1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594
|
// bpf internal classes
// Copyright (C) 2016-2022 Red Hat Inc.
//
// This file is part of systemtap, and is free software. You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.
#ifndef BPF_INTERNAL_H
#define BPF_INTERNAL_H
#include <iostream>
#include <vector>
#include <queue>
#include <cassert>
#include <unordered_set>
#include <unordered_map>
#include "bpf-bitset.h"
#include "staptree.h"
extern "C" {
#include <linux/bpf.h>
}
/* PR23829: These eBPF opcodes were added in recent kernels, and the
following 'ad hoc' defines are only used by the embedded-code
assembler. The code generator will convert these opcodes to
equivalent operations valid for earlier eBPF. */
#ifndef BPF_JLT
#define BPF_JLT 0xa0 /* LT is unsigned, '<' */
#define BPF_JLE 0xb0 /* LE is unsigned, '<=' */
#define BPF_JSLT 0xc0 /* SLT is signed, '<' */
#define BPF_JSLE 0xd0 /* SLE is signed, '<=' */
#endif
struct systemtap_session;
struct derived_probe;
struct vardecl;
namespace bpf {
// PR24528: Used to distinguish between different implementations of
// the BPF virtual machine. Different implementations have different
// capabilities, e.g. target_user_bpfinterp supports arbitrary loops
// whereas target_kernel_bpf restricts loops.
enum bpf_target {
target_kernel_bpf, // in-kernel JIT interpreter, restricted
target_user_bpfinterp, // userspace interpreter, relaxed
};
// TODO: target_kernel_bpf may later be split into two targets,
// one for older kernel versions (most restricted)
// and one for newer kernel versions (with loop support & other features)
// Constants for BPF code generation.
// TODO: BPF_MAX{STRING,FORMAT}LEN,BPF_MAXMAPENTRIES,BPF_MAXSPRINTFLEN should be user-configurable.
#define MAX_BPF_KERNEL_STACK 512
// PR24758: 64k ought to be enough for anyone
#define MAX_BPF_USER_STACK 65536
#define MAX_BPF_STACK(target) (((target) == target_kernel_bpf) ? \
MAX_BPF_KERNEL_STACK : MAX_BPF_USER_STACK)
#define BPF_REG_SIZE 8
#define BPF_MAXSTRINGLEN 64
#define BPF_MAXSTRINGLEN_PLUS 65
// #define BPF_MAXSTRINGLEN 128 // TODO: Longer strings require a smarter storage allocator.
// #define BPF_MAXSTRINGLEN_PLUS 129
// For foreach sorting, composite map keys cannot exceed kernel stack size:
#define BPF_MAXKEYLEN 512
#define BPF_MAXKEYLEN_PLUS 513
#define BPF_MAXFORMATLEN 256
#define BPF_MAXPRINTFARGS 32
// #define BPF_MAXPRINTFARGS 3 // Maximum for trace_printk() method.
#define BPF_MAXSPRINTFARGS 3 // Maximum for sprintf() method.
#define BPF_MAXMAPENTRIES 2048
// XXX: BPF_MAXMAPENTRIES may depend on kernel version. May need to experiment with rlimit in instantiate_maps().
// Constants for transport message layout.
// TODO: Try to reduce the size (to __u32) while keeping proper alignment.
#define BPF_TRANSPORT_VAL uint64_t
#define BPF_TRANSPORT_ARG uint64_t
// XXX: BPF_TRANSPORT_ARG is for small numerical arguments, not pe_long values.
// DEPRECATED constants for foreach sorting.
// Kept in the unlikely case we want to use new stapbpf to load old .bo's.
// Use globals::foreach_info instead for generating new .bo's.
//
// XXX Helpers take at most 5 arguments from BPF code. Hence we
// combine a couple arguments into one sort_flags for the
// map_get_next_key pseudo-helper:
#define SORT_FLAGS(sort_column, sort_direction) \
(((sort_column) << 4) | ((sort_direction) + 1))
#define GET_SORT_COLUMN(sort_flags) \
(((sort_flags) & ~0xf) >> 4)
#define GET_SORT_DIRECTION(sort_flags) \
((int64_t)((sort_flags) & 0xf) - 1)
// int sort_direction; // -1: decreasing, 0: none, 1: increasing
// unsigned sort_column; // 0: value, 1..N: index
// Will print out bpf assembly before and after optimization:
//#define DEBUG_CODEGEN
// TODO: DEBUG_CODEGEN should be configured dynamically e.g. as -DDEBUG_BPF_CODEGEN
typedef unsigned short regno;
static const regno max_regno = BPF_MAXINSNS;
static const regno noreg = -1;
typedef unsigned short opcode;
struct insn;
// BPF itself does not provide a full set of comparison codes.
