xref: /src/tests/lib/libc/sys/t_ptrace_wait.h

/*	$NetBSD: t_ptrace_wait.h,v 1.40 2025/05/02 02:52:40 riastradh Exp $	*/

/*-
 * Copyright (c) 2016, 2017, 2018, 2019 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/* Detect plain wait(2) use-case */
#if !defined(TWAIT_WAITPID) && \
    !defined(TWAIT_WAITID) && \
    !defined(TWAIT_WAIT3) && \
    !defined(TWAIT_WAIT4) && \
    !defined(TWAIT_WAIT6)
#define TWAIT_WAIT
#endif

/*
 * There are two classes of wait(2)-like functions:
 * - wait4(2)-like accepting pid_t, optional options parameter, struct rusage*
 * - wait6(2)-like accepting idtype_t, id_t, struct wrusage, mandatory options
 *
 * The TWAIT_FNAME value is to be used for convenience in debug messages.
 *
 * The TWAIT_GENERIC() macro is designed to reuse the same unmodified
 * code with as many wait(2)-like functions as possible.
 *
 * In a common use-case wait4(2) and wait6(2)-like function can work the almost
 * the same way, however there are few important differences:
 * wait6(2) must specify P_PID for idtype to match wpid from wait4(2).
 * To behave like wait4(2), wait6(2) the 'options' to wait must include
 * WEXITED|WTRUNCATED.
 *
 * There are two helper macros (they purpose it to mach more than one
 * wait(2)-like function):
 * The TWAIT_HAVE_STATUS - specifies whether a function can retrieve
 *                         status (as integer value).
 * The TWAIT_HAVE_PID    - specifies whether a function can request
 *                         exact process identifier
 * The TWAIT_HAVE_RUSAGE - specifies whether a function can request
 *                         the struct rusage value
 *
 */

#if defined(TWAIT_WAIT)
#	define TWAIT_FNAME			"wait"
#	define TWAIT_WAIT4TYPE(a,b,c,d)		wait((b))
#	define TWAIT_GENERIC(a,b,c)		wait((b))
#	define TWAIT_HAVE_STATUS		1
#elif defined(TWAIT_WAITPID)
#	define TWAIT_FNAME			"waitpid"
#	define TWAIT_WAIT4TYPE(a,b,c,d)		waitpid((a),(b),(c))
#	define TWAIT_GENERIC(a,b,c)		waitpid((a),(b),(c))
#	define TWAIT_HAVE_PID			1
#	define TWAIT_HAVE_STATUS		1
#	define TWAIT_HAVE_OPTIONS		1
#elif defined(TWAIT_WAITID)
#	define TWAIT_FNAME			"waitid"
#	define TWAIT_GENERIC(a,b,c)		\
		waitid(P_PID,(a),NULL,(c)|WEXITED|WTRAPPED)
#	define TWAIT_WAIT6TYPE(a,b,c,d,e,f)	waitid((a),(b),(f),(d))
#	define TWAIT_HAVE_PID			1
#	define TWAIT_HAVE_OPTIONS		1
#elif defined(TWAIT_WAIT3)
#	define TWAIT_FNAME			"wait3"
#	define TWAIT_WAIT4TYPE(a,b,c,d)		wait3((b),(c),(d))
#	define TWAIT_GENERIC(a,b,c)		wait3((b),(c),NULL)
#	define TWAIT_HAVE_STATUS		1
#	define TWAIT_HAVE_RUSAGE		1
#	define TWAIT_HAVE_OPTIONS		1
#elif defined(TWAIT_WAIT4)
#	define TWAIT_FNAME			"wait4"
#	define TWAIT_WAIT4TYPE(a,b,c,d)		wait4((a),(b),(c),(d))
#	define TWAIT_GENERIC(a,b,c)		wait4((a),(b),(c),NULL)
#	define TWAIT_HAVE_PID			1
#	define TWAIT_HAVE_STATUS		1
#	define TWAIT_HAVE_RUSAGE		1
#	define TWAIT_HAVE_OPTIONS		1
#elif defined(TWAIT_WAIT6)
#	define TWAIT_FNAME			"wait6"
#	define TWAIT_WAIT6TYPE(a,b,c,d,e,f)	wait6((a),(b),(c),(d),(e),(f))
#	define TWAIT_GENERIC(a,b,c)		\
		wait6(P_PID,(a),(b),(c)|WEXITED|WTRAPPED,NULL,NULL)
#	define TWAIT_HAVE_PID			1
#	define TWAIT_HAVE_STATUS		1
#	define TWAIT_HAVE_OPTIONS		1
#endif

