tools/testing/selftests/bpf/progs/timer.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2021 Facebook */
 #include <linux/bpf.h>
 #include <time.h>
 #include <errno.h>
 #include <bpf/bpf_helpers.h>
 #include "bpf_tcp_helpers.h"

 char _license[] SEC("license") = "GPL";
 struct hmap_elem {
 	int counter;
 	struct bpf_timer timer;
 	struct bpf_spin_lock lock; /* unused */
 };

 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
 	__uint(max_entries, 1000);
 	__type(key, int);
 	__type(value, struct hmap_elem);
 } hmap SEC(".maps");

 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
 	__uint(map_flags, BPF_F_NO_PREALLOC);
 	__uint(max_entries, 1000);
 	__type(key, int);
 	__type(value, struct hmap_elem);
 } hmap_malloc SEC(".maps");

 struct elem {
 	struct bpf_timer t;
 };

 struct {
 	__uint(type, BPF_MAP_TYPE_ARRAY);
 	__uint(max_entries, 2);
 	__type(key, int);
 	__type(value, struct elem);
 } array SEC(".maps");

 struct {
 	__uint(type, BPF_MAP_TYPE_LRU_HASH);
 	__uint(max_entries, 4);
 	__type(key, int);
 	__type(value, struct elem);
 } lru SEC(".maps");

 struct {
 	__uint(type, BPF_MAP_TYPE_ARRAY);
 	__uint(max_entries, 1);
 	__type(key, int);
 	__type(value, struct elem);
 } abs_timer SEC(".maps"), soft_timer_pinned SEC(".maps"), abs_timer_pinned SEC(".maps"),
 	race_array SEC(".maps");

 __u64 bss_data;
 __u64 abs_data;
 __u64 err;
 __u64 ok;
 __u64 callback_check = 52;
 __u64 callback2_check = 52;
 __u64 pinned_callback_check;
 __s32 pinned_cpu;

 #define ARRAY 1
 #define HTAB 2
 #define HTAB_MALLOC 3
 #define LRU 4

 /* callback for array and lru timers */
 static int timer_cb1(void *map, int *key, struct bpf_timer *timer)
 {
 	/* increment bss variable twice.
 	 * Once via array timer callback and once via lru timer callback
 	 */
 	bss_data += 5;

 	/* *key == 0 - the callback was called for array timer.
 	 * *key == 4 - the callback was called from lru timer.
 	 */
 	if (*key == ARRAY) {
 		struct bpf_timer *lru_timer;
 		int lru_key = LRU;

 		/* rearm array timer to be called again in ~35 seconds */
 		if (bpf_timer_start(timer, 1ull << 35, 0) != 0)
 			err |= 1;

 		lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
 		if (!lru_timer)
 			return 0;
 		bpf_timer_set_callback(lru_timer, timer_cb1);
 		if (bpf_timer_start(lru_timer, 0, 0) != 0)
 			err |= 2;
 	} else if (*key == LRU) {
 		int lru_key, i;

 		for (i = LRU + 1;
 		     i <= 100  /* for current LRU eviction algorithm this number
 				* should be larger than ~ lru->max_entries * 2
 				*/;
 		     i++) {
 			struct elem init = {};

 			/* lru_key cannot be used as loop induction variable
 			 * otherwise the loop will be unbounded.
 			 */
 			lru_key = i;

 			/* add more elements into lru map to push out current
 			 * element and force deletion of this timer
 			 */
 			bpf_map_update_elem(map, &lru_key, &init, 0);
 			/* look it up to bump it into active list */
 			bpf_map_lookup_elem(map, &lru_key);

 			/* keep adding until *key changes underneath,
 			 * which means that key/timer memory was reused
 			 */
 			if (*key != LRU)
 				break;
 		}

 		/* check that the timer was removed */
 		if (bpf_timer_cancel(timer) != -EINVAL)
 			err |= 4;
 		ok |= 1;
 	}
 	return 0;
 }

