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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 ME |
161 | |
162 | ||
163 | #ifdef CONFIG_CODE_PATCHING_SELFTEST | |
164 | ||
165 | static void __init test_trampoline(void) | |
166 | { | |
167 | asm ("nop;\n"); | |
168 | } | |
169 | ||
170 | #define check(x) \ | |
171 | if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__); | |
172 | ||
173 | static void __init test_branch_iform(void) | |
174 | { | |
175 | unsigned int instr; | |
176 | unsigned long addr; | |
177 | ||
178 | addr = (unsigned long)&instr; | |
179 | ||
180 | /* The simplest case, branch to self, no flags */ | |
181 | check(instr_is_branch_iform(0x48000000)); | |
182 | /* All bits of target set, and flags */ | |
183 | check(instr_is_branch_iform(0x4bffffff)); | |
184 | /* High bit of opcode set, which is wrong */ | |
185 | check(!instr_is_branch_iform(0xcbffffff)); | |
186 | /* Middle bits of opcode set, which is wrong */ | |
187 | check(!instr_is_branch_iform(0x7bffffff)); | |
188 | ||
189 | /* Simplest case, branch to self with link */ | |
190 | check(instr_is_branch_iform(0x48000001)); | |
191 | /* All bits of targets set */ | |
192 | check(instr_is_branch_iform(0x4bfffffd)); | |
193 | /* Some bits of targets set */ | |
194 | check(instr_is_branch_iform(0x4bff00fd)); | |
195 | /* Must be a valid branch to start with */ | |
196 | check(!instr_is_branch_iform(0x7bfffffd)); | |
197 | ||
198 | /* Absolute branch to 0x100 */ | |
199 | instr = 0x48000103; | |
200 | check(instr_is_branch_to_addr(&instr, 0x100)); | |
201 | /* Absolute branch to 0x420fc */ | |
202 | instr = 0x480420ff; | |
203 | check(instr_is_branch_to_addr(&instr, 0x420fc)); | |
204 | /* Maximum positive relative branch, + 20MB - 4B */ | |
205 | instr = 0x49fffffc; | |
206 | check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC)); | |
207 | /* Smallest negative relative branch, - 4B */ | |
208 | instr = 0x4bfffffc; | |
209 | check(instr_is_branch_to_addr(&instr, addr - 4)); | |
210 | /* Largest negative relative branch, - 32 MB */ | |
211 | instr = 0x4a000000; | |
212 | check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); | |
213 | ||
214 | /* Branch to self, with link */ | |
215 | instr = create_branch(&instr, addr, BRANCH_SET_LINK); | |
216 | check(instr_is_branch_to_addr(&instr, addr)); | |
217 | ||
218 | /* Branch to self - 0x100, with link */ | |
219 | instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK); | |
220 | check(instr_is_branch_to_addr(&instr, addr - 0x100)); | |
221 | ||
222 | /* Branch to self + 0x100, no link */ | |
223 | instr = create_branch(&instr, addr + 0x100, 0); | |
224 | check(instr_is_branch_to_addr(&instr, addr + 0x100)); | |
225 | ||
226 | /* Maximum relative negative offset, - 32 MB */ | |
227 | instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK); | |
228 | check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); | |
229 | ||
230 | /* Out of range relative negative offset, - 32 MB + 4*/ | |
231 | instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK); | |
232 | check(instr == 0); | |
233 | ||
234 | /* Out of range relative positive offset, + 32 MB */ | |
235 | instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK); | |
236 | check(instr == 0); | |
237 | ||
238 | /* Unaligned target */ | |
239 | instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK); | |
