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aaddd3ea ME |
1 | /* |
2 | * Copyright 2008 Michael Ellerman, IBM Corporation. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | */ | |
9 | ||
10 | #include <linux/kernel.h> | |
ae0dc736 ME |
11 | #include <linux/vmalloc.h> |
12 | #include <linux/init.h> | |
27ac792c | 13 | #include <linux/mm.h> |
ae0dc736 | 14 | #include <asm/page.h> |
aaddd3ea | 15 | #include <asm/code-patching.h> |
b6e37968 | 16 | #include <asm/uaccess.h> |
aaddd3ea ME |
17 | |
18 | ||
b6e37968 | 19 | int patch_instruction(unsigned int *addr, unsigned int instr) |
aaddd3ea | 20 | { |
b6e37968 SR |
21 | int err; |
22 | ||
636802ef | 23 | __put_user_size(instr, addr, 4, err); |
b6e37968 SR |
24 | if (err) |
25 | return err; | |
e7a57273 | 26 | asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr)); |
b6e37968 | 27 | return 0; |
aaddd3ea ME |
28 | } |
29 | ||
b6e37968 | 30 | int patch_branch(unsigned int *addr, unsigned long target, int flags) |
e7a57273 | 31 | { |
b6e37968 | 32 | return patch_instruction(addr, create_branch(addr, target, flags)); |
e7a57273 ME |
33 | } |
34 | ||
35 | unsigned int create_branch(const unsigned int *addr, | |
36 | unsigned long target, int flags) | |
aaddd3ea ME |
37 | { |
38 | unsigned int instruction; | |
053a858e | 39 | long offset; |
aaddd3ea | 40 | |
053a858e | 41 | offset = target; |
aaddd3ea | 42 | if (! (flags & BRANCH_ABSOLUTE)) |
053a858e ME |
43 | offset = offset - (unsigned long)addr; |
44 | ||
45 | /* Check we can represent the target in the instruction format */ | |
46 | if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3) | |
47 | return 0; | |
aaddd3ea ME |
48 | |
49 | /* Mask out the flags and target, so they don't step on each other. */ | |
053a858e | 50 | instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC); |
aaddd3ea | 51 | |
e7a57273 | 52 | return instruction; |
aaddd3ea | 53 | } |
411781a2 ME |
54 | |
55 | unsigned int create_cond_branch(const unsigned int *addr, | |
56 | unsigned long target, int flags) | |
57 | { | |
58 | unsigned int instruction; | |
59 | long offset; | |
60 | ||
61 | offset = target; | |
62 | if (! (flags & BRANCH_ABSOLUTE)) | |
63 | offset = offset - (unsigned long)addr; | |
64 | ||
65 | /* Check we can represent the target in the instruction format */ | |
66 | if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3) | |
67 | return 0; | |
68 | ||
69 | /* Mask out the flags and target, so they don't step on each other. */ | |
70 | instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC); | |
71 | ||
72 | return instruction; | |
73 | } | |
74 | ||
75 | static unsigned int branch_opcode(unsigned int instr) | |
76 | { | |
77 | return (instr >> 26) & 0x3F; | |
78 | } | |
79 | ||
80 | static int instr_is_branch_iform(unsigned int instr) | |
81 | { | |
82 | return branch_opcode(instr) == 18; | |
83 | } | |
84 | ||
85 | static int instr_is_branch_bform(unsigned int instr) | |
86 | { | |
87 | return branch_opcode(instr) == 16; | |
88 | } | |
89 | ||
90 | int instr_is_relative_branch(unsigned int instr) | |
91 | { | |
92 | if (instr & BRANCH_ABSOLUTE) | |
93 | return 0; | |
94 | ||
95 | return instr_is_branch_iform(instr) || instr_is_branch_bform(instr); | |
96 | } | |
97 | ||
98 | static unsigned long branch_iform_target(const unsigned int *instr) | |
99 | { | |
100 | signed long imm; | |
101 | ||
102 | imm = *instr & 0x3FFFFFC; | |
103 | ||
104 | /* If the top bit of the immediate value is set this is negative */ | |
