1#!/usr/bin/env python3 2# SPDX-License-Identifier: GPL-2.0-only 3# 4# Copyright (C) 2018-2019 Netronome Systems, Inc. 5# Copyright (C) 2021 Isovalent, Inc. 6 7# In case user attempts to run with Python 2. 8from __future__ import print_function 9 10import argparse 11import re 12import sys, os 13import subprocess 14 15helpersDocStart = 'Start of BPF helper function descriptions:' 16 17class NoHelperFound(BaseException): 18 pass 19 20class NoSyscallCommandFound(BaseException): 21 pass 22 23class 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 32 33class APIElement(object): 34 """ 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 39 """ 40 def __init__(self, proto='', desc='', ret='', attrs=[]): 41 self.proto = proto 42 self.desc = desc 43 self.ret = ret 44 self.attrs = attrs 45 46 47class Helper(APIElement): 48 """ 49 An object representing the description of an eBPF helper function. 50 @proto: function prototype of the helper function 51 @desc: textual description of the helper function 52 @ret: description of the return value of the helper function 53 """ 54 def __init__(self, *args, **kwargs): 55 super().__init__(*args, **kwargs) 56 self.enum_val = None 57 58 def proto_break_down(self): 59 """ 60 Break down helper function protocol into smaller chunks: return type, 61 name, distincts arguments. 62 """ 63 arg_re = re.compile(r'((\w+ )*?(\w+|...))( (\**)(\w+))?$') 64 res = {} 65 proto_re = re.compile(r'(.+) (\**)(\w+)\(((([^,]+)(, )?){1,5})\)$') 66 67 capture = proto_re.match(self.proto) 68 res['ret_type'] = capture.group(1) 69 res['ret_star'] = capture.group(2) 70 res['name'] = capture.group(3) 71 res['args'] = [] 72 73 args = capture.group(4).split(', ') 74 for a in args: 75 capture = arg_re.match(a) 76 res['args'].append({ 77 'type' : capture.group(1), 78 'star' : capture.group(5), 79 'name' : capture.group(6) 80 }) 81 82 return res 83 84 85ATTRS = { 86 '__bpf_fastcall': 'bpf_fastcall' 87} 88 89 90class HeaderParser(object): 91 """ 92 An object used to parse a file in order to extract the documentation of a 93 list of eBPF helper functions. All the helpers that can be retrieved are 94 stored as Helper object, in the self.helpers() array. 95 @filename: name of file to parse, usually include/uapi/linux/bpf.h in the 96 kernel tree 97 """ 98 def __init__(self, filename): 99 self.reader = open(filename, 'r') 100 self.line = '' 101 self.helpers = [] 102 self.commands = [] 103 self.desc_unique_helpers = set() 104 self.define_unique_helpers = [] 105 self.helper_enum_vals = {} 106 self.helper_enum_pos = {} 107 self.desc_syscalls = [] 108 self.enum_syscalls = [] 109 110 def parse_element(self): 111 proto = self.parse_symbol() 112 desc = self.parse_desc(proto) 113 ret = self.parse_ret(proto) 114 return APIElement(proto=proto, desc=desc, ret=ret) 115 116 def parse_helper(self): 117 proto = self.parse_proto() 118 desc = self.parse_desc(proto) 119 ret = self.parse_ret(proto) 120 attrs = self.parse_attrs(proto) 121 return Helper(proto=proto, desc=desc, ret=ret, attrs=attrs) 122 123 def parse_symbol(self): 124 p = re.compile(r' \* ?(BPF\w+)$') 125 capture = p.match(self.line) 126 if not capture: 127 raise NoSyscallCommandFound 128 end_re = re.compile(r' \* ?NOTES$') 129 end = end_re.match(self.line) 130 if end: 131 raise NoSyscallCommandFound 132 self.line = self.reader.readline() 133 return capture.group(1) 134 135 def parse_proto(self): 136 # Argument can be of shape: 137 # - "void" 138 # - "type name" 139 # - "type *name" 140 # - Same as above, with "const" and/or "struct" in front of type 141 # - "..." (undefined number of arguments, for bpf_trace_printk()) 142 # There is at least one term ("void"), and at most five arguments. 143 p = re.compile(r' \* ?((.+) \**\w+\((((const )?(struct )?(\w+|\.\.\.)( \**\w+)?)