#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

struct pagemaps {
    unsigned long long pfn:55;
    unsigned long long shift:6;
    unsigned long long rsvd:1;
    unsigned long long swapped:1;
    unsigned long long present:1;
};

static int translate_va2pa(uint64_t va, uint64_t pagesize, uint64_t *pa)
{
    int rc = 0;
    static const char *pagemap_file = "/proc/self/pagemap";
    struct pagemaps pinfo;
    uint64_t pinfo_size = sizeof(pinfo);
    uint64_t offset = va / pagesize * pinfo_size;
    int fd = open(pagemap_file, O_RDONLY);

    if (fd == -1) {
        rc = errno;
        fprintf(stderr, "Failed to open %s: %s\n", pagemap_file, strerror(rc));
        goto ret;
    }

    if (pread(fd, (void *) &pinfo, pinfo_size, offset) != pinfo_size) {
        rc = errno;
        fprintf(stderr, "Failed to read offset 0x%"PRIx64": %s\n",
                offset, strerror(rc));
        goto ret_close;
    }

    *pa = (pinfo.pfn * pagesize) | (va & (pagesize - 1));

 ret_close:
    close(fd);
 ret:
    return rc;
}

int main(int argc, char **argv)
{
    void *buf;
    uint64_t buf_pa;
    int pagesize = getpagesize();
    int rc = 0;

    buf = mmap(NULL, pagesize,
               PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS,
               -1, 0);
    if (buf == MAP_FAILED) {
        rc = errno;
        fprintf(stderr, "Failed to mmap a page: %s\n", strerror(rc));
        goto ret;
    }
    memset(buf, 0xcc, pagesize);

    rc = translate_va2pa((uint64_t) buf, pagesize, &buf_pa);
    if (rc || !buf_pa) {
        fprintf(stderr, "Failed to get physical address of mmaped page\n");
        goto ret_unmap;
    }

    fprintf(stderr, "Physical address of mmaped page = 0x%"PRIx64"\n", buf_pa);

    volatile int i = 1;
    while (i++);

 ret_unmap:
    munmap(buf, pagesize);
 ret:
    return rc;
}