB |
53 | def __init__(self, *args, **kwargs): |
54 | super().__init__(*args, **kwargs) | |
55 | self.enum_val = None | |
56 | ||
56a092c8 QM |
57 | def proto_break_down(self): |
58 | """ | |
59 | Break down helper function protocol into smaller chunks: return type, | |
60 | name, distincts arguments. | |
61 | """ | |
748c7c82 | 62 | arg_re = re.compile('((\w+ )*?(\w+|...))( (\**)(\w+))?$') |
56a092c8 | 63 | res = {} |
6f96674d | 64 | proto_re = re.compile('(.+) (\**)(\w+)\(((([^,]+)(, )?){1,5})\)$') |
56a092c8 QM |
65 | |
66 | capture = proto_re.match(self.proto) | |
67 | res['ret_type'] = capture.group(1) | |
68 | res['ret_star'] = capture.group(2) | |
69 | res['name'] = capture.group(3) | |
70 | res['args'] = [] | |
71 | ||
72 | args = capture.group(4).split(', ') | |
73 | for a in args: | |
74 | capture = arg_re.match(a) | |
75 | res['args'].append({ | |
76 | 'type' : capture.group(1), | |
748c7c82 QM |
77 | 'star' : capture.group(5), |
78 | 'name' : capture.group(6) | |
56a092c8 QM |
79 | }) |
80 | ||
81 | return res | |
82 | ||
a67882a2 | 83 | |
56a092c8 QM |
84 | class HeaderParser(object): |
85 | """ | |
86 | An object used to parse a file in order to extract the documentation of a | |
87 | list of eBPF helper functions. All the helpers that can be retrieved are | |
88 | stored as Helper object, in the self.helpers() array. | |
89 | @filename: name of file to parse, usually include/uapi/linux/bpf.h in the | |
90 | kernel tree | |
91 | """ | |
92 | def __init__(self, filename): | |
93 | self.reader = open(filename, 'r') | |
94 | self.line = '' | |
95 | self.helpers = [] | |
a67882a2 | 96 | self.commands = [] |
71a3cdf8 UA |
97 | self.desc_unique_helpers = set() |
98 | self.define_unique_helpers = [] | |
0a0d55ef | 99 | self.helper_enum_vals = {} |
0ba3929e UA |
100 | self.desc_syscalls = [] |
101 | self.enum_syscalls = [] | |
a67882a2 JS |
102 | |
103 | def parse_element(self): | |
104 | proto = self.parse_symbol() | |
f1f3f67f UA |
105 | desc = self.parse_desc(proto) |
106 | ret = self.parse_ret(proto) | |
a67882a2 | 107 | return APIElement(proto=proto, desc=desc, ret=ret) |
56a092c8 QM |
108 | |
109 | def parse_helper(self): | |
110 | proto = self.parse_proto() | |
f1f3f67f UA |
111 | desc = self.parse_desc(proto) |
112 | ret = self.parse_ret(proto) | |
56a092c8 QM |
113 | return Helper(proto=proto, desc=desc, ret=ret) |
114 | ||
a67882a2 | 115 | def parse_symbol(self): |
0ba3929e | 116 | p = re.compile(' \* ?(BPF\w+)$') |
a67882a2 JS |
117 | capture = p.match(self.line) |
118 | if not capture: | |
119 | raise NoSyscallCommandFound | |
120 | end_re = re.compile(' \* ?NOTES$') | |
121 | end = end_re.match(self.line) | |
122 | if end: | |
123 | raise NoSyscallCommandFound | |
124 | self.line = self.reader.readline() | |
125 | return capture.group(1) | |
126 | ||
56a092c8 QM |
127 | def parse_proto(self): |
128 | # Argument can be of shape: | |
129 | # - "void" | |
130 | # - "type name" | |
131 | # - "type *name" | |
132 | # - Same as above, with "const" and/or "struct" in front of type | |
133 | # - "..." (undefined number of arguments, for bpf_trace_printk()) | |
134 | # There is at least one term ("void"), and at most five arguments. | |
6f96674d | 135 | p = re.compile(' \* ?((.+) \**\w+\((((const )?(struct )?(\w+|\.\.\.)( \**\w+)?)(, )?){1,5}\))$') |
56a092c8 QM |
136 | capture = p.match(self.line) |
137 | if not capture: | |
138 | raise NoHelperFound | |
139 | self.line = self.reader.readline() | |
140 | return capture.group(1) | |
141 | ||
f1f3f67f | 142 | def parse_desc(self, proto): |
eeacb716 | 143 | p = re.compile(' \* ?(?:\t| {5,8})Description$') |
56a092c8 QM |
144 | capture = p.match(self.line) |
145 | if not capture: | |
f1f3f67f | 146 | raise Exception("No description section found for " + proto) |
56a092c8 QM |
147 | # Description can be several lines, some of them possibly empty, and it |
148 | # stops when another subsection title is met. | |
149 | desc = '' | |
f1f3f67f | 150 | desc_present = False |
56a092c8 QM |
151 | while True: |
152 | self.line = self.reader.readline() | |
153 | if self.line == ' *\n': | |
154 | desc += '\n' | |
155 | else: | |
eeacb716 | 156 | p = re.compile(' \* ?(?:\t| {5,8})(?:\t| {8})(.*)') |
56a092c8 QM |
157 | capture = p.match(self.line) |
158 | if capture: | |