240 | check(instr == 0); | |
241 | ||
242 | /* Check flags are masked correctly */ | |
243 | instr = create_branch(&instr, addr, 0xFFFFFFFC); | |
244 | check(instr_is_branch_to_addr(&instr, addr)); | |
245 | check(instr == 0x48000000); | |
246 | } | |
247 | ||
248 | static void __init test_create_function_call(void) | |
249 | { | |
250 | unsigned int *iptr; | |
251 | unsigned long dest; | |
252 | ||
253 | /* Check we can create a function call */ | |
254 | iptr = (unsigned int *)ppc_function_entry(test_trampoline); | |
255 | dest = ppc_function_entry(test_create_function_call); | |
256 | patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK)); | |
257 | check(instr_is_branch_to_addr(iptr, dest)); | |
258 | } | |
259 | ||
260 | static void __init test_branch_bform(void) | |
261 | { | |
262 | unsigned long addr; | |
263 | unsigned int *iptr, instr, flags; | |
264 | ||
265 | iptr = &instr; | |
266 | addr = (unsigned long)iptr; | |
267 | ||
268 | /* The simplest case, branch to self, no flags */ | |
269 | check(instr_is_branch_bform(0x40000000)); | |
270 | /* All bits of target set, and flags */ | |
271 | check(instr_is_branch_bform(0x43ffffff)); | |
272 | /* High bit of opcode set, which is wrong */ | |
273 | check(!instr_is_branch_bform(0xc3ffffff)); | |
274 | /* Middle bits of opcode set, which is wrong */ | |
275 | check(!instr_is_branch_bform(0x7bffffff)); | |
276 | ||
277 | /* Absolute conditional branch to 0x100 */ | |
278 | instr = 0x43ff0103; | |
279 | check(instr_is_branch_to_addr(&instr, 0x100)); | |
280 | /* Absolute conditional branch to 0x20fc */ | |
281 | instr = 0x43ff20ff; | |
282 | check(instr_is_branch_to_addr(&instr, 0x20fc)); | |
283 | /* Maximum positive relative conditional branch, + 32 KB - 4B */ | |
284 | instr = 0x43ff7ffc; | |
285 | check(instr_is_branch_to_addr(&instr, addr + 0x7FFC)); | |
286 | /* Smallest negative relative conditional branch, - 4B */ | |
287 | instr = 0x43fffffc; | |
288 | check(instr_is_branch_to_addr(&instr, addr - 4)); | |
289 | /* Largest negative relative conditional branch, - 32 KB */ | |
290 | instr = 0x43ff8000; | |
291 | check(instr_is_branch_to_addr(&instr, addr - 0x8000)); | |
292 | ||
293 | /* All condition code bits set & link */ | |
294 | flags = 0x3ff000 | BRANCH_SET_LINK; | |
295 | ||
296 | /* Branch to self */ | |
297 | instr = create_cond_branch(iptr, addr, flags); | |
298 | check(instr_is_branch_to_addr(&instr, addr)); | |
299 | ||
300 | /* Branch to self - 0x100 */ | |
301 | instr = create_cond_branch(iptr, addr - 0x100, flags); | |
302 | check(instr_is_branch_to_addr(&instr, addr - 0x100)); | |
303 | ||
304 | /* Branch to self + 0x100 */ | |
305 | instr = create_cond_branch(iptr, addr + 0x100, flags); | |
306 | check(instr_is_branch_to_addr(&instr, addr + 0x100)); | |
307 | ||
308 | /* Maximum relative negative offset, - 32 KB */ | |
309 | instr = create_cond_branch(iptr, addr - 0x8000, flags); | |
310 | check(instr_is_branch_to_addr(&instr, addr - 0x8000)); | |
311 | ||
312 | /* Out of range relative negative offset, - 32 KB + 4*/ | |
313 | instr = create_cond_branch(iptr, addr - 0x8004, flags); | |
314 | check(instr == 0); | |
315 | ||
316 | /* Out of range relative positive offset, + 32 KB */ | |
317 | instr = create_cond_branch(iptr, addr + 0x8000, flags); | |
318 | check(instr == 0); | |
319 | ||
320 | /* Unaligned target */ | |
