drivers/iommu/iommu-debugfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * IOMMU debugfs core infrastructure
   4  *
   5  * Copyright (C) 2018 Advanced Micro Devices, Inc.
   6  *
   7  * Author: Gary R Hook <gary.hook@amd.com>
   8  */
   9
  10 #include <linux/pci.h>
  11 #include <linux/iommu.h>
  12 #include <linux/debugfs.h>
  13
  14 struct dentry *iommu_debugfs_dir;
  15
  16 /**
  17  * iommu_debugfs_setup - create the top-level iommu directory in debugfs
  18  *
  19  * Provide base enablement for using debugfs to expose internal data of an
  20  * IOMMU driver. When called, this function creates the
  21  * /sys/kernel/debug/iommu directory.
  22  *
  23  * Emit a strong warning at boot time to indicate that this feature is
  24  * enabled.
  25  *
  26  * This function is called from iommu_init; drivers may then call
  27  * iommu_debugfs_new_driver_dir() to instantiate a vendor-specific
  28  * directory to be used to expose internal data.
  29  */
  30 void iommu_debugfs_setup(void)
  31 {
  32         if (!iommu_debugfs_dir) {
  33                 iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
  34                 pr_warn("\n");
  35                 pr_warn("*************************************************************\n");
  36                 pr_warn("**     NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE    **\n");
  37                 pr_warn("**                                                         **\n");
  38                 pr_warn("**  IOMMU DebugFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL  **\n");
  39                 pr_warn("**                                                         **\n");
  40                 pr_warn("** This means that this kernel is built to expose internal **\n");
  41                 pr_warn("** IOMMU data structures, which may compromise security on **\n");
  42                 pr_warn("** your system.                                            **\n");
  43                 pr_warn("**                                                         **\n");
  44                 pr_warn("** If you see this message and you are not debugging the   **\n");
  45                 pr_warn("** kernel, report this immediately to your vendor!         **\n");
  46                 pr_warn("**                                                         **\n");
  47                 pr_warn("**     NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE    **\n");
  48                 pr_warn("*************************************************************\n");
  49         }
  50 }
  51
  52 /**
  53  * iommu_debugfs_new_driver_dir - create a vendor directory under debugfs/iommu
  54  * @vendor: name of the vendor-specific subdirectory to create
  55  *
  56  * This function is called by an IOMMU driver to create the top-level debugfs
  57  * directory for that driver.
  58  *
  59  * Return: upon success, a pointer to the dentry for the new directory.
  60  *         NULL in case of failure.
  61  */
  62 struct dentry *iommu_debugfs_new_driver_dir(const char *vendor)
  63 {
  64         return debugfs_create_dir(vendor, iommu_debugfs_dir);
  65 }
  66 EXPORT_SYMBOL_GPL(iommu_debugfs_new_driver_dir);