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. | |
fb615d61 | 9 | * Authors: Matt Redfearn (matt.redfearn@mips.com) |
279b991b | 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> | |
f39650de | 21 | #include <linux/panic_notifier.h> |
ec62a3bd | 22 | #include <linux/sched/task.h> |
279b991b MR |
23 | #include <linux/start_kernel.h> |
24 | #include <linux/string.h> | |
405bc8fd | 25 | #include <linux/printk.h> |
279b991b MR |
26 | |
27 | #define RELOCATED(x) ((void *)((long)x + offset)) | |
28 | ||
29 | extern u32 _relocation_start[]; /* End kernel image / start relocation table */ | |
30 | extern u32 _relocation_end[]; /* End relocation table */ | |
31 | ||
32 | extern long __start___ex_table; /* Start exception table */ | |
33 | extern long __stop___ex_table; /* End exception table */ | |
34 | ||
4c9fff36 MN |
35 | extern void __weak plat_fdt_relocated(void *new_location); |
36 | ||
8cc709d7 SH |
37 | /* |
38 | * This function may be defined for a platform to perform any post-relocation | |
39 | * fixup necessary. | |
40 | * Return non-zero to abort relocation | |
41 | */ | |
42 | int __weak plat_post_relocation(long offset) | |
43 | { | |
44 | return 0; | |
45 | } | |
46 | ||
279b991b MR |
47 | static inline u32 __init get_synci_step(void) |
48 | { | |
49 | u32 res; | |
50 | ||
51 | __asm__("rdhwr %0, $1" : "=r" (res)); | |
52 | ||
53 | return res; | |
54 | } | |
55 | ||
56 | static void __init sync_icache(void *kbase, unsigned long kernel_length) | |
57 | { | |
58 | void *kend = kbase + kernel_length; | |
59 | u32 step = get_synci_step(); | |
60 | ||
61 | do { | |
62 | __asm__ __volatile__( | |
63 | "synci 0(%0)" | |
64 | : /* no output */ | |
65 | : "r" (kbase)); | |
66 | ||
67 | kbase += step; | |
c0aac3a5 | 68 | } while (step && kbase < kend); |
279b991b MR |
69 | |
70 | /* Completion barrier */ | |
71 | __sync(); | |
72 | } | |
73 | ||
d9e84fb1 | 74 | static void __init apply_r_mips_64_rel(u32 *loc_new, long offset) |
279b991b MR |
75 | { |
76 | *(u64 *)loc_new += offset; | |
279b991b MR |
77 | } |
78 | ||
d9e84fb1 | 79 | static void __init apply_r_mips_32_rel(u32 *loc_new, long offset) |
279b991b MR |
80 | { |
81 | *loc_new += offset; | |
279b991b MR |
82 | } |
83 | ||
84 | static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset) | |
85 | { | |
86 | unsigned long target_addr = (*loc_orig) & 0x03ffffff; | |
87 | ||
88 | if (offset % 4) { | |
89 | pr_err("Dangerous R_MIPS_26 REL relocation\n"); | |
90 | return -ENOEXEC; | |
91 | } | |
92 | ||
93 | /* Original target address */ | |
94 | target_addr <<= 2; | |
74a2810b | 95 | target_addr += (unsigned long)loc_orig & 0xf0000000; |
279b991b MR |
96 | |
97 | /* Get the new target address */ | |
98 | target_addr += offset; | |
99 | ||
100 | if ((target_addr & 0xf0000000) != ((unsigned long)loc_new & 0xf0000000)) { | |
101 | pr_err("R_MIPS_26 REL relocation overflow\n"); | |
102 | return -ENOEXEC; | |
103 | } | |
104 | ||
74a2810b | 105 | target_addr -= (unsigned long)loc_new & 0xf0000000; |
279b991b MR |
106 | target_addr >>= 2; |
107 | ||
108 | *loc_new = (*loc_new & ~0x03ffffff) | (target_addr & 0x03ffffff); | |
