546 lines · c
1/* SPDX-License-Identifier: GPL-2.0 */2 3#define _GNU_SOURCE4 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#include <sys/uio.h>22 23#include "helpers.h"24#include "../kselftest.h"25 26#ifdef __x86_64__27#define TOTAL_TESTS 1328#else29#define TOTAL_TESTS 830#endif31 32#ifdef __x86_64__33# define VSYS(x) (x)34#else35# define VSYS(x) 036#endif37 38#ifndef SYS_getcpu39# ifdef __x86_64__40# define SYS_getcpu 30941# else42# define SYS_getcpu 31843# endif44#endif45 46/* max length of lines in /proc/self/maps - anything longer is skipped here */47#define MAPS_LINE_LEN 12848 49/* vsyscalls and vDSO */50bool vsyscall_map_r = false, vsyscall_map_x = false;51 52typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);53const gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);54gtod_t vdso_gtod;55 56typedef int (*vgettime_t)(clockid_t, struct timespec *);57vgettime_t vdso_gettime;58 59typedef long (*time_func_t)(time_t *t);60const time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);61time_func_t vdso_time;62 63typedef long (*getcpu_t)(unsigned *, unsigned *, void *);64const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);65getcpu_t vdso_getcpu;66 67static void init_vdso(void)68{69 void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);70 if (!vdso)71 vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);72 if (!vdso) {73 ksft_print_msg("[WARN] failed to find vDSO\n");74 return;75 }76 77 vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");78 if (!vdso_gtod)79 ksft_print_msg("[WARN] failed to find gettimeofday in vDSO\n");80 81 vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");82 if (!vdso_gettime)83 ksft_print_msg("[WARN] failed to find clock_gettime in vDSO\n");84 85 vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");86 if (!vdso_time)87 ksft_print_msg("[WARN] failed to find time in vDSO\n");88 89 vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");90 if (!vdso_getcpu)91 ksft_print_msg("[WARN] failed to find getcpu in vDSO\n");92}93 94/* syscalls */95static inline long sys_gtod(struct timeval *tv, struct timezone *tz)96{97 return syscall(SYS_gettimeofday, tv, tz);98}99 100static inline long sys_time(time_t *t)101{102 return syscall(SYS_time, t);103}104 105static inline long sys_getcpu(unsigned * cpu, unsigned * node,106 void* cache)107{108 return syscall(SYS_getcpu, cpu, node, cache);109}110 111static double tv_diff(const struct timeval *a, const struct timeval *b)112{113 return (double)(a->tv_sec - b->tv_sec) +114 (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6;115}116 117static void check_gtod(const struct timeval *tv_sys1,118 const struct timeval *tv_sys2,119 const struct timezone *tz_sys,120 const char *which,121 const struct timeval *tv_other,122 const struct timezone *tz_other)123{124 double d1, d2;125 126 if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest ||127 tz_sys->tz_dsttime != tz_other->tz_dsttime))128 ksft_print_msg("%s tz mismatch\n", which);129 130 d1 = tv_diff(tv_other, tv_sys1);131 d2 = tv_diff(tv_sys2, tv_other); 132 133 ksft_print_msg("%s time offsets: %lf %lf\n", which, d1, d2);134 135 ksft_test_result(!