path: root/lib/igt_aux.c

/*
 * Copyright © 2007, 2011, 2013, 2014, 2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *    Daniel Vetter <daniel.vetter@ffwll.ch>
 *
 */

#ifndef ANDROID
#define _GNU_SOURCE
#else
#include <libgen.h>
#endif
#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <string.h>
#include <sys/mman.h>
#include <signal.h>
#include <pciaccess.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <sys/poll.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include <sys/utsname.h>
#include <termios.h>
#include <assert.h>

#include "drmtest.h"
#include "i915_drm.h"
#include "intel_chipset.h"
#include "igt_aux.h"
#include "igt_debugfs.h"
#include "igt_gt.h"
#include "igt_rand.h"
#include "config.h"
#include "intel_reg.h"
#include "ioctl_wrappers.h"
#include "igt_kms.h"
#include "igt_stats.h"
#include "igt_sysfs.h"

/**
 * SECTION:igt_aux
 * @short_description: Auxiliary libraries and support functions
 * @title: aux
 * @include: igt.h
 *
 * This library provides various auxiliary helper functions that don't really
 * fit into any other topic.
 */

static struct __igt_sigiter_global {
	pid_t tid;
	timer_t timer;
	struct timespec offset;
	struct {
		long hit, miss;
		long ioctls, signals;
	} stat;
} __igt_sigiter;

static void sigiter(int sig, siginfo_t *info, void *arg)
{
	__igt_sigiter.stat.signals++;
}

#if 0
#define SIG_ASSERT(expr) igt_assert(expr)
#else
#define SIG_ASSERT(expr)
#endif

static int
sig_ioctl(int fd, unsigned long request, void *arg)
{
	struct itimerspec its;
	int ret;

	SIG_ASSERT(__igt_sigiter.timer);
	SIG_ASSERT(__igt_sigiter.tid == gettid());

	memset(&its, 0, sizeof(its));
	if (timer_settime(__igt_sigiter.timer, 0, &its, NULL)) {
		/* oops, we didn't undo the interrupter (i.e. !unwound abort) */
		igt_ioctl = drmIoctl;
		return drmIoctl(fd, request, arg);
	}

	its.it_value = __igt_sigiter.offset;
	do {
		long serial;

		__igt_sigiter.stat.ioctls++;

		ret = 0;
		serial = __igt_sigiter.stat.signals;
		igt_assert(timer_settime(__igt_sigiter.timer, 0, &its, NULL) == 0);
		if (ioctl(fd, request, arg))
			ret = errno;
		if (__igt_sigiter.stat.signals == serial)
			__igt_sigiter.stat.miss++;
		if (ret == 0)
			break;

		if (ret == EINTR) {
			__igt_sigiter.stat.hit++;

			its.it_value.tv_sec *= 2;
			its.it_value.tv_nsec *= 2;
			while (its.it_value.tv_nsec >= NSEC_PER_SEC) {
				its.it_value.tv_nsec -= NSEC_PER_SEC;
				its.it_value.tv_sec += 1;
			}

			SIG_ASSERT(its.it_value.tv_nsec >= 0);
			SIG_ASSERT(its.it_value.tv_sec >= 0);
		}
	} while (ret == EAGAIN || ret == EINTR);

	memset(&its, 0, sizeof(its));
	timer_settime(__igt_sigiter.timer, 0, &its, NULL);

	errno = ret;
	return ret ? -1 : 0;
}

static bool igt_sigiter_start(struct __igt_sigiter *iter, bool enable)
{
	/* Note that until we can automatically clean up on failed/skipped
	 * tests, we cannot assume the state of the igt_ioctl indirection.
	 */
	SIG_ASSERT(igt_ioctl == drmIoctl);
	igt_ioctl = drmIoctl;

	if (enable) {
		struct timespec start, end;
		struct sigevent sev;
		struct sigaction act;
		struct itimerspec its;

		igt_ioctl = sig_ioctl;
		__igt_sigiter.tid = gettid();

		memset(&sev, 0, sizeof(sev));
		sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
		sev.sigev_notify_thread_id = __igt_sigiter.tid;
		sev.sigev_signo = SIGRTMIN;
		igt_assert(timer_create(CLOCK_MONOTONIC, &sev, &__igt_sigiter.timer) == 0);

		memset(&its, 0, sizeof(its));
		igt_assert(timer_settime(__igt_sigiter.timer, 0, &its, NULL) == 0);

		memset(&act, 0, sizeof(act));
		act.sa_sigaction = sigiter;
		act.sa_flags = SA_SIGINFO;
		igt_assert(sigaction(SIGRTMIN, &act, NULL) == 0);

		/* Try to find the approximate delay required to skip over
		 * the timer_setttime and into the following ioctl() to try
		 * and avoid the timer firing before we enter the drmIoctl.
		 */
		igt_assert(clock_gettime(CLOCK_MONOTONIC, &start) == 0);
		igt_assert(timer_settime(__igt_sigiter.timer, 0, &its, NULL) == 0);
		igt_assert(clock_gettime(CLOCK_MONOTONIC, &end) == 0);