/*
 * There are 3 groups of tests:
 * - TWAIT_GENERIC()	(wait, wait2, waitpid, wait3, wait4, wait6)
 * - TWAIT_WAIT4TYPE()	(wait2, waitpid, wait3, wait4)
 * - TWAIT_WAIT6TYPE()	(waitid, wait6)
 *
 * Tests only in the above categories are allowed. However some tests are not
 * possible in the context requested functionality to be verified, therefore
 * there are helper macros:
 * - TWAIT_HAVE_PID	(wait2, waitpid, waitid, wait4, wait6)
 * - TWAIT_HAVE_STATUS	(wait, wait2, waitpid, wait3, wait4, wait6)
 * - TWAIT_HAVE_RUSAGE	(wait3, wait4)
 * - TWAIT_HAVE_RETPID	(wait, wait2, waitpid, wait3, wait4, wait6)
 *
 * If there is an intention to test e.g. wait6(2) specific features in the
 * ptrace(2) context, find the most matching group and with #ifdefs reduce
 * functionality of less featured than wait6(2) interface (TWAIT_WAIT6TYPE).
 *
 * For clarity never use negative preprocessor checks, like:
 *     #if !defined(TWAIT_WAIT4)
 * always refer to checks for positive values.
 */

#define TEST_REQUIRE_EQ(x, y)						\
do {									\
	uintmax_t vx = (x);						\
	uintmax_t vy = (y);						\
	int ret = vx == vy;						\
	if (!ret)							\
		ATF_REQUIRE_EQ_MSG(vx, vy,				\
		    "%s(%ju=0x%jx) == %s(%ju=0x%jx)",			\
		    #x, vx, vx, #y, vy, vy);				\
} while (/*CONSTCOND*/0)

#define TEST_CHECK_EQ(x, y)						\
do {									\
	uintmax_t vx = (x);						\
	uintmax_t vy = (y);						\
	int ret = vx == vy;						\
	if (!ret)							\
		ATF_CHECK_EQ_MSG(vx, vy,				\
		    "%s(%ju=0x%jx) == %s(%ju=0x%jx)",			\
		    #x, vx, vx, #y, vy, vy);				\
} while (/*CONSTCOND*/0)

#define TEST_CHECK_MEMEQ(x, y, n)					\
do {									\
	const void *vx = (x);						\
	const void *vy = (y);						\
	const size_t vn = (n);						\
	if (__predict_true(memcmp(vx, vy, vn) == 0))			\
		break;							\
	hexdump(#x, vx, vn);						\
	hexdump(#y, vy, vn);						\
	atf_tc_fail_nonfatal("%s != %s (%s = %zu bytes)",		\
	    #x, #y, #n, vn);						\
} while (/*CONSTCOND*/0)

/*
 * A child process cannot call atf functions and expect them to magically
 * work like in the parent.
 * The printf(3) messaging from a child will not work out of the box as well
 * without establishing a communication protocol with its parent. To not
 * overcomplicate the tests - do not log from a child and use err(3)/errx(3)
 * wrapped with FORKEE_ASSERT()/FORKEE_ASSERTX() as that is guaranteed to work.
 */
#define FORKEE_ASSERT_EQ(x, y)						\
do {									\
	uintmax_t vx = (x);						\
	uintmax_t vy = (y);						\
	int ret = vx == vy;						\
	if (!ret)							\
		errx(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: "	\
		    "%s(%jd=0x%jx) == %s(%jd=0x%jx)",			\
		    __FILE__, __LINE__, __func__,			\
		    #x, vx, vx, #y, vy, vy);				\
} while (/*CONSTCOND*/0)