(d1 < 0 || d2 < 0), "%s gettimeofday()'s timeval\n", which);136}137 138static void test_gtod(void)139{140 struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys;141 struct timezone tz_sys, tz_vdso, tz_vsys;142 long ret_vdso = -1;143 long ret_vsys = -1;144 145 ksft_print_msg("test gettimeofday()\n");146 147 if (sys_gtod(&tv_sys1, &tz_sys) != 0)148 ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno));149 if (vdso_gtod)150 ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);151 if (vsyscall_map_x)152 ret_vsys = vgtod(&tv_vsys, &tz_vsys);153 if (sys_gtod(&tv_sys2, &tz_sys) != 0)154 ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno));155 156 if (vdso_gtod) {157 if (ret_vdso == 0)158 check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);159 else160 ksft_test_result_fail("vDSO gettimeofday() failed: %ld\n", ret_vdso);161 } else {162 ksft_test_result_skip("vdso_gtod isn't set\n");163 }164 165 if (vsyscall_map_x) {166 if (ret_vsys == 0)167 check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);168 else169 ksft_test_result_fail("vsys gettimeofday() failed: %ld\n", ret_vsys);170 } else {171 ksft_test_result_skip("vsyscall_map_x isn't set\n");172 }173}174 175static void test_time(void)176{177 long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;178 long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;179 180 ksft_print_msg("test time()\n");181 t_sys1 = sys_time(&t2_sys1);182 if (vdso_time)183 t_vdso = vdso_time(&t2_vdso);184 if (vsyscall_map_x)185 t_vsys = vtime(&t2_vsys);186 t_sys2 = sys_time(&t2_sys2);187 if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {188 ksft_print_msg("syscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n",189 t_sys1, t2_sys1, t_sys2, t2_sys2);190 ksft_test_result_skip("vdso_time\n");191 ksft_test_result_skip("vdso_time\n");192 return;193 }194 195 if (vdso_time) {196 if (t_vdso < 0 || t_vdso != t2_vdso)197 ksft_test_result_fail("vDSO failed (ret:%ld output:%ld)\n",198 t_vdso, t2_vdso);199 else if (t_vdso < t_sys1 || t_vdso > t_sys2)200 ksft_test_result_fail("vDSO returned the wrong time (%ld %ld %ld)\n",201 t_sys1, t_vdso, t_sys2);202 else203 ksft_test_result_pass("vDSO time() is okay\n");204 } else {205 ksft_test_result_skip("vdso_time isn't set\n");206 }207 208 if (vsyscall_map_x) {209 if (t_vsys < 0 || t_vsys != t2_vsys)210 ksft_test_result_fail("vsyscall failed (ret:%ld output:%ld)\n",211 t_vsys, t2_vsys);212 else if (t_vsys < t_sys1 || t_vsys > t_sys2)213 ksft_test_result_fail("vsyscall returned the wrong time (%ld %ld %ld)\n",214 t_sys1, t_vsys, t_sys2);215 else216 ksft_test_result_pass("vsyscall time() is okay\n");217 } else {218 ksft_test_result_skip("vsyscall_map_x isn't set\n");219 }220}221 222static void test_getcpu(int cpu)223{224 unsigned int cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;225 long ret_sys, ret_vdso = -1, ret_vsys = -1;226 unsigned int node = 0;227 bool have_node = false;228 cpu_set_t cpuset;229 230 ksft_print_msg("getcpu() on CPU %d\n", cpu);231 232 CPU_ZERO(&cpuset);233 CPU_SET(cpu, &cpuset);234 if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {235 ksft_print_msg("failed to force CPU %d\n", cpu);236 ksft_test_result_skip("vdso_getcpu\n");237 ksft_test_result_skip("vsyscall_map_x\n");238 239 return;240 }241 242 ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);243 if (vdso_getcpu)244 ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);245 if (vsyscall_map_x)246 ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);247 248 if (ret_sys == 0) {249 if (cpu_sys != cpu)250 ksft_print_msg("syscall reported CPU %u but should be %d\n",251 cpu_sys, cpu);252 253 have_node = true;254 node = node_sys;255 }256 257 if (vdso_getcpu) {258 if (ret_vdso) {259 ksft_test_result_fail("vDSO getcpu() failed\n");260 } else {261 if (!have_node) {262 have_node = true;263 node = node_vdso;264 }265 266 if (cpu_vdso != cpu || node_vdso != node) {267 if (cpu_vdso != cpu)268 ksft_print_msg("vDSO reported CPU %u but should be %d\n",269 cpu_vdso, cpu);270 if (node_vdso != node)271 ksft_print_msg("vDSO reported node %u