		__igt_sigiter.offset.tv_sec = end.tv_sec - start.tv_sec;
		__igt_sigiter.offset.tv_nsec = end.tv_nsec - start.tv_nsec;
		if (__igt_sigiter.offset.tv_nsec < 0) {
			__igt_sigiter.offset.tv_nsec += NSEC_PER_SEC;
			__igt_sigiter.offset.tv_sec -= 1;
		}
		if (__igt_sigiter.offset.tv_sec < 0) {
			__igt_sigiter.offset.tv_nsec = 0;
			__igt_sigiter.offset.tv_sec = 0;
		}
		igt_assert(__igt_sigiter.offset.tv_sec == 0);

		igt_debug("Initial delay for interruption: %ld.%09lds\n",
			  __igt_sigiter.offset.tv_sec,
			  __igt_sigiter.offset.tv_nsec);
	}

	return true;
}

static bool igt_sigiter_stop(struct __igt_sigiter *iter, bool enable)
{
	if (enable) {
		struct sigaction act;

		SIG_ASSERT(igt_ioctl == sig_ioctl);
		SIG_ASSERT(__igt_sigiter.tid == gettid());
		igt_ioctl = drmIoctl;

		timer_delete(__igt_sigiter.timer);

		memset(&act, 0, sizeof(act));
		act.sa_handler = SIG_IGN;
		sigaction(SIGRTMIN, &act, NULL);

		memset(&__igt_sigiter, 0, sizeof(__igt_sigiter));
	}

	memset(iter, 0, sizeof(*iter));
	return false;
}

bool __igt_sigiter_continue(struct __igt_sigiter *iter, bool enable)
{
	if (iter->pass++ == 0)
		return igt_sigiter_start(iter, enable);

	/* If nothing reported SIGINT, nothing will on the next pass, so
	 * give up! Also give up if everything is now executing faster
	 * than current sigtimer.
	 */
	if (__igt_sigiter.stat.hit == 0 ||
	    __igt_sigiter.stat.miss == __igt_sigiter.stat.ioctls)
		return igt_sigiter_stop(iter, enable);

	igt_debug("%s: pass %d, missed %ld/%ld\n",
		  __func__, iter->pass - 1,
		  __igt_sigiter.stat.miss,
		  __igt_sigiter.stat.ioctls);

	SIG_ASSERT(igt_ioctl == sig_ioctl);
	SIG_ASSERT(__igt_sigiter.timer);

	__igt_sigiter.offset.tv_sec *= 2;
	__igt_sigiter.offset.tv_nsec *= 2;
	while (__igt_sigiter.offset.tv_nsec >= NSEC_PER_SEC) {
		__igt_sigiter.offset.tv_nsec -= NSEC_PER_SEC;
		__igt_sigiter.offset.tv_sec += 1;
	}
	SIG_ASSERT(__igt_sigiter.offset.tv_nsec >= 0);
	SIG_ASSERT(__igt_sigiter.offset.tv_sec >= 0);

	memset(&__igt_sigiter.stat, 0, sizeof(__igt_sigiter.stat));
	return true;
}

static struct igt_helper_process signal_helper;
long long int sig_stat;
static void __attribute__((noreturn)) signal_helper_process(pid_t pid)
{
	/* Interrupt the parent process at 500Hz, just to be annoying */
	while (1) {
		usleep(1000 * 1000 / 500);
		if (kill(pid, SIGCONT)) /* Parent has died, so must we. */
			exit(0);
	}
}

static void sig_handler(int i)
{
	sig_stat++;
}

/**
 * igt_fork_signal_helper:
 *
 * Fork a child process using #igt_fork_helper to interrupt the parent process
 * with a SIGCONT signal at regular quick intervals. The corresponding dummy
 * signal handler is installed in the parent process.
 *
 * This is useful to exercise ioctl error paths, at least where those can be
 * exercises by interrupting blocking waits, like stalling for the gpu. This
 * helper can also be used from children spawned with #igt_fork.
 *
 * In tests with subtests this function can be called outside of failure
 * catching code blocks like #igt_fixture or #igt_subtest.
 *
 * Note that this just spews signals at the current process unconditionally and
 * hence incurs quite a bit of overhead. For a more focused approach, with less
 * overhead, look at the #igt_while_interruptible code block macro.
 */
void igt_fork_signal_helper(void)
{
	if (igt_only_list_subtests())
		return;

	/* We pick SIGCONT as it is a "safe" signal - if we send SIGCONT to
	 * an unexpecting process it spuriously wakes up and does nothing.
	 * Most other signals (e.g. SIGUSR1) cause the process to die if they
	 * are not handled. This is an issue in case the sighandler is not
	 * inherited correctly (or if there is a race in the inheritance
	 * and we send the signal at exactly the wrong time).
	 */
	signal(SIGCONT, sig_handler);
	setpgrp(); /* define a new process group for the tests */

	igt_fork_helper(&signal_helper) {
		setpgrp(); /* Escape from the test process group */