105 | if (imm & 0x2000000) | |
106 | imm -= 0x4000000; | |
107 | ||
108 | if ((*instr & BRANCH_ABSOLUTE) == 0) | |
109 | imm += (unsigned long)instr; | |
110 | ||
111 | return (unsigned long)imm; | |
112 | } | |
113 | ||
114 | static unsigned long branch_bform_target(const unsigned int *instr) | |
115 | { | |
116 | signed long imm; | |
117 | ||
118 | imm = *instr & 0xFFFC; | |
119 | ||
120 | /* If the top bit of the immediate value is set this is negative */ | |
121 | if (imm & 0x8000) | |
122 | imm -= 0x10000; | |
123 | ||
124 | if ((*instr & BRANCH_ABSOLUTE) == 0) | |
125 | imm += (unsigned long)instr; | |
126 | ||
127 | return (unsigned long)imm; | |
128 | } | |
129 | ||
130 | unsigned long branch_target(const unsigned int *instr) | |
131 | { | |
132 | if (instr_is_branch_iform(*instr)) | |
133 | return branch_iform_target(instr); | |
134 | else if (instr_is_branch_bform(*instr)) | |
135 | return branch_bform_target(instr); | |
136 | ||
137 | return 0; | |
138 | } | |
139 | ||
140 | int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr) | |
141 | { | |
142 | if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr)) | |
143 | return branch_target(instr) == addr; | |
144 | ||
145 | return 0; | |
146 | } | |
147 | ||
148 | unsigned int translate_branch(const unsigned int *dest, const unsigned int *src) | |
149 | { | |
150 | unsigned long target; | |
151 | ||
152 | target = branch_target(src); | |
153 | ||
154 | if (instr_is_branch_iform(*src)) | |
155 | return create_branch(dest, target, *src); | |
156 | else if (instr_is_branch_bform(*src)) | |
157 | return create_cond_branch(dest, target, *src); | |
158 | ||
159 | return 0; | |
160 | } | |
ae0dc736 | 161 | |
1e8341ae KH |
162 | #ifdef CONFIG_PPC_BOOK3E_64 |
163 | void __patch_exception(int exc, unsigned long addr) | |
164 | { | |
165 | extern unsigned int interrupt_base_book3e; | |
166 | unsigned int *ibase = &interrupt_base_book3e; | |
167 | ||
168 | /* Our exceptions vectors start with a NOP and -then- a branch | |
169 | * to deal with single stepping from userspace which stops on | |
170 | * the second instruction. Thus we need to patch the second | |
171 | * instruction of the exception, not the first one | |
172 | */ | |
173 | ||
174 | patch_branch(ibase + (exc / 4) + 1, addr, 0); | |
175 | } | |
176 | #endif | |
ae0dc736 ME |
177 | |
178 | #ifdef CONFIG_CODE_PATCHING_SELFTEST | |
179 | ||
180 | static void __init test_trampoline(void) | |
181 | { | |
182 | asm ("nop;\n"); | |
183 | } | |
184 | ||
185 | #define check(x) \ | |
186 | if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__); | |
187 | ||
188 | static void __init test_branch_iform(void) | |
189 | { | |
190 | unsigned int instr; | |
191 | unsigned long addr; | |
192 | ||
193 | addr = (unsigned long)&instr; | |
194 | ||
195 | /* The simplest case, branch to self, no flags */ | |
196 | check(instr_is_branch_iform(0x48000000)); | |
197 | /* All bits of target set, and flags */ | |
198 | check(instr_is_branch_iform(0x4bffffff)); | |
199 | /* High bit of opcode set, which is wrong */ | |
200 | check(!instr_is_branch_iform(0xcbffffff)); | |
201 | /* Middle bits of opcode set, which is wrong */ | |
202 | check(!instr_is_branch_iform(0x7bffffff)); | |
203 | ||
204 | /* Simplest case, branch to self with link */ | |
205 | check(instr_is_branch_iform(0x48000001)); | |
206 | /* All bits of targets set */ | |
207 | check(instr_is_branch_iform(0x4bfffffd)); | |
208 | /* Some bits of targets set */ | |
