Commit | Line | Data |
---|---|---|
279b991b MR |
1 | /* |
2 | * This file is subject to the terms and conditions of the GNU General Public | |
3 | * License. See the file "COPYING" in the main directory of this archive | |
4 | * for more details. | |
5 | * | |
6 | * Support for Kernel relocation at boot time | |
7 | * | |
8 | * Copyright (C) 2015, Imagination Technologies Ltd. | |
9 | * Authors: Matt Redfearn (matt.redfearn@imgtec.com) | |
10 | */ | |
405bc8fd | 11 | #include <asm/bootinfo.h> |
279b991b | 12 | #include <asm/cacheflush.h> |
405bc8fd | 13 | #include <asm/fw/fw.h> |
279b991b MR |
14 | #include <asm/sections.h> |
15 | #include <asm/setup.h> | |
16 | #include <asm/timex.h> | |
17 | #include <linux/elf.h> | |
18 | #include <linux/kernel.h> | |
405bc8fd MR |
19 | #include <linux/libfdt.h> |
20 | #include <linux/of_fdt.h> | |
279b991b MR |
21 | #include <linux/sched.h> |
22 | #include <linux/start_kernel.h> | |
23 | #include <linux/string.h> | |
405bc8fd | 24 | #include <linux/printk.h> |
279b991b MR |
25 | |
26 | #define RELOCATED(x) ((void *)((long)x + offset)) | |
27 | ||
28 | extern u32 _relocation_start[]; /* End kernel image / start relocation table */ | |
29 | extern u32 _relocation_end[]; /* End relocation table */ | |
30 | ||
31 | extern long __start___ex_table; /* Start exception table */ | |
32 | extern long __stop___ex_table; /* End exception table */ | |
33 | ||
4c9fff36 MN |
34 | extern void __weak plat_fdt_relocated(void *new_location); |
35 | ||
8cc709d7 SH |
36 | /* |
37 | * This function may be defined for a platform to perform any post-relocation | |
38 | * fixup necessary. | |
39 | * Return non-zero to abort relocation | |
40 | */ | |
41 | int __weak plat_post_relocation(long offset) | |
42 | { | |
43 | return 0; | |
44 | } | |
45 | ||
279b991b MR |
46 | static inline u32 __init get_synci_step(void) |
47 | { | |
48 | u32 res; | |
49 | ||
50 | __asm__("rdhwr %0, $1" : "=r" (res)); | |
51 | ||
52 | return res; | |
53 | } | |
54 | ||
55 | static void __init sync_icache(void *kbase, unsigned long kernel_length) | |
56 | { | |
57 | void *kend = kbase + kernel_length; | |
58 | u32 step = get_synci_step(); | |
59 | ||
60 | do { | |
61 | __asm__ __volatile__( | |
62 | "synci 0(%0)" | |
63 | : /* no output */ | |
64 | : "r" (kbase)); | |
65 | ||
66 | kbase += step; | |
67 | } while (kbase < kend); | |
68 | ||
69 | /* Completion barrier */ | |
70 | __sync(); | |
71 | } | |
72 | ||
73 | static int __init apply_r_mips_64_rel(u32 *loc_orig, u32 *loc_new, long offset) | |
74 | { | |
75 | *(u64 *)loc_new += offset; | |
76 | ||
77 | return 0; | |
78 | } | |
79 | ||
80 | static int __init apply_r_mips_32_rel(u32 *loc_orig, u32 *loc_new, long offset) | |
81 | { | |
82 | *loc_new += offset; | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
87 | static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset) | |
88 | { | |
89 | unsigned long target_addr = (*loc_orig) & 0x03ffffff; | |
90 | ||
91 | if (offset % 4) { | |
92 | pr_err("Dangerous R_MIPS_26 REL relocation\n"); | |
93 | return -ENOEXEC; | |
94 | } | |
95 | ||
96 | /* Original target address */ | |
97 | target_addr <<= 2; | |
98 | target_addr += (unsigned long)loc_orig & ~0x03ffffff; | |
99 | ||
100 | /* Get the new target address */ | |
101 | target_addr += offset; | |
102 | ||
103 | if ((target_addr & 0xf0000000) != ((unsigned long)loc_new & 0xf0000000)) { | |
104 | pr_err("R_MIPS_26 REL relocation overflow\n"); | |
105 | return -ENOEXEC; | |
106 | } | |
107 | ||
108 | target_addr -= (unsigned long)loc_new & ~0x03ffffff; | |
109 | target_addr >>= 2; | |
110 | ||
111 | *loc_new = (*loc_new & ~0x03ffffff) | (target_addr & 0x03ffffff); | |
112 | ||
113 | return 0; | |
114 | } | |
115 | ||
116 | ||