		/* Pass along the test process group identifier,
		 * negative pid => send signal to everyone in the group.
		 */
		signal_helper_process(-getppid());
	}
}

/**
 * igt_stop_signal_helper:
 *
 * Stops the child process spawned with igt_fork_signal_helper() again.
 *
 * In tests with subtests this function can be called outside of failure
 * catching code blocks like #igt_fixture or #igt_subtest.
 */
void igt_stop_signal_helper(void)
{
	if (igt_only_list_subtests())
		return;

	igt_stop_helper(&signal_helper);

	sig_stat = 0;
}

#if HAVE_UDEV
#include <libudev.h>

static struct igt_helper_process hang_detector;
static void __attribute__((noreturn))
hang_detector_process(pid_t pid, dev_t rdev)
{
	struct udev_monitor *mon =
		udev_monitor_new_from_netlink(udev_new(), "kernel");
	struct pollfd pfd;

	udev_monitor_filter_add_match_subsystem_devtype(mon, "drm", NULL);
	udev_monitor_enable_receiving(mon);

	pfd.fd = udev_monitor_get_fd(mon);
	pfd.events = POLLIN;

	while (poll(&pfd, 1, -1) > 0) {
		struct udev_device *dev = udev_monitor_receive_device(mon);
		dev_t devnum;

		if (dev == NULL)
			continue;

		devnum = udev_device_get_devnum(dev);
		if (memcmp(&rdev, &devnum, sizeof(dev_t)) == 0) {
			const char *str;

			str = udev_device_get_property_value(dev, "ERROR");
			if (str && atoi(str) == 1)
				kill(pid, SIGRTMAX);
		}

		udev_device_unref(dev);
		if (kill(pid, 0)) /* Parent has died, so must we. */
			break;
	}

	exit(0);
}

static void sig_abort(int sig)
{
	errno = 0; /* inside a signal, last errno reporting is confusing */
	igt_assert(!"GPU hung");
}

void igt_fork_hang_detector(int fd)
{
	struct stat st;

	igt_assert(fstat(fd, &st) == 0);

	signal(SIGRTMAX, sig_abort);
	igt_fork_helper(&hang_detector)
		hang_detector_process(getppid(), st.st_rdev);
}

void igt_stop_hang_detector(void)
{
	igt_stop_helper(&hang_detector);
}
#else
void igt_fork_hang_detector(int fd)
{
	if (igt_only_list_subtests())
		return;
}

void igt_stop_hang_detector(void)
{
}
#endif

/**
 * igt_check_boolean_env_var:
 * @env_var: environment variable name
 * @default_value: default value for the environment variable
 *
 * This function should be used to parse boolean environment variable options.
 *
 * Returns:
 * The boolean value of the environment variable @env_var as decoded by atoi()
 * if it is set and @default_value if the variable is not set.
 */
bool igt_check_boolean_env_var(const char *env_var, bool default_value)
{
	char *val;

	val = getenv(env_var);
	if (!val)
		return default_value;

	return atoi(val) != 0;
}

/**
 * igt_aub_dump_enabled:
 *
 * Returns:
 * True if AUB dumping is enabled with IGT_DUMP_AUB=1 in the environment, false
 * otherwise.
 */
bool igt_aub_dump_enabled(void)
{
	static int dump_aub = -1;

	if (dump_aub == -1)
		dump_aub = igt_check_boolean_env_var("IGT_DUMP_AUB", false);

	return dump_aub;
}

/* other helpers */
/**
 * igt_exchange_int:
 * @array: pointer to the array of integers
 * @i: first position
 * @j: second position
 *
 * Exchanges the two values at array indices @i and @j. Useful as an exchange
 * function for igt_permute_array().
 */
void igt_exchange_int(void *array, unsigned i, unsigned j)
{
	int *int_arr, tmp;
	int_arr = array;

	tmp = int_arr[i];
	int_arr[i] = int_arr[j];
	int_arr[j] = tmp;
}

/**
 * igt_permute_array:
 * @array: pointer to array
 * @size: size of the array
 * @exchange_func: function to exchange array elements
 *
 * This function randomly permutes the array using random() as the PRNG source.
 * The @exchange_func function is called to exchange two elements in the array
 * when needed.
 */
void igt_permute_array(void *array, unsigned size,
                       void (*exchange_func)(void *array,
                                             unsigned i,
                                             unsigned j))
{
	int i;

	for (i = size - 1; i > 1; i--) {
		/* yes, not perfectly uniform, who cares */
		long l = hars_petruska_f54_1_random_unsafe() % (i +1);
		if (i != l)
			exchange_func(array, i, l);
	}
}

