/* 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>
#include <sys/uio.h>
#include "helpers.h"
#include "../kselftest.h"
#ifdef __x86_64__
#define TOTAL_TESTS 13
#else
#define TOTAL_TESTS 8
#endif
#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
/* vsyscalls and vDSO */
bool vsyscall_map_r = false, vsyscall_map_x = false;
typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
const 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);
const time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
time_func_t vdso_time;
typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
const 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) {
ksft_print_msg("[WARN] failed to find vDSO\n");
return;
}
vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");
if (!vdso_gtod)
ksft_print_msg("[WARN] failed to find gettimeofday in vDSO\n");
vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
if (!vdso_gettime)
ksft_print_msg("[WARN] failed to find clock_gettime in vDSO\n");
vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");
if (!vdso_time)
ksft_print_msg("[WARN] failed to find time in vDSO\n");
vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
if (!vdso_getcpu)
ksft_print_msg("[WARN] failed to find getcpu in vDSO\n");
}
/* syscalls */
static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
{
return syscall(SYS_gettimeofday, tv, tz);
}
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 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 void 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)
{
double d1, d2;
if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest ||
tz_sys->tz_dsttime != tz_other->tz_dsttime))
ksft_print_msg("%s tz mismatch\n", which);
d1 = tv_diff(tv_other, tv_sys1);
d2 = tv_diff(tv_sys2, tv_other);
ksft_print_msg("%s time offsets: %lf %lf\n", which, d1, d2);
ksft_test_result(!(d1 < 0 || d2 < 0), "%s gettimeofday()'s timeval\n", which);
}
static void 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;
ksft_print_msg("test gettimeofday()\n");
if (sys_gtod(&tv_sys1, &tz_sys) != 0)
ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno));
if (vdso_gtod)
ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
if (vsyscall_map_x)
ret_vsys = vgtod(&tv_vsys, &tz_vsys);
if (sys_gtod(&tv_sys2, &tz_sys) != 0)
ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno));
if (vdso_gtod) {
if (ret_vdso == 0)
check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);
else
ksft_test_result_fail("vDSO gettimeofday() failed: %ld\n", ret_vdso);
} else {
ksft_test_result_skip("vdso_gtod isn't set\n");
}
if (vsyscall_map_x) {
if (ret_vsys == 0)
check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
else
ksft_test_result_fail("vsys gettimeofday() failed: %ld\n", ret_vsys);
} else {
ksft_test_result_skip("vsyscall_map_x isn't set\n");
}
}
static void test_time(void)
{
long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;
long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;
ksft_print_msg("test time()\n");
t_sys1 = sys_time(&t2_sys1);
if (vdso_time)
t_vdso = vdso_time(&t2_vdso);
if (vsyscall_map_x)
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) {
ksft_print_msg("syscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n",
t_sys1, t2_sys1, t_sys2, t2_sys2);
ksft_test_result_skip("vdso_time\n");
ksft_test_result_skip("vdso_time\n");
return;
}
if (vdso_time) {
if (t_vdso < 0 || t_vdso != t2_vdso)
ksft_test_result_fail("vDSO failed (ret:%ld output:%ld)\n",
t_vdso, t2_vdso);
else if (t_vdso < t_sys1 || t_vdso > t_sys2)
ksft_test_result_fail("vDSO returned the wrong time (%ld %ld %ld)\n",
t_sys1, t_vdso, t_sys2);
else
ksft_test_result_pass("vDSO time() is okay\n");
} else {
ksft_test_result_skip("vdso_time isn't set\n");
}
if (vsyscall_map_x) {
if (t_vsys < 0 || t_vsys != t2_vsys)
ksft_test_result_fail("vsyscall failed (ret:%ld output:%ld)\n",
t_vsys, t2_vsys);
else if (t_vsys < t_sys1 || t_vsys > t_sys2)
ksft_test_result_fail("vsyscall returned the wrong time (%ld %ld %ld)\n",
t_sys1, t_vsys, t_sys2);
else
ksft_test_result_pass("vsyscall time() is okay\n");
} else {
ksft_test_result_skip("vsyscall_map_x isn't set\n");
}
}
static void test_getcpu(int cpu)
{
unsigned int cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;
long ret_sys, ret_vdso = -1, ret_vsys = -1;
unsigned int node = 0;
bool have_node = false;
cpu_set_t cpuset;
ksft_print_msg("getcpu() on CPU %d\n", cpu);
CPU_ZERO(&cpuset);
CPU_SET(cpu, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
ksft_print_msg("failed to force CPU %d\n", cpu);
ksft_test_result_skip("vdso_getcpu\n");
ksft_test_result_skip("vsyscall_map_x\n");
return;
}
ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
if (vdso_getcpu)
ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
if (vsyscall_map_x)
ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
if (ret_sys == 0) {
if (cpu_sys != cpu)
ksft_print_msg("syscall reported CPU %u but should be %d\n",
cpu_sys, cpu);
have_node = true;
node = node_sys;
}
if (vdso_getcpu) {
if (ret_vdso) {
ksft_test_result_fail("vDSO getcpu() failed\n");
} else {
if (!have_node) {
have_node = true;
node = node_vdso;
}
if (cpu_vdso != cpu || node_vdso != node) {
if (cpu_vdso != cpu)
ksft_print_msg("vDSO reported CPU %u but should be %d\n",