 SEC("fentry/bpf_fentry_test1")
 int BPF_PROG2(test1, int, a)
 {
 	struct bpf_timer *arr_timer, *lru_timer;
 	struct elem init = {};
 	int lru_key = LRU;
 	int array_key = ARRAY;

 	arr_timer = bpf_map_lookup_elem(&array, &array_key);
 	if (!arr_timer)
 		return 0;
 	bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);

 	bpf_map_update_elem(&lru, &lru_key, &init, 0);
 	lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
 	if (!lru_timer)
 		return 0;
 	bpf_timer_init(lru_timer, &lru, CLOCK_MONOTONIC);

 	bpf_timer_set_callback(arr_timer, timer_cb1);
 	bpf_timer_start(arr_timer, 0 /* call timer_cb1 asap */, 0);

 	/* init more timers to check that array destruction
 	 * doesn't leak timer memory.
 	 */
 	array_key = 0;
 	arr_timer = bpf_map_lookup_elem(&array, &array_key);
 	if (!arr_timer)
 		return 0;
 	bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);
 	return 0;
 }

 /* callback for prealloc and non-prealloca hashtab timers */
 static int timer_cb2(void *map, int *key, struct hmap_elem *val)
 {
 	if (*key == HTAB)
 		callback_check--;
 	else
 		callback2_check--;
 	if (val->counter > 0 && --val->counter) {
 		/* re-arm the timer again to execute after 1 usec */
 		bpf_timer_start(&val->timer, 1000, 0);
 	} else if (*key == HTAB) {
 		struct bpf_timer *arr_timer;
 		int array_key = ARRAY;

 		/* cancel arr_timer otherwise bpf_fentry_test1 prog
 		 * will stay alive forever.
 		 */
 		arr_timer = bpf_map_lookup_elem(&array, &array_key);
 		if (!arr_timer)
 			return 0;
 		if (bpf_timer_cancel(arr_timer) != 1)
 			/* bpf_timer_cancel should return 1 to indicate
 			 * that arr_timer was active at this time
 			 */
 			err |= 8;

 		/* try to cancel ourself. It shouldn't deadlock. */
 		if (bpf_timer_cancel(&val->timer) != -EDEADLK)
 			err |= 16;

 		/* delete this key and this timer anyway.
 		 * It shouldn't deadlock either.
 		 */
 		bpf_map_delete_elem(map, key);

 		/* in preallocated hashmap both 'key' and 'val' could have been
 		 * reused to store another map element (like in LRU above),
 		 * but in controlled test environment the below test works.
 		 * It's not a use-after-free. The memory is owned by the map.
 		 */
 		if (bpf_timer_start(&val->timer, 1000, 0) != -EINVAL)
 			err |= 32;
 		ok |= 2;
 	} else {
 		if (*key != HTAB_MALLOC)
 			err |= 64;

 		/* try to cancel ourself. It shouldn't deadlock. */
 		if (bpf_timer_cancel(&val->timer) != -EDEADLK)
 			err |= 128;

 		/* delete this key and this timer anyway.
 		 * It shouldn't deadlock either.
 		 */
 		bpf_map_delete_elem(map, key);

 		ok |= 4;
 	}
 	return 0;
 }

 int bpf_timer_test(void)
 {
 	struct hmap_elem *val;
 	int key = HTAB, key_malloc = HTAB_MALLOC;

 	val = bpf_map_lookup_elem(&hmap, &key);
 	if (val) {
 		if (bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME) != 0)
 			err |= 512;
 		bpf_timer_set_callback(&val->timer, timer_cb2);
 		bpf_timer_start(&val->timer, 1000, 0);
 	}
 	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
 	if (val) {
 		if (bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME) != 0)
 			err |= 1024;
 		bpf_timer_set_callback(&val->timer, timer_cb2);
 		bpf_timer_start(&val->timer, 1000, 0);
 	}
 	return 0;
 }

 SEC("fentry/bpf_fentry_test2")
 int BPF_PROG2(test2, int, a, int, b)
 {
 	struct hmap_elem init = {}, *val;
 	int key = HTAB, key_malloc = HTAB_MALLOC;

 	init.counter = 10; /* number of times to trigger timer_cb2 */
 	bpf_map_update_elem(&hmap, &key, &init, 0);
 	val = bpf_map_lookup_elem(&hmap, &key);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
 	/* update the same key to free the timer */
 	bpf_map_update_elem(&hmap, &key, &init, 0);