__attribute__((format(printf, 1, 2)))
static void igt_interactive_info(const char *format, ...)
{
	va_list args;

	if (!isatty(STDERR_FILENO) || __igt_plain_output)
		return;

	if (igt_log_level > IGT_LOG_INFO)
		return;

	va_start(args, format);
	vfprintf(stderr, format, args);
	va_end(args);
}


/**
 * igt_progress:
 * @header: header string to prepend to the progress indicator
 * @i: work processed thus far
 * @total: total amount of work
 *
 * This function draws a progress indicator, which is useful for running
 * long-winded tests manually on the console. To avoid spamming log files in
 * automated runs the progress indicator is suppressed when not running on a
 * terminal.
 */
void igt_progress(const char *header, uint64_t i, uint64_t total)
{
	int divider = 200;

	if (i+1 >= total) {
		igt_interactive_info("\r%s100%%\n", header);
		return;
	}

	if (total / 200 == 0)
		divider = 1;

	/* only bother updating about every 0.5% */
	if (i % (total / divider) == 0)
		igt_interactive_info("\r%s%3llu%%", header,
				     (long long unsigned)i * 100 / total);
}

/**
 * igt_print_activity:
 *
 * Print a '.' to indicate activity. This is printed without a newline and
 * only if output is to a terminal.
 */
void igt_print_activity(void)
{
	igt_interactive_info(".");
}

/* mappable aperture trasher helper */
drm_intel_bo **trash_bos;
int num_trash_bos;

/**
 * igt_init_aperture_trashers:
 * @bufmgr: libdrm buffer manager
 *
 * Initialize the aperture trasher using @bufmgr, which can then be run with
 * igt_trash_aperture().
 */
void igt_init_aperture_trashers(drm_intel_bufmgr *bufmgr)
{
	int i;

	num_trash_bos = gem_mappable_aperture_size() / (1024*1024);

	trash_bos = malloc(num_trash_bos * sizeof(drm_intel_bo *));
	igt_assert(trash_bos);

	for (i = 0; i < num_trash_bos; i++)
		trash_bos[i] = drm_intel_bo_alloc(bufmgr, "trash bo", 1024*1024, 4096);
}

/**
 * igt_trash_aperture:
 *
 * Trash the aperture by walking a set of GTT memory mapped objects.
 */
void igt_trash_aperture(void)
{
	int i;
	uint8_t *gtt_ptr;

	for (i = 0; i < num_trash_bos; i++) {
		drm_intel_gem_bo_map_gtt(trash_bos[i]);
		gtt_ptr = trash_bos[i]->virtual;
		*gtt_ptr = 0;
		drm_intel_gem_bo_unmap_gtt(trash_bos[i]);
	}
}

/**
 * igt_cleanup_aperture_trashers:
 *
 * Clean up all aperture trasher state set up with igt_init_aperture_trashers().
 */
void igt_cleanup_aperture_trashers(void)
{
	int i;

	for (i = 0; i < num_trash_bos; i++)
		drm_intel_bo_unreference(trash_bos[i]);

	free(trash_bos);
}

static const char *suspend_state_name[] = {
	[SUSPEND_STATE_FREEZE] = "freeze",
	[SUSPEND_STATE_STANDBY] = "standby",
	[SUSPEND_STATE_MEM] = "mem",
	[SUSPEND_STATE_DISK] = "disk",
};

static const char *suspend_test_name[] = {
	[SUSPEND_TEST_NONE] = "none",
	[SUSPEND_TEST_FREEZER] = "freezer",
	[SUSPEND_TEST_DEVICES] = "devices",
	[SUSPEND_TEST_PLATFORM] = "platform",
	[SUSPEND_TEST_PROCESSORS] = "processors",
	[SUSPEND_TEST_CORE] = "core",
};

static enum igt_suspend_test get_suspend_test(int power_dir)
{
	char *test_line;
	char *test_name;
	enum igt_suspend_test test;

	if (faccessat(power_dir, "pm_test", R_OK, 0))
		return SUSPEND_TEST_NONE;

	igt_assert((test_line = igt_sysfs_get(power_dir, "pm_test")));
	for (test_name = strtok(test_line, " "); test_name;
	     test_name = strtok(NULL, " "))
		if (test_name[0] == '[') {
			test_name[strlen(test_name) - 1] = '\0';
			test_name++;
			break;
		}

	for (test = SUSPEND_TEST_NONE; test < SUSPEND_TEST_NUM; test++)
		if (strcmp(suspend_test_name[test], test_name) == 0)
			break;

	igt_assert(test < SUSPEND_TEST_NUM);

	free(test_line);

	return test;
}

static void set_suspend_test(int power_dir, enum igt_suspend_test test)
{
	igt_assert(test < SUSPEND_TEST_NUM);

	if (faccessat(power_dir, "pm_test", W_OK, 0)) {
		igt_require(test == SUSPEND_TEST_NONE);
		return;
	}

	igt_assert(igt_sysfs_set(power_dir, "pm_test", suspend_test_name[test]));
}

#define SQUELCH ">/dev/null 2>&1"

static void suspend_via_rtcwake(enum igt_suspend_state state)
{
	char cmd[128];
	int delay;

	igt_assert(state < SUSPEND_STATE_NUM);

	delay = state == SUSPEND_STATE_DISK ? 30 : 15;