#define FORKEE_ASSERT_NEQ(x, y)						\
do {									\
	uintmax_t vx = (x);						\
	uintmax_t vy = (y);						\
	int ret = vx != vy;						\
	if (!ret)							\
		errx(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: "	\
		    "%s(%ju=0x%jx) != %s(%ju=0x%jx)",			\
		    __FILE__, __LINE__, __func__,			\
		    #x, vx, vx, #y, vy, vy);				\
} while (/*CONSTCOND*/0)

__unused	/* used by FORKEE_ASSERT_MEMEQ, otherwise not used */
static void
hexdump(const char *title, const void *buf, size_t len)
{
	const unsigned char *p = buf;
	size_t i;

	fprintf(stderr, "%s (%zu bytes)\n", title, len);
	for (i = 0; i < len; i++) {
		if ((i % 8) == 0)
			fprintf(stderr, " ");
		fprintf(stderr, "%02hhx", p[i]);
		if ((i % 16) == 0)
			fprintf(stderr, "\n");
	}
	if (i % 16)
		fprintf(stderr, "\n");
}

#define	FORKEE_ASSERT_MEMEQ(x, y, n)					\
do {									\
	const void *const vx = (x);					\
	const void *const vy = (y);					\
	const size_t vn = (n);						\
									\
	if (__predict_true(memcmp(vx, vy, vn) == 0))			\
		break;							\
	fprintf(stderr, "%s != %s (%s = %zu bytes)\n", #x, #y, #n, vn);	\
	hexdump(#x, vx, vn);						\
	hexdump(#y, vy, vn);						\
} while (/*CONSTCOND*/0)

#define FORKEE_ASSERTX(x)						\
do {									\
	int ret = (x);							\
	if (!ret)							\
		errx(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s",\
		     __FILE__, __LINE__, __func__, #x);			\
} while (/*CONSTCOND*/0)

#define FORKEE_ASSERT(x)						\
do {									\
	int ret = (x);							\
	if (!ret)							\
		err(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s",\
		     __FILE__, __LINE__, __func__, #x);			\
} while (/*CONSTCOND*/0)

#define	FORKEE_PTHREAD(x)						\
do {									\
	int _forkee_pthread_error = (x);				\
	if (_forkee_pthread_error) {					\
		errno = _forkee_pthread_error;				\
		err(EXIT_FAILURE, "%s:%d %s(): %s", __FILE__, __LINE__,	\
		    __func__, #x);					\
	}								\
} while (/*CONSTCOND*/0)

/*
 * Simplify logic for functions using general purpose registers add HAVE_GPREGS
 *
 * For platforms that do not implement all needed calls for simplicity assume
 * that they are unsupported at all.
 */
#if defined(PT_GETREGS)			\
    && defined(PT_SETREGS)		\
    && defined(PTRACE_REG_PC)		\
    && defined(PTRACE_REG_SET_PC)	\
    && defined(PTRACE_REG_SP)		\
    && defined(PTRACE_REG_INTRV)
#define HAVE_GPREGS
#endif

/* Add guards for floating point registers */
#if defined(PT_GETFPREGS)		\
    && defined(PT_SETFPREGS)
#define HAVE_FPREGS
#endif

/* Add guards for cpu debug registers */
#if defined(PT_GETDBREGS)		\
    && defined(PT_SETDBREGS)
#define HAVE_DBREGS
#endif

/*
 * If waitid(2) returns because one or more processes have a state change to
 * report, 0 is returned.  If an error is detected, a value of -1 is returned
 * and errno is set to indicate the error. If WNOHANG is specified and there
 * are no stopped, continued or exited children, 0 is returned.
 */
#if defined(TWAIT_WAITID)
#define TWAIT_REQUIRE_SUCCESS(a,b)	TEST_REQUIRE_EQ((a), 0)
#define TWAIT_REQUIRE_FAILURE(a,b)	ATF_REQUIRE_ERRNO((a),(b) == -1)
#define FORKEE_REQUIRE_SUCCESS(a,b)	FORKEE_ASSERT_EQ(a, 0)
#define FORKEE_REQUIRE_FAILURE(a,b)	\
	FORKEE_ASSERTX(((a) == errno) && ((b) == -1))
#else
#define TWAIT_REQUIRE_SUCCESS(a,b)	TEST_REQUIRE_EQ((a), (b))
#define TWAIT_REQUIRE_FAILURE(a,b)	ATF_REQUIRE_ERRNO((a),(b) == -1)
#define FORKEE_REQUIRE_SUCCESS(a,b)	FORKEE_ASSERT_EQ(a, b)
#define FORKEE_REQUIRE_FAILURE(a,b)	\
	FORKEE_ASSERTX(((a) == errno) && ((b) == -1))
#endif

