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
trapped_io_setup(char * __unused)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
register_trapped_io(struct trapped_io * tiop)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
match_trapped_io_handler(struct list_head * list,unsigned long offset,unsigned long size)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
lookup_tiop(unsigned long address)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
lookup_address(struct trapped_io * tiop,unsigned long address)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
copy_word(unsigned long src_addr,int src_len,unsigned long dst_addr,int dst_len)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
from_device(void * dst,const void * src,unsigned long cnt)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
to_device(void * dst,const void * src,unsigned long cnt)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
handle_trapped_io(struct pt_regs * regs,unsigned long address)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