 	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
 	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
 	/* update the same key to free the timer */
 	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);

 	/* init more timers to check that htab operations
 	 * don't leak timer memory.
 	 */
 	key = 0;
 	bpf_map_update_elem(&hmap, &key, &init, 0);
 	val = bpf_map_lookup_elem(&hmap, &key);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
 	bpf_map_delete_elem(&hmap, &key);
 	bpf_map_update_elem(&hmap, &key, &init, 0);
 	val = bpf_map_lookup_elem(&hmap, &key);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);

 	/* and with non-prealloc htab */
 	key_malloc = 0;
 	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
 	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
 	bpf_map_delete_elem(&hmap_malloc, &key_malloc);
 	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
 	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
 	if (val)
 		bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);

 	return bpf_timer_test();
 }

 /* callback for absolute timer */
 static int timer_cb3(void *map, int *key, struct bpf_timer *timer)
 {
 	abs_data += 6;

 	if (abs_data < 12) {
 		bpf_timer_start(timer, bpf_ktime_get_boot_ns() + 1000,
 				BPF_F_TIMER_ABS);
 	} else {
 		/* Re-arm timer ~35 seconds in future */
 		bpf_timer_start(timer, bpf_ktime_get_boot_ns() + (1ull << 35),
 				BPF_F_TIMER_ABS);
 	}

 	return 0;
 }

 SEC("fentry/bpf_fentry_test3")
 int BPF_PROG2(test3, int, a)
 {
 	int key = 0;
 	struct bpf_timer *timer;

 	bpf_printk("test3");

 	timer = bpf_map_lookup_elem(&abs_timer, &key);
 	if (timer) {
 		if (bpf_timer_init(timer, &abs_timer, CLOCK_BOOTTIME) != 0)
 			err |= 2048;
 		bpf_timer_set_callback(timer, timer_cb3);
 		bpf_timer_start(timer, bpf_ktime_get_boot_ns() + 1000,
 				BPF_F_TIMER_ABS);
 	}

 	return 0;
 }

 /* callback for pinned timer */
 static int timer_cb_pinned(void *map, int *key, struct bpf_timer *timer)
 {
 	__s32 cpu = bpf_get_smp_processor_id();

 	if (cpu != pinned_cpu)
 		err |= 16384;

 	pinned_callback_check++;
 	return 0;
 }

 static void test_pinned_timer(bool soft)
 {
 	int key = 0;
 	void *map;
 	struct bpf_timer *timer;
 	__u64 flags = BPF_F_TIMER_CPU_PIN;
 	__u64 start_time;

 	if (soft) {
 		map = &soft_timer_pinned;
 		start_time = 0;
 	} else {
 		map = &abs_timer_pinned;
 		start_time = bpf_ktime_get_boot_ns();
 		flags |= BPF_F_TIMER_ABS;
 	}

 	timer = bpf_map_lookup_elem(map, &key);
 	if (timer) {
 		if (bpf_timer_init(timer, map, CLOCK_BOOTTIME) != 0)
 			err |= 4096;
 		bpf_timer_set_callback(timer, timer_cb_pinned);
 		pinned_cpu = bpf_get_smp_processor_id();
 		bpf_timer_start(timer, start_time + 1000, flags);
 	} else {
 		err |= 8192;
 	}
 }

 SEC("fentry/bpf_fentry_test4")
 int BPF_PROG2(test4, int, a)
 {
 	bpf_printk("test4");
 	test_pinned_timer(true);

 	return 0;
 }

 SEC("fentry/bpf_fentry_test5")
 int BPF_PROG2(test5, int, a)
 {
 	bpf_printk("test5");
 	test_pinned_timer(false);

 	return 0;
 }

 static int race_timer_callback(void *race_array, int *race_key, struct bpf_timer *timer)
 {
 	bpf_timer_start(timer, 1000000, 0);
 	return 0;
 }

 SEC("syscall")
 int race(void *ctx)
 {
 	struct bpf_timer *timer;
 	int err, race_key = 0;
 	struct elem init;