// To make things easy for ourselves, emulate them.
enum condition
{
EQ, NE, LT, LE, GT, GE, LTU, LEU, GTU, GEU, TEST
};
struct value
{
enum value_type { UNINIT,
IMM,
STR, /* <- lowered to HARDREG by the optimizer */
HARDREG,
TMPREG, /* <- lowered to HARDREG by the optimizer */ };
value_type type : 16;
regno reg_val : 16;
int64_t imm_val;
std::string str_val;
bool format_str; // marks format string
exp_type format_type; // marks format arguments
value(value_type t = UNINIT, regno r = noreg, int64_t c = 0,
std::string s = "", bool format_str = false)
: type(t), reg_val(r), imm_val(c), str_val(s),
format_str(format_str), format_type(pe_unknown)
{ }
static value mk_imm(int64_t i) { return value(IMM, noreg, i); }
static value mk_str(std::string s, bool format_str = false) {
return value(STR, noreg, 0, s, format_str);
}
static value mk_reg(regno r) { return value(TMPREG, r); }
static value mk_hardreg(regno r) { return value(HARDREG, r); }
bool is_reg() const { return type >= HARDREG; }
bool is_imm() const { return type == IMM; }
bool is_str() const { return type == STR; }
bool is_format() const { assert(is_str()); return format_str; }
regno reg() const { assert(is_reg()); return reg_val; }
int64_t imm() const { assert(is_imm()); return imm_val; }
std::string str() const { assert(is_str()); return str_val; }
std::ostream& print(std::ostream &) const;
};
inline std::ostream&
operator<< (std::ostream &o, const value &v)
{
return v.print (o);
}
inline bool is_call(opcode c) { return c == (BPF_JMP | BPF_CALL); }
bool is_jmp(opcode c);
bool is_move(opcode c);
bool is_ldst(opcode c);
bool is_binary(opcode c);
bool is_commutative(opcode c);
/* PR29307: BPF opcode categories for the embedded-code assembler: */
#define BPF_UNKNOWN_ARI 0
#define BPF_MEMORY_ARI4 1
#define BPF_BRANCH_ARI4 2
#define BPF_MEMORY_ARI34_SRCOFF 3
// -> can take [src+off]
#define BPF_MEMORY_ARI34_DSTOFF_IMM 4
// -> can take [dst+off]+imm
#define BPF_MEMORY_ARI34_DSTOFF 5
// -> can take [dst+off]+src
#define BPF_ALU_ARI3 6
// -> takes dst+src/imm
#define BPF_MEMORY_ARI3 7
// -> takes dst+imm
#define BPF_ALU_ARI2 8
// -> takes dst
#define BPF_BRANCH_ARI2 9
// -> takes jmp_target
#define BPF_CALL_ARI2 10
// -> takes imm
#define BPF_EXIT_ARI1 11
/* PR29307: BPF opcode lookup for the embedded-code assembler: */
void init_bpf_opcode_tables();
const char *bpf_opcode_name (opcode code);
opcode bpf_opcode_id (const std::string &name);
opcode bpf_opcode_variant_imm(opcode code);
unsigned bpf_opcode_category (opcode code);
const char *bpf_expected_args (unsigned cat);
/* BPF helper lookup for the translator: */
void init_bpf_helper_tables();
const char *bpf_function_name (unsigned id);
bpf_func_id bpf_function_id (const std::string &name);
unsigned bpf_function_nargs (unsigned id);
const opcode BPF_LD_MAP = BPF_LD | BPF_IMM | BPF_DW | (BPF_PSEUDO_MAP_FD << 8);
// Not actual BPF helpers, but treating them as such simplifies some of the
// interpreter logic. We give them IDs that shouldn't conflict with IDs of
// real BPF helpers.
