// SPDX-License-Identifier: GPL-2.0
/*
 * Example of using hugepage memory in a user application using the mmap
 * system call with MAP_HUGETLB flag.  Before running this program make
 * sure the administrator has allocated enough default sized huge pages
 * to cover the 256 MB allocation.
 */
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include "vm_util.h"
#include "kselftest.h"

#define LENGTH (256UL*1024*1024)
#define PROTECTION (PROT_READ | PROT_WRITE)

static void check_bytes(char *addr)
{
        ksft_print_msg("First hex is %x\n", *((unsigned int *)addr));
}

static void write_bytes(char *addr, size_t length)
{
        unsigned long i;

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

static void read_bytes(char *addr, size_t length)
{
        unsigned long i;

        check_bytes(addr);
        for (i = 0; i < length; i++)
                if (*(addr + i) != (char)i)
                        ksft_exit_fail_msg("Mismatch at %lu\n", i);

        ksft_test_result_pass("Read correct data\n");
}

int main(int argc, char **argv)
{
        void *addr;
        size_t hugepage_size;
        size_t length = LENGTH;
        int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;
        int shift = 0;

        hugepage_size = default_huge_page_size();
        /* munmap with fail if the length is not page aligned */
        if (hugepage_size > length)
                length = hugepage_size;

        ksft_print_header();
        ksft_set_plan(1);

        if (argc > 1)
                length = atol(argv[1]) << 20;
        if (argc > 2) {
                shift = atoi(argv[2]);
                if (shift)
                        flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT;
        }

        if (shift)
                ksft_print_msg("%u kB hugepages\n", 1 << (shift - 10));
        else
                ksft_print_msg("Default size hugepages\n");
        ksft_print_msg("Mapping %lu Mbytes\n", (unsigned long)length >> 20);

        addr = mmap(NULL, length, PROTECTION, flags, -1, 0);
        if (addr == MAP_FAILED)
                ksft_exit_fail_msg("mmap: %s\n", strerror(errno));

        ksft_print_msg("Returned address is %p\n", addr);
        check_bytes(addr);
        write_bytes(addr, length);
        read_bytes(addr, length);

        /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
        if (munmap(addr, length))
                ksft_exit_fail_msg("munmap: %s\n", strerror(errno));

        ksft_finished();
}