(, )?){1,5}\))$') 144 capture = p.match(self.line) 145 if not capture: 146 raise NoHelperFound 147 self.line = self.reader.readline() 148 return capture.group(1) 149 150 def parse_desc(self, proto): 151 p = re.compile(r' \* ?(?:\t| {5,8})Description$') 152 capture = p.match(self.line) 153 if not capture: 154 raise Exception("No description section found for " + proto) 155 # Description can be several lines, some of them possibly empty, and it 156 # stops when another subsection title is met. 157 desc = '' 158 desc_present = False 159 while True: 160 self.line = self.reader.readline() 161 if self.line == ' *\n': 162 desc += '\n' 163 else: 164 p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)') 165 capture = p.match(self.line) 166 if capture: 167 desc_present = True 168 desc += capture.group(1) + '\n' 169 else: 170 break 171 172 if not desc_present: 173 raise Exception("No description found for " + proto) 174 return desc 175 176 def parse_ret(self, proto): 177 p = re.compile(r' \* ?(?:\t| {5,8})Return$') 178 capture = p.match(self.line) 179 if not capture: 180 raise Exception("No return section found for " + proto) 181 # Return value description can be several lines, some of them possibly 182 # empty, and it stops when another subsection title is met. 183 ret = '' 184 ret_present = False 185 while True: 186 self.line = self.reader.readline() 187 if self.line == ' *\n': 188 ret += '\n' 189 else: 190 p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)') 191 capture = p.match(self.line) 192 if capture: 193 ret_present = True 194 ret += capture.group(1) + '\n' 195 else: 196 break 197 198 if not ret_present: 199 raise Exception("No return found for " + proto) 200 return ret 201 202 def parse_attrs(self, proto): 203 p = re.compile(r' \* ?(?:\t| {5,8})Attributes$') 204 capture = p.match(self.line) 205 if not capture: 206 return [] 207 # Expect a single line with mnemonics for attributes separated by spaces 208 self.line = self.reader.readline() 209 p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)') 210 capture = p.match(self.line) 211 if not capture: 212 raise Exception("Incomplete 'Attributes' section for " + proto) 213 attrs = capture.group(1).split(' ') 214 for attr in attrs: 215 if attr not in ATTRS: 216 raise Exception("Unexpected attribute '" + attr + "' specified for " + proto) 217 self.line = self.reader.readline() 218 if self.line != ' *\n': 219 raise Exception("Expecting empty line after 'Attributes' section for " + proto) 220 # Prepare a line for next self.parse_* to consume 221 self.line = self.reader.readline() 222 return attrs 223 224 def seek_to(self, target, help_message, discard_lines = 1): 225 self.reader.seek(0) 226 offset = self.reader.read().find(target) 227 if offset == -1: 228 raise Exception(help_message) 229 self.reader.seek(offset) 230 self.reader.readline() 231 for _ in range(discard_lines): 232 self.reader.readline() 233 self.line = self.reader.readline() 234 235 def parse_desc_syscall(self): 236 self.seek_to('* DOC: eBPF Syscall Commands', 237 'Could not find start of eBPF syscall descriptions list') 238 while True: 239 try: 240 command = self.parse_element() 241 self.commands.append(command) 242 self.desc_syscalls.append(command.proto) 243 244 except NoSyscallCommandFound: 245 break 246 247 def parse_enum_syscall(self): 248 self.seek_to('enum bpf_cmd {', 249 'Could not find start of bpf_cmd enum', 0) 250 # Searches for either one or more BPF\w+ enums 251 bpf_p = re.compile(r'\s*(BPF\w+)+') 252 # Searches for an enum entry assigned to another entry, 253 # for e.g. BPF_PROG_RUN = BPF_PROG_TEST_RUN, which is 254 # not documented hence should be skipped in check to 255 # determine if the right number of syscalls are documented 256 assign_p = re.compile(r'\s*(BPF\w+)\s*=\s*(BPF\w+)') 257 bpf_cmd_str = '' 258 while True: 259 capture = assign_p.match(self.line) 260 if capture: 261 # Skip line if an enum entry is assigned to another entry 262 self.line = self.reader.readline() 263 continue 264 capture = bpf_p.match(self.line) 265 if capture: 266 bpf_cmd_str += self.line 267 else: 268 break 269 self.line = self.reader.readline() 270 # Find the number of occurences of BPF\w+ 271 self.enum_syscalls = re.findall(r'(BPF\w+)+', bpf_cmd_str) 272 273 def parse_desc_helpers(self): 274 self.seek_to(helpersDocStart, 275 'Could not find start of eBPF helper descriptions list') 276 while True: 277 try: 278 helper = self.parse_helper() 279 self.helpers.append(helper) 280 proto = helper.proto_break_down() 281 self.desc_unique_helpers.add(proto['name']) 282 except NoHelperFound: 283 break 284 285 def parse_define_helpers(self): 286 # Parse FN(...) in #define ___BPF_FUNC_MAPPER to compare later with the 287 # number of unique function names present in description and use the 288 # correct enumeration value. 289 # Note: seek_to(..) discards the first line below the target search text, 290 # resulting in FN(unspec, 0, ##ctx) being skipped and not added to 291 # self.define_unique_helpers. 292 self.seek_to('#define ___BPF_FUNC_MAPPER(FN, ctx...)', 293 'Could not find start of eBPF helper definition list') 294 # Searches for one FN(\w+) define or a backslash for newline 295 p = re.compile(r'\s*FN\((\w+), (\d+), ##ctx\)|\\\\') 296 fn_defines_str = '' 297 i = 0 298 while True: 299 capture = p.match(self.line) 300 if capture: 301 fn_defines_str += self.line 302 helper_name = capture.expand(r'bpf_\1') 303 self.helper_enum_vals[helper_name] = int(capture.group(2)) 304 self.helper_enum_pos[helper_name] = i 305 i += 1 306 else: 307 break 308 self.line = self.reader.readline() 309 # Find the number of occurences of FN(\w+) 310 self.define_unique_helpers = re.findall(r'FN\(\w+, \d+, ##ctx\)', fn_defines_str) 311 312 def validate_helpers(self): 313 last_helper = '' 314 seen_helpers = set() 315 seen_enum_vals = set() 316 i = 0 317 for helper in self.helpers: 318 proto = helper.proto_break_down() 319 name = proto['name'] 320 try: 321 enum_val = self.helper_enum_vals[name] 322 enum_pos = self.helper_enum_pos[name] 323 except KeyError: 324 raise Exception("Helper %s is missing from enum bpf_func_id" % name) 325 326 if name in seen_helpers: 327 if last_helper != name: 328 raise Exception("Helper %s has multiple descriptions which are not grouped together" % name) 329 continue 330 331 # Enforce current practice of having the descriptions ordered 332 # by enum value. 333 if enum_pos != i: 334 raise Exception("Helper %s (ID %d) comment order (#%d) must be aligned with its position (#%d) in enum bpf_func_id" % (name, enum_val, i + 1, enum_pos + 1)) 335 if enum_val in seen_enum_vals: 336 raise Exception("Helper %s has duplicated value %d" % (name, enum_val)) 337 338 seen_helpers.add(name) 339 last_helper = name 340 seen_enum_vals.add(enum_val) 341 342 helper.enum_val = enum_val 343 i += 1 344 345 def run(self): 346 self.parse_desc_syscall() 347 self.parse_enum_syscall() 348 self.parse_desc_helpers() 349 self.parse_define_helpers() 350 self.validate_helpers() 351 self.reader.close() 352 353############################################################################### 354 355class Printer(object): 356 """ 357 A generic class for printers. Printers should be created with an array of 358 Helper objects, and implement a way to print them in the desired fashion. 359 @parser: A HeaderParser with objects to print to standard output 360 """ 361 def __init__(self, parser): 362 self.parser = parser 363 self.elements = [] 364 365 def print_header(self): 366 pass 367 368 def print_footer(self): 369 pass 370 371 def print_one(self, helper): 372 pass 373 374 def print_all(self): 375 self.print_header() 376 for elem in self.elements: 377 self.print_one(elem) 378 self.print_footer() 379 380 def elem_number_check(self, desc_unique_elem, define_unique_elem, type, instance): 381 """ 382 Checks the number of helpers/syscalls documented within the header file 383 description with those defined as part of enum/macro and raise an 384 Exception if they don't match. 