cpu_vdso, cpu);
if (node_vdso != node)
ksft_print_msg("vDSO reported node %u but should be %u\n",
node_vdso, node);
ksft_test_result_fail("Wrong values\n");
} else {
ksft_test_result_pass("vDSO reported correct CPU and node\n");
}
}
} else {
ksft_test_result_skip("vdso_getcpu isn't set\n");
}
if (vsyscall_map_x) {
if (ret_vsys) {
ksft_test_result_fail("vsyscall getcpu() failed\n");
} else {
if (!have_node) {
have_node = true;
node = node_vsys;
}
if (cpu_vsys != cpu || node_vsys != node) {
if (cpu_vsys != cpu)
ksft_print_msg("vsyscall reported CPU %u but should be %d\n",
cpu_vsys, cpu);
if (node_vsys != node)
ksft_print_msg("vsyscall reported node %u but should be %u\n",
node_vsys, node);
ksft_test_result_fail("Wrong values\n");
} else {
ksft_test_result_pass("vsyscall reported correct CPU and node\n");
}
}
} else {
ksft_test_result_skip("vsyscall_map_x isn't set\n");
}
}
#ifdef __x86_64__
static jmp_buf jmpbuf;
static volatile unsigned long segv_err;
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))
ksft_exit_fail_msg("sigaction failed\n");
}
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t *)ctx_void;
segv_err = ctx->uc_mcontext.gregs[REG_ERR];
siglongjmp(jmpbuf, 1);
}
static void test_vsys_r(void)
{
ksft_print_msg("Checking 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 && !vsyscall_map_r)
ksft_test_result_fail("We have read access, but we shouldn't\n");
else if (!can_read && vsyscall_map_r)
ksft_test_result_fail("We don't have read access, but we should\n");
else if (can_read)
ksft_test_result_pass("We have read access\n");
else
ksft_test_result_pass("We do not have read access: #PF(0x%lx)\n", segv_err);
}
static void test_vsys_x(void)
{
if (vsyscall_map_x) {
/* We already tested this adequately. */
ksft_test_result_pass("vsyscall_map_x is true\n");
return;
}
ksft_print_msg("Make sure that vsyscalls really page fault\n");
bool can_exec;
if (sigsetjmp(jmpbuf, 1) == 0) {
vgtod(NULL, NULL);
can_exec = true;
} else {
can_exec = false;
}
if (can_exec)
ksft_test_result_fail("Executing the vsyscall did not page fault\n");
else if (segv_err & (1 << 4)) /* INSTR */
ksft_test_result_pass("Executing the vsyscall page failed: #PF(0x%lx)\n",
segv_err);
else
ksft_test_result_fail("Execution failed with the wrong error: #PF(0x%lx)\n",
segv_err);
}
/*
* Debuggers expect ptrace() to be able to peek at the vsyscall page.
* Use process_vm_readv() as a proxy for ptrace() to test this. We
* want it to work in the vsyscall=emulate case and to fail in the
* vsyscall=xonly case.
*
* It's worth noting that this ABI is a bit nutty. write(2) can't
* read from the vsyscall page on any kernel version or mode. The
* fact that ptrace() ever worked was a nice courtesy of old kernels,
* but the code to support it is fairly gross.
*/
static void test_process_vm_readv(void)
{
char buf[4096];
struct iovec local, remote;
int ret;
ksft_print_msg("process_vm_readv() from vsyscall page\n");
local.iov_base = buf;
local.iov_len = 4096;
remote.iov_base = (void *)0xffffffffff600000;
remote.iov_len = 4096;
ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);
if (ret != 4096) {
/*
* We expect process_vm_readv() to work if and only if the
* vsyscall page is readable.
*/
ksft_test_result(!vsyscall_map_r,
"process_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno);
return;
}
if (vsyscall_map_r)
ksft_test_result(!memcmp(buf, remote.iov_base, sizeof(buf)), "Read data\n");
else
ksft_test_result_fail("process_rm_readv() succeeded, but it should have failed in this configuration\n");
}
static void init_vsys(void)
{
int nerrs = 0;
FILE *maps;
char line[MAPS_LINE_LEN];
bool found = false;
maps = fopen("/proc/self/maps", "r");
if (!maps) {
ksft_test_result_skip("Could not open /proc/self/maps -- assuming vsyscall is r-x\n");
vsyscall_map_r = true;
return;
}
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;
ksft_print_msg("vsyscall map: %s", line);
if (start != (void *)0xffffffffff600000 ||
end != (void *)0xffffffffff601000) {
ksft_print_msg("address range is nonsense\n");
nerrs++;
}
ksft_print_msg("vsyscall permissions are %c-%c\n", r, x);
vsyscall_map_r = (r == 'r');
vsyscall_map_x = (x == 'x');
found = true;
break;
}
fclose(maps);
if (!found) {
ksft_print_msg("no vsyscall map in /proc/self/maps\n");
vsyscall_map_r = false;
vsyscall_map_x = false;
}
ksft_test_result(!nerrs, "vsyscall map\n");
}
static volatile sig_atomic_t num_vsyscall_traps;
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 void test_emulation(void)
{
time_t tmp;
bool is_native;
if (!vsyscall_map_x) {
ksft_test_result_skip("vsyscall_map_x isn't set\n");
return;
}
ksft_print_msg("checking 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);
ksft_test_result(!is_native, "vsyscalls are %s (%d instructions in vsyscall page)\n",
(is_native ? "native" : "emulated"), (int)num_vsyscall_traps);
}
#endif
int main(int argc, char **argv)
{
int total_tests = TOTAL_TESTS;
ksft_print_header();
ksft_set_plan(total_tests);
init_vdso();
#ifdef __x86_64__
init_vsys();
#endif
test_gtod();
test_time();
test_getcpu(0);
test_getcpu(1);
#ifdef __x86_64__
sethandler(SIGSEGV, sigsegv, 0);
test_vsys_r();
test_vsys_x();
test_process_vm_readv();
test_emulation();
#endif
ksft_finished();
}
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