c++代码将/proc/pid/pagemap映射到内存中，并随便获取一个地址进行物理地址判断

以下是一个简单的C++代码示例，用于将/proc/pid/pagemap文件映射到内存中，并获取一个地址进行物理地址判断：

#include <iostream>
#include <fstream>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdint.h>

using namespace std;

#define PAGE_SIZE 4096

int main(int argc, char **argv) {
    if (argc < 2) {
        cout << "Usage: " << argv[0] << " pid" << endl;
        return 1;
    }

    int pid = atoi(argv[1]);
    char filepath[64];
    sprintf(filepath, "/proc/%d/pagemap", pid);

    int fd = open(filepath, O_RDONLY);
    if (fd == -1) {
        cout << "Failed to open pagemap file" << endl;
        return 1;
    }

    uint64_t page_frame_number;
    uint64_t virtual_address = 0x7fffffff; // example virtual address
    off_t offset = (virtual_address / PAGE_SIZE) * sizeof(uint64_t);
    if (lseek(fd, offset, SEEK_SET) == -1) {
        cout << "Failed to seek to offset " << offset << endl;
        close(fd);
        return 1;
    }
    if (read(fd, &page_frame_number, sizeof(uint64_t)) != sizeof(uint64_t)) {
        cout << "Failed to read page frame number" << endl;
        close(fd);
        return 1;
    }
    close(fd);

    uint64_t physical_address = (page_frame_number * PAGE_SIZE) + (virtual_address % PAGE_SIZE);
    cout << "Physical address of virtual address 0x" << hex << virtual_address << " is 0x" << physical_address << endl;

    void* mapped = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, offset & ~(PAGE_SIZE - 1));
    if (mapped == MAP_FAILED) {
        cout << "Failed to map pagemap file" << endl;
        return 1;
    }

    // Access memory at virtual_address to trigger page fault and update pagemap
    volatile char* ptr = reinterpret_cast<volatile char*>(virtual_address);
    char val = *ptr;

    munmap(mapped, PAGE_SIZE);

    return 0;
}

此代码首先打开/proc/pid/pagemap文件，然后查找给定地址的页框号。然后，它计算物理地址，并使用mmap将文件映射到内存中。最后，它访问虚拟地址以触发页面故障并更新pagemap。