	/*
	 * Skip if rtcwake would fail for a reason not related to the kernel's
	 * suspend functionality.
	 */
	snprintf(cmd, sizeof(cmd), "rtcwake -n -s %d -m %s " SQUELCH,
		 delay, suspend_state_name[state]);
	igt_require(system(cmd) == 0);

	snprintf(cmd, sizeof(cmd), "rtcwake -s %d -m %s ",
		 delay, suspend_state_name[state]);
	igt_assert_f(system(cmd) == 0,
		     "This failure means that something is wrong with "
		     "the rtcwake tool or how your distro is set up. "
		     "This is not a i915.ko or i-g-t bug.\n");
}

static void suspend_via_sysfs(int power_dir, enum igt_suspend_state state)
{
	igt_assert(state < SUSPEND_STATE_NUM);
	igt_assert(igt_sysfs_set(power_dir, "state",
				 suspend_state_name[state]));
}

static uint32_t get_supported_suspend_states(int power_dir)
{
	char *states;
	char *state_name;
	uint32_t state_mask;

	igt_assert((states = igt_sysfs_get(power_dir, "state")));
	state_mask = 0;
	for (state_name = strtok(states, " "); state_name;
	     state_name = strtok(NULL, " ")) {
		enum igt_suspend_state state;

		for (state = SUSPEND_STATE_FREEZE; state < SUSPEND_STATE_NUM;
		     state++)
			if (strcmp(state_name, suspend_state_name[state]) == 0)
				break;
		igt_assert(state < SUSPEND_STATE_NUM);
		state_mask |= 1 << state;
	}

	free(states);

	return state_mask;
}

/**
 * igt_system_suspend_autoresume:
 * @state: an #igt_suspend_state, the target suspend state
 * @test: an #igt_suspend_test, test point at which to complete the suspend
 *	  cycle
 *
 * Execute a system suspend cycle targeting the given @state optionally
 * completing the cycle at the given @test point and automaically wake up
 * again. Waking up is either achieved using the RTC wake-up alarm for a full
 * suspend cycle or a kernel timer for a suspend test cycle. The kernel timer
 * delay for a test cycle can be configured by the suspend.pm_test_delay
 * kernel parameter (5 sec by default).
 *
 * #SUSPEND_TEST_NONE specifies a full suspend cycle.
 * The #SUSPEND_TEST_FREEZER..#SUSPEND_TEST_CORE test points can make it
 * possible to collect error logs in case a full suspend cycle would prevent
 * this by hanging the machine, or they can provide an idea of the faulty
 * component by comparing fail/no-fail results at different test points.
 *
 * This is very handy for implementing any kind of suspend/resume test.
 */
void igt_system_suspend_autoresume(enum igt_suspend_state state,
				   enum igt_suspend_test test)
{
	int power_dir;
	enum igt_suspend_test orig_test;

	/* FIXME: Simulation doesn't like suspend/resume, and not even a lighter
	 * approach using /sys/power/pm_test to just test our driver's callbacks
	 * seems to fare better. We need to investigate what's going on. */
	igt_skip_on_simulation();

	igt_require((power_dir = open("/sys/power", O_RDONLY)) >= 0);
	igt_require(get_supported_suspend_states(power_dir) & (1 << state));
	igt_require(test == SUSPEND_TEST_NONE ||
		    faccessat(power_dir, "pm_test", R_OK | W_OK, 0) == 0);

	orig_test = get_suspend_test(power_dir);
	set_suspend_test(power_dir, test);

	if (test == SUSPEND_TEST_NONE)
		suspend_via_rtcwake(state);
	else
		suspend_via_sysfs(power_dir, state);

	set_suspend_test(power_dir, orig_test);
	close(power_dir);
}

/**
 * igt_drop_root:
 *
 * Drop root privileges and make sure it actually worked. Useful for tests
 * which need to check security constraints. Note that this should only be
 * called from manually forked processes, since the lack of root privileges
 * will wreak havoc with the automatic cleanup handlers.
 */
void igt_drop_root(void)
{
	igt_assert(getuid() == 0);

	igt_assert(setgid(2) == 0);
	igt_assert(setuid(2) == 0);

	igt_assert(getgid() == 2);
	igt_assert(getuid() == 2);
}

/**
 * igt_debug_wait_for_keypress:
 * @var: var lookup to to enable this wait
 *
 * Waits for a key press when run interactively and when the corresponding debug
 * var is set in the --interactive-debug=<var> variable. Multiple keys
 * can be specified as a comma-separated list or alternatively "all" if a wait
 * should happen for all cases.
 *
 * When not connected to a terminal interactive_debug is ignored
 * and execution immediately continues.
 *
 * This is useful for display tests where under certain situation manual
 * inspection of the display is useful. Or when running a testcase in the
 * background.
 */
void igt_debug_wait_for_keypress(const char *var)
{
	struct termios oldt, newt;