117 | static int __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new, long offset) | |
118 | { | |
119 | unsigned long insn = *loc_orig; | |
120 | unsigned long target = (insn & 0xffff) << 16; /* high 16bits of target */ | |
121 | ||
122 | target += offset; | |
123 | ||
124 | *loc_new = (insn & ~0xffff) | ((target >> 16) & 0xffff); | |
125 | return 0; | |
126 | } | |
127 | ||
128 | static int (*reloc_handlers_rel[]) (u32 *, u32 *, long) __initdata = { | |
129 | [R_MIPS_64] = apply_r_mips_64_rel, | |
130 | [R_MIPS_32] = apply_r_mips_32_rel, | |
131 | [R_MIPS_26] = apply_r_mips_26_rel, | |
132 | [R_MIPS_HI16] = apply_r_mips_hi16_rel, | |
133 | }; | |
134 | ||
135 | int __init do_relocations(void *kbase_old, void *kbase_new, long offset) | |
136 | { | |
137 | u32 *r; | |
138 | u32 *loc_orig; | |
139 | u32 *loc_new; | |
140 | int type; | |
141 | int res; | |
142 | ||
143 | for (r = _relocation_start; r < _relocation_end; r++) { | |
144 | /* Sentinel for last relocation */ | |
145 | if (*r == 0) | |
146 | break; | |
147 | ||
148 | type = (*r >> 24) & 0xff; | |
149 | loc_orig = (void *)(kbase_old + ((*r & 0x00ffffff) << 2)); | |
150 | loc_new = RELOCATED(loc_orig); | |
151 | ||
152 | if (reloc_handlers_rel[type] == NULL) { | |
153 | /* Unsupported relocation */ | |
154 | pr_err("Unhandled relocation type %d at 0x%pK\n", | |
155 | type, loc_orig); | |
156 | return -ENOEXEC; | |
157 | } | |
158 | ||
159 | res = reloc_handlers_rel[type](loc_orig, loc_new, offset); | |
160 | if (res) | |
161 | return res; | |
162 | } | |
163 | ||
164 | return 0; | |
165 | } | |
166 | ||
167 | /* | |
168 | * The exception table is filled in by the relocs tool after vmlinux is linked. | |
169 | * It must be relocated separately since there will not be any relocation | |
170 | * information for it filled in by the linker. | |
171 | */ | |
172 | static int __init relocate_exception_table(long offset) | |
173 | { | |
174 | unsigned long *etable_start, *etable_end, *e; | |
175 | ||
176 | etable_start = RELOCATED(&__start___ex_table); | |
177 | etable_end = RELOCATED(&__stop___ex_table); | |
178 | ||
179 | for (e = etable_start; e < etable_end; e++) | |
180 | *e += offset; | |
181 | ||
182 | return 0; | |
183 | } | |
184 | ||
405bc8fd MR |
185 | #ifdef CONFIG_RANDOMIZE_BASE |
186 | ||
187 | static inline __init unsigned long rotate_xor(unsigned long hash, | |
188 | const void *area, size_t size) | |
189 | { | |
190 | size_t i; | |
191 | unsigned long *ptr = (unsigned long *)area; | |
192 | ||
193 | for (i = 0; i < size / sizeof(hash); i++) { | |
194 | /* Rotate by odd number of bits and XOR. */ | |
195 | hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7); | |
196 | hash ^= ptr[i]; | |
197 | } | |
198 | ||
199 | return hash; | |
200 | } | |
201 | ||
202 | static inline __init unsigned long get_random_boot(void) | |
203 | { | |
204 | unsigned long entropy = random_get_entropy(); | |
205 | unsigned long hash = 0; | |
206 | ||
207 | /* Attempt to create a simple but unpredictable starting entropy. */ | |
208 | hash = rotate_xor(hash, linux_banner, strlen(linux_banner)); | |
209 | ||
210 | /* Add in any runtime entropy we can get */ | |
211 | hash = rotate_xor(hash, &entropy, sizeof(entropy)); | |
212 | ||
213 | #if defined(CONFIG_USE_OF) | |
214 | /* Get any additional entropy passed in device tree */ | |
47366979 | 215 | if (initial_boot_params) { |
405bc8fd MR |
216 | int node, len; |
217 | u64 *prop; | |
218 | ||
219 | node = fdt_path_offset(initial_boot_params, "/chosen"); | |
220 | if (node >= 0) { | |
221 | prop = fdt_getprop_w(initial_boot_params, node, | |
222 | "kaslr-seed", &len); | |
223 | if (prop && (len == sizeof(u64))) | |
224 | hash = rotate_xor(hash, prop, sizeof(*prop)); | |