f1f3f67f | 159 | desc_present = True |
56a092c8 QM |
160 | desc += capture.group(1) + '\n' |
161 | else: | |
162 | break | |
f1f3f67f UA |
163 | |
164 | if not desc_present: | |
165 | raise Exception("No description found for " + proto) | |
56a092c8 QM |
166 | return desc |
167 | ||
f1f3f67f | 168 | def parse_ret(self, proto): |
eeacb716 | 169 | p = re.compile(' \* ?(?:\t| {5,8})Return$') |
56a092c8 QM |
170 | capture = p.match(self.line) |
171 | if not capture: | |
f1f3f67f | 172 | raise Exception("No return section found for " + proto) |
56a092c8 QM |
173 | # Return value description can be several lines, some of them possibly |
174 | # empty, and it stops when another subsection title is met. | |
175 | ret = '' | |
f1f3f67f | 176 | ret_present = False |
56a092c8 QM |
177 | while True: |
178 | self.line = self.reader.readline() | |
179 | if self.line == ' *\n': | |
180 | ret += '\n' | |
181 | else: | |
eeacb716 | 182 | p = re.compile(' \* ?(?:\t| {5,8})(?:\t| {8})(.*)') |
56a092c8 QM |
183 | capture = p.match(self.line) |
184 | if capture: | |
f1f3f67f | 185 | ret_present = True |
56a092c8 QM |
186 | ret += capture.group(1) + '\n' |
187 | else: | |
188 | break | |
f1f3f67f UA |
189 | |
190 | if not ret_present: | |
191 | raise Exception("No return found for " + proto) | |
56a092c8 QM |
192 | return ret |
193 | ||
0ba3929e | 194 | def seek_to(self, target, help_message, discard_lines = 1): |
a67882a2 JS |
195 | self.reader.seek(0) |
196 | offset = self.reader.read().find(target) | |
56a092c8 | 197 | if offset == -1: |
a67882a2 | 198 | raise Exception(help_message) |
56a092c8 QM |
199 | self.reader.seek(offset) |
200 | self.reader.readline() | |
0ba3929e UA |
201 | for _ in range(discard_lines): |
202 | self.reader.readline() | |
56a092c8 QM |
203 | self.line = self.reader.readline() |
204 | ||
0ba3929e | 205 | def parse_desc_syscall(self): |
a67882a2 JS |
206 | self.seek_to('* DOC: eBPF Syscall Commands', |
207 | 'Could not find start of eBPF syscall descriptions list') | |
208 | while True: | |
209 | try: | |
210 | command = self.parse_element() | |
211 | self.commands.append(command) | |
0ba3929e UA |
212 | self.desc_syscalls.append(command.proto) |
213 | ||
a67882a2 JS |
214 | except NoSyscallCommandFound: |
215 | break | |
216 | ||
0ba3929e UA |
217 | def parse_enum_syscall(self): |
218 | self.seek_to('enum bpf_cmd {', | |
219 | 'Could not find start of bpf_cmd enum', 0) | |
220 | # Searches for either one or more BPF\w+ enums | |
221 | bpf_p = re.compile('\s*(BPF\w+)+') | |
222 | # Searches for an enum entry assigned to another entry, | |
223 | # for e.g. BPF_PROG_RUN = BPF_PROG_TEST_RUN, which is | |
224 | # not documented hence should be skipped in check to | |
225 | # determine if the right number of syscalls are documented | |
226 | assign_p = re.compile('\s*(BPF\w+)\s*=\s*(BPF\w+)') | |
227 | bpf_cmd_str = '' | |
228 | while True: | |
229 | capture = assign_p.match(self.line) | |
230 | if capture: | |
231 | # Skip line if an enum entry is assigned to another entry | |
232 | self.line = self.reader.readline() | |
233 | continue | |
234 | capture = bpf_p.match(self.line) | |
235 | if capture: | |
236 | bpf_cmd_str += self.line | |
237 | else: | |
238 | break | |
239 | self.line = self.reader.readline() | |
240 | # Find the number of occurences of BPF\w+ | |
241 | self.enum_syscalls = re.findall('(BPF\w+)+', bpf_cmd_str) | |
242 | ||
71a3cdf8 | 243 | def parse_desc_helpers(self): |
92ec1cc3 | 244 | self.seek_to(helpersDocStart, |
a67882a2 | 245 | 'Could not find start of eBPF helper descriptions list') |
56a092c8 QM |
246 | while True: |
247 | try: | |
248 | helper = self.parse_helper() | |
249 | self.helpers.append(helper) | |
71a3cdf8 UA |
250 | proto = helper.proto_break_down() |
251 | self.desc_unique_helpers.add(proto['name']) | |
56a092c8 QM |
252 | except NoHelperFound: |
253 | break | |
254 | ||
71a3cdf8 | 255 | def parse_define_helpers(self): |
0a0d55ef EB |
256 | # Parse FN(...) in #define __BPF_FUNC_MAPPER to compare later with the |
257 | # number of unique function names present in description and use the | |
258 | # correct enumeration value. | |
71a3cdf8 UA |
259 | # Note: seek_to(..) discards the first line below the target search text, |
260 | # resulting in FN(unspec) being skipped and not added to self.define_unique_helpers. | |