109 | ||
110 | return 0; | |
111 | } | |
112 | ||
113 | ||
d9e84fb1 AL |
114 | static void __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new, |
115 | long offset) | |
279b991b MR |
116 | { |
117 | unsigned long insn = *loc_orig; | |
118 | unsigned long target = (insn & 0xffff) << 16; /* high 16bits of target */ | |
119 | ||
120 | target += offset; | |
121 | ||
122 | *loc_new = (insn & ~0xffff) | ((target >> 16) & 0xffff); | |
279b991b MR |
123 | } |
124 | ||
d9e84fb1 AL |
125 | static int __init reloc_handler(u32 type, u32 *loc_orig, u32 *loc_new, |
126 | long offset) | |
127 | { | |
128 | switch (type) { | |
129 | case R_MIPS_64: | |
130 | apply_r_mips_64_rel(loc_new, offset); | |
131 | break; | |
132 | case R_MIPS_32: | |
133 | apply_r_mips_32_rel(loc_new, offset); | |
134 | break; | |
135 | case R_MIPS_26: | |
136 | return apply_r_mips_26_rel(loc_orig, loc_new, offset); | |
137 | case R_MIPS_HI16: | |
138 | apply_r_mips_hi16_rel(loc_orig, loc_new, offset); | |
139 | break; | |
140 | default: | |
141 | pr_err("Unhandled relocation type %d at 0x%pK\n", type, | |
142 | loc_orig); | |
143 | return -ENOEXEC; | |
144 | } | |
279b991b | 145 | |
d9e84fb1 AL |
146 | return 0; |
147 | } | |
279b991b | 148 | |
d9e84fb1 | 149 | static int __init do_relocations(void *kbase_old, void *kbase_new, long offset) |
279b991b MR |
150 | { |
151 | u32 *r; | |
152 | u32 *loc_orig; | |
153 | u32 *loc_new; | |
154 | int type; | |
155 | int res; | |
156 | ||
157 | for (r = _relocation_start; r < _relocation_end; r++) { | |
158 | /* Sentinel for last relocation */ | |
159 | if (*r == 0) | |
160 | break; | |
161 | ||
162 | type = (*r >> 24) & 0xff; | |
49881542 | 163 | loc_orig = kbase_old + ((*r & 0x00ffffff) << 2); |
279b991b MR |
164 | loc_new = RELOCATED(loc_orig); |
165 | ||
d9e84fb1 | 166 | res = reloc_handler(type, loc_orig, loc_new, offset); |
279b991b MR |
167 | if (res) |
168 | return res; | |
169 | } | |
170 | ||
171 | return 0; | |
172 | } | |
173 | ||
174 | /* | |
175 | * The exception table is filled in by the relocs tool after vmlinux is linked. | |
176 | * It must be relocated separately since there will not be any relocation | |
177 | * information for it filled in by the linker. | |
178 | */ | |
179 | static int __init relocate_exception_table(long offset) | |
180 | { | |
181 | unsigned long *etable_start, *etable_end, *e; | |
182 | ||
183 | etable_start = RELOCATED(&__start___ex_table); | |
184 | etable_end = RELOCATED(&__stop___ex_table); | |
185 | ||
186 | for (e = etable_start; e < etable_end; e++) | |
187 | *e += offset; | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
405bc8fd MR |
192 | #ifdef CONFIG_RANDOMIZE_BASE |
193 | ||
194 | static inline __init unsigned long rotate_xor(unsigned long hash, | |
195 | const void *area, size_t size) | |
196 | { | |
69e97683 AL |
197 | const typeof(hash) *ptr = PTR_ALIGN(area, sizeof(hash)); |
198 | size_t diff, i; | |
199 | ||
200 | diff = (void *)ptr - area; | |
201 | if (unlikely(size < diff + sizeof(hash))) | |
202 | return hash; | |
203 | ||
