LXR linux/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
  13static unsigned long mmio_address;
  14module_param_hw(mmio_address, ulong, iomem, 0);
  15MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
  16                                "(or 8 MB if read_far is non-zero).");
  17
  18static unsigned long read_far = 0x400100;
  19module_param(read_far, ulong, 0);
  20MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
  21                                "(default: 0x400100).");
  22
  23static unsigned v16(unsigned i)
  24{
  25        return i * 12 + 7;
  26}
  27
  28static unsigned v32(unsigned i)
  29{
  30        return i * 212371 + 13;
  31}
  32
  33static 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
  49static 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
  72static 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
  80static 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 */
 101static 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
 116static 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
 139static void __exit cleanup(void)
 140{
 141        pr_debug("unloaded.\n");
 142}
 143
 144module_init(init);
 145module_exit(cleanup);
 146MODULE_LICENSE("GPL");
 147