385 """ 386 nr_desc_unique_elem = len(desc_unique_elem) 387 nr_define_unique_elem = len(define_unique_elem) 388 if nr_desc_unique_elem != nr_define_unique_elem: 389 exception_msg = ''' 390The number of unique %s in description (%d) doesn\'t match the number of unique %s defined in %s (%d) 391''' % (type, nr_desc_unique_elem, type, instance, nr_define_unique_elem) 392 if nr_desc_unique_elem < nr_define_unique_elem: 393 # Function description is parsed until no helper is found (which can be due to 394 # misformatting). Hence, only print the first missing/misformatted helper/enum. 395 exception_msg += ''' 396The description for %s is not present or formatted correctly. 397''' % (define_unique_elem[nr_desc_unique_elem]) 398 raise Exception(exception_msg) 399 400class PrinterRST(Printer): 401 """ 402 A generic class for printers that print ReStructured Text. Printers should 403 be created with a HeaderParser object, and implement a way to print API 404 elements in the desired fashion. 405 @parser: A HeaderParser with objects to print to standard output 406 """ 407 def __init__(self, parser): 408 self.parser = parser 409 410 def print_license(self): 411 license = '''\ 412.. Copyright (C) All BPF authors and contributors from 2014 to present. 413.. See git log include/uapi/linux/bpf.h in kernel tree for details. 414.. 415.. SPDX-License-Identifier: Linux-man-pages-copyleft 416.. 417.. Please do not edit this file. It was generated from the documentation 418.. located in file include/uapi/linux/bpf.h of the Linux kernel sources 419.. (helpers description), and from scripts/bpf_doc.py in the same 420.. repository (header and footer). 421''' 422 print(license) 423 424 def print_elem(self, elem): 425 if (elem.desc): 426 print('\tDescription') 427 # Do not strip all newline characters: formatted code at the end of 428 # a section must be followed by a blank line. 429 for line in re.sub('\n$', '', elem.desc, count=1).split('\n'): 430 print('{}{}'.format('\t\t' if line else '', line)) 431 432 if (elem.ret): 433 print('\tReturn') 434 for line in elem.ret.rstrip().split('\n'): 435 print('{}{}'.format('\t\t' if line else '', line)) 436 437 print('') 438 439 def get_kernel_version(self): 440 try: 441 version = subprocess.run(['git', 'describe'], cwd=linuxRoot, 442 capture_output=True, check=True) 443 version = version.stdout.decode().rstrip() 444 except: 445 try: 446 version = subprocess.run(['make', '-s', '--no-print-directory', 'kernelversion'], 447 cwd=linuxRoot, capture_output=True, check=True) 448 version = version.stdout.decode().rstrip() 449 except: 450 return 'Linux' 451 return 'Linux {version}'.format(version=version) 452 453 def get_last_doc_update(self, delimiter): 454 try: 455 cmd = ['git', 'log', '-1', '--pretty=format:%cs', '--no-patch', 456 '-L', 457 '/{}/,/\\*\\//:include/uapi/linux/bpf.h'.format(delimiter)] 458 date = subprocess.run(cmd, cwd=linuxRoot, 459 capture_output=True, check=True) 460 return date.stdout.decode().rstrip() 461 except: 462 return '' 463 464class PrinterHelpersRST(PrinterRST): 465 """ 466 A printer for dumping collected information about helpers as a ReStructured 467 Text page compatible with the rst2man program, which can be used to 468 generate a manual page for the helpers. 