 	__builtin_memset(&init, 0, sizeof(struct elem));
 	bpf_map_update_elem(&race_array, &race_key, &init, BPF_ANY);

 	timer = bpf_map_lookup_elem(&race_array, &race_key);
 	if (!timer)
 		return 1;

 	err = bpf_timer_init(timer, &race_array, CLOCK_MONOTONIC);
 	if (err && err != -EBUSY)
 		return 1;

 	bpf_timer_set_callback(timer, race_timer_callback);
 	bpf_timer_start(timer, 0, 0);
 	bpf_timer_cancel(timer);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright (c) 2021 Facebook */
	#include <linux/bpf.h>
	#include <time.h>
	#include <errno.h>
	#include <bpf/bpf_helpers.h>
	#include "bpf_tcp_helpers.h"

	char _license[] SEC("license") = "GPL";
	struct hmap_elem {
	int counter;
	struct bpf_timer timer;
	struct bpf_spin_lock lock; /* unused */
	};

	struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(max_entries, 1000);
	__type(key, int);
	__type(value, struct hmap_elem);
	} hmap SEC(".maps");

	struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(map_flags, BPF_F_NO_PREALLOC);
	__uint(max_entries, 1000);
	__type(key, int);
	__type(value, struct hmap_elem);
	} hmap_malloc SEC(".maps");

	struct elem {
	struct bpf_timer t;
	};

	struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 2);
	__type(key, int);
	__type(value, struct elem);
	} array SEC(".maps");

	struct {
	__uint(type, BPF_MAP_TYPE_LRU_HASH);
	__uint(max_entries, 4);
	__type(key, int);
	__type(value, struct elem);
	} lru SEC(".maps");

	struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 1);
	__type(key, int);
	__type(value, struct elem);
	} abs_timer SEC(".maps"), soft_timer_pinned SEC(".maps"), abs_timer_pinned SEC(".maps"),
	race_array SEC(".maps");

	__u64 bss_data;
	__u64 abs_data;
	__u64 err;
	__u64 ok;
	__u64 callback_check = 52;
	__u64 callback2_check = 52;
	__u64 pinned_callback_check;
	__s32 pinned_cpu;

	#define ARRAY 1
	#define HTAB 2
	#define HTAB_MALLOC 3
	#define LRU 4

	/* callback for array and lru timers */
	static int timer_cb1(void map, int key, struct bpf_timer *timer)
	{
	/* increment bss variable twice.
	* Once via array timer callback and once via lru timer callback
	*/
	bss_data += 5;

	/* *key == 0 - the callback was called for array timer.
	* *key == 4 - the callback was called from lru timer.
	*/
	if (*key == ARRAY) {
	struct bpf_timer *lru_timer;
	int lru_key = LRU;

	/* rearm array timer to be called again in ~35 seconds */
	if (bpf_timer_start(timer, 1ull << 35, 0) != 0)
	err \|= 1;

	lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
	if (!lru_timer)
	return 0;
	bpf_timer_set_callback(lru_timer, timer_cb1);
	if (bpf_timer_start(lru_timer, 0, 0) != 0)
	err \|= 2;
	} else if (*key == LRU) {
	int lru_key, i;

	for (i = LRU + 1;
	i <= 100 /* for current LRU eviction algorithm this number
	* should be larger than ~ lru->max_entries * 2
	*/;
	i++) {
	struct elem init = {};

	/* lru_key cannot be used as loop induction variable
	* otherwise the loop will be unbounded.
	*/
	lru_key = i;

	/* add more elements into lru map to push out current
	* element and force deletion of this timer
	*/
	bpf_map_update_elem(map, &lru_key, &init, 0);
	/* look it up to bump it into active list */
	bpf_map_lookup_elem(map, &lru_key);

	/* keep adding until *key changes underneath,
	* which means that key/timer memory was reused
	*/
	if (*key != LRU)
	break;
	}

	/* check that the timer was removed */
	if (bpf_timer_cancel(timer) != -EINVAL)
	err \|= 4;
	ok \|= 1;
	}
	return 0;
	}