261 | self.seek_to('#define __BPF_FUNC_MAPPER(FN)', | |
262 | 'Could not find start of eBPF helper definition list') | |
0a0d55ef EB |
263 | # Searches for one FN(\w+) define or a backslash for newline |
264 | p = re.compile('\s*FN\((\w+)\)|\\\\') | |
71a3cdf8 | 265 | fn_defines_str = '' |
0a0d55ef | 266 | i = 1 # 'unspec' is skipped as mentioned above |
71a3cdf8 UA |
267 | while True: |
268 | capture = p.match(self.line) | |
269 | if capture: | |
270 | fn_defines_str += self.line | |
0a0d55ef EB |
271 | self.helper_enum_vals[capture.expand(r'bpf_\1')] = i |
272 | i += 1 | |
71a3cdf8 UA |
273 | else: |
274 | break | |
275 | self.line = self.reader.readline() | |
276 | # Find the number of occurences of FN(\w+) | |
277 | self.define_unique_helpers = re.findall('FN\(\w+\)', fn_defines_str) | |
278 | ||
0a0d55ef EB |
279 | def assign_helper_values(self): |
280 | seen_helpers = set() | |
281 | for helper in self.helpers: | |
282 | proto = helper.proto_break_down() | |
283 | name = proto['name'] | |
284 | try: | |
285 | enum_val = self.helper_enum_vals[name] | |
286 | except KeyError: | |
287 | raise Exception("Helper %s is missing from enum bpf_func_id" % name) | |
288 | ||
289 | # Enforce current practice of having the descriptions ordered | |
290 | # by enum value. | |
291 | seen_helpers.add(name) | |
292 | desc_val = len(seen_helpers) | |
293 | if desc_val != enum_val: | |
294 | raise Exception("Helper %s comment order (#%d) must be aligned with its position (#%d) in enum bpf_func_id" % (name, desc_val, enum_val)) | |
295 | ||
296 | helper.enum_val = enum_val | |
297 | ||
a67882a2 | 298 | def run(self): |
0ba3929e UA |
299 | self.parse_desc_syscall() |
300 | self.parse_enum_syscall() | |
71a3cdf8 UA |
301 | self.parse_desc_helpers() |
302 | self.parse_define_helpers() | |
0a0d55ef | 303 | self.assign_helper_values() |
56a092c8 | 304 | self.reader.close() |
56a092c8 QM |
305 | |
306 | ############################################################################### | |
307 | ||
308 | class Printer(object): | |
309 | """ | |
310 | A generic class for printers. Printers should be created with an array of | |
311 | Helper objects, and implement a way to print them in the desired fashion. | |
923a932c | 312 | @parser: A HeaderParser with objects to print to standard output |
56a092c8 | 313 | """ |
923a932c JS |
314 | def __init__(self, parser): |
315 | self.parser = parser | |
316 | self.elements = [] | |
56a092c8 QM |
317 | |
318 | def print_header(self): | |
319 | pass | |
320 | ||
321 | def print_footer(self): | |
322 | pass | |
323 | ||
324 | def print_one(self, helper): | |
325 | pass | |
326 | ||
327 | def print_all(self): | |
328 | self.print_header() | |
923a932c JS |
329 | for elem in self.elements: |
330 | self.print_one(elem) | |
56a092c8 QM |
331 | self.print_footer() |
332 | ||
0ba3929e UA |
333 | def elem_number_check(self, desc_unique_elem, define_unique_elem, type, instance): |
334 | """ | |
335 | Checks the number of helpers/syscalls documented within the header file | |
336 | description with those defined as part of enum/macro and raise an | |
337 | Exception if they don't match. | |
338 | """ | |
339 | nr_desc_unique_elem = len(desc_unique_elem) | |
340 | nr_define_unique_elem = len(define_unique_elem) | |
341 | if nr_desc_unique_elem != nr_define_unique_elem: | |
342 | exception_msg = ''' | |
343 | The number of unique %s in description (%d) doesn\'t match the number of unique %s defined in %s (%d) | |
344 | ''' % (type, nr_desc_unique_elem, type, instance, nr_define_unique_elem) | |
345 | if nr_desc_unique_elem < nr_define_unique_elem: | |
346 | # Function description is parsed until no helper is found (which can be due to | |
347 | # misformatting). Hence, only print the first missing/misformatted helper/enum. | |
348 | exception_msg += ''' | |
349 | The description for %s is not present or formatted correctly. | |
350 | ''' % (define_unique_elem[nr_desc_unique_elem]) | |
351 | raise Exception(exception_msg) | |
923a932c | 352 | |
56a092c8 QM |
353 | class PrinterRST(Printer): |
354 | """ | |
923a932c JS |
355 | A generic class for printers that print ReStructured Text. Printers should |
356 | be created with a HeaderParser object, and implement a way to print API | |
