arch/x86/mm/debug_pagetables.c

   1 #include <linux/debugfs.h>
   2 #include <linux/module.h>
   3 #include <linux/seq_file.h>
   4 #include <asm/pgtable.h>
   5
   6 static int ptdump_show(struct seq_file *m, void *v)
   7 {
   8         ptdump_walk_pgd_level_debugfs(m, NULL, false);
   9         return 0;
  10 }
  11
  12 static int ptdump_open(struct inode *inode, struct file *filp)
  13 {
  14         return single_open(filp, ptdump_show, NULL);
  15 }
  16
  17 static const struct file_operations ptdump_fops = {
  18         .owner          = THIS_MODULE,
  19         .open           = ptdump_open,
  20         .read           = seq_read,
  21         .llseek         = seq_lseek,
  22         .release        = single_release,
  23 };
  24
  25 static int ptdump_show_curknl(struct seq_file *m, void *v)
  26 {
  27         if (current->mm->pgd) {
  28                 down_read(&current->mm->mmap_sem);
  29                 ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, false);
  30                 up_read(&current->mm->mmap_sem);
  31         }
  32         return 0;
  33 }
  34
  35 static int ptdump_open_curknl(struct inode *inode, struct file *filp)
  36 {
  37         return single_open(filp, ptdump_show_curknl, NULL);
  38 }
  39
  40 static const struct file_operations ptdump_curknl_fops = {
  41         .owner          = THIS_MODULE,
  42         .open           = ptdump_open_curknl,
  43         .read           = seq_read,
  44         .llseek         = seq_lseek,
  45         .release        = single_release,
  46 };
  47
  48 #ifdef CONFIG_PAGE_TABLE_ISOLATION
  49 static struct dentry *pe_curusr;
  50
  51 static int ptdump_show_curusr(struct seq_file *m, void *v)
  52 {
  53         if (current->mm->pgd) {
  54                 down_read(&current->mm->mmap_sem);
  55                 ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, true);
  56                 up_read(&current->mm->mmap_sem);
  57         }
  58         return 0;
  59 }
  60
  61 static int ptdump_open_curusr(struct inode *inode, struct file *filp)
  62 {
  63         return single_open(filp, ptdump_show_curusr, NULL);
  64 }
  65
  66 static const struct file_operations ptdump_curusr_fops = {
  67         .owner          = THIS_MODULE,
  68         .open           = ptdump_open_curusr,
  69         .read           = seq_read,
  70         .llseek         = seq_lseek,
  71         .release        = single_release,
  72 };
  73 #endif
  74
  75 static struct dentry *dir, *pe_knl, *pe_curknl;
  76
  77 static int __init pt_dump_debug_init(void)
  78 {
  79         dir = debugfs_create_dir("page_tables", NULL);
  80         if (!dir)
  81                 return -ENOMEM;
  82
  83         pe_knl = debugfs_create_file("kernel", 0400, dir, NULL,
  84                                      &ptdump_fops);
  85         if (!pe_knl)
  86                 goto err;
  87
  88         pe_curknl = debugfs_create_file("current_kernel", 0400,
  89                                         dir, NULL, &ptdump_curknl_fops);
  90         if (!pe_curknl)
  91                 goto err;
  92
  93 #ifdef CONFIG_PAGE_TABLE_ISOLATION
  94         pe_curusr = debugfs_create_file("current_user", 0400,
  95                                         dir, NULL, &ptdump_curusr_fops);
  96         if (!pe_curusr)
  97                 goto err;
  98 #endif
  99         return 0;
 100 err:
 101         debugfs_remove_recursive(dir);
 102         return -ENOMEM;
 103 }
 104
 105 static void __exit pt_dump_debug_exit(void)
 106 {
 107         debugfs_remove_recursive(dir);
 108 }
 109
 110 module_init(pt_dump_debug_init);
 111 module_exit(pt_dump_debug_exit);
 112 MODULE_LICENSE("GPL");
 113 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
 114 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");