// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2020 ARM Limited

#define _GNU_SOURCE

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ucontext.h>
#include <sys/mman.h>

#include "kselftest.h"
#include "mte_common_util.h"
#include "mte_def.h"

#define TEST_UNIT       10
#define PATH_KSM        "/sys/kernel/mm/ksm/"
#define MAX_LOOP        4

static size_t page_sz;
static unsigned long ksm_sysfs[5];

static unsigned long read_sysfs(char *str)
{
        FILE *f;
        unsigned long val = 0;

        f = fopen(str, "r");
        if (!f) {
                ksft_print_msg("ERR: missing %s\n", str);
                return 0;
        }
        if (fscanf(f, "%lu", &val) != 1) {
                ksft_print_msg("ERR: parsing %s\n", str);
                val = 0;
        }
        fclose(f);
        return val;
}

static void write_sysfs(char *str, unsigned long val)
{
        FILE *f;

        f = fopen(str, "w");
        if (!f) {
                ksft_print_msg("ERR: missing %s\n", str);
                return;
        }
        fprintf(f, "%lu", val);
        fclose(f);
}

static void mte_ksm_setup(void)
{
        ksm_sysfs[0] = read_sysfs(PATH_KSM "merge_across_nodes");
        write_sysfs(PATH_KSM "merge_across_nodes", 1);
        ksm_sysfs[1] = read_sysfs(PATH_KSM "sleep_millisecs");
        write_sysfs(PATH_KSM "sleep_millisecs", 0);
        ksm_sysfs[2] = read_sysfs(PATH_KSM "run");
        write_sysfs(PATH_KSM "run", 1);
        ksm_sysfs[3] = read_sysfs(PATH_KSM "max_page_sharing");
        write_sysfs(PATH_KSM "max_page_sharing", ksm_sysfs[3] + TEST_UNIT);
        ksm_sysfs[4] = read_sysfs(PATH_KSM "pages_to_scan");
        write_sysfs(PATH_KSM "pages_to_scan", ksm_sysfs[4] + TEST_UNIT);
}

static void mte_ksm_restore(void)
{
        write_sysfs(PATH_KSM "merge_across_nodes", ksm_sysfs[0]);
        write_sysfs(PATH_KSM "sleep_millisecs", ksm_sysfs[1]);
        write_sysfs(PATH_KSM "run", ksm_sysfs[2]);
        write_sysfs(PATH_KSM "max_page_sharing", ksm_sysfs[3]);
        write_sysfs(PATH_KSM "pages_to_scan", ksm_sysfs[4]);
}

static void mte_ksm_scan(void)
{
        int cur_count = read_sysfs(PATH_KSM "full_scans");
        int scan_count = cur_count + 1;
        int max_loop_count = MAX_LOOP;

        while ((cur_count < scan_count) && max_loop_count) {
                sleep(1);
                cur_count = read_sysfs(PATH_KSM "full_scans");
                max_loop_count--;
        }
#ifdef DEBUG
        ksft_print_msg("INFO: pages_shared=%lu pages_sharing=%lu\n",
                        read_sysfs(PATH_KSM "pages_shared"),
                        read_sysfs(PATH_KSM "pages_sharing"));
#endif
}

static int check_madvise_options(int mem_type, int mode, int mapping)
{
        char *ptr;
        int err, ret;

        err = KSFT_FAIL;
        if (access(PATH_KSM, F_OK) == -1) {
                ksft_print_msg("ERR: Kernel KSM config not enabled\n");
                return err;
        }

        mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG, false);
        ptr = mte_allocate_memory(TEST_UNIT * page_sz, mem_type, mapping, true);
        if (check_allocated_memory(ptr, TEST_UNIT * page_sz, mem_type, false) != KSFT_PASS)
                return KSFT_FAIL;

        /* Insert same data in all the pages */
        memset(ptr, 'A', TEST_UNIT * page_sz);
        ret = madvise(ptr, TEST_UNIT * page_sz, MADV_MERGEABLE);
        if (ret) {
                ksft_print_msg("ERR: madvise failed to set MADV_UNMERGEABLE\n");
                goto madvise_err;
        }
        mte_ksm_scan();
        /* Tagged pages should not merge */
        if ((read_sysfs(PATH_KSM "pages_shared") < 1) ||
            (read_sysfs(PATH_KSM "pages_sharing") < (TEST_UNIT - 1)))
                err = KSFT_PASS;
madvise_err:
        mte_free_memory(ptr, TEST_UNIT * page_sz, mem_type, true);
        return err;
}

int main(int argc, char *argv[])
{
        int err;

        err = mte_default_setup();
        if (err)
                return err;
        page_sz = getpagesize();
        if (!page_sz) {
                ksft_print_msg("ERR: Unable to get page size\n");
                return KSFT_FAIL;
        }
        /* Register signal handlers */
        mte_register_signal(SIGBUS, mte_default_handler, false);
        mte_register_signal(SIGSEGV, mte_default_handler, false);

        /* Set test plan */
        ksft_set_plan(4);

        /* Enable KSM */
        mte_ksm_setup();

        evaluate_test(check_madvise_options(USE_MMAP, MTE_SYNC_ERR, MAP_PRIVATE),
                "Check KSM mte page merge for private mapping, sync mode and mmap memory\n");
        evaluate_test(check_madvise_options(USE_MMAP, MTE_ASYNC_ERR, MAP_PRIVATE),
                "Check KSM mte page merge for private mapping, async mode and mmap memory\n");
        evaluate_test(check_madvise_options(USE_MMAP, MTE_SYNC_ERR, MAP_SHARED),
                "Check KSM mte page merge for shared mapping, sync mode and mmap memory\n");
        evaluate_test(check_madvise_options(USE_MMAP, MTE_ASYNC_ERR, MAP_SHARED),
                "Check KSM mte page merge for shared mapping, async mode and mmap memory\n");

        mte_ksm_restore();
        mte_restore_setup();
        ksft_print_cnts();
        return ksft_get_fail_cnt() == 0 ? KSFT_PASS : KSFT_FAIL;
}