469 @parser: A HeaderParser with Helper objects to print to standard output 470 """ 471 def __init__(self, parser): 472 self.elements = parser.helpers 473 self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '___BPF_FUNC_MAPPER') 474 475 def print_header(self): 476 header = '''\ 477=========== 478BPF-HELPERS 479=========== 480------------------------------------------------------------------------------- 481list of eBPF helper functions 482------------------------------------------------------------------------------- 483 484:Manual section: 7 485:Version: {version} 486{date_field}{date} 487 488DESCRIPTION 489=========== 490 491The extended Berkeley Packet Filter (eBPF) subsystem consists in programs 492written in a pseudo-assembly language, then attached to one of the several 493kernel hooks and run in reaction of specific events. This framework differs 494from the older, "classic" BPF (or "cBPF") in several aspects, one of them being 495the ability to call special functions (or "helpers") from within a program. 496These functions are restricted to a white-list of helpers defined in the 497kernel. 498 499These helpers are used by eBPF programs to interact with the system, or with 500the context in which they work. For instance, they can be used to print 501debugging messages, to get the time since the system was booted, to interact 502with eBPF maps, or to manipulate network packets. Since there are several eBPF 503program types, and that they do not run in the same context, each program type 504can only call a subset of those helpers. 505 506Due to eBPF conventions, a helper can not have more than five arguments. 507 508Internally, eBPF programs call directly into the compiled helper functions 509without requiring any foreign-function interface. As a result, calling helpers 510introduces no overhead, thus offering excellent performance. 511 512This document is an attempt to list and document the helpers available to eBPF 513developers. They are sorted by chronological order (the oldest helpers in the 514kernel at the top). 515 516HELPERS 517======= 518''' 519 kernelVersion = self.get_kernel_version() 520 lastUpdate = self.get_last_doc_update(helpersDocStart) 521 522 PrinterRST.print_license(self) 523 print(header.format(version=kernelVersion, 524 date_field = ':Date: ' if lastUpdate else '', 525 date=lastUpdate)) 526 527 def print_footer(self): 528 footer = ''' 529EXAMPLES 530======== 531 532Example usage for most of the eBPF helpers listed in this manual page are 533available within the Linux kernel sources, at the following locations: 534 535* *samples/bpf/* 536* *tools/testing/selftests/bpf/* 537 538LICENSE 539======= 540 541eBPF programs can have an associated license, passed along with the bytecode 542instructions to the kernel when the programs are loaded. The format for that 543string is identical to the one in use for kernel modules (Dual licenses, such 544as "Dual BSD/GPL", may be used). Some helper functions are only accessible to 545programs that are compatible with the GNU General Public License (GNU GPL). 546 547In order to use such helpers, the eBPF program must be loaded with the correct 548license string passed (via **attr**) to the **bpf**\\ () system call, and this 549generally translates into the C source code of the program containing a line 550similar to the following: 551 552:: 553 554 char ____license[] __attribute__((section("license"), used)) = "GPL"; 555 556IMPLEMENTATION 557============== 558 559This manual page is an effort to document the existing eBPF helper functions. 560But as of this writing, the BPF sub-system is under heavy development. New eBPF 561program or map types are added, along with new helper functions. Some helpers 562are occasionally made available for additional program types. So in spite of 563the efforts of the community, this page might not be up-to-date. If you want to 564check by yourself what helper functions exist in your kernel, or what types of 565programs they can support, here are some files among the kernel tree that you 566may be interested in: 567 568* *include/uapi/linux/bpf.h* is the main BPF header. It contains the full list 569 of all helper functions, as well as many other BPF definitions including most 570 of the flags, structs or constants used by the helpers. 