357 | elements in the desired fashion. | |
358 | @parser: A HeaderParser with objects to print to standard output | |
56a092c8 | 359 | """ |
923a932c JS |
360 | def __init__(self, parser): |
361 | self.parser = parser | |
362 | ||
363 | def print_license(self): | |
364 | license = '''\ | |
56a092c8 QM |
365 | .. Copyright (C) All BPF authors and contributors from 2014 to present. |
366 | .. See git log include/uapi/linux/bpf.h in kernel tree for details. | |
367 | .. | |
5cb62b75 | 368 | .. SPDX-License-Identifier: Linux-man-pages-copyleft |
56a092c8 QM |
369 | .. |
370 | .. Please do not edit this file. It was generated from the documentation | |
371 | .. located in file include/uapi/linux/bpf.h of the Linux kernel sources | |
923a932c | 372 | .. (helpers description), and from scripts/bpf_doc.py in the same |
56a092c8 | 373 | .. repository (header and footer). |
923a932c JS |
374 | ''' |
375 | print(license) | |
376 | ||
377 | def print_elem(self, elem): | |
378 | if (elem.desc): | |
379 | print('\tDescription') | |
380 | # Do not strip all newline characters: formatted code at the end of | |
381 | # a section must be followed by a blank line. | |
382 | for line in re.sub('\n$', '', elem.desc, count=1).split('\n'): | |
383 | print('{}{}'.format('\t\t' if line else '', line)) | |
384 | ||
385 | if (elem.ret): | |
386 | print('\tReturn') | |
387 | for line in elem.ret.rstrip().split('\n'): | |
388 | print('{}{}'.format('\t\t' if line else '', line)) | |
389 | ||
390 | print('') | |
56a092c8 | 391 | |
fd0a38f9 QM |
392 | def get_kernel_version(self): |
393 | try: | |
394 | version = subprocess.run(['git', 'describe'], cwd=linuxRoot, | |
395 | capture_output=True, check=True) | |
396 | version = version.stdout.decode().rstrip() | |
397 | except: | |
398 | try: | |
399 | version = subprocess.run(['make', 'kernelversion'], cwd=linuxRoot, | |
400 | capture_output=True, check=True) | |
401 | version = version.stdout.decode().rstrip() | |
402 | except: | |
403 | return 'Linux' | |
404 | return 'Linux {version}'.format(version=version) | |
405 | ||
92ec1cc3 QM |
406 | def get_last_doc_update(self, delimiter): |
407 | try: | |
408 | cmd = ['git', 'log', '-1', '--pretty=format:%cs', '--no-patch', | |
409 | '-L', | |
410 | '/{}/,/\*\//:include/uapi/linux/bpf.h'.format(delimiter)] | |
411 | date = subprocess.run(cmd, cwd=linuxRoot, | |
412 | capture_output=True, check=True) | |
413 | return date.stdout.decode().rstrip() | |
414 | except: | |
415 | return '' | |
416 | ||
923a932c JS |
417 | class PrinterHelpersRST(PrinterRST): |
418 | """ | |
419 | A printer for dumping collected information about helpers as a ReStructured | |
420 | Text page compatible with the rst2man program, which can be used to | |
421 | generate a manual page for the helpers. | |
422 | @parser: A HeaderParser with Helper objects to print to standard output | |
423 | """ | |
424 | def __init__(self, parser): | |
425 | self.elements = parser.helpers | |
0ba3929e | 426 | self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '__BPF_FUNC_MAPPER') |
923a932c JS |
427 | |
428 | def print_header(self): | |
429 | header = '''\ | |
56a092c8 QM |
430 | =========== |
431 | BPF-HELPERS | |
432 | =========== | |
433 | ------------------------------------------------------------------------------- | |
434 | list of eBPF helper functions | |
435 | ------------------------------------------------------------------------------- | |
436 | ||
437 | :Manual section: 7 | |
fd0a38f9 | 438 | :Version: {version} |
92ec1cc3 | 439 | {date_field}{date} |
56a092c8 QM |
440 | |
441 | DESCRIPTION | |
442 | =========== | |
443 | ||
444 | The extended Berkeley Packet Filter (eBPF) subsystem consists in programs | |
445 | written in a pseudo-assembly language, then attached to one of the several | |
446 | kernel hooks and run in reaction of specific events. This framework differs | |
447 | from the older, "classic" BPF (or "cBPF") in several aspects, one of them being | |
448 | the ability to call special functions (or "helpers") from within a program. | |
449 | These functions are restricted to a white-list of helpers defined in the | |
450 | kernel. | |
451 | ||
452 | These helpers are used by eBPF programs to interact with the system, or with | |
