// SPDX-License-Identifier: GPL-2.0

/*
 * Test module for stress and analyze performance of vmalloc allocator.
 * (C) 2018 Uladzislau Rezki (Sony) <urezki@gmail.com>
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/random.h>
#include <linux/kthread.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/rwsem.h>
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>

#define __param(type, name, init, msg)          \
        static type name = init;                                \
        module_param(name, type, 0444);                 \
        MODULE_PARM_DESC(name, msg)                             \

__param(int, nr_threads, 0,
        "Number of workers to perform tests(min: 1 max: USHRT_MAX)");

__param(bool, sequential_test_order, false,
        "Use sequential stress tests order");

__param(int, test_repeat_count, 1,
        "Set test repeat counter");

__param(int, test_loop_count, 1000000,
        "Set test loop counter");

__param(int, nr_pages, 0,
        "Set number of pages for fix_size_alloc_test(default: 1)");

__param(int, run_test_mask, INT_MAX,
        "Set tests specified in the mask.\n\n"
                "\t\tid: 1,    name: fix_size_alloc_test\n"
                "\t\tid: 2,    name: full_fit_alloc_test\n"
                "\t\tid: 4,    name: long_busy_list_alloc_test\n"
                "\t\tid: 8,    name: random_size_alloc_test\n"
                "\t\tid: 16,   name: fix_align_alloc_test\n"
                "\t\tid: 32,   name: random_size_align_alloc_test\n"
                "\t\tid: 64,   name: align_shift_alloc_test\n"
                "\t\tid: 128,  name: pcpu_alloc_test\n"
                "\t\tid: 256,  name: kvfree_rcu_1_arg_vmalloc_test\n"
                "\t\tid: 512,  name: kvfree_rcu_2_arg_vmalloc_test\n"
                /* Add a new test case description here. */
);

/*
 * Read write semaphore for synchronization of setup
 * phase that is done in main thread and workers.
 */
static DECLARE_RWSEM(prepare_for_test_rwsem);

/*
 * Completion tracking for worker threads.
 */
static DECLARE_COMPLETION(test_all_done_comp);
static atomic_t test_n_undone = ATOMIC_INIT(0);

static inline void
test_report_one_done(void)
{
        if (atomic_dec_and_test(&test_n_undone))
                complete(&test_all_done_comp);
}

static int random_size_align_alloc_test(void)
{
        unsigned long size, align, rnd;
        void *ptr;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                get_random_bytes(&rnd, sizeof(rnd));

                /*
                 * Maximum 1024 pages, if PAGE_SIZE is 4096.
                 */
                align = 1 << (rnd % 23);

                /*
                 * Maximum 10 pages.
                 */
                size = ((rnd % 10) + 1) * PAGE_SIZE;

                ptr = __vmalloc_node(size, align, GFP_KERNEL | __GFP_ZERO, 0,
                                __builtin_return_address(0));
                if (!ptr)
                        return -1;

                vfree(ptr);
        }

        return 0;
}

/*
 * This test case is supposed to be failed.
 */
static int align_shift_alloc_test(void)
{
        unsigned long align;
        void *ptr;
        int i;

        for (i = 0; i < BITS_PER_LONG; i++) {
                align = ((unsigned long) 1) << i;

                ptr = __vmalloc_node(PAGE_SIZE, align, GFP_KERNEL|__GFP_ZERO, 0,
                                __builtin_return_address(0));
                if (!ptr)
                        return -1;

                vfree(ptr);
        }

        return 0;
}

static int fix_align_alloc_test(void)
{
        void *ptr;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                ptr = __vmalloc_node(5 * PAGE_SIZE, THREAD_ALIGN << 1,
                                GFP_KERNEL | __GFP_ZERO, 0,
                                __builtin_return_address(0));
                if (!ptr)
                        return -1;

                vfree(ptr);
        }

        return 0;
}

static int random_size_alloc_test(void)
{
        unsigned int n;
        void *p;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                get_random_bytes(&n, sizeof(i));
                n = (n % 100) + 1;

                p = vmalloc(n * PAGE_SIZE);

                if (!p)
                        return -1;

                *((__u8 *)p) = 1;
                vfree(p);
        }

        return 0;
}

static int long_busy_list_alloc_test(void)
{
        void *ptr_1, *ptr_2;
        void **ptr;
        int rv = -1;
        int i;

        ptr = vmalloc(sizeof(void *) * 15000);
        if (!ptr)
                return rv;

        for (i = 0; i < 15000; i++)
                ptr[i] = vmalloc(1 * PAGE_SIZE);

        for (i = 0; i < test_loop_count; i++) {
                ptr_1 = vmalloc(100 * PAGE_SIZE);
                if (!ptr_1)
                        goto leave;

                ptr_2 = vmalloc(1 * PAGE_SIZE);
                if (!ptr_2) {
                        vfree(ptr_1);
                        goto leave;
                }