225 | } | |
226 | } | |
227 | #endif /* CONFIG_USE_OF */ | |
228 | ||
229 | return hash; | |
230 | } | |
231 | ||
232 | static inline __init bool kaslr_disabled(void) | |
233 | { | |
234 | char *str; | |
235 | ||
236 | #if defined(CONFIG_CMDLINE_BOOL) | |
237 | const char *builtin_cmdline = CONFIG_CMDLINE; | |
238 | ||
239 | str = strstr(builtin_cmdline, "nokaslr"); | |
240 | if (str == builtin_cmdline || | |
241 | (str > builtin_cmdline && *(str - 1) == ' ')) | |
242 | return true; | |
243 | #endif | |
244 | str = strstr(arcs_cmdline, "nokaslr"); | |
245 | if (str == arcs_cmdline || (str > arcs_cmdline && *(str - 1) == ' ')) | |
246 | return true; | |
247 | ||
248 | return false; | |
249 | } | |
250 | ||
251 | static inline void __init *determine_relocation_address(void) | |
252 | { | |
253 | /* Choose a new address for the kernel */ | |
254 | unsigned long kernel_length; | |
255 | void *dest = &_text; | |
256 | unsigned long offset; | |
257 | ||
258 | if (kaslr_disabled()) | |
259 | return dest; | |
260 | ||
261 | kernel_length = (long)_end - (long)(&_text); | |
262 | ||
263 | offset = get_random_boot() << 16; | |
264 | offset &= (CONFIG_RANDOMIZE_BASE_MAX_OFFSET - 1); | |
265 | if (offset < kernel_length) | |
266 | offset += ALIGN(kernel_length, 0xffff); | |
267 | ||
268 | return RELOCATED(dest); | |
269 | } | |
270 | ||
271 | #else | |
272 | ||
279b991b MR |
273 | static inline void __init *determine_relocation_address(void) |
274 | { | |
275 | /* | |
276 | * Choose a new address for the kernel | |
277 | * For now we'll hard code the destination | |
278 | */ | |
279 | return (void *)0xffffffff81000000; | |
280 | } | |
281 | ||
405bc8fd MR |
282 | #endif |
283 | ||
279b991b MR |
284 | static inline int __init relocation_addr_valid(void *loc_new) |
285 | { | |
286 | if ((unsigned long)loc_new & 0x0000ffff) { | |
287 | /* Inappropriately aligned new location */ | |
288 | return 0; | |
289 | } | |
290 | if ((unsigned long)loc_new < (unsigned long)&_end) { | |
291 | /* New location overlaps original kernel */ | |
292 | return 0; | |
293 | } | |
294 | return 1; | |
295 | } | |
296 | ||
297 | void *__init relocate_kernel(void) | |
298 | { | |
299 | void *loc_new; | |
300 | unsigned long kernel_length; | |
301 | unsigned long bss_length; | |
302 | long offset = 0; | |
303 | int res = 1; | |
304 | /* Default to original kernel entry point */ | |
305 | void *kernel_entry = start_kernel; | |
4c9fff36 | 306 | void *fdt = NULL; |
279b991b | 307 | |
405bc8fd MR |
308 | /* Get the command line */ |
309 | fw_init_cmdline(); | |
310 | #if defined(CONFIG_USE_OF) | |
311 | /* Deal with the device tree */ | |
4c9fff36 MN |
312 | fdt = plat_get_fdt(); |
313 | early_init_dt_scan(fdt); | |
405bc8fd MR |
314 | if (boot_command_line[0]) { |
315 | /* Boot command line was passed in device tree */ | |
316 | strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE); | |
317 | } | |
318 | #endif /* CONFIG_USE_OF */ | |
319 | ||
279b991b MR |
320 | kernel_length = (long)(&_relocation_start) - (long)(&_text); |
321 | bss_length = (long)&__bss_stop - (long)&__bss_start; | |
322 | ||
323 | loc_new = determine_relocation_address(); | |
324 | ||
325 | /* Sanity check relocation address */ | |
326 | if (relocation_addr_valid(loc_new)) | |
327 | offset = (unsigned long)loc_new - (unsigned long)(&_text); | |
328 | ||
405bc8fd MR |
329 | /* Reset the command line now so we don't end up with a duplicate */ |
330 | arcs_cmdline[0] = '\0'; | |
331 | ||
279b991b | 332 | if (offset) { |
4c9fff36 MN |
333 | void (*fdt_relocated_)(void *) = NULL; |
334 | #if defined(CONFIG_USE_OF) | |
335 | unsigned long fdt_phys = virt_to_phys(fdt); | |
336 | ||
337 | /* | |
338 | * If built-in dtb is used then it will have been relocated | |
