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
sethandler(int sig,void (* handler)(int,siginfo_t *,void *),int flags)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
init_vdso(void)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
init_vsys(void)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 */
sys_gtod(struct timeval * tv,struct timezone * tz)159 static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
160 {
161 return syscall(SYS_gettimeofday, tv, tz);
162 }
163
sys_clock_gettime(clockid_t id,struct timespec * ts)164 static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
165 {
166 return syscall(SYS_clock_gettime, id, ts);
167 }
168
sys_time(time_t * t)169 static inline long sys_time(time_t *t)
170 {
171 return syscall(SYS_time, t);
172 }
173
sys_getcpu(unsigned * cpu,unsigned * node,void * cache)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
sigsegv(int sig,siginfo_t * info,void * ctx_void)182 static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
183 {
184 siglongjmp(jmpbuf, 1);
185 }
186
tv_diff(const struct timeval * a,const struct timeval * b)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
check_gtod(const struct timeval * tv_sys1,const struct timeval * tv_sys2,const struct timezone * tz_sys,const char * which,const struct timeval * tv_other,const struct timezone * tz_other)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
test_gtod(void)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
test_time(void)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
test_getcpu(int cpu)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
test_vsys_r(void)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
get_eflags(void)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
set_eflags(unsigned long eflags)434 static void set_eflags(unsigned long eflags)
435 {
436 asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags");
437 }
438
sigtrap(int sig,siginfo_t * info,void * ctx_void)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
test_native_vsyscall(void)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
main(int argc,char ** argv)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