                *((__u8 *)ptr_1) = 0;
                *((__u8 *)ptr_2) = 1;

                vfree(ptr_1);
                vfree(ptr_2);
        }

        /*  Success */
        rv = 0;

leave:
        for (i = 0; i < 15000; i++)
                vfree(ptr[i]);

        vfree(ptr);
        return rv;
}

static int full_fit_alloc_test(void)
{
        void **ptr, **junk_ptr, *tmp;
        int junk_length;
        int rv = -1;
        int i;

        junk_length = fls(num_online_cpus());
        junk_length *= (32 * 1024 * 1024 / PAGE_SIZE);

        ptr = vmalloc(sizeof(void *) * junk_length);
        if (!ptr)
                return rv;

        junk_ptr = vmalloc(sizeof(void *) * junk_length);
        if (!junk_ptr) {
                vfree(ptr);
                return rv;
        }

        for (i = 0; i < junk_length; i++) {
                ptr[i] = vmalloc(1 * PAGE_SIZE);
                junk_ptr[i] = vmalloc(1 * PAGE_SIZE);
        }

        for (i = 0; i < junk_length; i++)
                vfree(junk_ptr[i]);

        for (i = 0; i < test_loop_count; i++) {
                tmp = vmalloc(1 * PAGE_SIZE);

                if (!tmp)
                        goto error;

                *((__u8 *)tmp) = 1;
                vfree(tmp);
        }

        /* Success */
        rv = 0;

error:
        for (i = 0; i < junk_length; i++)
                vfree(ptr[i]);

        vfree(ptr);
        vfree(junk_ptr);

        return rv;
}

static int fix_size_alloc_test(void)
{
        void *ptr;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                ptr = vmalloc((nr_pages > 0 ? nr_pages:1) * PAGE_SIZE);

                if (!ptr)
                        return -1;

                *((__u8 *)ptr) = 0;

                vfree(ptr);
        }

        return 0;
}

static int
pcpu_alloc_test(void)
{
        int rv = 0;
#ifndef CONFIG_NEED_PER_CPU_KM
        void __percpu **pcpu;
        size_t size, align;
        int i;

        pcpu = vmalloc(sizeof(void __percpu *) * 35000);
        if (!pcpu)
                return -1;

        for (i = 0; i < 35000; i++) {
                unsigned int r;

                get_random_bytes(&r, sizeof(i));
                size = (r % (PAGE_SIZE / 4)) + 1;

                /*
                 * Maximum PAGE_SIZE
                 */
                get_random_bytes(&r, sizeof(i));
                align = 1 << ((i % 11) + 1);

                pcpu[i] = __alloc_percpu(size, align);
                if (!pcpu[i])
                        rv = -1;
        }

        for (i = 0; i < 35000; i++)
                free_percpu(pcpu[i]);

        vfree(pcpu);
#endif
        return rv;
}

struct test_kvfree_rcu {
        struct rcu_head rcu;
        unsigned char array[20];
};

static int
kvfree_rcu_1_arg_vmalloc_test(void)
{
        struct test_kvfree_rcu *p;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                p = vmalloc(1 * PAGE_SIZE);
                if (!p)
                        return -1;

                p->array[0] = 'a';
                kvfree_rcu(p);
        }

        return 0;
}

static int
kvfree_rcu_2_arg_vmalloc_test(void)
{
        struct test_kvfree_rcu *p;
        int i;

        for (i = 0; i < test_loop_count; i++) {
                p = vmalloc(1 * PAGE_SIZE);
                if (!p)
                        return -1;

                p->array[0] = 'a';
                kvfree_rcu(p, rcu);
        }

        return 0;
}

struct test_case_desc {
        const char *test_name;
        int (*test_func)(void);
};

static struct test_case_desc test_case_array[] = {
        { "fix_size_alloc_test", fix_size_alloc_test },
        { "full_fit_alloc_test", full_fit_alloc_test },
        { "long_busy_list_alloc_test", long_busy_list_alloc_test },
        { "random_size_alloc_test", random_size_alloc_test },
        { "fix_align_alloc_test", fix_align_alloc_test },
        { "random_size_align_alloc_test", random_size_align_alloc_test },
        { "align_shift_alloc_test", align_shift_alloc_test },
        { "pcpu_alloc_test", pcpu_alloc_test },
        { "kvfree_rcu_1_arg_vmalloc_test", kvfree_rcu_1_arg_vmalloc_test },
        { "kvfree_rcu_2_arg_vmalloc_test", kvfree_rcu_2_arg_vmalloc_test },
        /* Add a new test case here. */
};

struct test_case_data {
        int test_failed;
        int test_passed;
        u64 time;
};

static struct test_driver {
        struct task_struct *task;
        struct test_case_data data[ARRAY_SIZE(test_case_array)];

        unsigned long start;
        unsigned long stop;
} *tdriver;

static void shuffle_array(int *arr, int n)
{
        unsigned int rnd;
        int i, j, x;

        for (i = n - 1; i > 0; i--)  {
                get_random_bytes(&rnd, sizeof(rnd));

