arch/x86/mm/debug_pagetables.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/debugfs.h>
   3 #include <linux/efi.h>
   4 #include <linux/module.h>
   5 #include <linux/seq_file.h>
   6 #include <linux/pgtable.h>
   7
   8 static int ptdump_show(struct seq_file *m, void *v)
   9 {
  10         ptdump_walk_pgd_level_debugfs(m, &init_mm, false);
  11         return 0;
  12 }
  13
  14 DEFINE_SHOW_ATTRIBUTE(ptdump);
  15
  16 static int ptdump_curknl_show(struct seq_file *m, void *v)
  17 {
  18         if (current->mm->pgd)
  19                 ptdump_walk_pgd_level_debugfs(m, current->mm, false);
  20         return 0;
  21 }
  22
  23 DEFINE_SHOW_ATTRIBUTE(ptdump_curknl);
  24
  25 #ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
  26 static int ptdump_curusr_show(struct seq_file *m, void *v)
  27 {
  28         if (current->mm->pgd)
  29                 ptdump_walk_pgd_level_debugfs(m, current->mm, true);
  30         return 0;
  31 }
  32
  33 DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
  34 #endif
  35
  36 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
  37 static int ptdump_efi_show(struct seq_file *m, void *v)
  38 {
  39         if (efi_mm.pgd)
  40                 ptdump_walk_pgd_level_debugfs(m, &efi_mm, false);
  41         return 0;
  42 }
  43
  44 DEFINE_SHOW_ATTRIBUTE(ptdump_efi);
  45 #endif
  46
  47 static struct dentry *dir;
  48
  49 static int __init pt_dump_debug_init(void)
  50 {
  51         dir = debugfs_create_dir("page_tables", NULL);
  52
  53         debugfs_create_file("kernel", 0400, dir, NULL, &ptdump_fops);
  54         debugfs_create_file("current_kernel", 0400, dir, NULL,
  55                             &ptdump_curknl_fops);
  56
  57 #ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
  58         debugfs_create_file("current_user", 0400, dir, NULL,
  59                             &ptdump_curusr_fops);
  60 #endif
  61 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
  62         debugfs_create_file("efi", 0400, dir, NULL, &ptdump_efi_fops);
  63 #endif
  64         return 0;
  65 }
  66
  67 static void __exit pt_dump_debug_exit(void)
  68 {
  69         debugfs_remove_recursive(dir);
  70 }
  71
  72 module_init(pt_dump_debug_init);
  73 module_exit(pt_dump_debug_exit);
  74 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
  75 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");