selftests/x86: Add test_vsyscall

TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall test_mremap_vdso \

			check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test ioperm \

			protection_keys test_vdso

			protection_keys test_vdso test_vsyscall

TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \

			test_FCMOV test_FCOMI test_FISTTP \

			vdso_restorer

/* 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

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[128];

	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, sizeof(line), maps)) {

		char r, x;

		void *start, *end;

		char name[128];

		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_native_vsyscall(void)

{

	time_t tmp;

	bool is_native;

	if (!vtime)

		return 0;

	printf("[RUN]\tchecking for native vsyscall\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("\tvsyscalls are %s (%d instructions in vsyscall page)\n",

	       (is_native ? "native" : "emulated"),

	       (int)num_vsyscall_traps);

	return 0;

}

#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_native_vsyscall();

#endif

	return nerrs ? 1 : 0;

}