/*
 * Helper tools to verify whether status reports exited value
 */
#if TWAIT_HAVE_STATUS
static void __used
validate_status_exited(int status, int expected)
{
        ATF_REQUIRE_MSG(WIFEXITED(status), "Reported !exited process");
        ATF_REQUIRE_MSG(!WIFCONTINUED(status), "Reported continued process");
        ATF_REQUIRE_MSG(!WIFSIGNALED(status), "Reported signaled process");
        ATF_REQUIRE_MSG(!WIFSTOPPED(status), "Reported stopped process");

	ATF_REQUIRE_EQ_MSG(WEXITSTATUS(status), expected,
	    "The process has exited with invalid value %d != %d",
	    WEXITSTATUS(status), expected);
}

static void __used
forkee_status_exited(int status, int expected)
{
	FORKEE_ASSERTX(WIFEXITED(status));
	FORKEE_ASSERTX(!WIFCONTINUED(status));
	FORKEE_ASSERTX(!WIFSIGNALED(status));
	FORKEE_ASSERTX(!WIFSTOPPED(status));

	FORKEE_ASSERT_EQ(WEXITSTATUS(status), expected);
}

static void __used
validate_status_continued(int status)
{
	ATF_REQUIRE_MSG(!WIFEXITED(status), "Reported exited process");
	ATF_REQUIRE_MSG(WIFCONTINUED(status), "Reported !continued process");
	ATF_REQUIRE_MSG(!WIFSIGNALED(status), "Reported signaled process");
	ATF_REQUIRE_MSG(!WIFSTOPPED(status), "Reported stopped process");
}

static void __used
forkee_status_continued(int status)
{
	FORKEE_ASSERTX(!WIFEXITED(status));
	FORKEE_ASSERTX(WIFCONTINUED(status));
	FORKEE_ASSERTX(!WIFSIGNALED(status));
	FORKEE_ASSERTX(!WIFSTOPPED(status));
}

static void __used
validate_status_signaled(int status, int expected_termsig, int expected_core)
{
	ATF_REQUIRE_MSG(!WIFEXITED(status), "Reported exited process");
	ATF_REQUIRE_MSG(!WIFCONTINUED(status), "Reported continued process");
	ATF_REQUIRE_MSG(WIFSIGNALED(status), "Reported !signaled process");
	ATF_REQUIRE_MSG(!WIFSTOPPED(status), "Reported stopped process");

	ATF_REQUIRE_EQ_MSG(WTERMSIG(status), expected_termsig,
	    "Unexpected signal received");

	ATF_REQUIRE_EQ_MSG(!!WCOREDUMP(status), expected_core,
	    "Unexpectedly core file %s generated", expected_core ? "not" : "");
}

static void __used
forkee_status_signaled(int status, int expected_termsig, int expected_core)
{
	FORKEE_ASSERTX(!WIFEXITED(status));
	FORKEE_ASSERTX(!WIFCONTINUED(status));
	FORKEE_ASSERTX(WIFSIGNALED(status));
	FORKEE_ASSERTX(!WIFSTOPPED(status));

	FORKEE_ASSERT_EQ(WTERMSIG(status), expected_termsig);
	FORKEE_ASSERT_EQ(!!WCOREDUMP(status), expected_core);
}

static void __used
validate_status_stopped(int status, int expected)
{
	ATF_REQUIRE_MSG(!WIFEXITED(status), "Reported exited process");
	ATF_REQUIRE_MSG(!WIFCONTINUED(status), "Reported continued process");
	ATF_REQUIRE_MSG(!WIFSIGNALED(status), "Reported signaled process");
	ATF_REQUIRE_MSG(WIFSTOPPED(status), "Reported !stopped process");

	char st[128], ex[128];
	strlcpy(st, strsignal(WSTOPSIG(status)), sizeof(st));
	strlcpy(ex, strsignal(expected), sizeof(ex));

