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| #include <stdio.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h> /* open */
#include <stdint.h> /* uint64_t */
#include <stdlib.h> /* size_t */
#include <unistd.h> /* pread, sysconf */
typedef struct {
uint64_t pfn : 54;
unsigned int soft_dirty : 1;
unsigned int file_page : 1;
unsigned int swapped : 1;
unsigned int present : 1;
} PagemapEntry;
int pagemap_get_entry(PagemapEntry *entry, int pagemap_fd, uintptr_t vaddr)
{
size_t nread;
ssize_t ret;
uint64_t data;
uintptr_t vpn;
vpn = vaddr / sysconf(_SC_PAGE_SIZE);
nread = 0;
while (nread < sizeof(data)) {
ret = pread(pagemap_fd, &data, sizeof(data) - nread,
vpn * sizeof(data) + nread);
nread += ret;
if (ret <= 0) {
return 1;
}
}
entry->pfn = data & (((uint64_t)1 << 54) - 1);
entry->soft_dirty = (data >> 54) & 1;
entry->file_page = (data >> 61) & 1;
entry->swapped = (data >> 62) & 1;
entry->present = (data >> 63) & 1;
return 0;
}
int virt_to_phys_user(uintptr_t *paddr, pid_t pid, uintptr_t vaddr)
{
char pagemap_file[BUFSIZ];
int pagemap_fd;
//读取对应进程地址映射
snprintf(pagemap_file, sizeof(pagemap_file), "/proc/%ju/pagemap", (uintmax_t)pid);
pagemap_fd = open(pagemap_file, O_RDONLY);
if (pagemap_fd < 0) {
return 1;
}
PagemapEntry entry;
//条目获取
if (pagemap_get_entry(&entry, pagemap_fd, vaddr)) {
return 1;
}
close(pagemap_fd);
*paddr = (entry.pfn * sysconf(_SC_PAGE_SIZE)) + (vaddr % sysconf(_SC_PAGE_SIZE));
return 0;
}
int main(void) {
setbuf(stdout, 0);
int a = 0;
pid_t pid = fork();
if (pid == 0)
{
//子进程
printf("Pid:%d\n",getpid());
printf("child: \n\tvirtual address:\t%llx\n\tphysical address:\t%llx\n", &a, syscall(335, &a));
sleep(2);
}
else
{
//父进程
printf("Pid:%d\n",getpid());
printf("parent: \n\tvirtual address:\t%llx\n\tphysical address:\t%llx\n", &a, syscall(335, &a));
uintptr_t aptr = &a;
uintptr_t aphy = NULL;
//子进程中该变量的物理地址
virt_to_phys_user(&aphy, pid, aptr);
printf("child:\n\tpagemap approach:\t%llx\n", aphy);
sleep(2);
}
return 0;
}
|