用户空间获取物理地址的方法

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

#define page_map_file "/proc/self/pagemap"

#define PFN_MASK ((((uint64_t)1)<<55)-1)

#define PFN_PRESENT_FLAG (((uint64_t)1)<<63)

int mem_addr_vir2phy(unsigned long vir, unsigned long *phy)
{
    int fd;
    int page_size=getpagesize();
    unsigned long vir_page_idx = vir/page_size;
    unsigned long pfn_item_offset = vir_page_idx*sizeof(uint64_t);
    uint64_t pfn_item;

    fd = open(page_map_file, O_RDONLY);
    if (fd<0)
    {
        printf("open %s failed", page_map_file);
        return -1;
    }
    if ((off_t)-1 == lseek(fd, pfn_item_offset, SEEK_SET))
    {
        printf("lseek %s failed", page_map_file);
        return -1;
    }
    if (sizeof(uint64_t) != read(fd, &pfn_item, sizeof(uint64_t)))
    {
        printf("read %s failed", page_map_file);
        return -1;
    }
    if (0==(pfn_item & PFN_PRESENT_FLAG))
    {
        printf("page is not present");
        return -1;
    }
    *phy = (pfn_item & PFN_MASK)*page_size + vir % page_size;
    return 0;
}

void main()
{
    int a=0x12345678;
    unsigned long phy;
    mem_addr_vir2phy((unsigned long)&a, &phy);
    printf("vaddr=%p,phy=0x%lx\n", &a, phy);
    while(1)
    {
        sleep(100);
    }
}

http://blog.csdn.net/wangcong02345/article/details/52326083