209 | check(instr_is_branch_iform(0x4bff00fd)); | |
210 | /* Must be a valid branch to start with */ | |
211 | check(!instr_is_branch_iform(0x7bfffffd)); | |
212 | ||
213 | /* Absolute branch to 0x100 */ | |
214 | instr = 0x48000103; | |
215 | check(instr_is_branch_to_addr(&instr, 0x100)); | |
216 | /* Absolute branch to 0x420fc */ | |
217 | instr = 0x480420ff; | |
218 | check(instr_is_branch_to_addr(&instr, 0x420fc)); | |
219 | /* Maximum positive relative branch, + 20MB - 4B */ | |
220 | instr = 0x49fffffc; | |
221 | check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC)); | |
222 | /* Smallest negative relative branch, - 4B */ | |
223 | instr = 0x4bfffffc; | |
224 | check(instr_is_branch_to_addr(&instr, addr - 4)); | |
225 | /* Largest negative relative branch, - 32 MB */ | |
226 | instr = 0x4a000000; | |
227 | check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); | |
228 | ||
229 | /* Branch to self, with link */ | |
230 | instr = create_branch(&instr, addr, BRANCH_SET_LINK); | |
231 | check(instr_is_branch_to_addr(&instr, addr)); | |
232 | ||
233 | /* Branch to self - 0x100, with link */ | |
234 | instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK); | |
235 | check(instr_is_branch_to_addr(&instr, addr - 0x100)); | |
236 | ||
237 | /* Branch to self + 0x100, no link */ | |
238 | instr = create_branch(&instr, addr + 0x100, 0); | |
239 | check(instr_is_branch_to_addr(&instr, addr + 0x100)); | |
240 | ||
241 | /* Maximum relative negative offset, - 32 MB */ | |
242 | instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK); | |
243 | check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); | |
244 | ||
245 | /* Out of range relative negative offset, - 32 MB + 4*/ | |
246 | instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK); | |
247 | check(instr == 0); | |
248 | ||
249 | /* Out of range relative positive offset, + 32 MB */ | |
250 | instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK); | |
251 | check(instr == 0); | |
252 | ||
253 | /* Unaligned target */ | |
254 | instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK); | |
255 | check(instr == 0); | |
256 | ||
257 | /* Check flags are masked correctly */ | |
258 | instr = create_branch(&instr, addr, 0xFFFFFFFC); | |
259 | check(instr_is_branch_to_addr(&instr, addr)); | |
260 | check(instr == 0x48000000); | |
261 | } | |
262 | ||
263 | static void __init test_create_function_call(void) | |
264 | { | |
265 | unsigned int *iptr; | |
266 | unsigned long dest; | |
267 | ||
268 | /* Check we can create a function call */ | |
269 | iptr = (unsigned int *)ppc_function_entry(test_trampoline); | |
270 | dest = ppc_function_entry(test_create_function_call); | |
271 | patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK)); | |
272 | check(instr_is_branch_to_addr(iptr, dest)); | |
273 | } | |
274 | ||
275 | static void __init test_branch_bform(void) | |
276 | { | |
277 | unsigned long addr; | |
278 | unsigned int *iptr, instr, flags; | |
279 | ||
280 | iptr = &instr; | |
281 | addr = (unsigned long)iptr; | |
282 | ||
283 | /* The simplest case, branch to self, no flags */ | |
284 | check(instr_is_branch_bform(0x40000000)); | |
285 | /* All bits of target set, and flags */ | |
286 | check(instr_is_branch_bform(0x43ffffff)); | |
287 | /* High bit of opcode set, which is wrong */ | |
288 | check(!instr_is_branch_bform(0xc3ffffff)); | |
289 | /* Middle bits of opcode set, which is wrong */ | |
290 | check(!instr_is_branch_bform(0x7bffffff)); | |
