arch/sh/kernel/io_trapped.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Trapped io support
   4  *
   5  * Copyright (C) 2008 Magnus Damm
   6  *
   7  * Intercept io operations by trapping.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/mm.h>
  11 #include <linux/bitops.h>
  12 #include <linux/vmalloc.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <asm/mmu_context.h>
  16 #include <linux/uaccess.h>
  17 #include <asm/io.h>
  18 #include <asm/io_trapped.h>
  19
  20 #define TRAPPED_PAGES_MAX 16
  21
  22 #ifdef CONFIG_HAS_IOPORT_MAP
  23 LIST_HEAD(trapped_io);
  24 EXPORT_SYMBOL_GPL(trapped_io);
  25 #endif
  26 #ifdef CONFIG_HAS_IOMEM
  27 LIST_HEAD(trapped_mem);
  28 EXPORT_SYMBOL_GPL(trapped_mem);
  29 #endif
  30 static DEFINE_SPINLOCK(trapped_lock);
  31
  32 static int trapped_io_disable __read_mostly;
  33
  34 static int __init trapped_io_setup(char *__unused)
  35 {
  36         trapped_io_disable = 1;
  37         return 1;
  38 }
  39 __setup("noiotrap", trapped_io_setup);
  40
  41 int register_trapped_io(struct trapped_io *tiop)
  42 {
  43         struct resource *res;
  44         unsigned long len = 0, flags = 0;
  45         struct page *pages[TRAPPED_PAGES_MAX];
  46         int k, n;
  47
  48         if (unlikely(trapped_io_disable))
  49                 return 0;
  50
  51         /* structure must be page aligned */
  52         if ((unsigned long)tiop & (PAGE_SIZE - 1))
  53                 goto bad;
  54
  55         for (k = 0; k < tiop->num_resources; k++) {
  56                 res = tiop->resource + k;
  57                 len += roundup(resource_size(res), PAGE_SIZE);
  58                 flags |= res->flags;
  59         }
  60
  61         /* support IORESOURCE_IO _or_ MEM, not both */
  62         if (hweight_long(flags) != 1)
  63                 goto bad;
  64
  65         n = len >> PAGE_SHIFT;
  66
  67         if (n >= TRAPPED_PAGES_MAX)
  68                 goto bad;
  69
  70         for (k = 0; k < n; k++)
  71                 pages[k] = virt_to_page(tiop);
  72
  73         tiop->virt_base = vmap(pages, n, VM_MAP, PAGE_NONE);
  74         if (!tiop->virt_base)
  75                 goto bad;
  76
  77         len = 0;
  78         for (k = 0; k < tiop->num_resources; k++) {
  79                 res = tiop->resource + k;
  80                 pr_info("trapped io 0x%08lx overrides %s 0x%08lx\n",
  81                        (unsigned long)(tiop->virt_base + len),
  82                        res->flags & IORESOURCE_IO ? "io" : "mmio",
  83                        (unsigned long)res->start);
  84                 len += roundup(resource_size(res), PAGE_SIZE);
  85         }
  86
  87         tiop->magic = IO_TRAPPED_MAGIC;
  88         INIT_LIST_HEAD(&tiop->list);
  89         spin_lock_irq(&trapped_lock);
  90 #ifdef CONFIG_HAS_IOPORT_MAP
  91         if (flags & IORESOURCE_IO)
  92                 list_add(&tiop->list, &trapped_io);
  93 #endif
  94 #ifdef CONFIG_HAS_IOMEM
  95         if (flags & IORESOURCE_MEM)
  96                 list_add(&tiop->list, &trapped_mem);
  97 #endif
  98         spin_unlock_irq(&trapped_lock);
  99
 100         return 0;
 101  bad:
 102         pr_warn("unable to install trapped io filter\n");
 103         return -1;
 104 }
 105
 106 void __iomem *match_trapped_io_handler(struct list_head *list,
 107                                        unsigned long offset,
 108                                        unsigned long size)
 109 {
 110         unsigned long voffs;
 111         struct trapped_io *tiop;
 112         struct resource *res;
 113         int k, len;
 114         unsigned long flags;
 115
 116         spin_lock_irqsave(&trapped_lock, flags);
 117         list_for_each_entry(tiop, list, list) {
 118                 voffs = 0;
 119                 for (k = 0; k < tiop->num_resources; k++) {
 120                         res = tiop->resource + k;
 121                         if (res->start == offset) {
 122                                 spin_unlock_irqrestore(&trapped_lock, flags);
 123                                 return tiop->virt_base + voffs;
 124                         }
 125
 126                         len = resource_size(res);
 127                         voffs += roundup(len, PAGE_SIZE);
 128                 }
 129         }
 130         spin_unlock_irqrestore(&trapped_lock, flags);
 131         return NULL;
 132 }
 133
 134 static struct trapped_io *lookup_tiop(unsigned long address)
 135 {
 136         pgd_t *pgd_k;
 137         p4d_t *p4d_k;
 138         pud_t *pud_k;
 139         pmd_t *pmd_k;
 140         pte_t *pte_k;
 141         pte_t entry;
 142
 143         pgd_k = swapper_pg_dir + pgd_index(address);
 144         if (!pgd_present(*pgd_k))
 145                 return NULL;
 146
 147         p4d_k = p4d_offset(pgd_k, address);
 148         if (!p4d_present(*p4d_k))
 149                 return NULL;
 150