204 | size = ALIGN_DOWN(size - diff, sizeof(hash)); | |
405bc8fd MR |
205 | |
206 | for (i = 0; i < size / sizeof(hash); i++) { | |
207 | /* Rotate by odd number of bits and XOR. */ | |
208 | hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7); | |
209 | hash ^= ptr[i]; | |
210 | } | |
211 | ||
212 | return hash; | |
213 | } | |
214 | ||
215 | static inline __init unsigned long get_random_boot(void) | |
216 | { | |
217 | unsigned long entropy = random_get_entropy(); | |
218 | unsigned long hash = 0; | |
219 | ||
220 | /* Attempt to create a simple but unpredictable starting entropy. */ | |
221 | hash = rotate_xor(hash, linux_banner, strlen(linux_banner)); | |
222 | ||
223 | /* Add in any runtime entropy we can get */ | |
224 | hash = rotate_xor(hash, &entropy, sizeof(entropy)); | |
225 | ||
226 | #if defined(CONFIG_USE_OF) | |
227 | /* Get any additional entropy passed in device tree */ | |
47366979 | 228 | if (initial_boot_params) { |
405bc8fd MR |
229 | int node, len; |
230 | u64 *prop; | |
231 | ||
232 | node = fdt_path_offset(initial_boot_params, "/chosen"); | |
233 | if (node >= 0) { | |
234 | prop = fdt_getprop_w(initial_boot_params, node, | |
235 | "kaslr-seed", &len); | |
236 | if (prop && (len == sizeof(u64))) | |
237 | hash = rotate_xor(hash, prop, sizeof(*prop)); | |
238 | } | |
239 | } | |
240 | #endif /* CONFIG_USE_OF */ | |
241 | ||
242 | return hash; | |
243 | } | |
244 | ||
245 | static inline __init bool kaslr_disabled(void) | |
246 | { | |
247 | char *str; | |
248 | ||
249 | #if defined(CONFIG_CMDLINE_BOOL) | |
250 | const char *builtin_cmdline = CONFIG_CMDLINE; | |
251 | ||
252 | str = strstr(builtin_cmdline, "nokaslr"); | |
253 | if (str == builtin_cmdline || | |
254 | (str > builtin_cmdline && *(str - 1) == ' ')) | |
255 | return true; | |
256 | #endif | |
257 | str = strstr(arcs_cmdline, "nokaslr"); | |
258 | if (str == arcs_cmdline || (str > arcs_cmdline && *(str - 1) == ' ')) | |
259 | return true; | |
260 | ||
261 | return false; | |
262 | } | |
263 | ||
264 | static inline void __init *determine_relocation_address(void) | |
265 | { | |
266 | /* Choose a new address for the kernel */ | |
267 | unsigned long kernel_length; | |
268 | void *dest = &_text; | |
269 | unsigned long offset; | |
270 | ||
271 | if (kaslr_disabled()) | |
272 | return dest; | |
273 | ||
274 | kernel_length = (long)_end - (long)(&_text); | |
275 | ||
276 | offset = get_random_boot() << 16; | |
277 | offset &= (CONFIG_RANDOMIZE_BASE_MAX_OFFSET - 1); | |
278 | if (offset < kernel_length) | |
279 | offset += ALIGN(kernel_length, 0xffff); | |
280 | ||
281 | return RELOCATED(dest); | |
282 | } | |
283 | ||
284 | #else | |
285 | ||
279b991b MR |
286 | static inline void __init *determine_relocation_address(void) |
287 | { | |
288 | /* | |
289 | * Choose a new address for the kernel | |
290 | * For now we'll hard code the destination | |
291 | */ | |
292 | return (void *)0xffffffff81000000; | |
293 | } | |
294 | ||
405bc8fd MR |
295 | #endif |
296 | ||
279b991b MR |
297 | static inline int __init relocation_addr_valid(void *loc_new) |
298 | { | |
