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 <asm/pgtable.h>
   7
   8 static int ptdump_show(struct seq_file *m, void *v)
   9 {
  10         ptdump_walk_pgd_level_debugfs(m, NULL, 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                 down_read(&current->mm->mmap_sem);
  20                 ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, false);
  21                 up_read(&current->mm->mmap_sem);
  22         }
  23         return 0;
  24 }
  25
  26 DEFINE_SHOW_ATTRIBUTE(ptdump_curknl);
  27
  28 #ifdef CONFIG_PAGE_TABLE_ISOLATION
  29 static struct dentry *pe_curusr;
  30
  31 static int ptdump_curusr_show(struct seq_file *m, void *v)
  32 {
  33         if (current->mm->pgd) {
  34                 down_read(&current->mm->mmap_sem);
  35                 ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, true);
  36                 up_read(&current->mm->mmap_sem);
  37         }
  38         return 0;
  39 }
  40
  41 DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
  42 #endif
  43
  44 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
  45 static struct dentry *pe_efi;
  46
  47 static int ptdump_efi_show(struct seq_file *m, void *v)
  48 {
  49         if (efi_mm.pgd)
  50                 ptdump_walk_pgd_level_debugfs(m, efi_mm.pgd, false);
  51         return 0;
  52 }
  53
  54 DEFINE_SHOW_ATTRIBUTE(ptdump_efi);
  55 #endif
  56
  57 static struct dentry *dir, *pe_knl, *pe_curknl;
  58
  59 static int __init pt_dump_debug_init(void)
  60 {
  61         dir = debugfs_create_dir("page_tables", NULL);
  62         if (!dir)
  63                 return -ENOMEM;
  64
  65         pe_knl = debugfs_create_file("kernel", 0400, dir, NULL,
  66                                      &ptdump_fops);
  67         if (!pe_knl)
  68                 goto err;
  69
  70         pe_curknl = debugfs_create_file("current_kernel", 0400,
  71                                         dir, NULL, &ptdump_curknl_fops);
  72         if (!pe_curknl)
  73                 goto err;
  74
  75 #ifdef CONFIG_PAGE_TABLE_ISOLATION
  76         pe_curusr = debugfs_create_file("current_user", 0400,
  77                                         dir, NULL, &ptdump_curusr_fops);
  78         if (!pe_curusr)
  79                 goto err;
  80 #endif
  81
  82 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
  83         pe_efi = debugfs_create_file("efi", 0400, dir, NULL, &ptdump_efi_fops);
  84         if (!pe_efi)
  85                 goto err;
  86 #endif
  87
  88         return 0;
  89 err:
  90         debugfs_remove_recursive(dir);
  91         return -ENOMEM;
  92 }
  93
  94 static void __exit pt_dump_debug_exit(void)
  95 {
  96         debugfs_remove_recursive(dir);
  97 }
  98
  99 module_init(pt_dump_debug_init);
 100 module_exit(pt_dump_debug_exit);
 101 MODULE_LICENSE("GPL");
 102 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
 103 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");