	SEC("fentry/bpf_fentry_test1")
	int BPF_PROG2(test1, int, a)
	{
	struct bpf_timer arr_timer, lru_timer;
	struct elem init = {};
	int lru_key = LRU;
	int array_key = ARRAY;

	arr_timer = bpf_map_lookup_elem(&array, &array_key);
	if (!arr_timer)
	return 0;
	bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);

	bpf_map_update_elem(&lru, &lru_key, &init, 0);
	lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
	if (!lru_timer)
	return 0;
	bpf_timer_init(lru_timer, &lru, CLOCK_MONOTONIC);

	bpf_timer_set_callback(arr_timer, timer_cb1);
	bpf_timer_start(arr_timer, 0 /* call timer_cb1 asap */, 0);

	/* init more timers to check that array destruction
	* doesn't leak timer memory.
	*/
	array_key = 0;
	arr_timer = bpf_map_lookup_elem(&array, &array_key);
	if (!arr_timer)
	return 0;
	bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);
	return 0;
	}

	/* callback for prealloc and non-prealloca hashtab timers */
	static int timer_cb2(void map, int key, struct hmap_elem *val)
	{
	if (*key == HTAB)
	callback_check--;
	else
	callback2_check--;
	if (val->counter > 0 && --val->counter) {
	/* re-arm the timer again to execute after 1 usec */
	bpf_timer_start(&val->timer, 1000, 0);
	} else if (*key == HTAB) {
	struct bpf_timer *arr_timer;
	int array_key = ARRAY;

	/* cancel arr_timer otherwise bpf_fentry_test1 prog
	* will stay alive forever.
	*/
	arr_timer = bpf_map_lookup_elem(&array, &array_key);
	if (!arr_timer)
	return 0;
	if (bpf_timer_cancel(arr_timer) != 1)
	/* bpf_timer_cancel should return 1 to indicate
	* that arr_timer was active at this time
	*/
	err \|= 8;

	/* try to cancel ourself. It shouldn't deadlock. */
	if (bpf_timer_cancel(&val->timer) != -EDEADLK)
	err \|= 16;

	/* delete this key and this timer anyway.
	* It shouldn't deadlock either.
	*/
	bpf_map_delete_elem(map, key);

	/* in preallocated hashmap both 'key' and 'val' could have been
	* reused to store another map element (like in LRU above),
	* but in controlled test environment the below test works.
	* It's not a use-after-free. The memory is owned by the map.
	*/
	if (bpf_timer_start(&val->timer, 1000, 0) != -EINVAL)
	err \|= 32;
	ok \|= 2;
	} else {
	if (*key != HTAB_MALLOC)
	err \|= 64;

	/* try to cancel ourself. It shouldn't deadlock. */
	if (bpf_timer_cancel(&val->timer) != -EDEADLK)
	err \|= 128;

	/* delete this key and this timer anyway.
	* It shouldn't deadlock either.
	*/
	bpf_map_delete_elem(map, key);

	ok \|= 4;
	}
	return 0;
	}

	int bpf_timer_test(void)
	{
	struct hmap_elem *val;
	int key = HTAB, key_malloc = HTAB_MALLOC;

	val = bpf_map_lookup_elem(&hmap, &key);
	if (val) {
	if (bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME) != 0)
	err \|= 512;
	bpf_timer_set_callback(&val->timer, timer_cb2);
	bpf_timer_start(&val->timer, 1000, 0);
	}
	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
	if (val) {
	if (bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME) != 0)
	err \|= 1024;
	bpf_timer_set_callback(&val->timer, timer_cb2);
	bpf_timer_start(&val->timer, 1000, 0);
	}
	return 0;
	}

	SEC("fentry/bpf_fentry_test2")
	int BPF_PROG2(test2, int, a, int, b)
	{
	struct hmap_elem init = {}, *val;
	int key = HTAB, key_malloc = HTAB_MALLOC;

	init.counter = 10; /* number of times to trigger timer_cb2 */
	bpf_map_update_elem(&hmap, &key, &init, 0);
	val = bpf_map_lookup_elem(&hmap, &key);
	if (val)
	bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
	/* update the same key to free the timer */
	bpf_map_update_elem(&hmap, &key, &init, 0);

	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
	if (val)
	bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
	/* update the same key to free the timer */
	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);