299 | if ((unsigned long)loc_new & 0x0000ffff) { | |
300 | /* Inappropriately aligned new location */ | |
301 | return 0; | |
302 | } | |
303 | if ((unsigned long)loc_new < (unsigned long)&_end) { | |
304 | /* New location overlaps original kernel */ | |
305 | return 0; | |
306 | } | |
307 | return 1; | |
308 | } | |
309 | ||
d4d3ef8b JH |
310 | static inline void __init update_kaslr_offset(unsigned long *addr, long offset) |
311 | { | |
312 | unsigned long *new_addr = (unsigned long *)RELOCATED(addr); | |
313 | ||
314 | *new_addr = (unsigned long)offset; | |
315 | } | |
316 | ||
a307a4ce JH |
317 | #if defined(CONFIG_USE_OF) |
318 | void __weak *plat_get_fdt(void) | |
319 | { | |
320 | return NULL; | |
321 | } | |
322 | #endif | |
323 | ||
279b991b MR |
324 | void *__init relocate_kernel(void) |
325 | { | |
326 | void *loc_new; | |
327 | unsigned long kernel_length; | |
328 | unsigned long bss_length; | |
329 | long offset = 0; | |
330 | int res = 1; | |
331 | /* Default to original kernel entry point */ | |
332 | void *kernel_entry = start_kernel; | |
4c9fff36 | 333 | void *fdt = NULL; |
279b991b | 334 | |
405bc8fd MR |
335 | /* Get the command line */ |
336 | fw_init_cmdline(); | |
337 | #if defined(CONFIG_USE_OF) | |
338 | /* Deal with the device tree */ | |
4c9fff36 MN |
339 | fdt = plat_get_fdt(); |
340 | early_init_dt_scan(fdt); | |
405bc8fd MR |
341 | if (boot_command_line[0]) { |
342 | /* Boot command line was passed in device tree */ | |
877336c1 | 343 | strscpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE); |
405bc8fd MR |
344 | } |
345 | #endif /* CONFIG_USE_OF */ | |
346 | ||
279b991b MR |
347 | kernel_length = (long)(&_relocation_start) - (long)(&_text); |
348 | bss_length = (long)&__bss_stop - (long)&__bss_start; | |
349 | ||
350 | loc_new = determine_relocation_address(); | |
351 | ||
352 | /* Sanity check relocation address */ | |
353 | if (relocation_addr_valid(loc_new)) | |
354 | offset = (unsigned long)loc_new - (unsigned long)(&_text); | |
355 | ||
405bc8fd MR |
356 | /* Reset the command line now so we don't end up with a duplicate */ |
357 | arcs_cmdline[0] = '\0'; | |
358 | ||
279b991b | 359 | if (offset) { |
4c9fff36 MN |
360 | void (*fdt_relocated_)(void *) = NULL; |
361 | #if defined(CONFIG_USE_OF) | |
362 | unsigned long fdt_phys = virt_to_phys(fdt); | |
363 | ||
364 | /* | |
365 | * If built-in dtb is used then it will have been relocated | |
366 | * during kernel _text relocation. If appended DTB is used | |
367 | * then it will not be relocated, but it should remain | |
368 | * intact in the original location. If dtb is loaded by | |
369 | * the bootloader then it may need to be moved if it crosses | |
370 | * the target memory area | |
371 | */ | |
372 | ||
373 | if (fdt_phys >= virt_to_phys(RELOCATED(&_text)) && | |
374 | fdt_phys <= virt_to_phys(RELOCATED(&_end))) { | |
375 | void *fdt_relocated = | |
376 | RELOCATED(ALIGN((long)&_end, PAGE_SIZE)); | |
377 | memcpy(fdt_relocated, fdt, fdt_totalsize(fdt)); | |
378 | fdt = fdt_relocated; | |
379 | fdt_relocated_ = RELOCATED(&plat_fdt_relocated); | |
380 | } | |
381 | #endif /* CONFIG_USE_OF */ | |