453 | the context in which they work. For instance, they can be used to print | |
454 | debugging messages, to get the time since the system was booted, to interact | |
455 | with eBPF maps, or to manipulate network packets. Since there are several eBPF | |
456 | program types, and that they do not run in the same context, each program type | |
457 | can only call a subset of those helpers. | |
458 | ||
459 | Due to eBPF conventions, a helper can not have more than five arguments. | |
460 | ||
461 | Internally, eBPF programs call directly into the compiled helper functions | |
462 | without requiring any foreign-function interface. As a result, calling helpers | |
463 | introduces no overhead, thus offering excellent performance. | |
464 | ||
465 | This document is an attempt to list and document the helpers available to eBPF | |
466 | developers. They are sorted by chronological order (the oldest helpers in the | |
467 | kernel at the top). | |
468 | ||
469 | HELPERS | |
470 | ======= | |
471 | ''' | |
fd0a38f9 | 472 | kernelVersion = self.get_kernel_version() |
92ec1cc3 | 473 | lastUpdate = self.get_last_doc_update(helpersDocStart) |
fd0a38f9 | 474 | |
923a932c | 475 | PrinterRST.print_license(self) |
92ec1cc3 QM |
476 | print(header.format(version=kernelVersion, |
477 | date_field = ':Date: ' if lastUpdate else '', | |
478 | date=lastUpdate)) | |
56a092c8 QM |
479 | |
480 | def print_footer(self): | |
481 | footer = ''' | |
482 | EXAMPLES | |
483 | ======== | |
484 | ||
485 | Example usage for most of the eBPF helpers listed in this manual page are | |
486 | available within the Linux kernel sources, at the following locations: | |
487 | ||
488 | * *samples/bpf/* | |
489 | * *tools/testing/selftests/bpf/* | |
490 | ||
491 | LICENSE | |
492 | ======= | |
493 | ||
494 | eBPF programs can have an associated license, passed along with the bytecode | |
495 | instructions to the kernel when the programs are loaded. The format for that | |
496 | string is identical to the one in use for kernel modules (Dual licenses, such | |
497 | as "Dual BSD/GPL", may be used). Some helper functions are only accessible to | |
498 | programs that are compatible with the GNU Privacy License (GPL). | |
499 | ||
500 | In order to use such helpers, the eBPF program must be loaded with the correct | |
501 | license string passed (via **attr**) to the **bpf**\ () system call, and this | |
502 | generally translates into the C source code of the program containing a line | |
503 | similar to the following: | |
504 | ||
505 | :: | |
506 | ||
507 | char ____license[] __attribute__((section("license"), used)) = "GPL"; | |
508 | ||
509 | IMPLEMENTATION | |
510 | ============== | |
511 | ||
512 | This manual page is an effort to document the existing eBPF helper functions. | |
513 | But as of this writing, the BPF sub-system is under heavy development. New eBPF | |
514 | program or map types are added, along with new helper functions. Some helpers | |
515 | are occasionally made available for additional program types. So in spite of | |
516 | the efforts of the community, this page might not be up-to-date. If you want to | |
517 | check by yourself what helper functions exist in your kernel, or what types of | |
518 | programs they can support, here are some files among the kernel tree that you | |
519 | may be interested in: | |
520 | ||
521 | * *include/uapi/linux/bpf.h* is the main BPF header. It contains the full list | |
522 | of all helper functions, as well as many other BPF definitions including most | |
523 | of the flags, structs or constants used by the helpers. | |
524 | * *net/core/filter.c* contains the definition of most network-related helper | |
525 | functions, and the list of program types from which they can be used. | |
526 | * *kernel/trace/bpf_trace.c* is the equivalent for most tracing program-related | |
527 | helpers. | |
528 | * *kernel/bpf/verifier.c* contains the functions used to check that valid types | |
529 | of eBPF maps are used with a given helper function. | |
530 | * *kernel/bpf/* directory contains other files in which additional helpers are | |
531 | defined (for cgroups, sockmaps, etc.). | |
ab8d7809 QM |
532 | * The bpftool utility can be used to probe the availability of helper functions |