291 | ||
292 | /* Absolute conditional branch to 0x100 */ | |
293 | instr = 0x43ff0103; | |
294 | check(instr_is_branch_to_addr(&instr, 0x100)); | |
295 | /* Absolute conditional branch to 0x20fc */ | |
296 | instr = 0x43ff20ff; | |
297 | check(instr_is_branch_to_addr(&instr, 0x20fc)); | |
298 | /* Maximum positive relative conditional branch, + 32 KB - 4B */ | |
299 | instr = 0x43ff7ffc; | |
300 | check(instr_is_branch_to_addr(&instr, addr + 0x7FFC)); | |
301 | /* Smallest negative relative conditional branch, - 4B */ | |
302 | instr = 0x43fffffc; | |
303 | check(instr_is_branch_to_addr(&instr, addr - 4)); | |
304 | /* Largest negative relative conditional branch, - 32 KB */ | |
305 | instr = 0x43ff8000; | |
306 | check(instr_is_branch_to_addr(&instr, addr - 0x8000)); | |
307 | ||
308 | /* All condition code bits set & link */ | |
309 | flags = 0x3ff000 | BRANCH_SET_LINK; | |
310 | ||
311 | /* Branch to self */ | |
312 | instr = create_cond_branch(iptr, addr, flags); | |
313 | check(instr_is_branch_to_addr(&instr, addr)); | |
314 | ||
315 | /* Branch to self - 0x100 */ | |
316 | instr = create_cond_branch(iptr, addr - 0x100, flags); | |
317 | check(instr_is_branch_to_addr(&instr, addr - 0x100)); | |
318 | ||
319 | /* Branch to self + 0x100 */ | |
320 | instr = create_cond_branch(iptr, addr + 0x100, flags); | |
321 | check(instr_is_branch_to_addr(&instr, addr + 0x100)); | |
322 | ||
323 | /* Maximum relative negative offset, - 32 KB */ | |
324 | instr = create_cond_branch(iptr, addr - 0x8000, flags); | |
325 | check(instr_is_branch_to_addr(&instr, addr - 0x8000)); | |
326 | ||
327 | /* Out of range relative negative offset, - 32 KB + 4*/ | |
328 | instr = create_cond_branch(iptr, addr - 0x8004, flags); | |
329 | check(instr == 0); | |
330 | ||
331 | /* Out of range relative positive offset, + 32 KB */ | |
332 | instr = create_cond_branch(iptr, addr + 0x8000, flags); | |
333 | check(instr == 0); | |
334 | ||
335 | /* Unaligned target */ | |
336 | instr = create_cond_branch(iptr, addr + 3, flags); | |
337 | check(instr == 0); | |
338 | ||
339 | /* Check flags are masked correctly */ | |
340 | instr = create_cond_branch(iptr, addr, 0xFFFFFFFC); | |
341 | check(instr_is_branch_to_addr(&instr, addr)); | |
342 | check(instr == 0x43FF0000); | |
343 | } | |
344 | ||
345 | static void __init test_translate_branch(void) | |
346 | { | |
347 | unsigned long addr; | |
348 | unsigned int *p, *q; | |
349 | void *buf; | |
350 | ||
351 | buf = vmalloc(PAGE_ALIGN(0x2000000 + 1)); | |
352 | check(buf); | |
353 | if (!buf) | |
354 | return; | |
355 | ||
356 | /* Simple case, branch to self moved a little */ | |
357 | p = buf; | |
358 | addr = (unsigned long)p; | |
359 | patch_branch(p, addr, 0); | |
360 | check(instr_is_branch_to_addr(p, addr)); | |
361 | q = p + 1; | |
362 | patch_instruction(q, translate_branch(q, p)); | |
363 | check(instr_is_branch_to_addr(q, addr)); | |
364 | ||
365 | /* Maximum negative case, move b . to addr + 32 MB */ | |
366 | p = buf; | |
367 | addr = (unsigned long)p; | |
368 | patch_branch(p, addr, 0); | |
369 | q = buf + 0x2000000; | |
370 | patch_instruction(q, translate_branch(q, p)); | |
371 | check(instr_is_branch_to_addr(p, addr)); | |
372 | check(instr_is_branch_to_addr(q, addr)); | |
373 | check(*q == 0x4a000000); | |
374 | ||
375 | /* Maximum positive case, move x to x - 32 MB + 4 */ | |
376 | p = buf + 0x2000000; | |
377 | addr = (unsigned long)p; | |
378 | patch_branch(p, addr, 0); | |
379 | q = buf + 4; | |