	ATF_REQUIRE_EQ_MSG(WSTOPSIG(status), expected,
	    "Unexpected stop signal received [%s] != [%s]", st, ex);
}

static void __used
forkee_status_stopped(int status, int expected)
{
	FORKEE_ASSERTX(!WIFEXITED(status));
	FORKEE_ASSERTX(!WIFCONTINUED(status));
	FORKEE_ASSERTX(!WIFSIGNALED(status));
	FORKEE_ASSERTX(WIFSTOPPED(status));

	FORKEE_ASSERT_EQ(WSTOPSIG(status), expected);
}
#else
#define validate_status_exited(a,b)
#define forkee_status_exited(a,b)
#define validate_status_continued(a,b)
#define forkee_status_continued(a,b)
#define validate_status_signaled(a,b,c)
#define forkee_status_signaled(a,b,c)
#define validate_status_stopped(a,b)
#define forkee_status_stopped(a,b)
#endif

/* This function is currently designed to be run in the main/parent process */
static void __used
await_zombie_raw(pid_t process, useconds_t ms)
{
	struct kinfo_proc2 p;
	size_t len = sizeof(p);

	const int name[] = {
		[0] = CTL_KERN,
		[1] = KERN_PROC2,
		[2] = KERN_PROC_PID,
		[3] = process,
		[4] = sizeof(p),
		[5] = 1
	};

	const size_t namelen = __arraycount(name);

	/* Await the process becoming a zombie */
	while(1) {
		ATF_REQUIRE(sysctl(name, namelen, &p, &len, NULL, 0) == 0);

		if (p.p_stat == LSZOMB)
			break;

		if (ms > 0) {
			ATF_REQUIRE(usleep(ms) == 0);
		}
	}
}

static void __used
await_zombie(pid_t process)
{

	await_zombie_raw(process, 1000);
}

static void __used
await_stopped(pid_t process)
{
	struct kinfo_proc2 p;
	size_t len = sizeof(p);

	const int name[] = {
		[0] = CTL_KERN,
		[1] = KERN_PROC2,
		[2] = KERN_PROC_PID,
		[3] = process,
		[4] = sizeof(p),
		[5] = 1
	};

	const size_t namelen = __arraycount(name);

	/* Await the process becoming a zombie */
	while(1) {
		ATF_REQUIRE(sysctl(name, namelen, &p, &len, NULL, 0) == 0);

		if (p.p_stat == LSSTOP)
			break;

		ATF_REQUIRE(usleep(1000) == 0);
	}
}

static pid_t __used
await_stopped_child(pid_t process)
{
	struct kinfo_proc2 *p = NULL;
	size_t i, len;
	pid_t child = -1;

	int name[] = {
		[0] = CTL_KERN,
		[1] = KERN_PROC2,
		[2] = KERN_PROC_ALL,
		[3] = 0,
		[4] = sizeof(struct kinfo_proc2),
		[5] = 0
	};

	const size_t namelen = __arraycount(name);

	/* Await the process becoming a zombie */
	while(1) {
		name[5] = 0;

		FORKEE_ASSERT_EQ(sysctl(name, namelen, 0, &len, NULL, 0), 0);

		FORKEE_ASSERT_EQ(reallocarr(&p,
		                            len,
		                            sizeof(struct kinfo_proc2)), 0);

		name[5] = len;

		FORKEE_ASSERT_EQ(sysctl(name, namelen, p, &len, NULL, 0), 0);

		for (i = 0; i < len/sizeof(struct kinfo_proc2); i++) {
			if (p[i].p_pid == getpid())
				continue;
			if (p[i].p_ppid != process)
				continue;
			if (p[i].p_stat != LSSTOP)
				continue;
			child = p[i].p_pid;
			break;
		}

		if (child != -1)
			break;