533 | on the system (as well as supported program and map types, and a number of | |
534 | other parameters). To do so, run **bpftool feature probe** (see | |
535 | **bpftool-feature**\ (8) for details). Add the **unprivileged** keyword to | |
536 | list features available to unprivileged users. | |
56a092c8 QM |
537 | |
538 | Compatibility between helper functions and program types can generally be found | |
539 | in the files where helper functions are defined. Look for the **struct | |
540 | bpf_func_proto** objects and for functions returning them: these functions | |
541 | contain a list of helpers that a given program type can call. Note that the | |
542 | **default:** label of the **switch ... case** used to filter helpers can call | |
543 | other functions, themselves allowing access to additional helpers. The | |
544 | requirement for GPL license is also in those **struct bpf_func_proto**. | |
545 | ||
546 | Compatibility between helper functions and map types can be found in the | |
547 | **check_map_func_compatibility**\ () function in file *kernel/bpf/verifier.c*. | |
548 | ||
549 | Helper functions that invalidate the checks on **data** and **data_end** | |
550 | pointers for network processing are listed in function | |
551 | **bpf_helper_changes_pkt_data**\ () in file *net/core/filter.c*. | |
552 | ||
553 | SEE ALSO | |
554 | ======== | |
555 | ||
556 | **bpf**\ (2), | |
ab8d7809 | 557 | **bpftool**\ (8), |
56a092c8 QM |
558 | **cgroups**\ (7), |
559 | **ip**\ (8), | |
560 | **perf_event_open**\ (2), | |
561 | **sendmsg**\ (2), | |
562 | **socket**\ (7), | |
563 | **tc-bpf**\ (8)''' | |
564 | print(footer) | |
565 | ||
566 | def print_proto(self, helper): | |
567 | """ | |
568 | Format function protocol with bold and italics markers. This makes RST | |
569 | file less readable, but gives nice results in the manual page. | |
570 | """ | |
571 | proto = helper.proto_break_down() | |
572 | ||
573 | print('**%s %s%s(' % (proto['ret_type'], | |
574 | proto['ret_star'].replace('*', '\\*'), | |
575 | proto['name']), | |
576 | end='') | |
577 | ||
578 | comma = '' | |
579 | for a in proto['args']: | |
580 | one_arg = '{}{}'.format(comma, a['type']) | |
581 | if a['name']: | |
582 | if a['star']: | |
583 | one_arg += ' {}**\ '.format(a['star'].replace('*', '\\*')) | |
584 | else: | |
585 | one_arg += '** ' | |
586 | one_arg += '*{}*\\ **'.format(a['name']) | |
587 | comma = ', ' | |
588 | print(one_arg, end='') | |
589 | ||
590 | print(')**') | |
591 | ||
592 | def print_one(self, helper): | |
593 | self.print_proto(helper) | |
923a932c | 594 | self.print_elem(helper) |
56a092c8 | 595 | |
56a092c8 | 596 | |
a67882a2 JS |
597 | class PrinterSyscallRST(PrinterRST): |
598 | """ | |
599 | A printer for dumping collected information about the syscall API as a | |
600 | ReStructured Text page compatible with the rst2man program, which can be | |
601 | used to generate a manual page for the syscall. | |
602 | @parser: A HeaderParser with APIElement objects to print to standard | |
603 | output | |
604 | """ | |
605 | def __init__(self, parser): | |
606 | self.elements = parser.commands | |
0ba3929e | 607 | self.elem_number_check(parser.desc_syscalls, parser.enum_syscalls, 'syscall', 'bpf_cmd') |
a67882a2 JS |
608 | |
609 | def print_header(self): | |
610 | header = '''\ | |
611 | === | |
612 | bpf | |
613 | === | |
614 | ------------------------------------------------------------------------------- | |
615 | Perform a command on an extended BPF object | |
616 | ------------------------------------------------------------------------------- | |
617 | ||
618 | :Manual section: 2 | |
619 | ||
620 | COMMANDS | |
621 | ======== | |
622 | ''' | |
623 | PrinterRST.print_license(self) | |
624 | print(header) | |
625 | ||
626 | def print_one(self, command): | |
627 | print('**%s**' % (command.proto)) | |
628 | self.print_elem(command) | |
56a092c8 | 629 | |
56a092c8 | 630 | |
7a387bed AN |
631 | class PrinterHelpers(Printer): |
632 | """ | |
633 | A printer for dumping collected information about helpers as C header to | |
634 | be included from BPF program. | |
923a932c | 635 | @parser: A HeaderParser with Helper objects to print to standard output |
7a387bed | 636 | """ |
923a932c JS |
637 | def __init__(self, parser): |
638 | self.elements = parser.helpers | |
