1
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
37#define MAPS_LINE_LEN 128
38
39static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
40 int flags)
41{
42 struct sigaction sa;
43 memset(&sa, 0, sizeof(sa));
44 sa.sa_sigaction = handler;
45 sa.sa_flags = SA_SIGINFO | flags;
46 sigemptyset(&sa.sa_mask);
47 if (sigaction(sig, &sa, 0))
48 err(1, "sigaction");
49}
50
51
52bool should_read_vsyscall = false;
53
54typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
55gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
56gtod_t vdso_gtod;
57
58typedef int (*vgettime_t)(clockid_t, struct timespec *);
59vgettime_t vdso_gettime;
60
61typedef long (*time_func_t)(time_t *t);
62time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
63time_func_t vdso_time;
64
65typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
66getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
67getcpu_t vdso_getcpu;
68
69static void init_vdso(void)
70{
71 void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
72 if (!vdso)
73 vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
74 if (!vdso) {
75 printf("[WARN]\tfailed to find vDSO\n");
76 return;
77 }
78
79 vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");
80 if (!vdso_gtod)
81 printf("[WARN]\tfailed to find gettimeofday in vDSO\n");
82
83 vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
84 if (!vdso_gettime)
85 printf("[WARN]\tfailed to find clock_gettime in vDSO\n");
86
87 vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");
88 if (!vdso_time)
89 printf("[WARN]\tfailed to find time in vDSO\n");
90
91 vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
92 if (!vdso_getcpu) {
93
94 printf("[%s]\tfailed to find getcpu in vDSO\n",
95 sizeof(long) == 8 ? "WARN" : "NOTE");
96 }
97}
98
99static int init_vsys(void)
100{
101#ifdef __x86_64__
102 int nerrs = 0;
103 FILE *maps;
104 char line[MAPS_LINE_LEN];
105 bool found = false;
106
107 maps = fopen("/proc/self/maps", "r");
108 if (!maps) {
109 printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n");
110 should_read_vsyscall = true;
111 return 0;
112 }
113
114 while (fgets(line, MAPS_LINE_LEN, maps)) {
115 char r, x;
116 void *start, *end;
117 char name[MAPS_LINE_LEN];
118
119
120 if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
121 &start, &end, &r, &x, name) != 5)
122 continue;
123
124 if (strcmp(name, "[vsyscall]"))
125 continue;
126
127 printf("\tvsyscall map: %s", line);
128
129 if (start != (void *)0xffffffffff600000 ||
130 end != (void *)0xffffffffff601000) {
131 printf("[FAIL]\taddress range is nonsense\n");
132 nerrs++;
133 }
134
135 printf("\tvsyscall permissions are %c-%c\n", r, x);
136 should_read_vsyscall = (r == 'r');
137 if (x != 'x') {
138 vgtod = NULL;
139 vtime = NULL;
140 vgetcpu = NULL;
141 }
142
143 found = true;
144 break;
145 }
146
147 fclose(maps);
148
149 if (!found) {
150 printf("\tno vsyscall map in /proc/self/maps\n");
151 should_read_vsyscall = false;
152 vgtod = NULL;
153 vtime = NULL;
154 vgetcpu = NULL;
155 }
156
157 return nerrs;
158#else
159 return 0;
160#endif
161}
162
163
164static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
165{
166 return syscall(SYS_gettimeofday, tv, tz);
167}
168
169static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
170{
171 return syscall(SYS_clock_gettime, id, ts);
172}
173
174static inline long sys_time(time_t *t)
175{
176 return syscall(SYS_time, t);
177}
178
179static inline long sys_getcpu(unsigned * cpu, unsigned * node,
180 void* cache)
181{
182 return syscall(SYS_getcpu, cpu, node, cache);
183}
184
185static jmp_buf jmpbuf;
186
187static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
188{
189 siglongjmp(jmpbuf, 1);
190}
191
192static double tv_diff(const struct timeval *a, const struct timeval *b)
193{
