/* SPDX-License-Identifier: GPL-2.0 */
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <dlfcn.h>
#include <string.h>
#include <inttypes.h>
#include <signal.h>
#include <sys/ucontext.h>
#include <errno.h>
#include <err.h>
#include <sched.h>
#include <stdbool.h>
#include <setjmp.h>
#ifdef __x86_64__
# define VSYS(x) (x)
#else
# define VSYS(x) 0
#endif
#ifndef SYS_getcpu
# ifdef __x86_64__
# define SYS_getcpu 309
# else
# define SYS_getcpu 318
# endif
#endif
/* max length of lines in /proc/self/maps - anything longer is skipped here */
#define MAPS_LINE_LEN 128
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
int flags)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = handler;
sa.sa_flags = SA_SIGINFO | flags;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, 0))
err(1, "sigaction");
}
/* vsyscalls and vDSO */
bool should_read_vsyscall = false;
typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
gtod_t vdso_gtod;
typedef int (*vgettime_t)(clockid_t, struct timespec *);
vgettime_t vdso_gettime;
typedef long (*time_func_t)(time_t *t);
time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
time_func_t vdso_time;
typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
getcpu_t vdso_getcpu;
static void init_vdso(void)
{
void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
if (!vdso)
vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
if (!vdso) {
printf("[WARN]\tfailed to find vDSO\n");
return;
}
vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");
if (!vdso_gtod)
printf("[WARN]\tfailed to find gettimeofday in vDSO\n");
vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
if (!vdso_gettime)
printf("[WARN]\tfailed to find clock_gettime in vDSO\n");
vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");
if (!vdso_time)
printf("[WARN]\tfailed to find time in vDSO\n");
vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
if (!vdso_getcpu) {
/* getcpu() was never wired up in the 32-bit vDSO. */
printf("[%s]\tfailed to find getcpu in vDSO\n",
sizeof(long) == 8 ? "WARN" : "NOTE");
}
}
static int init_vsys(void)
{
#ifdef __x86_64__
int nerrs = 0;
FILE *maps;
char line[MAPS_LINE_LEN];
bool found = false;
maps = fopen("/proc/self/maps", "r");
if (!maps) {
printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n");
should_read_vsyscall = true;
return 0;
}
while (fgets(line, MAPS_LINE_LEN, maps)) {
char r, x;
void *start, *end;
char name[MAPS_LINE_LEN];
/* sscanf() is safe here as strlen(name) >= strlen(line) */
if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
&start, &end, &r, &x, name) != 5)
continue;
if (strcmp(name, "[vsyscall]"))
continue;
printf("\tvsyscall map: %s", line);
if (start != (void *)0xffffffffff600000 ||
end != (void *)0xffffffffff601000) {
printf("[FAIL]\taddress range is nonsense\n");
nerrs++;
}
printf("\tvsyscall permissions are %c-%c\n", r, x);
should_read_vsyscall = (r == 'r');
if (x != 'x') {
vgtod = NULL;
vtime = NULL;
vgetcpu = NULL;
}
found = true;
break;
}
fclose(maps);
if (!found) {
printf("\tno vsyscall map in /proc/self/maps\n");
should_read_vsyscall = false;
vgtod = NULL;
vtime = NULL;
vgetcpu = NULL;
}
return nerrs;
#else
return 0;
#endif
}
/* syscalls */
static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
{
return syscall(SYS_gettimeofday, tv, tz);
}
static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
{
return syscall(SYS_clock_gettime, id, ts);
}
static inline long sys_time(time_t *t)
{
return syscall(SYS_time, t);
}
static inline long sys_getcpu(unsigned * cpu, unsigned * node,
void* cache)
{
return syscall(SYS_getcpu, cpu, node, cache);
}
static jmp_buf jmpbuf;
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
siglongjmp(jmpbuf, 1);
}
static double tv_diff(const struct timeval *a, const struct timeval *b)
{
return (double)(a->tv_sec - b->tv_sec) +
(double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6;
}
static int 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)
{
int nerrs = 0;
double d1, d2;
if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) {
printf("[FAIL] %s tz mismatch\n", which);
nerrs++;
}
d1 = tv_diff(tv_other, tv_sys1);
d2 = tv_diff(tv_sys2, tv_other);
printf("\t%s time offsets: %lf %lf\n", which, d1, d2);
if (d1 < 0 || d2 < 0) {
printf("[FAIL]\t%s time was inconsistent with the syscall\n", which);
nerrs++;
} else {
printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which);
}
return nerrs;
}
static int test_gtod(void)
{
struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys;
struct timezone tz_sys, tz_vdso, tz_vsys;
long ret_vdso = -1;
long ret_vsys = -1;
int nerrs = 0;
printf("[RUN]\ttest gettimeofday()\n");
if (sys_gtod(&tv_sys1, &tz_sys) != 0)
err(1, "syscall gettimeofday");
if (vdso_gtod)
ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
if (vgtod)
ret_vsys = vgtod(&tv_vsys, &tz_vsys);
if (sys_gtod(&tv_sys2, &tz_sys) != 0)
err(1, "syscall gettimeofday");
if (vdso_gtod) {
if (ret_vdso == 0) {
nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);
} else {
printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso);
nerrs++;
}
}
if (vgtod) {
if (ret_vsys == 0) {
nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