but should be %u\n",272 node_vdso, node);273 ksft_test_result_fail("Wrong values\n");274 } else {275 ksft_test_result_pass("vDSO reported correct CPU and node\n");276 }277 }278 } else {279 ksft_test_result_skip("vdso_getcpu isn't set\n");280 }281 282 if (vsyscall_map_x) {283 if (ret_vsys) {284 ksft_test_result_fail("vsyscall getcpu() failed\n");285 } else {286 if (!have_node) {287 have_node = true;288 node = node_vsys;289 }290 291 if (cpu_vsys != cpu || node_vsys != node) {292 if (cpu_vsys != cpu)293 ksft_print_msg("vsyscall reported CPU %u but should be %d\n",294 cpu_vsys, cpu);295 if (node_vsys != node)296 ksft_print_msg("vsyscall reported node %u but should be %u\n",297 node_vsys, node);298 ksft_test_result_fail("Wrong values\n");299 } else {300 ksft_test_result_pass("vsyscall reported correct CPU and node\n");301 }302 }303 } else {304 ksft_test_result_skip("vsyscall_map_x isn't set\n");305 }306}307 308#ifdef __x86_64__309 310static jmp_buf jmpbuf;311static volatile unsigned long segv_err;312 313static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),314 int flags)315{316 struct sigaction sa;317 318 memset(&sa, 0, sizeof(sa));319 sa.sa_sigaction = handler;320 sa.sa_flags = SA_SIGINFO | flags;321 sigemptyset(&sa.sa_mask);322 if (sigaction(sig, &sa, 0))323 ksft_exit_fail_msg("sigaction failed\n");324}325 326static void sigsegv(int sig, siginfo_t *info, void *ctx_void)327{328 ucontext_t *ctx = (ucontext_t *)ctx_void;329 330 segv_err = ctx->uc_mcontext.gregs[REG_ERR];331 siglongjmp(jmpbuf, 1);332}333 334static void test_vsys_r(void)335{336 ksft_print_msg("Checking read access to the vsyscall page\n");337 bool can_read;338 if (sigsetjmp(jmpbuf, 1) == 0) {339 *(volatile int *)0xffffffffff600000;340 can_read = true;341 } else {342 can_read = false;343 }344 345 if (can_read && !vsyscall_map_r)346 ksft_test_result_fail("We have read access, but we shouldn't\n");347 else if (!can_read && vsyscall_map_r)348 ksft_test_result_fail("We don't have read access, but we should\n");349 else if (can_read)350 ksft_test_result_pass("We have read access\n");351 else352 ksft_test_result_pass("We do not have read access: #PF(0x%lx)\n", segv_err);353}354 355static void test_vsys_x(void)356{357 if (vsyscall_map_x) {358 /* We already tested this adequately. */359 ksft_test_result_pass("vsyscall_map_x is true\n");360 return;361 }362 363 ksft_print_msg("Make sure that vsyscalls really page fault\n");364 365 bool can_exec;366 if (sigsetjmp(jmpbuf, 1) == 0) {367 vgtod(NULL, NULL);368 can_exec = true;369 } else {370 can_exec = false;371 }372 373 if (can_exec)374 ksft_test_result_fail("Executing the vsyscall did not page fault\n");375 else if (segv_err & (1 << 4)) /* INSTR */376 ksft_test_result_pass("Executing the vsyscall page failed: #PF(0x%lx)\n",377 segv_err);378 else379 ksft_test_result_fail("Execution failed with the wrong error: #PF(0x%lx)\n",380 segv_err);381}382 383/*384 * Debuggers expect ptrace() to be able to peek at the vsyscall page.385 * Use process_vm_readv() as a proxy for ptrace() to test this. We386 * want it to work in the vsyscall=emulate case and to fail in the387 * vsyscall=xonly case.388 *389 * It's worth noting that this ABI is a bit nutty. write(2) can't390 * read from the vsyscall page on any kernel version or mode. The391 * fact that ptrace() ever worked was a nice courtesy of old kernels,392 * but the code to support it is fairly gross.393 */394static void test_process_vm_readv(void)395{396 char buf[4096];397 struct iovec local, remote;398 int ret;399 400 ksft_print_msg("process_vm_readv() from vsyscall page\n");401 402 local.iov_base = buf;403 