debug_mem.c

#include <linux/debugfs.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <linux/uaccess.h>
#include "common.h"

static struct dentry *topdir;
static struct dentry *memory;

static ssize_t memory_read(struct file *file, char __user *buf, size_t len, loff_t *ppos) {
  void __iomem *io_addr;
  phys_addr_t addr = DEPLOY_PHYS_ADDR_START + *ppos;
  void *tmp_buf;

  if (len > KMALLOC_MAX_SIZE) {
    len = KMALLOC_MAX_SIZE;
  }
  
  if (*ppos + DEPLOY_PHYS_ADDR_START > DEPLOY_PHYS_ADDR_END) {
    len = 0;
  } else if (len + *ppos + DEPLOY_PHYS_ADDR_START > DEPLOY_PHYS_ADDR_END) {
    len = DEPLOY_PHYS_ADDR_END - *ppos - DEPLOY_PHYS_ADDR_START;
  }

  tmp_buf = kmalloc(len, GFP_KERNEL);
  
  io_addr = ioremap(addr, len);
  memcpy_fromio(tmp_buf, io_addr, len);
  iounmap(io_addr);
  
  len -= copy_to_user(buf, tmp_buf, len);
  kfree(tmp_buf);
  *ppos += len;
  return len;
}

static loff_t memory_llseek(struct file *file, loff_t offset, int origin) {
  switch (origin) {
  case SEEK_END:
    offset += DEPLOY_PHYS_ADDR_END - DEPLOY_PHYS_ADDR_START;
    break;
  case SEEK_CUR:
    offset += file->f_pos;
    break;
  }
  file->f_pos = offset;

  return offset;
}

static struct file_operations memory_fops = {
  .owner = THIS_MODULE,
  .read = memory_read,
  .llseek = memory_llseek,
};

int __init debugmem_init(void) {
  topdir = debugfs_create_dir("friend_loader", NULL);
  if (!topdir) {
    return -ENOMEM;
  }
  
  memory = debugfs_create_file("memory", 0400, topdir, NULL, &memory_fops);
  if (!memory) {
    return -ENOMEM;
  }

  return 0;
}

void __exit debugmem_exit(void) {
  debugfs_remove_recursive(topdir);
}