339 | * during kernel _text relocation. If appended DTB is used | |
340 | * then it will not be relocated, but it should remain | |
341 | * intact in the original location. If dtb is loaded by | |
342 | * the bootloader then it may need to be moved if it crosses | |
343 | * the target memory area | |
344 | */ | |
345 | ||
346 | if (fdt_phys >= virt_to_phys(RELOCATED(&_text)) && | |
347 | fdt_phys <= virt_to_phys(RELOCATED(&_end))) { | |
348 | void *fdt_relocated = | |
349 | RELOCATED(ALIGN((long)&_end, PAGE_SIZE)); | |
350 | memcpy(fdt_relocated, fdt, fdt_totalsize(fdt)); | |
351 | fdt = fdt_relocated; | |
352 | fdt_relocated_ = RELOCATED(&plat_fdt_relocated); | |
353 | } | |
354 | #endif /* CONFIG_USE_OF */ | |
355 | ||
279b991b MR |
356 | /* Copy the kernel to it's new location */ |
357 | memcpy(loc_new, &_text, kernel_length); | |
358 | ||
359 | /* Perform relocations on the new kernel */ | |
360 | res = do_relocations(&_text, loc_new, offset); | |
361 | if (res < 0) | |
362 | goto out; | |
363 | ||
364 | /* Sync the caches ready for execution of new kernel */ | |
365 | sync_icache(loc_new, kernel_length); | |
366 | ||
367 | res = relocate_exception_table(offset); | |
368 | if (res < 0) | |
369 | goto out; | |
370 | ||
371 | /* | |
372 | * The original .bss has already been cleared, and | |
373 | * some variables such as command line parameters | |
374 | * stored to it so make a copy in the new location. | |
375 | */ | |
376 | memcpy(RELOCATED(&__bss_start), &__bss_start, bss_length); | |
377 | ||
4c9fff36 MN |
378 | /* |
379 | * If fdt was stored outside of the kernel image and | |
380 | * had to be moved then update platform's state data | |
381 | * with the new fdt location | |
382 | */ | |
383 | if (fdt_relocated_) | |
384 | fdt_relocated_(fdt); | |
385 | ||
8cc709d7 SH |
386 | /* |
387 | * Last chance for the platform to abort relocation. | |
388 | * This may also be used by the platform to perform any | |
389 | * initialisation required now that the new kernel is | |
390 | * resident in memory and ready to be executed. | |
391 | */ | |
392 | if (plat_post_relocation(offset)) | |
393 | goto out; | |
394 | ||
279b991b MR |
395 | /* The current thread is now within the relocated image */ |
396 | __current_thread_info = RELOCATED(&init_thread_union); | |
397 | ||
398 | /* Return the new kernel's entry point */ | |
399 | kernel_entry = RELOCATED(start_kernel); | |
400 | } | |
401 | out: | |
402 | return kernel_entry; | |
403 | } | |
405bc8fd MR |
404 | |
405 | /* | |
406 | * Show relocation information on panic. | |
407 | */ | |
408 | void show_kernel_relocation(const char *level) | |
409 | { | |
410 | unsigned long offset; | |
411 | ||
412 | offset = __pa_symbol(_text) - __pa_symbol(VMLINUX_LOAD_ADDRESS); | |
413 | ||
414 | if (IS_ENABLED(CONFIG_RELOCATABLE) && offset > 0) { | |
415 | printk(level); | |
416 | pr_cont("Kernel relocated by 0x%pK\n", (void *)offset); | |
417 | pr_cont(" .text @ 0x%pK\n", _text); | |
418 | pr_cont(" .data @ 0x%pK\n", _sdata); | |
419 | pr_cont(" .bss @ 0x%pK\n", __bss_start); | |
420 | } | |
421 | } | |
422 | ||
423 | static int kernel_location_notifier_fn(struct notifier_block *self, | |
424 | unsigned long v, void *p) | |
425 | { | |
426 | show_kernel_relocation(KERN_EMERG); | |
427 | return NOTIFY_DONE; | |
428 | } | |
429 | ||
430 | static struct notifier_block kernel_location_notifier = { | |
431 | .notifier_call = kernel_location_notifier_fn | |
432 | }; | |
433 | ||
434 | static int __init register_kernel_offset_dumper(void) | |
435 | { | |
436 | atomic_notifier_chain_register(&panic_notifier_list, | |
437 | &kernel_location_notifier); | |
438 | return 0; | |
439 | } | |
440 | __initcall(register_kernel_offset_dumper); |