// $Id: read_pgd.c,v 1.4 2004/11/03 11:42:39 kaiya Exp $
#define __KERNEL__
#define SEEK_SET 0

#include <linux/mm.h>
#include <linux/sched.h>
#include <asm-i386/page.h>

#define pidhash_addr 0xc032d8a0

void readkmem(int fd, void *buf, unsigned off, int sz)
{
	if(lseek(fd, off, SEEK_SET) != off){
		perror("kmen lseek");
		exit(1);
	}
	if(read(fd, buf, sz) != sz){
		perror("kmen read");
		exit(1);
	}
}

void find_task(int fd, int pid, struct task_struct* task)
{
struct task_struct *htable_ptr;

	readkmem(fd, &htable_ptr, pidhash_addr + (pid_hashfn(pid)*4), 
		sizeof(htable_ptr));
	while(1){
		readkmem(fd, task, (unsigned)htable_ptr, sizeof(*task));
		if(pid == task->pid){
			return;
		}
		htable_ptr=task->next_task;
	}
}

void print_pte(int fd, pgd_t pgd, unsigned pgd_index)
{
pte_t pgt[1024];
int i;
unsigned vaddr = pgd_index << PGDIR_SHIFT;
unsigned pte_addr = pgd_val(pgd) & PAGE_MASK;

	/* 4MB page */
	if(pgd_val(pgd) & _PAGE_PSE){
		printf("%08x -- %08x m -> [%s%s]         %08x\n", 
			vaddr, vaddr + 4*1024*1024-1, 
			(pgd_val(pgd) & _PAGE_USER)? "U": " ", 
			(pgd_val(pgd) & _PAGE_RW)? "W": " ", 
			pte_addr
		);
	}
	/* 4KB page */
	else {
		/* read page table */
		readkmem(fd, pgt, (unsigned)pte_addr, sizeof(pgt));
		for(i=0; i<1024; i++){
			pte_t pte=pgt[i];
			if(!pte_none(pte)){
				unsigned page_addr = pte_val(pte) & PAGE_MASK;
				printf("%08x -- %08x k -> [%s%s]  ", 
					vaddr + (i << PAGE_SHIFT), 
					vaddr + (i << PAGE_SHIFT) + 4*1024-1,
					(pgd_val(pgd) & _PAGE_USER)? "U": " ", 
					(pgd_val(pgd) & _PAGE_RW)? "W": " "
				);
				if(pte_val(pte) & _PAGE_PRESENT){
					printf("[%s%s]   %08x\n", 
						(pgd_val(pgd) & _PAGE_USER)? "U": " ", 
						(pgd_val(pgd) & _PAGE_RW)? "W": " ", page_addr
					);
				}else{
					printf("       page out\n");
				}
			}
		}
	}
}

main(int argc, char* argv[]){
	pgd_t pgd[1024];
	int i, kmemfd, memfd;
	struct task_struct task;
	struct mm_struct mm;
	int pid;

	if(argc != 2){
		printf("%s pid\n", argv[0]);
		exit(1);
	}

	pid=atoi(argv[1]);
	if(pid < 1){
		printf("Invalid pid %d\n", pid);
		exit(1);
	}

	kmemfd = open("/dev/kmem", O_RDONLY);
	if(kmemfd < 0){
		perror("kmem open");
		exit(1);
	}

	memfd = open("/dev/mem", O_RDONLY);
	if(memfd < 0){
		perror("mem open");
		exit(1);
	}

	/* find a task struct from pidhash table */
	find_task(kmemfd, pid, &task);
	if(task.pid != pid){
		printf("pid not found %d\n", pid);
		exit(1);
	}

	/* read mm_struct */
	readkmem(kmemfd, &mm, (unsigned)task.active_mm, sizeof(mm));

	/* read page directory */
	readkmem(kmemfd, pgd, (unsigned)mm.pgd, sizeof(pgd));

	printf("   Virtual Address   t    PGD   PTE    Physical Address\n");
	printf("----------------------------------------------\n");

	for(i=0; i<1024; i++){
		if(pgd_val(pgd[i]) & _PAGE_PRESENT){
			print_pte(memfd, pgd[i], i);
		}
	}
	return 0;
}