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