local.iov_len = 4096;404 remote.iov_base = (void *)0xffffffffff600000;405 remote.iov_len = 4096;406 ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);407 if (ret != 4096) {408 /*409 * We expect process_vm_readv() to work if and only if the410 * vsyscall page is readable.411 */412 ksft_test_result(!vsyscall_map_r,413 "process_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno);414 return;415 }416 417 if (vsyscall_map_r)418 ksft_test_result(!memcmp(buf, remote.iov_base, sizeof(buf)), "Read data\n");419 else420 ksft_test_result_fail("process_rm_readv() succeeded, but it should have failed in this configuration\n");421}422 423static void init_vsys(void)424{425 int nerrs = 0;426 FILE *maps;427 char line[MAPS_LINE_LEN];428 bool found = false;429 430 maps = fopen("/proc/self/maps", "r");431 if (!maps) {432 ksft_test_result_skip("Could not open /proc/self/maps -- assuming vsyscall is r-x\n");433 vsyscall_map_r = true;434 return;435 }436 437 while (fgets(line, MAPS_LINE_LEN, maps)) {438 char r, x;439 void *start, *end;440 char name[MAPS_LINE_LEN];441 442 /* sscanf() is safe here as strlen(name) >= strlen(line) */443 if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",444 &start, &end, &r, &x, name) != 5)445 continue;446 447 if (strcmp(name, "[vsyscall]"))448 continue;449 450 ksft_print_msg("vsyscall map: %s", line);451 452 if (start != (void *)0xffffffffff600000 ||453 end != (void *)0xffffffffff601000) {454 ksft_print_msg("address range is nonsense\n");455 nerrs++;456 }457 458 ksft_print_msg("vsyscall permissions are %c-%c\n", r, x);459 vsyscall_map_r = (r == 'r');460 vsyscall_map_x = (x == 'x');461 462 found = true;463 break;464 }465 466 fclose(maps);467 468 if (!found) {469 ksft_print_msg("no vsyscall map in /proc/self/maps\n");470 vsyscall_map_r = false;471 vsyscall_map_x = false;472 }473 474 ksft_test_result(!nerrs, "vsyscall map\n");475}476 477static volatile sig_atomic_t num_vsyscall_traps;478 479static void sigtrap(int sig, siginfo_t *info, void *ctx_void)480{481 ucontext_t *ctx = (ucontext_t *)ctx_void;482 unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP];483 484 if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0)485 num_vsyscall_traps++;486}487 488static void test_emulation(void)489{490 time_t tmp;491 bool is_native;492 493 if (!vsyscall_map_x) {494 ksft_test_result_skip("vsyscall_map_x isn't set\n");495 return;496 }497 498 ksft_print_msg("checking that vsyscalls are emulated\n");499 sethandler(SIGTRAP, sigtrap, 0);500 set_eflags(get_eflags() | X86_EFLAGS_TF);501 vtime(&tmp);502 set_eflags(get_eflags() & ~X86_EFLAGS_TF);503 504 /*505 * If vsyscalls are emulated, we expect a single trap in the506 * vsyscall page -- the call instruction will trap with RIP507 * pointing to the entry point before emulation takes over.508 * In native mode, we expect two traps, since whatever code509 * the vsyscall page contains will be more than just a ret510 * instruction.511 */512 is_native = (num_vsyscall_traps > 1);513 514 ksft_test_result(!is_native, "vsyscalls are %s (%d instructions in vsyscall page)\n",515 (is_native ? "native" : "emulated"), (int)num_vsyscall_traps);516}517#endif518 519int main(int argc, char **argv)520{521 int total_tests = TOTAL_TESTS;522 523 ksft_print_header();524 ksft_set_plan(total_tests);525 526 init_vdso();527#ifdef __x86_64__528 init_vsys();529#endif530 531 test_gtod();532 test_time();533 test_getcpu(0);534 test_getcpu(1);535 536#ifdef __x86_64__537 sethandler(SIGSEGV, sigsegv, 0);538 test_vsys_r();539 test_vsys_x();540 test_process_vm_readv();541 test_emulation();542#endif543 544 ksft_finished();545}546