	if (!isatty(STDIN_FILENO))
		return;

	if (!igt_interactive_debug)
		return;

	if (!strstr(igt_interactive_debug, var) &&
	    !strstr(igt_interactive_debug, "all"))
		return;

	igt_info("Press any key to continue ...\n");

	tcgetattr ( STDIN_FILENO, &oldt );
	newt = oldt;
	newt.c_lflag &= ~( ICANON | ECHO );
	tcsetattr ( STDIN_FILENO, TCSANOW, &newt );
	getchar();
	tcsetattr ( STDIN_FILENO, TCSANOW, &oldt );
}

/**
 * igt_debug_manual_check:
 * @var: var lookup to to enable this wait
 * @expected: message to be printed as expected behaviour before wait for keys Y/n
 *
 * Waits for a key press when run interactively and when the corresponding debug
 * var is set in the --interactive-debug=<var> variable. Multiple vars
 * can be specified as a comma-separated list or alternatively "all" if a wait
 * should happen for all cases.
 *
 * This is useful for display tests where under certain situation manual
 * inspection of the display is useful. Or when running a testcase in the
 * background.
 *
 * When not connected to a terminal interactive_debug is ignored
 * and execution immediately continues. For this reason by default this function
 * returns true. It returns false only when N/n is pressed indicating the
 * user isn't seeing what was expected.
 *
 * Force test fail when N/n is pressed.
 */
void igt_debug_manual_check(const char *var, const char *expected)
{
	struct termios oldt, newt;
	char key;

	if (!isatty(STDIN_FILENO))
		return;

	if (!igt_interactive_debug)
		return;

	if (!strstr(igt_interactive_debug, var) &&
	    !strstr(igt_interactive_debug, "all"))
		return;

	igt_info("Is %s [Y/n]", expected);

	tcgetattr ( STDIN_FILENO, &oldt );
	newt = oldt;
	newt.c_lflag &= ~ICANON;
	tcsetattr ( STDIN_FILENO, TCSANOW, &newt );
	key = getchar();
	tcsetattr ( STDIN_FILENO, TCSANOW, &oldt );

	igt_info("\n");

	igt_assert(key != 'n' && key != 'N');
}

/* Functions with prefix kmstest_ independent of cairo library are pulled out
 * from file igt_kms.c since this file is skipped in lib/Android.mk when flag
 * ANDROID_HAS_CAIRO is 0. This ensures the usability of these functions even
 * when cairo library is not present on Android.
 */

struct type_name {
	int type;
	const char *name;
};

static const char *find_type_name(const struct type_name *names, int type)
{
	for (; names->name; names++) {
		if (names->type == type)
			return names->name;
	}

	return "(invalid)";
}

static const struct type_name encoder_type_names[] = {
	{ DRM_MODE_ENCODER_NONE, "none" },
	{ DRM_MODE_ENCODER_DAC, "DAC" },
	{ DRM_MODE_ENCODER_TMDS, "TMDS" },
	{ DRM_MODE_ENCODER_LVDS, "LVDS" },
	{ DRM_MODE_ENCODER_TVDAC, "TVDAC" },
	{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
	{ DRM_MODE_ENCODER_DSI, "DSI" },
	{ DRM_MODE_ENCODER_DPMST, "DP MST" },
	{}
};

/**
 * kmstest_encoder_type_str:
 * @type: DRM_MODE_ENCODER_* enumeration value
 *
 * Returns: A string representing the drm encoder @type.
 */
const char *kmstest_encoder_type_str(int type)
{
	return find_type_name(encoder_type_names, type);
}

static const struct type_name connector_status_names[] = {
	{ DRM_MODE_CONNECTED, "connected" },
	{ DRM_MODE_DISCONNECTED, "disconnected" },
	{ DRM_MODE_UNKNOWNCONNECTION, "unknown" },
	{}
};

/**
 * kmstest_connector_status_str:
 * @status: DRM_MODE_* connector status value
 *
 * Returns: A string representing the drm connector status @status.
 */
const char *kmstest_connector_status_str(int status)
{
	return find_type_name(connector_status_names, status);
}