194 return (double)(a->tv_sec - b->tv_sec) +
195 (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6;
196}
197
198static int check_gtod(const struct timeval *tv_sys1,
199 const struct timeval *tv_sys2,
200 const struct timezone *tz_sys,
201 const char *which,
202 const struct timeval *tv_other,
203 const struct timezone *tz_other)
204{
205 int nerrs = 0;
206 double d1, d2;
207
208 if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) {
209 printf("[FAIL] %s tz mismatch\n", which);
210 nerrs++;
211 }
212
213 d1 = tv_diff(tv_other, tv_sys1);
214 d2 = tv_diff(tv_sys2, tv_other);
215 printf("\t%s time offsets: %lf %lf\n", which, d1, d2);
216
217 if (d1 < 0 || d2 < 0) {
218 printf("[FAIL]\t%s time was inconsistent with the syscall\n", which);
219 nerrs++;
220 } else {
221 printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which);
222 }
223
224 return nerrs;
225}
226
227static int test_gtod(void)
228{
229 struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys;
230 struct timezone tz_sys, tz_vdso, tz_vsys;
231 long ret_vdso = -1;
232 long ret_vsys = -1;
233 int nerrs = 0;
234
235 printf("[RUN]\ttest gettimeofday()\n");
236
237 if (sys_gtod(&tv_sys1, &tz_sys) != 0)
238 err(1, "syscall gettimeofday");
239 if (vdso_gtod)
240 ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
241 if (vgtod)
242 ret_vsys = vgtod(&tv_vsys, &tz_vsys);
243 if (sys_gtod(&tv_sys2, &tz_sys) != 0)
244 err(1, "syscall gettimeofday");
245
246 if (vdso_gtod) {
247 if (ret_vdso == 0) {
248 nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);
249 } else {
250 printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso);
251 nerrs++;
252 }
253 }
254
255 if (vgtod) {
256 if (ret_vsys == 0) {
257 nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
258 } else {
259 printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys);
260 nerrs++;
261 }
262 }
263
264 return nerrs;
265}
266
267static int test_time(void) {
268 int nerrs = 0;
269
270 printf("[RUN]\ttest time()\n");
271 long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;
272 long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;
273 t_sys1 = sys_time(&t2_sys1);
274 if (vdso_time)
275 t_vdso = vdso_time(&t2_vdso);
276 if (vtime)
277 t_vsys = vtime(&t2_vsys);
278 t_sys2 = sys_time(&t2_sys2);
279 if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {
280 printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2);
281 nerrs++;
282 return nerrs;
283 }
284
285 if (vdso_time) {
286 if (t_vdso < 0 || t_vdso != t2_vdso) {
287 printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso);
288 nerrs++;
289 } else if (t_vdso < t_sys1 || t_vdso > t_sys2) {
290 printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2);
291 nerrs++;
292 } else {
293 printf("[OK]\tvDSO time() is okay\n");
294 }
295 }
296
297 if (vtime) {
298 if (t_vsys < 0 || t_vsys != t2_vsys) {
299 printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys);
300 nerrs++;
301 } else if (t_vsys < t_sys1 || t_vsys > t_sys2) {
302 printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2);
303 nerrs++;
304 } else {
305 printf("[OK]\tvsyscall time() is okay\n");
306 }
307 }
308
309 return nerrs;
310}
311
312static int test_getcpu(int cpu)
313{
314 int nerrs = 0;
315 long ret_sys, ret_vdso = -1, ret_vsys = -1;
316
317 printf("[RUN]\tgetcpu() on CPU %d\n", cpu);
318
319 cpu_set_t cpuset;
320 CPU_ZERO(&cpuset);
321 CPU_SET(cpu, &cpuset);
322 if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
323 printf("[SKIP]\tfailed to force CPU %d\n", cpu);
324 return nerrs;
325 }
326
327 unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;
328 unsigned node = 0;
329 bool have_node = false;
330 ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
331 if (vdso_getcpu)
332 ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