		FORKEE_ASSERT_EQ(usleep(1000), 0);
	}

	/* Free the buffer */
	FORKEE_ASSERT_EQ(reallocarr(&p, 0, sizeof(struct kinfo_proc2)), 0);

	return child;
}

static void __used
await_collected(pid_t process)
{
	struct kinfo_proc2 p;
	size_t len = sizeof(p);

	const int name[] = {
		[0] = CTL_KERN,
		[1] = KERN_PROC2,
		[2] = KERN_PROC_PID,
		[3] = process,
		[4] = sizeof(p),
		[5] = 1
	};

	const size_t namelen = __arraycount(name);

	/* Await the process to disappear */
	while(1) {
		FORKEE_ASSERT_EQ(sysctl(name, namelen, &p, &len, NULL, 0), 0);
		if (len == 0)
			break;

		ATF_REQUIRE(usleep(1000) == 0);
	}
}

/* Happy number sequence -- this function is used to just consume cpu cycles */
#define	HAPPY_NUMBER	1

/* If n is not happy then its sequence ends in the cycle:
 * 4, 16, 37, 58, 89, 145, 42, 20, 4, ... */
#define	SAD_NUMBER	4

/* Calculate the sum of the squares of the digits of n */
static unsigned __used
dsum(unsigned n)
{
	unsigned sum, x;
	for (sum = 0; n; n /= 10) {
		x = n % 10;
		sum += x * x;
	}
	return sum;
}

/*
 * XXX: Disabled optimization is required to make tests for hardware assisted
 * traps in .text functional
 *
 * Tested with GCC 5.4 on NetBSD 7.99.47 amd64
 */
static int __used
#ifdef __clang__
__attribute__((__optnone__))
#else
__attribute__((__optimize__("O0")))
#endif
check_happy(unsigned n)
{
	for (;;) {
		unsigned total = dsum(n);

		if (total == HAPPY_NUMBER)
			return 1;
		if (total == SAD_NUMBER)
			return 0;

		n = total;
	}
}

static void * __used
infinite_thread(void *arg __unused)
{

        while (true)
                continue;

        __unreachable();
}

static int __used
clone_func(void *arg)
{
	int ret;

	ret = (int)(intptr_t)arg;

	return ret;
}

#if defined(HAVE_DBREGS)
static bool __used
can_we_set_dbregs(void)
{
	static long euid = -1;
	static int user_set_dbregs  = -1;
	size_t user_set_dbregs_len = sizeof(user_set_dbregs);

	if (euid == -1)
		euid = geteuid();

	if (euid == 0)
		return true;

	if (user_set_dbregs == -1) {
		if (sysctlbyname("security.models.extensions.user_set_dbregs",
			&user_set_dbregs, &user_set_dbregs_len, NULL, 0)
			== -1) {
			return false;
		}
	}

	if (user_set_dbregs > 0)
		return true;
	else
		return false;
}
#endif

static bool __used
get_user_va0_disable(void)
{
	static int user_va0_disable = -1;
	size_t user_va0_disable_len = sizeof(user_va0_disable);

	if (user_va0_disable == -1) {
		if (sysctlbyname("vm.user_va0_disable",
			&user_va0_disable, &user_va0_disable_len, NULL, 0)
			== -1) {
			return true;
		}
	}

	if (user_va0_disable > 0)
		return true;
	else
		return false;
}

static bool __used
can_we_write_to_text(pid_t pid)
{
	int mib[3];
	int paxflags;
	size_t len = sizeof(int);

	mib[0] = CTL_PROC;
	mib[1] = pid;
	mib[2] = PROC_PID_PAXFLAGS;

	if (sysctl(mib, 3, &paxflags, &len, NULL, 0) == -1)
		return false;

	return !(paxflags & CTL_PROC_PAXFLAGS_MPROTECT);
}

static void __used
trigger_trap(void)
{

	/* Software breakpoint causes CPU trap, translated to SIGTRAP */
#ifdef PTRACE_BREAKPOINT_ASM
	PTRACE_BREAKPOINT_ASM;
#else
	/* port me */
#endif
}

static void __used
trigger_segv(void)
{
	static volatile char *ptr = NULL;

	/* Access to unmapped memory causes CPU trap, translated to SIGSEGV */
	*ptr = 1;
}

static void __used
trigger_ill(void)
{

	/* Illegal instruction causes CPU trap, translated to SIGILL */
#ifdef PTRACE_ILLEGAL_ASM
#ifndef __mips__ /* To avoid GXemul crash */
	PTRACE_ILLEGAL_ASM;
#endif
#else
	/* port me */
#endif
}