382 | ||
2f9060b1 | 383 | /* Copy the kernel to its new location */ |
279b991b MR |
384 | memcpy(loc_new, &_text, kernel_length); |
385 | ||
386 | /* Perform relocations on the new kernel */ | |
387 | res = do_relocations(&_text, loc_new, offset); | |
388 | if (res < 0) | |
389 | goto out; | |
390 | ||
391 | /* Sync the caches ready for execution of new kernel */ | |
392 | sync_icache(loc_new, kernel_length); | |
393 | ||
394 | res = relocate_exception_table(offset); | |
395 | if (res < 0) | |
396 | goto out; | |
397 | ||
398 | /* | |
399 | * The original .bss has already been cleared, and | |
400 | * some variables such as command line parameters | |
401 | * stored to it so make a copy in the new location. | |
402 | */ | |
403 | memcpy(RELOCATED(&__bss_start), &__bss_start, bss_length); | |
404 | ||
4c9fff36 MN |
405 | /* |
406 | * If fdt was stored outside of the kernel image and | |
407 | * had to be moved then update platform's state data | |
408 | * with the new fdt location | |
409 | */ | |
410 | if (fdt_relocated_) | |
411 | fdt_relocated_(fdt); | |
412 | ||
8cc709d7 SH |
413 | /* |
414 | * Last chance for the platform to abort relocation. | |
415 | * This may also be used by the platform to perform any | |
416 | * initialisation required now that the new kernel is | |
417 | * resident in memory and ready to be executed. | |
418 | */ | |
419 | if (plat_post_relocation(offset)) | |
420 | goto out; | |
421 | ||
279b991b MR |
422 | /* The current thread is now within the relocated image */ |
423 | __current_thread_info = RELOCATED(&init_thread_union); | |
424 | ||
425 | /* Return the new kernel's entry point */ | |
426 | kernel_entry = RELOCATED(start_kernel); | |
d4d3ef8b JH |
427 | |
428 | /* Error may occur before, so keep it at last */ | |
429 | update_kaslr_offset(&__kaslr_offset, offset); | |
279b991b MR |
430 | } |
431 | out: | |
432 | return kernel_entry; | |
433 | } | |
405bc8fd MR |
434 | |
435 | /* | |
436 | * Show relocation information on panic. | |
437 | */ | |
d9e84fb1 | 438 | static void show_kernel_relocation(const char *level) |
405bc8fd | 439 | { |
457d2fc5 | 440 | if (__kaslr_offset > 0) { |
405bc8fd | 441 | printk(level); |
457d2fc5 | 442 | pr_cont("Kernel relocated by 0x%pK\n", (void *)__kaslr_offset); |
405bc8fd MR |
443 | pr_cont(" .text @ 0x%pK\n", _text); |
444 | pr_cont(" .data @ 0x%pK\n", _sdata); | |
445 | pr_cont(" .bss @ 0x%pK\n", __bss_start); | |
446 | } | |
447 | } | |
448 | ||
449 | static int kernel_location_notifier_fn(struct notifier_block *self, | |
450 | unsigned long v, void *p) | |
451 | { | |
452 | show_kernel_relocation(KERN_EMERG); | |
453 | return NOTIFY_DONE; | |
454 | } | |
455 | ||
456 | static struct notifier_block kernel_location_notifier = { | |
457 | .notifier_call = kernel_location_notifier_fn | |
458 | }; | |
459 | ||
460 | static int __init register_kernel_offset_dumper(void) | |
461 | { | |
462 | atomic_notifier_chain_register(&panic_notifier_list, | |
463 | &kernel_location_notifier); | |
464 | return 0; | |
465 | } | |
466 | __initcall(register_kernel_offset_dumper); |