1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 #define _GNU_SOURCE 4 5 #include <stdio.h> 6 #include <sys/time.h> 7 #include <time.h> 8 #include <stdlib.h> 9 #include <sys/syscall.h> 10 #include <unistd.h> 11 #include <dlfcn.h> 12 #include <string.h> 13 #include <inttypes.h> 14 #include <signal.h> 15 #include <sys/ucontext.h> 16 #include <errno.h> 17 #include <err.h> 18 #include <sched.h> 19 #include <stdbool.h> 20 #include <setjmp.h> 21 22 #ifdef __x86_64__ 23 # define VSYS(x) (x) 24 #else 25 # define VSYS(x) 0 26 #endif 27 28 #ifndef SYS_getcpu 29 # ifdef __x86_64__ 30 # define SYS_getcpu 309 31 # else 32 # define SYS_getcpu 318 33 # endif 34 #endif 35 36 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), 37 int flags) 38 { 39 struct sigaction sa; 40 memset(&sa, 0, sizeof(sa)); 41 sa.sa_sigaction = handler; 42 sa.sa_flags = SA_SIGINFO | flags; 43 sigemptyset(&sa.sa_mask); 44 if (sigaction(sig, &sa, 0)) 45 err(1, "sigaction"); 46 } 47 48 /* vsyscalls and vDSO */ 49 bool should_read_vsyscall = false; 50 51 typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); 52 gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000); 53 gtod_t vdso_gtod; 54 55 typedef int (*vgettime_t)(clockid_t, struct timespec *); 56 vgettime_t vdso_gettime; 57 58 typedef long (*time_func_t)(time_t *t); 59 time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400); 60 time_func_t vdso_time; 61 62 typedef long (*getcpu_t)(unsigned *, unsigned *, void *); 63 getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800); 64 getcpu_t vdso_getcpu; 65 66 static void init_vdso(void) 67 { 68 void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); 69 if (!vdso) 70 vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); 71 if (!vdso) { 72 printf("[WARN]\tfailed to find vDSO\n"); 73 return; 74 } 75 76 vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday"); 77 if (!vdso_gtod) 78 printf("[WARN]\tfailed to find gettimeofday in vDSO\n"); 79 80 vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime"); 81 if (!vdso_gettime) 82 printf("[WARN]\tfailed to find clock_gettime in vDSO\n"); 83 84 vdso_time = (time_func_t)dlsym(vdso, "__vdso_time"); 85 if (!vdso_time) 86 printf("[WARN]\tfailed to find time in vDSO\n"); 87 88 vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu"); 89 if (!vdso_getcpu) { 90 /* getcpu() was never wired up in the 32-bit vDSO. */ 91 printf("[%s]\tfailed to find getcpu in vDSO\n", 92 sizeof(long) == 8 ? "WARN" : "NOTE"); 93 } 94 } 95 96 static int init_vsys(void) 97 { 98 #ifdef __x86_64__ 99 int nerrs = 0; 100 FILE *maps; 101 char line[128]; 102 bool found = false; 103 104 maps = fopen("/proc/self/maps", "r"); 105 if (!maps) { 106 printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n"); 107 should_read_vsyscall = true; 108 return 0; 109 } 110 111 while (fgets(line, sizeof(line), maps)) { 112 char r, x; 113 void *start, *end; 114 char name[128]; 115 if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s", 116 &start, &end, &r, &x, name) != 5) 117 continue; 118 119 if (strcmp(name, "[vsyscall]")) 120 continue; 121 122 printf("\tvsyscall map: %s", line); 123 124 if (start != (void *)0xffffffffff600000 || 125 end != (void *)0xffffffffff601000) { 126 printf("[FAIL]\taddress range is nonsense\n"); 127 nerrs++; 128 } 129 130 printf("\tvsyscall permissions are %c-%c\n", r, x); 131 should_read_vsyscall = (r == 'r'); 132 if (x != 'x') { 133 vgtod = NULL; 134 vtime = NULL; 135 vgetcpu = NULL; 136 } 137 138 found = true; 139 break; 140 } 141 142 fclose(maps); 143 144 if (!found) { 145 printf("\tno vsyscall map in /proc/self/maps\n"); 146 should_read_vsyscall = false; 147 vgtod = NULL; 148 vtime = NULL; 149 vgetcpu = NULL; 150 } 151 152 return nerrs; 153 #else 154 return 0; 155 #endif 156 } 157 158 /* syscalls */ 159 static inline long sys_gtod(struct timeval *tv, struct timezone *tz) 160 { 161 return syscall(SYS_gettimeofday, tv, tz); 162 } 163 164 static inline int sys_clock_gettime(clockid_t id, struct timespec *ts) 165 { 166 return syscall(SYS_clock_gettime, id, ts); 167 } 168 169 static inline long sys_time(time_t *t) 170 { 171 return syscall(SYS_time, t); 172 } 