#define __STAPBPF_FUNC_MAPPER(FN) \
FN(map_get_next_key), \
FN(sprintf), \
FN(stapbpf_stat_get), \
FN(gettimeofday_ns), \
FN(set_procfs_value), \
FN(append_procfs_value), \
FN(get_procfs_value), \
FN(str_concat), \
FN(text_str), \
FN(string_quoted),
const bpf_func_id BPF_FUNC_map_get_next_key = (bpf_func_id) -1;
const bpf_func_id BPF_FUNC_sprintf = (bpf_func_id) -2;
const bpf_func_id BPF_FUNC_stapbpf_stat_get = (bpf_func_id) -3;
const bpf_func_id BPF_FUNC_gettimeofday_ns = (bpf_func_id) -4;
const bpf_func_id BPF_FUNC_get_target = (bpf_func_id) -5;
const bpf_func_id BPF_FUNC_set_procfs_value = (bpf_func_id) -6;
const bpf_func_id BPF_FUNC_append_procfs_value = (bpf_func_id) -7;
const bpf_func_id BPF_FUNC_get_procfs_value = (bpf_func_id) -8;
const bpf_func_id BPF_FUNC_str_concat = (bpf_func_id) -9;
const bpf_func_id BPF_FUNC_text_str = (bpf_func_id) -10;
const bpf_func_id BPF_FUNC_string_quoted = (bpf_func_id) -11;
struct insn
{
opcode code : 16; // The usual bpf opcode
unsigned id : 16; // Context-dependent unique identifier
signed off : 16; // The memory offset operand
value *dest; // The usual destination operand
value *src0; // The destination input, pre-allocation
value *src1; // The usual source register operand
insn *prev, *next; // Linked list of insns in the block
#ifdef DEBUG_CODEGEN
std::string note; // For additional diagnostics.
#endif
insn();
bool is_jmp() const { return bpf::is_jmp(code); }
bool is_call() const { return bpf::is_call(code); }
bool is_move() const { return bpf::is_move(code); }
bool is_ldst() const { return bpf::is_ldst(code); }
bool is_binary() const { return bpf::is_binary(code); }
bool is_commutative() const { return bpf::is_commutative(code); }
void mark_sets(bitset::set1_ref &s, bool v) const;
void mark_uses(bitset::set1_ref &s, bool v) const;
std::ostream& print(std::ostream &o) const;
};
inline std::ostream&
operator<< (std::ostream &o, const insn &i)
{
return i.print (o);
}
struct block;
struct edge
{
block *prev, *next;
edge(block *p, block *n);
~edge();
void redirect_next(block *n);
};
struct block
{
typedef std::unordered_set<edge *> edge_set;
edge_set prevs; // All incoming edges
insn *first, *last; // Linked list of insns in the block
edge *taken; // Taken (conditional or not) edge
edge *fallthru; // Not taken conditional edge
unsigned short id; // Index in cfg
block(int);
~block();
block *is_forwarder() const;
void print(std::ostream &o) const;
};
inline std::ostream&
operator<< (std::ostream &o, const block &b)
{
b.print (o);
return o;
}
class insn_inserter
{
private:
insn_inserter(); // not present
public:
block *b;
insn *i;
#ifdef DEBUG_CODEGEN
std::stack<std::string> notes;
#endif
insn_inserter(block *bb, insn *ii) : b(bb), i(ii) { }
insn_inserter(block *bb, insn *ii, const std::string& note) : b(bb), i(ii) {
#ifdef DEBUG_CODEGEN
notes.push(note);
#else
(void)note; // unused
#endif
}
virtual ~insn_inserter() { }
virtual void insert(insn *i) = 0;
insn *new_insn();
block *get_block() const { return b; }
insn_inserter& operator++ () { if (i) i = i->next; return *this; }
insn_inserter& operator-- () { if (i) i = i->prev; return *this; }
operator bool () const { return i != NULL; }
};
struct insn_before_inserter : public insn_inserter
{
insn_before_inserter() : insn_inserter(NULL, NULL) { }
insn_before_inserter(block *b, insn *i) : insn_inserter(b,i) { }
insn_before_inserter(block *b, insn *i, const std::string& note)
: insn_inserter(b,i,note) { }
virtual void insert(insn *i);
};
struct insn_after_inserter : public insn_inserter
{
insn_after_inserter() : insn_inserter(NULL, NULL) { }
insn_after_inserter(block *b, insn *i) : insn_inserter(b,i) { }
insn_after_inserter(block *b, insn *i, const std::string& note)
: insn_inserter(b,i,note) { }
virtual void insert(insn *i);
};
struct insn_append_inserter : public insn_after_inserter
{
insn_append_inserter() : insn_after_inserter(NULL, NULL) { }
insn_append_inserter(block *b) : insn_after_inserter(b, NULL) { }
insn_append_inserter(block *b, const std::string& note)
: insn_after_inserter(b, NULL, note) { }
};
struct program
{
enum bpf_target target;
std::vector<block *> blocks; // All blocks in the program
block *new_block();
std::vector<value> hardreg_vals;
std::vector<value *> reg_vals;
// Store at most one of each IMM and STR value:
std::unordered_map<int64_t, value *> imm_map;
std::unordered_map<std::string, value *> str_map;
std::unordered_map<std::string, value *> format_map;
regno max_reg() const { return reg_vals.size() + MAX_BPF_REG; }
value *lookup_reg(regno r);
value *new_reg();
value *new_imm(int64_t);
value *new_str(std::string, bool format_str = false);
// The BPF local stack is [0, -512] indexed off BPF_REG_10.