static const struct type_name connector_type_names[] = {
	{ DRM_MODE_CONNECTOR_Unknown, "unknown" },
	{ DRM_MODE_CONNECTOR_VGA, "VGA" },
	{ DRM_MODE_CONNECTOR_DVII, "DVI-I" },
	{ DRM_MODE_CONNECTOR_DVID, "DVI-D" },
	{ DRM_MODE_CONNECTOR_DVIA, "DVI-A" },
	{ DRM_MODE_CONNECTOR_Composite, "composite" },
	{ DRM_MODE_CONNECTOR_SVIDEO, "s-video" },
	{ DRM_MODE_CONNECTOR_LVDS, "LVDS" },
	{ DRM_MODE_CONNECTOR_Component, "component" },
	{ DRM_MODE_CONNECTOR_9PinDIN, "9-pin DIN" },
	{ DRM_MODE_CONNECTOR_DisplayPort, "DP" },
	{ DRM_MODE_CONNECTOR_HDMIA, "HDMI-A" },
	{ DRM_MODE_CONNECTOR_HDMIB, "HDMI-B" },
	{ DRM_MODE_CONNECTOR_TV, "TV" },
	{ DRM_MODE_CONNECTOR_eDP, "eDP" },
	{ DRM_MODE_CONNECTOR_VIRTUAL, "Virtual" },
	{ DRM_MODE_CONNECTOR_DSI, "DSI" },
	{}
};

/**
 * kmstest_connector_type_str:
 * @type: DRM_MODE_CONNECTOR_* enumeration value
 *
 * Returns: A string representing the drm connector @type.
 */
const char *kmstest_connector_type_str(int type)
{
	return find_type_name(connector_type_names, type);
}

/**
 * igt_lock_mem:
 * @size: the amount of memory to lock into RAM, in MB
 *
 * Allocate @size MB of memory and lock it into RAM. This releases any
 * previously locked memory.
 *
 * Use #igt_unlock_mem to release the currently locked memory.
 */
static char *locked_mem;
static size_t locked_size;

void igt_lock_mem(size_t size)
{
	long pagesize = sysconf(_SC_PAGESIZE);
	size_t i;
	int ret;

	if (size == 0) {
		return;
	}

	if (locked_mem) {
		igt_unlock_mem();
		igt_warn("Unlocking previously locked memory.\n");
	}

	locked_size = size * 1024 * 1024;

	locked_mem = malloc(locked_size);
	igt_require_f(locked_mem,
		      "Could not allocate enough memory to lock.\n");

	/* write into each page to ensure it is allocated */
	for (i = 0; i < locked_size; i += pagesize)
		locked_mem[i] = i;

	ret = mlock(locked_mem, locked_size);
	igt_assert_f(ret == 0, "Could not lock memory into RAM.\n");
}

/**
 * igt_unlock_mem:
 *
 * Release and free the RAM used by #igt_lock_mem.
 */
void igt_unlock_mem(void)
{
	if (!locked_mem)
		return;

	munlock(locked_mem, locked_size);

	free(locked_mem);
	locked_mem = NULL;
}


#define MODULE_PARAM_DIR "/sys/module/i915/parameters/"
#define PARAM_NAME_MAX_SZ 32
#define PARAM_VALUE_MAX_SZ 16
#define PARAM_FILE_PATH_MAX_SZ (strlen(MODULE_PARAM_DIR) + PARAM_NAME_MAX_SZ)

struct module_param_data {
	char name[PARAM_NAME_MAX_SZ];
	char original_value[PARAM_VALUE_MAX_SZ];

	struct module_param_data *next;
};
struct module_param_data *module_params = NULL;

static void igt_module_param_exit_handler(int sig)
{
	const size_t dir_len = strlen(MODULE_PARAM_DIR);
	char file_path[PARAM_FILE_PATH_MAX_SZ];
	struct module_param_data *data;
	int fd;

	/* We don't need to assert string sizes on this function since they were
	 * already checked before being stored on the lists. Besides,
	 * igt_assert() is not AS-Safe. */
	strcpy(file_path, MODULE_PARAM_DIR);

	for (data = module_params; data != NULL; data = data->next) {
		strcpy(file_path + dir_len, data->name);

		fd = open(file_path, O_RDWR);
		if (fd >= 0) {
			int size = strlen (data->original_value);

			if (size != write(fd, data->original_value, size)) {
				const char msg[] = "WARNING: Module parameters "
					"may not have been reset to their "
					"original values\n";
				assert(write(STDERR_FILENO, msg, sizeof(msg))
				       == sizeof(msg));
			}

			close(fd);
		}
	}
	/* free() is not AS-Safe, so we can't call it here. */
}

/**
 * igt_save_module_param:
 * @name: name of the i915.ko module parameter
 * @file_path: full sysfs file path for the parameter
 *
 * Reads the current value of an i915.ko module parameter, saves it on an array,
 * then installs an exit handler to restore it when the program exits.
 *
 * It is safe to call this function multiple times for the same parameter.
 *
 * Notice that this function is called by igt_set_module_param(), so that one -
 * or one of its wrappers - is the only function the test programs need to call.
 */
static void igt_save_module_param(const char *name, const char *file_path)
{
	struct module_param_data *data;
	size_t n;
	int fd;