#include <fenv.h>

#if (__arm__ && !__SOFTFP__) || __aarch64__
#include <ieeefp.h> /* only need for ARM Cortex/Neon hack */

static bool __used
are_fpu_exceptions_supported(void)
{
	/*
	 * Some NEON fpus do not trap on IEEE 754 FP exceptions.
	 * Skip these tests if running on them and compiled for
	 * hard float.
	 */
	if (0 == fpsetmask(fpsetmask(FP_X_INV)))
		return false;
	return true;
}
#elif defined __riscv__
#define are_fpu_exceptions_supported() 0
#else
#define are_fpu_exceptions_supported() 1
#endif

volatile double ignore_result;

static void __used
trigger_fpe(void)
{
#if __i386__ || __x86_64__
	/*
	 * XXX
	 * Hack for QEMU bug #1668041, by which floating-point division by
	 * zero is not trapped correctly. Also, assertions for si_code in
	 * ptrace_signal_wait.h are commented out. Clean them up after the
	 * bug is fixed.
	 */
	volatile int a, b;
#else
	volatile double a, b;
#endif

	a = getpid();
	b = atoi("0");

#ifdef __HAVE_FENV
	feenableexcept(FE_ALL_EXCEPT);
#endif

	/* Division by zero causes CPU trap, translated to SIGFPE */
	ignore_result = (int)(a / b);
}

static void __used
trigger_bus(void)
{
	FILE *fp;
	char *p;

	/* Open an empty file for writing. */
	fp = tmpfile();
	FORKEE_ASSERT_NEQ((uintptr_t)fp, (uintptr_t)NULL);

	/*
	 * Map an empty file with mmap(2) to a pointer.
	 *
	 * PROT_READ handles read-modify-write sequences emitted for
	 * certain combinations of CPUs and compilers (e.g. Alpha AXP).
	 */
	p = mmap(0, 1, PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(fp), 0);
	FORKEE_ASSERT_NEQ((uintptr_t)p, (uintptr_t)MAP_FAILED);

	/* Invalid memory access causes CPU trap, translated to SIGBUS */
	*p = 'a';
}

struct lwp_event_count {
	lwpid_t lec_lwp;
	int lec_count;
};

static int * __used
find_event_count(struct lwp_event_count list[], lwpid_t lwp, size_t max_lwps)
{
	size_t i;

	for (i = 0; i < max_lwps; i++) {
		if (list[i].lec_lwp == 0)
			list[i].lec_lwp = lwp;
		if (list[i].lec_lwp == lwp)
			return &list[i].lec_count;
	}

	atf_tc_fail("More LWPs reported than expected");
}

#define FIND_EVENT_COUNT(list, lwp)			\
	find_event_count(list, lwp, __arraycount(list))

#if defined(TWAIT_HAVE_PID)
#define ATF_TP_ADD_TC_HAVE_PID(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_PID(a,b)
#endif

#if defined(TWAIT_HAVE_STATUS)
#define ATF_TP_ADD_TC_HAVE_STATUS(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_STATUS(a,b)
#endif

#if defined(TWAIT_HAVE_STATUS) && (defined(__i386__) || defined(__x86_64__))
#define ATF_TP_ADD_TC_HAVE_STATUS_X86(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_STATUS_X86(a,b)
#endif

#if defined(HAVE_GPREGS)
#define ATF_TP_ADD_TC_HAVE_GPREGS(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_GPREGS(a,b)
#endif

#if defined(HAVE_FPREGS)
#define ATF_TP_ADD_TC_HAVE_FPREGS(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_FPREGS(a,b)
#endif

#if defined(HAVE_DBREGS)
#define ATF_TP_ADD_TC_HAVE_DBREGS(a,b) ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_HAVE_DBREGS(a,b)
#endif

#if defined(PT_STEP)
#define ATF_TP_ADD_TC_PT_STEP(a,b)	ATF_TP_ADD_TC(a,b)
#else
#define ATF_TP_ADD_TC_PT_STEP(a,b)
#endif