0ba3929e | 639 | self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '__BPF_FUNC_MAPPER') |
7a387bed AN |
640 | |
641 | type_fwds = [ | |
642 | 'struct bpf_fib_lookup', | |
e9ddbb77 | 643 | 'struct bpf_sk_lookup', |
7a387bed AN |
644 | 'struct bpf_perf_event_data', |
645 | 'struct bpf_perf_event_value', | |
5996a587 | 646 | 'struct bpf_pidns_info', |
821f5c90 | 647 | 'struct bpf_redir_neigh', |
7a387bed AN |
648 | 'struct bpf_sock', |
649 | 'struct bpf_sock_addr', | |
650 | 'struct bpf_sock_ops', | |
651 | 'struct bpf_sock_tuple', | |
652 | 'struct bpf_spin_lock', | |
653 | 'struct bpf_sysctl', | |
654 | 'struct bpf_tcp_sock', | |
655 | 'struct bpf_tunnel_key', | |
656 | 'struct bpf_xfrm_state', | |
3f6719c7 | 657 | 'struct linux_binprm', |
7a387bed AN |
658 | 'struct pt_regs', |
659 | 'struct sk_reuseport_md', | |
660 | 'struct sockaddr', | |
661 | 'struct tcphdr', | |
492e639f | 662 | 'struct seq_file', |
af7ec138 | 663 | 'struct tcp6_sock', |
478cfbdf YS |
664 | 'struct tcp_sock', |
665 | 'struct tcp_timewait_sock', | |
666 | 'struct tcp_request_sock', | |
0d4fad3e | 667 | 'struct udp6_sock', |
9eeb3aa3 | 668 | 'struct unix_sock', |
fa28dcb8 | 669 | 'struct task_struct', |
7a387bed AN |
670 | |
671 | 'struct __sk_buff', | |
672 | 'struct sk_msg_md', | |
e0b68fb1 | 673 | 'struct xdp_md', |
6e22ab9d | 674 | 'struct path', |
c4d0bfb4 | 675 | 'struct btf_ptr', |
27672f0d | 676 | 'struct inode', |
4f19cab7 FR |
677 | 'struct socket', |
678 | 'struct file', | |
b00628b1 | 679 | 'struct bpf_timer', |
3bc253c2 | 680 | 'struct mptcp_sock', |
97e03f52 | 681 | 'struct bpf_dynptr', |
33bf9885 MM |
682 | 'struct iphdr', |
683 | 'struct ipv6hdr', | |
7a387bed AN |
684 | ] |
685 | known_types = { | |
686 | '...', | |
687 | 'void', | |
688 | 'const void', | |
689 | 'char', | |
690 | 'const char', | |
691 | 'int', | |
692 | 'long', | |
693 | 'unsigned long', | |
694 | ||
695 | '__be16', | |
696 | '__be32', | |
697 | '__wsum', | |
698 | ||
699 | 'struct bpf_fib_lookup', | |
700 | 'struct bpf_perf_event_data', | |
701 | 'struct bpf_perf_event_value', | |
b4490c5c | 702 | 'struct bpf_pidns_info', |
ba452c9e | 703 | 'struct bpf_redir_neigh', |
e9ddbb77 | 704 | 'struct bpf_sk_lookup', |
7a387bed AN |
705 | 'struct bpf_sock', |
706 | 'struct bpf_sock_addr', | |
707 | 'struct bpf_sock_ops', | |
708 | 'struct bpf_sock_tuple', | |
709 | 'struct bpf_spin_lock', | |
710 | 'struct bpf_sysctl', | |
711 | 'struct bpf_tcp_sock', | |
712 | 'struct bpf_tunnel_key', | |
713 | 'struct bpf_xfrm_state', | |
3f6719c7 | 714 | 'struct linux_binprm', |
7a387bed AN |
715 | 'struct pt_regs', |
716 | 'struct sk_reuseport_md', | |
717 | 'struct sockaddr', | |
718 | 'struct tcphdr', | |
492e639f | 719 | 'struct seq_file', |
af7ec138 | 720 | 'struct tcp6_sock', |
478cfbdf YS |
721 | 'struct tcp_sock', |
722 | 'struct tcp_timewait_sock', | |
723 | 'struct tcp_request_sock', | |
0d4fad3e | 724 | 'struct udp6_sock', |
9eeb3aa3 | 725 | 'struct unix_sock', |
fa28dcb8 | 726 | 'struct task_struct', |
6e22ab9d | 727 | 'struct path', |
c4d0bfb4 | 728 | 'struct btf_ptr', |
27672f0d | 729 | 'struct inode', |
4f19cab7 FR |
730 | 'struct socket', |
731 | 'struct file', | |
b00628b1 | 732 | 'struct bpf_timer', |
3bc253c2 | 733 | 'struct mptcp_sock', |
97e03f52 | 734 | 'struct bpf_dynptr', |
33bf9885 MM |
735 | 'struct iphdr', |
736 | 'struct ipv6hdr', | |
7a387bed AN |
737 | } |
738 | mapped_types = { | |
739 | 'u8': '__u8', | |
740 | 'u16': '__u16', | |
741 | 'u32': '__u32', | |
742 | 'u64': '__u64', | |
743 | 's8': '__s8', | |
744 | 's16': '__s16', | |
745 | 's32': '__s32', | |
746 | 's64': '__s64', | |
747 | 'size_t': 'unsigned long', | |
748 | 'struct bpf_map': 'void', | |
749 | 'struct sk_buff': 'struct __sk_buff', | |
750 | 'const struct sk_buff': 'const struct __sk_buff', | |
751 | 'struct sk_msg_buff': 'struct sk_msg_md', | |
752 | 'struct xdp_buff': 'struct xdp_md', | |
753 | } | |
e9ddbb77 JS |
754 | # Helpers overloaded for different context types. |
755 | overloaded_helpers = [ | |
756 | 'bpf_get_socket_cookie', | |
757 | 'bpf_sk_assign', | |
758 | ] | |
7a387bed AN |
759 | |
760 | def print_header(self): | |
761 | header = '''\ | |
923a932c | 762 | /* This is auto-generated file. See bpf_doc.py for details. */ |
7a387bed AN |
763 | |