} else {
printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys);
nerrs++;
}
}
return nerrs;
}
static int test_time(void) {
int nerrs = 0;
printf("[RUN]\ttest time()\n");
long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;
long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;
t_sys1 = sys_time(&t2_sys1);
if (vdso_time)
t_vdso = vdso_time(&t2_vdso);
if (vtime)
t_vsys = vtime(&t2_vsys);
t_sys2 = sys_time(&t2_sys2);
if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {
printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2);
nerrs++;
return nerrs;
}
if (vdso_time) {
if (t_vdso < 0 || t_vdso != t2_vdso) {
printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso);
nerrs++;
} else if (t_vdso < t_sys1 || t_vdso > t_sys2) {
printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2);
nerrs++;
} else {
printf("[OK]\tvDSO time() is okay\n");
}
}
if (vtime) {
if (t_vsys < 0 || t_vsys != t2_vsys) {
printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys);
nerrs++;
} else if (t_vsys < t_sys1 || t_vsys > t_sys2) {
printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2);
nerrs++;
} else {
printf("[OK]\tvsyscall time() is okay\n");
}
}
return nerrs;
}
static int test_getcpu(int cpu)
{
int nerrs = 0;
long ret_sys, ret_vdso = -1, ret_vsys = -1;
printf("[RUN]\tgetcpu() on CPU %d\n", cpu);
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(cpu, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
printf("[SKIP]\tfailed to force CPU %d\n", cpu);
return nerrs;
}
unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;
unsigned node = 0;
bool have_node = false;
ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
if (vdso_getcpu)
ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
if (vgetcpu)
ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
if (ret_sys == 0) {
if (cpu_sys != cpu) {
printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu);
nerrs++;
}
have_node = true;
node = node_sys;
}
if (vdso_getcpu) {
if (ret_vdso) {
printf("[FAIL]\tvDSO getcpu() failed\n");
nerrs++;
} else {
if (!have_node) {
have_node = true;
node = node_vdso;
}
if (cpu_vdso != cpu) {
printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu);
nerrs++;
} else {
printf("[OK]\tvDSO reported correct CPU\n");
}
if (node_vdso != node) {
printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node);
nerrs++;
} else {
printf("[OK]\tvDSO reported correct node\n");
}
}
}
if (vgetcpu) {
if (ret_vsys) {
printf("[FAIL]\tvsyscall getcpu() failed\n");
nerrs++;
} else {
if (!have_node) {
have_node = true;
node = node_vsys;
}
if (cpu_vsys != cpu) {
printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu);
nerrs++;
} else {
printf("[OK]\tvsyscall reported correct CPU\n");
}
if (node_vsys != node) {
printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node);
nerrs++;
} else {
printf("[OK]\tvsyscall reported correct node\n");
}
}
}
return nerrs;
}
static int test_vsys_r(void)
{
#ifdef __x86_64__
printf("[RUN]\tChecking read access to the vsyscall page\n");
bool can_read;
if (sigsetjmp(jmpbuf, 1) == 0) {
*(volatile int *)0xffffffffff600000;
can_read = true;
} else {
can_read = false;
}
if (can_read && !should_read_vsyscall) {
printf("[FAIL]\tWe have read access, but we shouldn't\n");
return 1;
} else if (!can_read && should_read_vsyscall) {
printf("[FAIL]\tWe don't have read access, but we should\n");
return 1;
} else {
printf("[OK]\tgot expected result\n");
}
#endif
return 0;
}
#ifdef __x86_64__
#define X86_EFLAGS_TF (1UL << 8)
static volatile sig_atomic_t num_vsyscall_traps;
static unsigned long get_eflags(void)
{
unsigned long eflags;
asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags));
return eflags;
}
static void set_eflags(unsigned long eflags)
{
asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags");
}
static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t *)ctx_void;
unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP];
if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0)
num_vsyscall_traps++;
}
static int test_emulation(void)
{
time_t tmp;
bool is_native;
if (!vtime)
return 0;
printf("[RUN]\tchecking that vsyscalls are emulated\n");
sethandler(SIGTRAP, sigtrap, 0);
set_eflags(get_eflags() | X86_EFLAGS_TF);
vtime(&tmp);
set_eflags(get_eflags() & ~X86_EFLAGS_TF);
/*
* If vsyscalls are emulated, we expect a single trap in the
* vsyscall page -- the call instruction will trap with RIP
* pointing to the entry point before emulation takes over.
* In native mode, we expect two traps, since whatever code
* the vsyscall page contains will be more than just a ret
* instruction.
*/
is_native = (num_vsyscall_traps > 1);
printf("[%s]\tvsyscalls are %s (%d instructions in vsyscall page)\n",
(is_native ? "FAIL" : "OK"),
(is_native ? "native" : "emulated"),
(int)num_vsyscall_traps);
return is_native;
}
#endif
int main(int argc, char **argv)
{
int nerrs = 0;
init_vdso();
nerrs += init_vsys();
nerrs += test_gtod();
nerrs += test_time();
nerrs += test_getcpu(0);
nerrs += test_getcpu(1);
sethandler(SIGSEGV, sigsegv, 0);
nerrs += test_vsys_r();
#ifdef __x86_64__
nerrs += test_emulation();
#endif
return nerrs ? 1 : 0;
}