571* *net/core/filter.c* contains the definition of most network-related helper 572 functions, and the list of program types from which they can be used. 573* *kernel/trace/bpf_trace.c* is the equivalent for most tracing program-related 574 helpers. 575* *kernel/bpf/verifier.c* contains the functions used to check that valid types 576 of eBPF maps are used with a given helper function. 577* *kernel/bpf/* directory contains other files in which additional helpers are 578 defined (for cgroups, sockmaps, etc.). 579* The bpftool utility can be used to probe the availability of helper functions 580 on the system (as well as supported program and map types, and a number of 581 other parameters). To do so, run **bpftool feature probe** (see 582 **bpftool-feature**\\ (8) for details). Add the **unprivileged** keyword to 583 list features available to unprivileged users. 584 585Compatibility between helper functions and program types can generally be found 586in the files where helper functions are defined. Look for the **struct 587bpf_func_proto** objects and for functions returning them: these functions 588contain a list of helpers that a given program type can call. Note that the 589**default:** label of the **switch ... case** used to filter helpers can call 590other functions, themselves allowing access to additional helpers. The 591requirement for GPL license is also in those **struct bpf_func_proto**. 592 593Compatibility between helper functions and map types can be found in the 594**check_map_func_compatibility**\\ () function in file *kernel/bpf/verifier.c*. 595 596Helper functions that invalidate the checks on **data** and **data_end** 597pointers for network processing are listed in function 598**bpf_helper_changes_pkt_data**\\ () in file *net/core/filter.c*. 599 600SEE ALSO 601======== 602 603**bpf**\\ (2), 604**bpftool**\\ (8), 605**cgroups**\\ (7), 606**ip**\\ (8), 607**perf_event_open**\\ (2), 608**sendmsg**\\ (2), 609**socket**\\ (7), 610**tc-bpf**\\ (8)''' 611 print(footer) 612 613 def print_proto(self, helper): 614 """ 615 Format function protocol with bold and italics markers. This makes RST 616 file less readable, but gives nice results in the manual page. 617 """ 618 proto = helper.proto_break_down() 619 620 print('**%s %s%s(' % (proto['ret_type'], 621 proto['ret_star'].replace('*', '\\*'), 622 proto['name']), 623 end='') 624 625 comma = '' 626 for a in proto['args']: 627 one_arg = '{}{}'.format(comma, a['type']) 628 if a['name']: 629 if a['star']: 630 one_arg += ' {}**\\ '.format(a['star'].replace('*', '\\*')) 631 else: 632 one_arg += '** ' 633 one_arg += '*{}*\\ **'.format(a['name']) 634 comma = ', ' 635 print(one_arg, end='') 636 637 print(')**') 638 639 def print_one(self, helper): 640 self.print_proto(helper) 641 self.print_elem(helper) 642 643 644class PrinterSyscallRST(PrinterRST): 645 """ 646 A printer for dumping collected information about the syscall API as a 647 ReStructured Text page compatible with the rst2man program, which can be 648 used to generate a manual page for the syscall. 649 @parser: A HeaderParser with APIElement objects to print to standard 650 output 651 """ 652 def __init__(self, parser): 653 self.elements = parser.commands 654 self.elem_number_check(parser.desc_syscalls, parser.enum_syscalls, 'syscall', 'bpf_cmd') 655 656 def print_header(self): 657 header = '''\ 658=== 659bpf 660=== 661------------------------------------------------------------------------------- 662Perform a command on an extended BPF object 663------------------------------------------------------------------------------- 664 665:Manual section: 2 666 667COMMANDS 668======== 669''' 670 PrinterRST.print_license(self) 671 print(header) 672 673 def print_one(self, command): 674 print('**%s**' % (command.proto)) 675 self.print_elem(command) 676 677 678class PrinterHelpers(Printer): 679 """ 680 A printer for dumping collected information about helpers as C header to 681 be included from BPF program. 