173 174 static inline long sys_getcpu(unsigned * cpu, unsigned * node, 175 void* cache) 176 { 177 return syscall(SYS_getcpu, cpu, node, cache); 178 } 179 180 static jmp_buf jmpbuf; 181 182 static void sigsegv(int sig, siginfo_t *info, void *ctx_void) 183 { 184 siglongjmp(jmpbuf, 1); 185 } 186 187 static double tv_diff(const struct timeval *a, const struct timeval *b) 188 { 189 return (double)(a->tv_sec - b->tv_sec) + 190 (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6; 191 } 192 193 static int check_gtod(const struct timeval *tv_sys1, 194 const struct timeval *tv_sys2, 195 const struct timezone *tz_sys, 196 const char *which, 197 const struct timeval *tv_other, 198 const struct timezone *tz_other) 199 { 200 int nerrs = 0; 201 double d1, d2; 202 203 if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) { 204 printf("[FAIL] %s tz mismatch\n", which); 205 nerrs++; 206 } 207 208 d1 = tv_diff(tv_other, tv_sys1); 209 d2 = tv_diff(tv_sys2, tv_other); 210 printf("\t%s time offsets: %lf %lf\n", which, d1, d2); 211 212 if (d1 < 0 || d2 < 0) { 213 printf("[FAIL]\t%s time was inconsistent with the syscall\n", which); 214 nerrs++; 215 } else { 216 printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which); 217 } 218 219 return nerrs; 220 } 221 222 static int test_gtod(void) 223 { 224 struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys; 225 struct timezone tz_sys, tz_vdso, tz_vsys; 226 long ret_vdso = -1; 227 long ret_vsys = -1; 228 int nerrs = 0; 229 230 printf("[RUN]\ttest gettimeofday()\n"); 231 232 if (sys_gtod(&tv_sys1, &tz_sys) != 0) 233 err(1, "syscall gettimeofday"); 234 if (vdso_gtod) 235 ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso); 236 if (vgtod) 237 ret_vsys = vgtod(&tv_vsys, &tz_vsys); 238 if (sys_gtod(&tv_sys2, &tz_sys) != 0) 239 err(1, "syscall gettimeofday"); 240 241 if (vdso_gtod) { 242 if (ret_vdso == 0) { 243 nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso); 244 } else { 245 printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso); 246 nerrs++; 247 } 248 } 249 250 if (vgtod) { 251 if (ret_vsys == 0) { 252 nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys); 253 } else { 254 printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys); 255 nerrs++; 256 } 257 } 258 259 return nerrs; 260 } 261 262 static int test_time(void) { 263 int nerrs = 0; 264 265 printf("[RUN]\ttest time()\n"); 266 long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0; 267 long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1; 268 t_sys1 = sys_time(&t2_sys1); 269 if (vdso_time) 270 t_vdso = vdso_time(&t2_vdso); 271 if (vtime) 272 t_vsys = vtime(&t2_vsys); 273 t_sys2 = sys_time(&t2_sys2); 274 if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) { 275 printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2); 276 nerrs++; 277 return nerrs; 278 } 279 280 if (vdso_time) { 281 if (t_vdso < 0 || t_vdso != t2_vdso) { 282 printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso); 283 nerrs++; 284 } else if (t_vdso < t_sys1 || t_vdso > t_sys2) { 285 printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2); 286 nerrs++; 287 } else { 288 printf("[OK]\tvDSO time() is okay\n"); 289 } 290 } 291 292 if (vtime) { 293 if (t_vsys < 0 || t_vsys != t2_vsys) { 294 printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys); 295 nerrs++; 296 } else if (t_vsys < t_sys1 || t_vsys > t_sys2) { 297 printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2); 298 nerrs++; 299 } else { 300 printf("[OK]\tvsyscall time() is okay\n"); 301 } 302 } 303 304 return nerrs; 305 } 306 307 static int test_getcpu(int cpu) 308 { 309 int nerrs = 0; 310 long ret_sys, ret_vdso = -1, ret_vsys = -1; 311 312 printf("[RUN]\tgetcpu() on CPU %d\n", cpu); 313 314 cpu_set_t cpuset; 315 CPU_ZERO(&cpuset); 316 CPU_SET(cpu, &cpuset); 317 if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) { 318 printf("[SKIP]\tfailed to force CPU %d\n", cpu); 319 return nerrs; 320 } 321 322 unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys; 323 unsigned node = 0; 324 bool have_node = false; 325 ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0); 326 if (vdso_getcpu) 327 ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0); 328 if (vgetcpu) 329 ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0); 330 331 if (ret_sys == 0) { 332 if (cpu_sys != cpu) { 333 printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu); 334 nerrs++; 335 } 336 337 have_node = true; 338 node = node_sys; 339 } 340 341 if (vdso_getcpu) { 342 if (ret_vdso) { 343 printf("[FAIL]\tvDSO getcpu() failed\n"); 344 nerrs++; 345 } else { 346 if (!have_node) { 347 have_node = true; 348 node = node_vdso; 349 } 350 351 if (cpu_vdso != cpu) { 352 printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu); 353 nerrs++; 354 } else { 355 printf("[OK]\tvDSO reported correct CPU\n"); 356 } 357 358 if (node_vdso != node) { 359 printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node); 360 nerrs++; 361 } else { 362 printf("[OK]\tvDSO reported correct node\n"); 363 } 364 } 365 } 366 367 if (vgetcpu) { 368 if (ret_vsys) { 369 printf("[FAIL]\tvsyscall getcpu() failed\n"); 370 nerrs++; 371 } else { 372 if (!have_node) { 373 have_node = true; 374 node = node_vsys; 375 } 376 377 if (cpu_vsys != cpu) { 378 printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu); 379 nerrs++; 380 } else { 381 printf("[OK]\tvsyscall reported correct CPU\n"); 382 } 383 384 if (node_vsys != node) { 385 printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node); 386 nerrs++; 387 } else { 388 printf("[OK]\tvsyscall reported correct node\n"); 389 } 390 } 391 } 392 393 return nerrs; 394 } 395 396 static int test_vsys_r(void) 397 { 398 #ifdef __x86_64__ 399 printf("[RUN]\tChecking read access to the vsyscall page\n"); 400 bool can_read; 401 if (sigsetjmp(jmpbuf, 1) == 0) { 402 *(volatile int *)0xffffffffff600000; 403 can_read = true; 404 } else { 405 can_read = false; 406 } 407 408 if (can_read && !should_read_vsyscall) { 409 printf("[FAIL]\tWe have read access, but we shouldn't\n"); 410 return 1; 411 } else if (!can_read && should_read_vsyscall) { 412 printf("[FAIL]\tWe don't have read access, but we should\n"); 413 return 1; 414 } else { 415 printf("[OK]\tgot expected result\n"); 416 } 417 #endif 418 419 return 0; 420 } 421 422 423 #ifdef __x86_64__ 424 #define X86_EFLAGS_TF (1UL << 8) 425 static volatile sig_atomic_t num_vsyscall_traps; 426 427 static unsigned long get_eflags(void) 428 { 429 unsigned long eflags; 430 asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags)); 431 return eflags; 432 } 433 434 static void set_eflags(unsigned long eflags) 435 { 436 asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags"); 437 } 438 439 static void sigtrap(int sig, siginfo_t *info, void *ctx_void) 440 { 441 ucontext_t *ctx = (ucontext_t *)ctx_void; 442 unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP]; 443 444 if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0) 445 num_vsyscall_traps++; 446 } 447 448 static int test_native_vsyscall(void) 449 { 450 time_t tmp; 451 bool is_native; 452 453 if (!vtime) 454 return 0; 455 456 printf("[RUN]\tchecking for native vsyscall\n"); 457 sethandler(SIGTRAP, sigtrap, 0); 458 set_eflags(get_eflags() | X86_EFLAGS_TF); 459 vtime(&tmp); 460 set_eflags(get_eflags() & ~X86_EFLAGS_TF); 461 462 /* 463 * If vsyscalls are emulated, we expect a single trap in the 464 * vsyscall page -- the call instruction will trap with RIP 465 * pointing to the entry point before emulation takes over. 466 * In native mode, we expect two traps, since whatever code 467 * the vsyscall page contains will be more than just a ret 468 * instruction. 469 */ 470 is_native = (num_vsyscall_traps > 1); 471 472 printf("\tvsyscalls are %s (%d instructions in vsyscall page)\n", 473 (is_native ? "native" : "emulated"), 474 (int)num_vsyscall_traps); 475 476 return 0; 477 } 478 #endif 479 480 int main(int argc, char **argv) 481 { 482 int nerrs = 0; 483 484 init_vdso(); 485 nerrs += init_vsys(); 486 487 nerrs += test_gtod(); 488 nerrs += test_time(); 489 nerrs += test_getcpu(0); 490 nerrs += test_getcpu(1); 491 492 sethandler(SIGSEGV, sigsegv, 0); 493 nerrs += test_vsys_r(); 494 495 #ifdef __x86_64__ 496 nerrs += test_native_vsyscall(); 497 #endif 498 499 return nerrs ? 1 : 0; 500 } 501