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