arch/x86/mm/testmmiotrace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
   4  */
   5
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/module.h>
   9 #include <linux/io.h>
  10 #include <linux/mmiotrace.h>
  11 #include <linux/security.h>
  12
  13 static unsigned long mmio_address;
  14 module_param_hw(mmio_address, ulong, iomem, 0);
  15 MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
  16                                 "(or 8 MB if read_far is non-zero).");
  17
  18 static unsigned long read_far = 0x400100;
  19 module_param(read_far, ulong, 0);
  20 MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
  21                                 "(default: 0x400100).");
  22
  23 static unsigned v16(unsigned i)
  24 {
  25         return i * 12 + 7;
  26 }
  27
  28 static unsigned v32(unsigned i)
  29 {
  30         return i * 212371 + 13;
  31 }
  32
  33 static void do_write_test(void __iomem *p)
  34 {
  35         unsigned int i;
  36         pr_info("write test.\n");
  37         mmiotrace_printk("Write test.\n");
  38
  39         for (i = 0; i < 256; i++)
  40                 iowrite8(i, p + i);
  41
  42         for (i = 1024; i < (5 * 1024); i += 2)
  43                 iowrite16(v16(i), p + i);
  44
  45         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  46                 iowrite32(v32(i), p + i);
  47 }
  48
  49 static void do_read_test(void __iomem *p)
  50 {
  51         unsigned int i;
  52         unsigned errs[3] = { 0 };
  53         pr_info("read test.\n");
  54         mmiotrace_printk("Read test.\n");
  55
  56         for (i = 0; i < 256; i++)
  57                 if (ioread8(p + i) != i)
  58                         ++errs[0];
  59
  60         for (i = 1024; i < (5 * 1024); i += 2)
  61                 if (ioread16(p + i) != v16(i))
  62                         ++errs[1];
  63
  64         for (i = (5 * 1024); i < (16 * 1024); i += 4)
  65                 if (ioread32(p + i) != v32(i))
  66                         ++errs[2];
  67
  68         mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
  69                                                 errs[0], errs[1], errs[2]);
  70 }
  71
  72 static void do_read_far_test(void __iomem *p)
  73 {
  74         pr_info("read far test.\n");
  75         mmiotrace_printk("Read far test.\n");
  76
  77         ioread32(p + read_far);
  78 }
  79
  80 static void do_test(unsigned long size)
  81 {
  82         void __iomem *p = ioremap(mmio_address, size);
  83         if (!p) {
  84                 pr_err("could not ioremap, aborting.\n");
  85                 return;
  86         }
  87         mmiotrace_printk("ioremap returned %p.\n", p);
  88         do_write_test(p);
  89         do_read_test(p);
  90         if (read_far && read_far < size - 4)
  91                 do_read_far_test(p);
  92         iounmap(p);
  93 }
  94
  95 /*
  96  * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
  97  * a short time. We had a bug in deferred freeing procedure which tried
  98  * to free this region multiple times (ioremap can reuse the same address
  99  * for many mappings).
 100  */
 101 static void do_test_bulk_ioremapping(void)
 102 {
 103         void __iomem *p;
 104         int i;
 105
 106         for (i = 0; i < 10; ++i) {
 107                 p = ioremap(mmio_address, PAGE_SIZE);
 108                 if (p)
 109                         iounmap(p);
 110         }
 111
 112         /* Force freeing. If it will crash we will know why. */
 113         synchronize_rcu();
 114 }
 115
 116 static int __init init(void)
 117 {
 118         unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
 119         int ret = security_locked_down(LOCKDOWN_MMIOTRACE);
 120
 121         if (ret)
 122                 return ret;
 123
 124         if (mmio_address == 0) {
 125                 pr_err("you have to use the module argument mmio_address.\n");
 126                 pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
 127                 return -ENXIO;
 128         }
 129
 130         pr_warn("WARNING: mapping %lu kB @ 0x%08lx in PCI address space, "
 131                 "and writing 16 kB of rubbish in there.\n",
 132                 size >> 10, mmio_address);
 133         do_test(size);
 134         do_test_bulk_ioremapping();
 135         pr_info("All done.\n");
 136         return 0;
 137 }
 138
 139 static void __exit cleanup(void)
 140 {
 141         pr_debug("unloaded.\n");
 142 }
 143
 144 module_init(init);
 145 module_exit(cleanup);
 146 MODULE_LICENSE("GPL");