// The translator has dibs on the low bytes, [0, -max_tmp_space],
// for use with various function calls that pass data by reference.
// The register allocator may use [-max_tmp_space, -512] for spills.
unsigned max_tmp_space;
void use_tmp_space(unsigned bytes)
{
if (max_tmp_space < bytes)
max_tmp_space = bytes;
assert(max_tmp_space <= MAX_BPF_STACK(target));
}
// After register allocation, record the lowest offset actually
// used for spills. Then [-max_reg_space, -512] will be
// the unused portion of the stack.
unsigned max_reg_space;
void mk_ld(insn_inserter &ins, int sz, value *dest, value *base, int off);
void mk_st(insn_inserter &ins, int sz, value *base, int off, value *src);
void mk_unary(insn_inserter &ins, opcode op, value *dest, value *src);
void mk_binary(insn_inserter &ins, opcode op, value *d,
value *s0, value *s1);
void mk_mov(insn_inserter &ins, value *dest, value *src);
void mk_call(insn_inserter &ins, enum bpf_func_id id, unsigned nargs);
void mk_exit(insn_inserter &ins);
void mk_jmp(insn_inserter &ins, block *dest);
void mk_jcond(insn_inserter &ins, condition c, value *s0, value *s1,
block *t, block *f);
void load_map(insn_inserter &ins, value *dest, int src);
program(enum bpf_target target);
~program();
void generate();
void print(std::ostream &) const;
};
// ??? Properly belongs to bpf_unparser but must be visible from bpf-opt.cxx:
value *emit_simple_literal_str(program &this_prog, insn_inserter &this_ins,
value *dest, int ofs, const std::string &src,
bool zero_pad = false);
inline std::ostream&
operator<< (std::ostream &o, const program &c)
{
c.print (o);
return o;
}
struct globals
{
// The list of BPF maps used to store global data:
struct bpf_map_def
{
unsigned type;
unsigned key_size;
unsigned value_size;
unsigned max_entries;
unsigned map_flags;
};
typedef std::vector<bpf_map_def> map_vect;
map_vect maps;
// Used to identify a numbered bpf_map (within map_vect):
using map_idx = int;
// How to locate a value within the maps, based on vardecl vd:
//
// (1) lookup globals_map[vd] --> yields map_slot ms
// (2) if ms.is_stat(), vd is an aggregate (scalar_stats, array_stats explained below)
// - (s).count --> (scalar_stats['count'])[ms.this_idx][cpuid] if ms.is_scalar()
// - (s[key]).count --> (array_stats[vd]['count'])[key][cpuid] otherwise
// (3) otherwise, vd is a regular value
// - v --> (ms.this_map)[ms.this_idx] if ms.is_scalar()
// - v[key] --> (ms.this_map)[key] otherwise
//
// Above, v is a regular value, s is a statistical aggregate.
// The indexing operations inside parens are performed at translation time,
// the indexing operations outside parens are performed at runtime.
//
// TODOXXX PR24424: For histogram data, the indexing scheme will be:
// - (s).histogram[n] --> (scalar_stats['histogram'])[ms.this_idx,n][cpuid]
// Here, map[idx,n] is map[idx << shift | n] (rudimentary multi-key map).
struct map_slot {
map_idx map_id; // -- -1 indicates is_stat()
int idx; // -- -1 indicates !is_scalar()
bool is_scalar() { return idx >= 0; }
bool is_stat() { return map_id < 0; }
map_slot(map_idx map_id, int idx) : map_id(map_id), idx(idx) {}
};
typedef std::unordered_map<vardecl *, map_slot> globals_map;
globals_map globals;
bool empty() { return this->globals.empty(); }
// PR23476: Each statistical aggregate is represented by a percpu data structure
// with fields such as count, sum, ... (see struct stat_data in runtime/stat.h).