380 | patch_instruction(q, translate_branch(q, p)); | |
381 | check(instr_is_branch_to_addr(p, addr)); | |
382 | check(instr_is_branch_to_addr(q, addr)); | |
383 | check(*q == 0x49fffffc); | |
384 | ||
385 | /* Jump to x + 16 MB moved to x + 20 MB */ | |
386 | p = buf; | |
387 | addr = 0x1000000 + (unsigned long)buf; | |
388 | patch_branch(p, addr, BRANCH_SET_LINK); | |
389 | q = buf + 0x1400000; | |
390 | patch_instruction(q, translate_branch(q, p)); | |
391 | check(instr_is_branch_to_addr(p, addr)); | |
392 | check(instr_is_branch_to_addr(q, addr)); | |
393 | ||
394 | /* Jump to x + 16 MB moved to x - 16 MB + 4 */ | |
395 | p = buf + 0x1000000; | |
396 | addr = 0x2000000 + (unsigned long)buf; | |
397 | patch_branch(p, addr, 0); | |
398 | q = buf + 4; | |
399 | patch_instruction(q, translate_branch(q, p)); | |
400 | check(instr_is_branch_to_addr(p, addr)); | |
401 | check(instr_is_branch_to_addr(q, addr)); | |
402 | ||
403 | ||
404 | /* Conditional branch tests */ | |
405 | ||
406 | /* Simple case, branch to self moved a little */ | |
407 | p = buf; | |
408 | addr = (unsigned long)p; | |
409 | patch_instruction(p, create_cond_branch(p, addr, 0)); | |
410 | check(instr_is_branch_to_addr(p, addr)); | |
411 | q = p + 1; | |
412 | patch_instruction(q, translate_branch(q, p)); | |
413 | check(instr_is_branch_to_addr(q, addr)); | |
414 | ||
415 | /* Maximum negative case, move b . to addr + 32 KB */ | |
416 | p = buf; | |
417 | addr = (unsigned long)p; | |
418 | patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); | |
419 | q = buf + 0x8000; | |
420 | patch_instruction(q, translate_branch(q, p)); | |
421 | check(instr_is_branch_to_addr(p, addr)); | |
422 | check(instr_is_branch_to_addr(q, addr)); | |
423 | check(*q == 0x43ff8000); | |
424 | ||
425 | /* Maximum positive case, move x to x - 32 KB + 4 */ | |
426 | p = buf + 0x8000; | |
427 | addr = (unsigned long)p; | |
428 | patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); | |
429 | q = buf + 4; | |
430 | patch_instruction(q, translate_branch(q, p)); | |
431 | check(instr_is_branch_to_addr(p, addr)); | |
432 | check(instr_is_branch_to_addr(q, addr)); | |
433 | check(*q == 0x43ff7ffc); | |
434 | ||
435 | /* Jump to x + 12 KB moved to x + 20 KB */ | |
436 | p = buf; | |
437 | addr = 0x3000 + (unsigned long)buf; | |
438 | patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK)); | |
439 | q = buf + 0x5000; | |
440 | patch_instruction(q, translate_branch(q, p)); | |
441 | check(instr_is_branch_to_addr(p, addr)); | |
442 | check(instr_is_branch_to_addr(q, addr)); | |
443 | ||
444 | /* Jump to x + 8 KB moved to x - 8 KB + 4 */ | |
445 | p = buf + 0x2000; | |
446 | addr = 0x4000 + (unsigned long)buf; | |
447 | patch_instruction(p, create_cond_branch(p, addr, 0)); | |
448 | q = buf + 4; | |
449 | patch_instruction(q, translate_branch(q, p)); | |
450 | check(instr_is_branch_to_addr(p, addr)); | |
451 | check(instr_is_branch_to_addr(q, addr)); | |
452 | ||
453 | /* Free the buffer we were using */ | |
454 | vfree(buf); | |
455 | } | |
456 | ||
457 | static int __init test_code_patching(void) | |
458 | { | |
459 | printk(KERN_DEBUG "Running code patching self-tests ...\n"); | |
460 | ||
461 | test_branch_iform(); | |
462 | test_branch_bform(); | |
463 | test_create_function_call(); | |
464 | test_translate_branch(); | |
465 | ||
466 | return 0; | |
467 | } | |
468 | late_initcall(test_code_patching); | |
469 | ||
470 | #endif /* CONFIG_CODE_PATCHING_SELFTEST */ |