	/* init more timers to check that htab operations
	* don't leak timer memory.
	*/
	key = 0;
	bpf_map_update_elem(&hmap, &key, &init, 0);
	val = bpf_map_lookup_elem(&hmap, &key);
	if (val)
	bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
	bpf_map_delete_elem(&hmap, &key);
	bpf_map_update_elem(&hmap, &key, &init, 0);
	val = bpf_map_lookup_elem(&hmap, &key);
	if (val)
	bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);

	/* and with non-prealloc htab */
	key_malloc = 0;
	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
	if (val)
	bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
	bpf_map_delete_elem(&hmap_malloc, &key_malloc);
	bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
	val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
	if (val)
	bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);

	return bpf_timer_test();
	}

	/* callback for absolute timer */
	static int timer_cb3(void map, int key, struct bpf_timer *timer)
	{
	abs_data += 6;

	if (abs_data < 12) {
	bpf_timer_start(timer, bpf_ktime_get_boot_ns() + 1000,
	BPF_F_TIMER_ABS);
	} else {
	/* Re-arm timer ~35 seconds in future */
	bpf_timer_start(timer, bpf_ktime_get_boot_ns() + (1ull << 35),
	BPF_F_TIMER_ABS);
	}

	return 0;
	}

	SEC("fentry/bpf_fentry_test3")
	int BPF_PROG2(test3, int, a)
	{
	int key = 0;
	struct bpf_timer *timer;

	bpf_printk("test3");

	timer = bpf_map_lookup_elem(&abs_timer, &key);
	if (timer) {
	if (bpf_timer_init(timer, &abs_timer, CLOCK_BOOTTIME) != 0)
	err \|= 2048;
	bpf_timer_set_callback(timer, timer_cb3);
	bpf_timer_start(timer, bpf_ktime_get_boot_ns() + 1000,
	BPF_F_TIMER_ABS);
	}

	return 0;
	}

	/* callback for pinned timer */
	static int timer_cb_pinned(void map, int key, struct bpf_timer *timer)
	{
	__s32 cpu = bpf_get_smp_processor_id();

	if (cpu != pinned_cpu)
	err \|= 16384;

	pinned_callback_check++;
	return 0;
	}

	static void test_pinned_timer(bool soft)
	{
	int key = 0;
	void *map;
	struct bpf_timer *timer;
	__u64 flags = BPF_F_TIMER_CPU_PIN;
	__u64 start_time;

	if (soft) {
	map = &soft_timer_pinned;
	start_time = 0;
	} else {
	map = &abs_timer_pinned;
	start_time = bpf_ktime_get_boot_ns();
	flags \|= BPF_F_TIMER_ABS;
	}

	timer = bpf_map_lookup_elem(map, &key);
	if (timer) {
	if (bpf_timer_init(timer, map, CLOCK_BOOTTIME) != 0)
	err \|= 4096;
	bpf_timer_set_callback(timer, timer_cb_pinned);
	pinned_cpu = bpf_get_smp_processor_id();
	bpf_timer_start(timer, start_time + 1000, flags);
	} else {
	err \|= 8192;
	}
	}

	SEC("fentry/bpf_fentry_test4")
	int BPF_PROG2(test4, int, a)
	{
	bpf_printk("test4");
	test_pinned_timer(true);

	return 0;
	}

	SEC("fentry/bpf_fentry_test5")
	int BPF_PROG2(test5, int, a)
	{
	bpf_printk("test5");
	test_pinned_timer(false);

	return 0;
	}

	static int race_timer_callback(void race_array, int race_key, struct bpf_timer *timer)
	{
	bpf_timer_start(timer, 1000000, 0);
	return 0;
	}

	SEC("syscall")
	int race(void *ctx)
	{
	struct bpf_timer *timer;
	int err, race_key = 0;
	struct elem init;

	__builtin_memset(&init, 0, sizeof(struct elem));
	bpf_map_update_elem(&race_array, &race_key, &init, BPF_ANY);

	timer = bpf_map_lookup_elem(&race_array, &race_key);
	if (!timer)
	return 1;

	err = bpf_timer_init(timer, &race_array, CLOCK_MONOTONIC);
	if (err && err != -EBUSY)
	return 1;

	bpf_timer_set_callback(timer, race_timer_callback);
	bpf_timer_start(timer, 0, 0);
	bpf_timer_cancel(timer);

	return 0;
	}