	/* Check if this parameter is already saved. */
	for (data = module_params; data != NULL; data = data->next)
		if (strncmp(data->name, name, PARAM_NAME_MAX_SZ) == 0)
			return;

	if (!module_params)
		igt_install_exit_handler(igt_module_param_exit_handler);

	data = calloc(1, sizeof (*data));
	igt_assert(data);

	strncpy(data->name, name, PARAM_NAME_MAX_SZ);

	fd = open(file_path, O_RDONLY);
	igt_assert(fd >= 0);

	n = read(fd, data->original_value, PARAM_VALUE_MAX_SZ);
	igt_assert_f(n > 0 && n < PARAM_VALUE_MAX_SZ,
		     "Need to increase PARAM_VALUE_MAX_SZ\n");

	igt_assert(close(fd) == 0);

	data->next = module_params;
	module_params = data;
}

/**
 * igt_set_module_param:
 * @name: i915.ko parameter name
 * @val: i915.ko parameter value
 *
 * This function sets the desired value for the given i915.ko parameter. It also
 * takes care of saving and restoring the values that were already set before
 * the test was run.
 *
 * Please consider using igt_set_module_param_int() for the integer and bool
 * parameters.
 */
void igt_set_module_param(const char *name, const char *val)
{
	char file_path[PARAM_FILE_PATH_MAX_SZ];
	size_t len = strlen(val);
	int fd;

	igt_assert_f(strlen(name) < PARAM_NAME_MAX_SZ,
		     "Need to increase PARAM_NAME_MAX_SZ\n");
	strcpy(file_path, MODULE_PARAM_DIR);
	strcpy(file_path + strlen(MODULE_PARAM_DIR), name);

	igt_save_module_param(name, file_path);

	fd = open(file_path, O_RDWR);
	igt_assert(write(fd, val, len) == len);
	igt_assert(close(fd) == 0);
}

/**
 * igt_set_module_param_int:
 * @name: i915.ko parameter name
 * @val: i915.ko parameter value
 *
 * This is a wrapper for igt_set_module_param() that takes an integer instead of
 * a string. Please see igt_set_module_param().
 */
void igt_set_module_param_int(const char *name, int val)
{
	char str[PARAM_VALUE_MAX_SZ];
	int n;

	n = snprintf(str, PARAM_VALUE_MAX_SZ, "%d\n", val);
	igt_assert_f(n < PARAM_VALUE_MAX_SZ,
		     "Need to increase PARAM_VALUE_MAX_SZ\n");

	igt_set_module_param(name, str);
}

static struct igt_siglatency {
	timer_t timer;
	struct timespec target;
	struct sigaction oldact;
	struct igt_mean mean;

	int sig;
} igt_siglatency;

static long delay(void)
{
	return hars_petruska_f54_1_random_unsafe() % (NSEC_PER_SEC / 1000);
}

static double elapsed(const struct timespec *now, const struct timespec *last)
{
	double nsecs;

	nsecs = now->tv_nsec - last ->tv_nsec;
	nsecs += 1e9*(now->tv_sec - last->tv_sec);

	return nsecs;
}

static void siglatency(int sig, siginfo_t *info, void *arg)
{
	struct itimerspec its;

	clock_gettime(CLOCK_MONOTONIC, &its.it_value);
	if (info)
		igt_mean_add(&igt_siglatency.mean,
			     elapsed(&its.it_value, &igt_siglatency.target));
	igt_siglatency.target = its.it_value;

	its.it_value.tv_nsec += 100 * 1000;
	its.it_value.tv_nsec += delay();
	if (its.it_value.tv_nsec >= NSEC_PER_SEC) {
		its.it_value.tv_nsec -= NSEC_PER_SEC;
		its.it_value.tv_sec += 1;
	}
	its.it_interval.tv_sec = its.it_interval.tv_nsec = 0;
	timer_settime(igt_siglatency.timer, TIMER_ABSTIME, &its, NULL);
}

void igt_start_siglatency(int sig)
{
	struct sigevent sev;
	struct sigaction act;

	if (sig <= 0)
		sig = SIGRTMIN;

	if (igt_siglatency.sig)
		(void)igt_stop_siglatency(NULL);
	igt_assert(igt_siglatency.sig == 0);
	igt_siglatency.sig = sig;

	memset(&sev, 0, sizeof(sev));
	sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
	sev.sigev_notify_thread_id = gettid();
	sev.sigev_signo = sig;
	timer_create(CLOCK_MONOTONIC, &sev, &igt_siglatency.timer);

	memset(&act, 0, sizeof(act));
	act.sa_sigaction = siglatency;
	sigaction(sig, &act, &igt_siglatency.oldact);

	siglatency(sig, NULL, NULL);
}

double igt_stop_siglatency(struct igt_mean *result)
{
	double mean = igt_mean_get(&igt_siglatency.mean);

	if (result)
		*result = igt_siglatency.mean;

	sigaction(igt_siglatency.sig, &igt_siglatency.oldact, NULL);
	timer_delete(igt_siglatency.timer);
	memset(&igt_siglatency, 0, sizeof(igt_siglatency));

	return mean;
}