333 if (vgetcpu)
334 ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
335
336 if (ret_sys == 0) {
337 if (cpu_sys != cpu) {
338 printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu);
339 nerrs++;
340 }
341
342 have_node = true;
343 node = node_sys;
344 }
345
346 if (vdso_getcpu) {
347 if (ret_vdso) {
348 printf("[FAIL]\tvDSO getcpu() failed\n");
349 nerrs++;
350 } else {
351 if (!have_node) {
352 have_node = true;
353 node = node_vdso;
354 }
355
356 if (cpu_vdso != cpu) {
357 printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu);
358 nerrs++;
359 } else {
360 printf("[OK]\tvDSO reported correct CPU\n");
361 }
362
363 if (node_vdso != node) {
364 printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node);
365 nerrs++;
366 } else {
367 printf("[OK]\tvDSO reported correct node\n");
368 }
369 }
370 }
371
372 if (vgetcpu) {
373 if (ret_vsys) {
374 printf("[FAIL]\tvsyscall getcpu() failed\n");
375 nerrs++;
376 } else {
377 if (!have_node) {
378 have_node = true;
379 node = node_vsys;
380 }
381
382 if (cpu_vsys != cpu) {
383 printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu);
384 nerrs++;
385 } else {
386 printf("[OK]\tvsyscall reported correct CPU\n");
387 }
388
389 if (node_vsys != node) {
390 printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node);
391 nerrs++;
392 } else {
393 printf("[OK]\tvsyscall reported correct node\n");
394 }
395 }
396 }
397
398 return nerrs;
399}
400
401static int test_vsys_r(void)
402{
403#ifdef __x86_64__
404 printf("[RUN]\tChecking read access to the vsyscall page\n");
405 bool can_read;
406 if (sigsetjmp(jmpbuf, 1) == 0) {
407 *(volatile int *)0xffffffffff600000;
408 can_read = true;
409 } else {
410 can_read = false;
411 }
412
413 if (can_read && !should_read_vsyscall) {
414 printf("[FAIL]\tWe have read access, but we shouldn't\n");
415 return 1;
416 } else if (!can_read && should_read_vsyscall) {
417 printf("[FAIL]\tWe don't have read access, but we should\n");
418 return 1;
419 } else {
420 printf("[OK]\tgot expected result\n");
421 }
422#endif
423
424 return 0;
425}
426
427
428#ifdef __x86_64__
429#define X86_EFLAGS_TF (1UL << 8)
430static volatile sig_atomic_t num_vsyscall_traps;
431
432static unsigned long get_eflags(void)
433{
434 unsigned long eflags;
435 asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags));
436 return eflags;
437}
438
439static void set_eflags(unsigned long eflags)
440{
441 asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags");
442}
443
444static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
445{
446 ucontext_t *ctx = (ucontext_t *)ctx_void;
447 unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP];
448
449 if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0)
450 num_vsyscall_traps++;
451}
452
453static int test_emulation(void)
454{
455 time_t tmp;
456 bool is_native;
457
458 if (!vtime)
459 return 0;
460
461 printf("[RUN]\tchecking that vsyscalls are emulated\n");
462 sethandler(SIGTRAP, sigtrap, 0);
463 set_eflags(get_eflags() | X86_EFLAGS_TF);
464 vtime(&tmp);
465 set_eflags(get_eflags() & ~X86_EFLAGS_TF);
466
467
468
469
470
471
472
473
474
475 is_native = (num_vsyscall_traps > 1);
476
477 printf("[%s]\tvsyscalls are %s (%d instructions in vsyscall page)\n",
478 (is_native ? "FAIL" : "OK"),
479 (is_native ? "native" : "emulated"),
480 (int)num_vsyscall_traps);
481
482 return is_native;
483}
484#endif
485
486int main(int argc, char **argv)
487{
488 int nerrs = 0;
489
490 init_vdso();
491 nerrs += init_vsys();
492
493 nerrs += test_gtod();
494 nerrs += test_time();
495 nerrs += test_getcpu(0);
496 nerrs += test_getcpu(1);
497
498 sethandler(SIGSEGV, sigsegv, 0);
499 nerrs += test_vsys_r();
500
501#ifdef __x86_64__
502 nerrs += test_emulation();
503#endif
504
505 return nerrs ? 1 : 0;
506}
507