682 @parser: A HeaderParser with Helper objects to print to standard output 683 """ 684 def __init__(self, parser): 685 self.elements = parser.helpers 686 self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '___BPF_FUNC_MAPPER') 687 688 type_fwds = [ 689 'struct bpf_fib_lookup', 690 'struct bpf_sk_lookup', 691 'struct bpf_perf_event_data', 692 'struct bpf_perf_event_value', 693 'struct bpf_pidns_info', 694 'struct bpf_redir_neigh', 695 'struct bpf_sock', 696 'struct bpf_sock_addr', 697 'struct bpf_sock_ops', 698 'struct bpf_sock_tuple', 699 'struct bpf_spin_lock', 700 'struct bpf_sysctl', 701 'struct bpf_tcp_sock', 702 'struct bpf_tunnel_key', 703 'struct bpf_xfrm_state', 704 'struct linux_binprm', 705 'struct pt_regs', 706 'struct sk_reuseport_md', 707 'struct sockaddr', 708 'struct tcphdr', 709 'struct seq_file', 710 'struct tcp6_sock', 711 'struct tcp_sock', 712 'struct tcp_timewait_sock', 713 'struct tcp_request_sock', 714 'struct udp6_sock', 715 'struct unix_sock', 716 'struct task_struct', 717 'struct cgroup', 718 719 'struct __sk_buff', 720 'struct sk_msg_md', 721 'struct xdp_md', 722 'struct path', 723 'struct btf_ptr', 724 'struct inode', 725 'struct socket', 726 'struct file', 727 'struct bpf_timer', 728 'struct mptcp_sock', 729 'struct bpf_dynptr', 730 'struct iphdr', 731 'struct ipv6hdr', 732 ] 733 known_types = { 734 '...', 735 'void', 736 'const void', 737 'char', 738 'const char', 739 'int', 740 'long', 741 'unsigned long', 742 743 '__be16', 744 '__be32', 745 '__wsum', 746 747 'struct bpf_fib_lookup', 748 'struct bpf_perf_event_data', 749 'struct bpf_perf_event_value', 750 'struct bpf_pidns_info', 751 'struct bpf_redir_neigh', 752 'struct bpf_sk_lookup', 753 'struct bpf_sock', 754 'struct bpf_sock_addr', 755 'struct bpf_sock_ops', 756 'struct bpf_sock_tuple', 757 'struct bpf_spin_lock', 758 'struct bpf_sysctl', 759 'struct bpf_tcp_sock', 760 'struct bpf_tunnel_key', 761 'struct bpf_xfrm_state', 762 'struct linux_binprm', 763 'struct pt_regs', 764 'struct sk_reuseport_md', 765 'struct sockaddr', 766 'struct tcphdr', 767 'struct seq_file', 768 'struct tcp6_sock', 769 'struct tcp_sock', 770 'struct tcp_timewait_sock', 771 'struct tcp_request_sock', 772 'struct udp6_sock', 773 'struct unix_sock', 774 'struct task_struct', 775 'struct cgroup', 776 'struct path', 777 'struct btf_ptr', 778 'struct inode', 779 'struct socket', 780 'struct file', 781 'struct bpf_timer', 782 'struct mptcp_sock', 783 'struct bpf_dynptr', 784 'const struct bpf_dynptr', 785 'struct iphdr', 786 'struct ipv6hdr', 787 } 788 mapped_types = { 789 'u8': '__u8', 790 'u16': '__u16', 791 'u32': '__u32', 792 'u64': '__u64', 793 's8': '__s8', 794 's16': '__s16', 795 's32': '__s32', 796 's64': '__s64', 797 'size_t': 'unsigned long', 798 'struct bpf_map': 'void', 799 'struct sk_buff': 'struct __sk_buff', 800 'const struct sk_buff': 'const struct __sk_buff', 801 'struct sk_msg_buff': 'struct sk_msg_md', 802 'struct xdp_buff': 'struct xdp_md', 803 } 804 # Helpers overloaded for different context types. 