 151         pud_k = pud_offset(p4d_k, address);
 152         if (!pud_present(*pud_k))
 153                 return NULL;
 154
 155         pmd_k = pmd_offset(pud_k, address);
 156         if (!pmd_present(*pmd_k))
 157                 return NULL;
 158
 159         pte_k = pte_offset_kernel(pmd_k, address);
 160         entry = *pte_k;
 161
 162         return pfn_to_kaddr(pte_pfn(entry));
 163 }
 164
 165 static unsigned long lookup_address(struct trapped_io *tiop,
 166                                     unsigned long address)
 167 {
 168         struct resource *res;
 169         unsigned long vaddr = (unsigned long)tiop->virt_base;
 170         unsigned long len;
 171         int k;
 172
 173         for (k = 0; k < tiop->num_resources; k++) {
 174                 res = tiop->resource + k;
 175                 len = roundup(resource_size(res), PAGE_SIZE);
 176                 if (address < (vaddr + len))
 177                         return res->start + (address - vaddr);
 178                 vaddr += len;
 179         }
 180         return 0;
 181 }
 182
 183 static unsigned long long copy_word(unsigned long src_addr, int src_len,
 184                                     unsigned long dst_addr, int dst_len)
 185 {
 186         unsigned long long tmp = 0;
 187
 188         switch (src_len) {
 189         case 1:
 190                 tmp = __raw_readb(src_addr);
 191                 break;
 192         case 2:
 193                 tmp = __raw_readw(src_addr);
 194                 break;
 195         case 4:
 196                 tmp = __raw_readl(src_addr);
 197                 break;
 198         case 8:
 199                 tmp = __raw_readq(src_addr);
 200                 break;
 201         }
 202
 203         switch (dst_len) {
 204         case 1:
 205                 __raw_writeb(tmp, dst_addr);
 206                 break;
 207         case 2:
 208                 __raw_writew(tmp, dst_addr);
 209                 break;
 210         case 4:
 211                 __raw_writel(tmp, dst_addr);
 212                 break;
 213         case 8:
 214                 __raw_writeq(tmp, dst_addr);
 215                 break;
 216         }
 217
 218         return tmp;
 219 }
 220
 221 static unsigned long from_device(void *dst, const void *src, unsigned long cnt)
 222 {
 223         struct trapped_io *tiop;
 224         unsigned long src_addr = (unsigned long)src;
 225         unsigned long long tmp;
 226
 227         pr_debug("trapped io read 0x%08lx (%ld)\n", src_addr, cnt);
 228         tiop = lookup_tiop(src_addr);
 229         WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
 230
 231         src_addr = lookup_address(tiop, src_addr);
 232         if (!src_addr)
 233                 return cnt;
 234
 235         tmp = copy_word(src_addr,
 236                         max_t(unsigned long, cnt,
 237                               (tiop->minimum_bus_width / 8)),
 238                         (unsigned long)dst, cnt);
 239
 240         pr_debug("trapped io read 0x%08lx -> 0x%08llx\n", src_addr, tmp);
 241         return 0;
 242 }
 243
 244 static unsigned long to_device(void *dst, const void *src, unsigned long cnt)
 245 {
 246         struct trapped_io *tiop;
 247         unsigned long dst_addr = (unsigned long)dst;
 248         unsigned long long tmp;
 249
 250         pr_debug("trapped io write 0x%08lx (%ld)\n", dst_addr, cnt);
 251         tiop = lookup_tiop(dst_addr);
 252         WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
 253
 254         dst_addr = lookup_address(tiop, dst_addr);
 255         if (!dst_addr)
 256                 return cnt;
 257
 258         tmp = copy_word((unsigned long)src, cnt,
 259                         dst_addr, max_t(unsigned long, cnt,
 260                                         (tiop->minimum_bus_width / 8)));
 261
 262         pr_debug("trapped io write 0x%08lx -> 0x%08llx\n", dst_addr, tmp);
 263         return 0;
 264 }
 265
 266 static struct mem_access trapped_io_access = {
 267         from_device,
 268         to_device,
 269 };
 270
 271 int handle_trapped_io(struct pt_regs *regs, unsigned long address)
 272 {
 273         mm_segment_t oldfs;
 274         insn_size_t instruction;
 275         int tmp;
 276
 277         if (trapped_io_disable)
 278                 return 0;
 279         if (!lookup_tiop(address))
 280                 return 0;
 281
 282         WARN_ON(user_mode(regs));
 283
 284         oldfs = get_fs();
 285         set_fs(KERNEL_DS);
 286         if (copy_from_user(&instruction, (void *)(regs->pc),
 287                            sizeof(instruction))) {
 288                 set_fs(oldfs);
 289                 return 0;
 290         }
 291
 292         tmp = handle_unaligned_access(instruction, regs,
 293                                       &trapped_io_access, 1, address);
 294         set_fs(oldfs);
 295         return tmp == 0;
 296 }