using stat_field = std::string; // XXX: could make an enum
static std::vector<stat_field> stat_fields; // XXX: initialized in bpf-translate.cxx
static stat_field stat_iter_field; // XXX: used to obtain keys for foreach, in, &c
// scalar_stats, array_stats: For each stats field, create one map
// for scalar aggregates, plus one map per one-dimensional array of
// aggregates.
typedef std::map<stat_field, map_idx> stats_map;
stats_map scalar_stats;
std::unordered_map<vardecl *, stats_map> array_stats;
// XXX: Used to store stats_map elements in a canonical order for serialization:
typedef std::vector<map_idx> interned_stats_map;
static interned_stats_map intern_stats_map(const stats_map &sm);
static stats_map deintern_stats_map(const interned_stats_map &ism);
// XXX: Used to identify stat_component_types within BPF code:
static uint64_t intern_sc_type(stat_component_type sc_type) {
return (uint64_t)sc_type;
}
static stat_component_type deintern_sc_type(uint64_t x) {
return (stat_component_type)x;
}
// To pass stats_map information to the bpf userspace helper,
// assign each stats_map a numerical 'agg_idx'. Index 0 is reserved
// for scalar_stats, other stats_maps are given consecutive indices:
using agg_idx = int;
std::unordered_map<vardecl *, agg_idx> aggregates;
// The .bo ELF file will have a section (agg_idx -> interned_stats_map).
// PR23478: To pass foreach iteration settings, assign each foreach loop
// a numerical index into a table of these foreach_info structs.
// Pass the index into the map_get_next_key userspace-only helper.
struct foreach_info {
// XXX replicate fields from struct foreach_loop in staptree.h
int sort_direction; // -1: decreasing, 0: none, 1: increasing
unsigned sort_column; // 0: value, 1..N: index
// TODO PR24908: also encode s->sort_aggr
// used to locate the sort column in a composite map key
size_t keysize;
size_t sort_column_size; // 0: sort_column is value
int sort_column_ofs; // -1: key is scalar long or str
};
std::vector<foreach_info> foreach_loop_info;
/// XXX Used to store loop_info structs for serialization:
typedef std::vector<uint64_t> interned_foreach_info;
static const size_t n_foreach_info_fields = 5;
static interned_foreach_info intern_foreach_info(const foreach_info &fi);
static foreach_info deintern_foreach_info(const interned_foreach_info &ifi);
using loop_idx = int;
// XXX: Not actually used in any tables.
// The .bo ELF file will have a section (loop_idx -> interned_loop_info).
// Index into globals. This element represents the map of internal globals
// used for sharing data between stapbpf and kernel-side bpf programs.
static const map_idx internal_map_idx = 0;
// Indicates whether exit() has been called from within a bpf program.
struct vardecl internal_exit;
struct vardecl internal_errors;
// Indexes into the bpf map of internal globals.
enum internal_global_idx
{
EXIT = 0,
ERRORS, // Tracks the total number of errors.
NUM_INTERNALS, // non-ABI
};
// PR22330: Index into globals. This element represents the
// perf_event_map used to send messages from kernel-side bpf
// programs to stapbpf.
static const map_idx perf_event_map_idx = 1;
// XXX: The number of elements for the perf_event_map is not known
// at translation time and must be determined by the stapbpf loader:
static const int NUM_CPUS_PLACEHOLDER = 0;
// Types of transport messages supported:
enum perf_event_type
{
STP_EXIT = 0,
STP_ERROR,
STP_STORE_ERROR_MSG,
STP_PRINT_ERROR_MSG,
STP_PRINTF_START,
STP_PRINTF_END,
STP_PRINTF_FORMAT,
STP_PRINTF_ARG_LONG,
STP_PRINTF_ARG_STR,
// TODO PR23476: Yet more messages to request things such as histogram printing.
};
// Converts a string to an index usable in STP_PRINTF_FORMAT messages:
int intern_string(std::string& str);
// Interned strings by index:
std::vector<std::string> interned_strings;
// The set of already interned strings:
std::map<std::string, int> interned_str_map;
// XXX: Hacky, used to resolve function symbols in embedded code:
systemtap_session *session;
};
} // namespace bpf
#endif // BPF_INTERNAL_H
|