                /* Cut the range. */
                j = rnd % i;

                /* Swap indexes. */
                x = arr[i];
                arr[i] = arr[j];
                arr[j] = x;
        }
}

static int test_func(void *private)
{
        struct test_driver *t = private;
        int random_array[ARRAY_SIZE(test_case_array)];
        int index, i, j;
        ktime_t kt;
        u64 delta;

        for (i = 0; i < ARRAY_SIZE(test_case_array); i++)
                random_array[i] = i;

        if (!sequential_test_order)
                shuffle_array(random_array, ARRAY_SIZE(test_case_array));

        /*
         * Block until initialization is done.
         */
        down_read(&prepare_for_test_rwsem);

        t->start = get_cycles();
        for (i = 0; i < ARRAY_SIZE(test_case_array); i++) {
                index = random_array[i];

                /*
                 * Skip tests if run_test_mask has been specified.
                 */
                if (!((run_test_mask & (1 << index)) >> index))
                        continue;

                kt = ktime_get();
                for (j = 0; j < test_repeat_count; j++) {
                        if (!test_case_array[index].test_func())
                                t->data[index].test_passed++;
                        else
                                t->data[index].test_failed++;
                }

                /*
                 * Take an average time that test took.
                 */
                delta = (u64) ktime_us_delta(ktime_get(), kt);
                do_div(delta, (u32) test_repeat_count);

                t->data[index].time = delta;
        }
        t->stop = get_cycles();

        up_read(&prepare_for_test_rwsem);
        test_report_one_done();

        /*
         * Wait for the kthread_stop() call.
         */
        while (!kthread_should_stop())
                msleep(10);

        return 0;
}

static int
init_test_configurtion(void)
{
        /*
         * A maximum number of workers is defined as hard-coded
         * value and set to USHRT_MAX. We add such gap just in
         * case and for potential heavy stressing.
         */
        nr_threads = clamp(nr_threads, 1, (int) USHRT_MAX);

        /* Allocate the space for test instances. */
        tdriver = kvcalloc(nr_threads, sizeof(*tdriver), GFP_KERNEL);
        if (tdriver == NULL)
                return -1;

        if (test_repeat_count <= 0)
                test_repeat_count = 1;

        if (test_loop_count <= 0)
                test_loop_count = 1;

        return 0;
}

static void do_concurrent_test(void)
{
        int i, ret;

        /*
         * Set some basic configurations plus sanity check.
         */
        ret = init_test_configurtion();
        if (ret < 0)
                return;

        /*
         * Put on hold all workers.
         */
        down_write(&prepare_for_test_rwsem);

        for (i = 0; i < nr_threads; i++) {
                struct test_driver *t = &tdriver[i];

                t->task = kthread_run(test_func, t, "vmalloc_test/%d", i);

                if (!IS_ERR(t->task))
                        /* Success. */
                        atomic_inc(&test_n_undone);
                else
                        pr_err("Failed to start %d kthread\n", i);
        }

        /*
         * Now let the workers do their job.
         */
        up_write(&prepare_for_test_rwsem);

        /*
         * Sleep quiet until all workers are done with 1 second
         * interval. Since the test can take a lot of time we
         * can run into a stack trace of the hung task. That is
         * why we go with completion_timeout and HZ value.
         */
        do {
                ret = wait_for_completion_timeout(&test_all_done_comp, HZ);
        } while (!ret);

        for (i = 0; i < nr_threads; i++) {
                struct test_driver *t = &tdriver[i];
                int j;

                if (!IS_ERR(t->task))
                        kthread_stop(t->task);

                for (j = 0; j < ARRAY_SIZE(test_case_array); j++) {
                        if (!((run_test_mask & (1 << j)) >> j))
                                continue;

                        pr_info(
                                "Summary: %s passed: %d failed: %d repeat: %d loops: %d avg: %llu usec\n",
                                test_case_array[j].test_name,
                                t->data[j].test_passed,
                                t->data[j].test_failed,
                                test_repeat_count, test_loop_count,
                                t->data[j].time);
                }

                pr_info("All test took worker%d=%lu cycles\n",
                        i, t->stop - t->start);
        }

        kvfree(tdriver);
}

static int vmalloc_test_init(void)
{
        do_concurrent_test();
        return -EAGAIN; /* Fail will directly unload the module */
}

static void vmalloc_test_exit(void)
{
}

module_init(vmalloc_test_init)
module_exit(vmalloc_test_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Uladzislau Rezki");
MODULE_DESCRIPTION("vmalloc test module");