764 | /* Forward declarations of BPF structs */''' | |
765 | ||
766 | print(header) | |
767 | for fwd in self.type_fwds: | |
768 | print('%s;' % fwd) | |
769 | print('') | |
770 | ||
771 | def print_footer(self): | |
772 | footer = '' | |
773 | print(footer) | |
774 | ||
775 | def map_type(self, t): | |
776 | if t in self.known_types: | |
777 | return t | |
778 | if t in self.mapped_types: | |
779 | return self.mapped_types[t] | |
ab81e203 JS |
780 | print("Unrecognized type '%s', please add it to known types!" % t, |
781 | file=sys.stderr) | |
7a387bed AN |
782 | sys.exit(1) |
783 | ||
784 | seen_helpers = set() | |
785 | ||
786 | def print_one(self, helper): | |
787 | proto = helper.proto_break_down() | |
788 | ||
789 | if proto['name'] in self.seen_helpers: | |
790 | return | |
791 | self.seen_helpers.add(proto['name']) | |
792 | ||
793 | print('/*') | |
794 | print(" * %s" % proto['name']) | |
795 | print(" *") | |
796 | if (helper.desc): | |
797 | # Do not strip all newline characters: formatted code at the end of | |
798 | # a section must be followed by a blank line. | |
799 | for line in re.sub('\n$', '', helper.desc, count=1).split('\n'): | |
800 | print(' *{}{}'.format(' \t' if line else '', line)) | |
801 | ||
802 | if (helper.ret): | |
803 | print(' *') | |
804 | print(' * Returns') | |
805 | for line in helper.ret.rstrip().split('\n'): | |
806 | print(' *{}{}'.format(' \t' if line else '', line)) | |
807 | ||
808 | print(' */') | |
809 | print('static %s %s(*%s)(' % (self.map_type(proto['ret_type']), | |
810 | proto['ret_star'], proto['name']), end='') | |
811 | comma = '' | |
812 | for i, a in enumerate(proto['args']): | |
813 | t = a['type'] | |
814 | n = a['name'] | |
e9ddbb77 | 815 | if proto['name'] in self.overloaded_helpers and i == 0: |
7a387bed AN |
816 | t = 'void' |
817 | n = 'ctx' | |
818 | one_arg = '{}{}'.format(comma, self.map_type(t)) | |
819 | if n: | |
820 | if a['star']: | |
821 | one_arg += ' {}'.format(a['star']) | |
822 | else: | |
823 | one_arg += ' ' | |
824 | one_arg += '{}'.format(n) | |
825 | comma = ', ' | |
826 | print(one_arg, end='') | |
827 | ||
0a0d55ef | 828 | print(') = (void *) %d;' % helper.enum_val) |
7a387bed AN |
829 | print('') |
830 | ||
56a092c8 QM |
831 | ############################################################################### |
832 | ||
833 | # If script is launched from scripts/ from kernel tree and can access | |
834 | # ../include/uapi/linux/bpf.h, use it as a default name for the file to parse, | |
835 | # otherwise the --filename argument will be required from the command line. | |
836 | script = os.path.abspath(sys.argv[0]) | |
837 | linuxRoot = os.path.dirname(os.path.dirname(script)) | |
838 | bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h') | |
839 | ||
923a932c JS |
840 | printers = { |
841 | 'helpers': PrinterHelpersRST, | |
a67882a2 | 842 | 'syscall': PrinterSyscallRST, |
923a932c JS |
843 | } |
844 | ||
56a092c8 | 845 | argParser = argparse.ArgumentParser(description=""" |
923a932c | 846 | Parse eBPF header file and generate documentation for the eBPF API. |
56a092c8 QM |
847 | The RST-formatted output produced can be turned into a manual page with the |
848 | rst2man utility. | |
849 | """) | |
7a387bed AN |
850 | argParser.add_argument('--header', action='store_true', |
851 | help='generate C header file') | |
56a092c8 QM |
852 | if (os.path.isfile(bpfh)): |
853 | argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h', | |
854 | default=bpfh) | |
855 | else: | |
856 | argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h') | |
923a932c JS |
857 | argParser.add_argument('target', nargs='?', default='helpers', |
858 | choices=printers.keys(), help='eBPF API target') | |
56a092c8 QM |
859 | args = argParser.parse_args() |
860 | ||
861 | # Parse file. | |
862 | headerParser = HeaderParser(args.filename) | |
863 | headerParser.run() | |
864 | ||
865 | # Print formatted output to standard output. | |
7a387bed | 866 | if args.header: |
a67882a2 JS |
867 | if args.target != 'helpers': |
868 | raise NotImplementedError('Only helpers header generation is supported') | |
923a932c | 869 | printer = PrinterHelpers(headerParser) |
7a387bed | 870 | else: |
923a932c | 871 | printer = printers[args.target](headerParser) |
56a092c8 | 872 | printer.print_all() |