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 insn_size_t instruction; 274 int tmp; 275 276 if (trapped_io_disable) 277 return 0; 278 if (!lookup_tiop(address)) 279 return 0; 280 281 WARN_ON(user_mode(regs)); 282 283 if (copy_from_kernel_nofault(&instruction, (void *)(regs->pc), 284 sizeof(instruction))) { 285 return 0; 286 } 287 288 tmp = handle_unaligned_access(instruction, regs, 289 &trapped_io_access, 1, address); 290 return tmp == 0; 291 } 292