805 overloaded_helpers = [ 806 'bpf_get_socket_cookie', 807 'bpf_sk_assign', 808 ] 809 810 def print_header(self): 811 header = '''\ 812/* This is auto-generated file. See bpf_doc.py for details. */ 813 814/* Forward declarations of BPF structs */''' 815 816 print(header) 817 for fwd in self.type_fwds: 818 print('%s;' % fwd) 819 print('') 820 821 used_attrs = set() 822 for helper in self.elements: 823 for attr in helper.attrs: 824 used_attrs.add(attr) 825 for attr in sorted(used_attrs): 826 print('#ifndef %s' % attr) 827 print('#if __has_attribute(%s)' % ATTRS[attr]) 828 print('#define %s __attribute__((%s))' % (attr, ATTRS[attr])) 829 print('#else') 830 print('#define %s' % attr) 831 print('#endif') 832 print('#endif') 833 if used_attrs: 834 print('') 835 836 def print_footer(self): 837 footer = '' 838 print(footer) 839 840 def map_type(self, t): 841 if t in self.known_types: 842 return t 843 if t in self.mapped_types: 844 return self.mapped_types[t] 845 print("Unrecognized type '%s', please add it to known types!" % t, 846 file=sys.stderr) 847 sys.exit(1) 848 849 seen_helpers = set() 850 851 def print_one(self, helper): 852 proto = helper.proto_break_down() 853 854 if proto['name'] in self.seen_helpers: 855 return 856 self.seen_helpers.add(proto['name']) 857 858 print('/*') 859 print(" * %s" % proto['name']) 860 print(" *") 861 if (helper.desc): 862 # Do not strip all newline characters: formatted code at the end of 863 # a section must be followed by a blank line. 864 for line in re.sub('\n$', '', helper.desc, count=1).split('\n'): 865 print(' *{}{}'.format(' \t' if line else '', line)) 866 867 if (helper.ret): 868 print(' *') 869 print(' * Returns') 870 for line in helper.ret.rstrip().split('\n'): 871 print(' *{}{}'.format(' \t' if line else '', line)) 872 873 print(' */') 874 print('static ', end='') 875 if helper.attrs: 876 print('%s ' % (" ".join(helper.attrs)), end='') 877 print('%s %s(* const %s)(' % (self.map_type(proto['ret_type']), 878 proto['ret_star'], proto['name']), end='') 879 comma = '' 880 for i, a in enumerate(proto['args']): 881 t = a['type'] 882 n = a['name'] 883 if proto['name'] in self.overloaded_helpers and i == 0: 884 t = 'void' 885 n = 'ctx' 886 one_arg = '{}{}'.format(comma, self.map_type(t)) 887 if n: 888 if a['star']: 889 one_arg += ' {}'.format(a['star']) 890 else: 891 one_arg += ' ' 892 one_arg += '{}'.format(n) 893 comma = ', ' 894 print(one_arg, end='') 895 896 print(') = (void *) %d;' % helper.enum_val) 897 print('') 898 899############################################################################### 900 901# If script is launched from scripts/ from kernel tree and can access 902# ../include/uapi/linux/bpf.h, use it as a default name for the file to parse, 903# otherwise the --filename argument will be required from the command line. 904script = os.path.abspath(sys.argv[0]) 905linuxRoot = os.path.dirname(os.path.dirname(script)) 906bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h') 907 908printers = { 909 'helpers': PrinterHelpersRST, 910 'syscall': PrinterSyscallRST, 911} 912 913argParser = argparse.ArgumentParser(description=""" 914Parse eBPF header file and generate documentation for the eBPF API. 915The RST-formatted output produced can be turned into a manual page with the 916rst2man utility. 917""") 918argParser.add_argument('--header', action='store_true', 919 help='generate C header file') 920if (os.path.isfile(bpfh)): 921 argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h', 922 default=bpfh) 923else: 924 argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h') 925argParser.add_argument('target', nargs='?', default='helpers', 926 choices=printers.keys(), help='eBPF API target') 927args = argParser.parse_args() 928 929# Parse file. 930headerParser = HeaderParser(args.filename) 931headerParser.run() 932 933# Print formatted output to standard output. 934if args.header: 935 if args.target != 'helpers': 936 raise NotImplementedError('Only helpers header generation is supported') 937 printer = PrinterHelpers(headerParser) 938else: 939 printer = printers[args.target](headerParser) 940printer.print_all() 941