// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE

#include <linux/limits.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include "kselftest.h"
#include "cgroup_util.h"

#define ADDR ((void *)(0x0UL))
#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
/* mapping 8 MBs == 4 hugepages */
#define LENGTH (8UL*1024*1024)
#define PROTECTION (PROT_READ | PROT_WRITE)

/* borrowed from mm/hmm-tests.c */
static long get_hugepage_size(void)
{
        int fd;
        char buf[2048];
        int len;
        char *p, *q, *path = "/proc/meminfo", *tag = "Hugepagesize:";
        long val;

        fd = open(path, O_RDONLY);
        if (fd < 0) {
                /* Error opening the file */
                return -1;
        }

        len = read(fd, buf, sizeof(buf));
        close(fd);
        if (len < 0) {
                /* Error in reading the file */
                return -1;
        }
        if (len == sizeof(buf)) {
                /* Error file is too large */
                return -1;
        }
        buf[len] = '\0';

        /* Search for a tag if provided */
        if (tag) {
                p = strstr(buf, tag);
                if (!p)
                        return -1; /* looks like the line we want isn't there */
                p += strlen(tag);
        } else
                p = buf;

        val = strtol(p, &q, 0);
        if (*q != ' ') {
                /* Error parsing the file */
                return -1;
        }

        return val;
}

static int set_file(const char *path, long value)
{
        FILE *file;
        int ret;

        file = fopen(path, "w");
        if (!file)
                return -1;
        ret = fprintf(file, "%ld\n", value);
        fclose(file);
        return ret;
}

static int set_nr_hugepages(long value)
{
        return set_file("/proc/sys/vm/nr_hugepages", value);
}

static unsigned int check_first(char *addr)
{
        return *(unsigned int *)addr;
}

static void write_data(char *addr)
{
        unsigned long i;

        for (i = 0; i < LENGTH; i++)
                *(addr + i) = (char)i;
}

static int hugetlb_test_program(const char *cgroup, void *arg)
{
        char *test_group = (char *)arg;
        void *addr;
        long old_current, expected_current, current;
        int ret = EXIT_FAILURE;

        old_current = cg_read_long(test_group, "memory.current");
        set_nr_hugepages(20);
        current = cg_read_long(test_group, "memory.current");
        if (current - old_current >= MB(2)) {
                ksft_print_msg(
                        "setting nr_hugepages should not increase hugepage usage.\n");
                ksft_print_msg("before: %ld, after: %ld\n", old_current, current);
                return EXIT_FAILURE;
        }

        addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0);
        if (addr == MAP_FAILED) {
                ksft_print_msg("fail to mmap.\n");
                return EXIT_FAILURE;
        }
        current = cg_read_long(test_group, "memory.current");
        if (current - old_current >= MB(2)) {
                ksft_print_msg("mmap should not increase hugepage usage.\n");
                ksft_print_msg("before: %ld, after: %ld\n", old_current, current);
                goto out_failed_munmap;
        }
        old_current = current;

        /* read the first page */
        check_first(addr);
        expected_current = old_current + MB(2);
        current = cg_read_long(test_group, "memory.current");
        if (!values_close(expected_current, current, 5)) {
                ksft_print_msg("memory usage should increase by around 2MB.\n");
                ksft_print_msg(
                        "expected memory: %ld, actual memory: %ld\n",
                        expected_current, current);
                goto out_failed_munmap;
        }

        /* write to the whole range */
        write_data(addr);
        current = cg_read_long(test_group, "memory.current");
        expected_current = old_current + MB(8);
        if (!values_close(expected_current, current, 5)) {
                ksft_print_msg("memory usage should increase by around 8MB.\n");
                ksft_print_msg(
                        "expected memory: %ld, actual memory: %ld\n",
                        expected_current, current);
                goto out_failed_munmap;
        }

        /* unmap the whole range */
        munmap(addr, LENGTH);
        current = cg_read_long(test_group, "memory.current");
        expected_current = old_current;
        if (!values_close(expected_current, current, 5)) {
                ksft_print_msg("memory usage should go back down.\n");
                ksft_print_msg(
                        "expected memory: %ld, actual memory: %ld\n",
                        expected_current, current);
                return ret;
        }

        ret = EXIT_SUCCESS;
        return ret;

out_failed_munmap:
        munmap(addr, LENGTH);
        return ret;
}

static int test_hugetlb_memcg(char *root)
{
        int ret = KSFT_FAIL;
        char *test_group;

        test_group = cg_name(root, "hugetlb_memcg_test");
        if (!test_group || cg_create(test_group)) {
                ksft_print_msg("fail to create cgroup.\n");
                goto out;
        }

        if (cg_write(test_group, "memory.max", "100M")) {
                ksft_print_msg("fail to set cgroup memory limit.\n");
                goto out;
        }

        /* disable swap */
        if (cg_write(test_group, "memory.swap.max", "0")) {
                ksft_print_msg("fail to disable swap.\n");
                goto out;
        }

        if (!cg_run(test_group, hugetlb_test_program, (void *)test_group))
                ret = KSFT_PASS;
out:
        cg_destroy(test_group);
        free(test_group);
        return ret;
}

int main(int argc, char **argv)
{
        char root[PATH_MAX];
        int ret = EXIT_SUCCESS, has_memory_hugetlb_acc;

        has_memory_hugetlb_acc = proc_mount_contains("memory_hugetlb_accounting");
        if (has_memory_hugetlb_acc < 0)
                ksft_exit_skip("Failed to query cgroup mount option\n");
        else if (!has_memory_hugetlb_acc)
                ksft_exit_skip("memory hugetlb accounting is disabled\n");

        /* Unit is kB! */
        if (get_hugepage_size() != 2048) {
                ksft_print_msg("test_hugetlb_memcg requires 2MB hugepages\n");
                ksft_test_result_skip("test_hugetlb_memcg\n");
                return ret;
        }

        if (cg_find_unified_root(root, sizeof(root), NULL))
                ksft_exit_skip("cgroup v2 isn't mounted\n");

        switch (test_hugetlb_memcg(root)) {
        case KSFT_PASS:
                ksft_test_result_pass("test_hugetlb_memcg\n");
                break;
        case KSFT_SKIP:
                ksft_test_result_skip("test_hugetlb_memcg\n");
                break;
        default:
                ret = EXIT_FAILURE;
                ksft_test_result_fail("test_hugetlb_memcg\n");
                break;
        }

        return ret;
}