321 | instr = create_cond_branch(iptr, addr + 3, flags); | |
322 | check(instr == 0); | |
323 | ||
324 | /* Check flags are masked correctly */ | |
325 | instr = create_cond_branch(iptr, addr, 0xFFFFFFFC); | |
326 | check(instr_is_branch_to_addr(&instr, addr)); | |
327 | check(instr == 0x43FF0000); | |
328 | } | |
329 | ||
330 | static void __init test_translate_branch(void) | |
331 | { | |
332 | unsigned long addr; | |
333 | unsigned int *p, *q; | |
334 | void *buf; | |
335 | ||
336 | buf = vmalloc(PAGE_ALIGN(0x2000000 + 1)); | |
337 | check(buf); | |
338 | if (!buf) | |
339 | return; | |
340 | ||
341 | /* Simple case, branch to self moved a little */ | |
342 | p = buf; | |
343 | addr = (unsigned long)p; | |
344 | patch_branch(p, addr, 0); | |
345 | check(instr_is_branch_to_addr(p, addr)); | |
346 | q = p + 1; | |
347 | patch_instruction(q, translate_branch(q, p)); | |
348 | check(instr_is_branch_to_addr(q, addr)); | |
349 | ||
350 | /* Maximum negative case, move b . to addr + 32 MB */ | |
351 | p = buf; | |
352 | addr = (unsigned long)p; | |
353 | patch_branch(p, addr, 0); | |
354 | q = buf + 0x2000000; | |
355 | patch_instruction(q, translate_branch(q, p)); | |
356 | check(instr_is_branch_to_addr(p, addr)); | |
357 | check(instr_is_branch_to_addr(q, addr)); | |
358 | check(*q == 0x4a000000); | |
359 | ||
360 | /* Maximum positive case, move x to x - 32 MB + 4 */ | |
361 | p = buf + 0x2000000; | |
362 | addr = (unsigned long)p; | |
363 | patch_branch(p, addr, 0); | |
364 | q = buf + 4; | |
365 | patch_instruction(q, translate_branch(q, p)); | |
366 | check(instr_is_branch_to_addr(p, addr)); | |
367 | check(instr_is_branch_to_addr(q, addr)); | |
368 | check(*q == 0x49fffffc); | |
369 | ||
370 | /* Jump to x + 16 MB moved to x + 20 MB */ | |
371 | p = buf; | |
372 | addr = 0x1000000 + (unsigned long)buf; | |
373 | patch_branch(p, addr, BRANCH_SET_LINK); | |
374 | q = buf + 0x1400000; | |
375 | patch_instruction(q, translate_branch(q, p)); | |
376 | check(instr_is_branch_to_addr(p, addr)); | |
377 | check(instr_is_branch_to_addr(q, addr)); | |
378 | ||
379 | /* Jump to x + 16 MB moved to x - 16 MB + 4 */ | |
380 | p = buf + 0x1000000; | |
381 | addr = 0x2000000 + (unsigned long)buf; | |
382 | patch_branch(p, addr, 0); | |
383 | q = buf + 4; | |
384 | patch_instruction(q, translate_branch(q, p)); | |
385 | check(instr_is_branch_to_addr(p, addr)); | |
386 | check(instr_is_branch_to_addr(q, addr)); | |
387 | ||
388 | ||
389 | /* Conditional branch tests */ | |
390 | ||
391 | /* Simple case, branch to self moved a little */ | |
392 | p = buf; | |
393 | addr = (unsigned long)p; | |
394 | patch_instruction(p, create_cond_branch(p, addr, 0)); | |
395 | check(instr_is_branch_to_addr(p, addr)); | |
396 | q = p + 1; | |
397 | patch_instruction(q, translate_branch(q, p)); | |
398 | check(instr_is_branch_to_addr(q, addr)); | |
399 | ||
400 | /* Maximum negative case, move b . to addr + 32 KB */ | |
401 | p = buf; | |
402 | addr = (unsigned long)p; | |
403 | patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); | |
404 | q = buf + 0x8000; | |
405 | patch_instruction(q, translate_branch(q, p)); | |
406 | check(instr_is_branch_to_addr(p, addr)); | |
407 | check(instr_is_branch_to_addr(q, addr)); | |
408 | check(*q == 0x43ff8000); | |
409 | ||
410 | /* Maximum positive case, move x to x - 32 KB + 4 */ | |
411 | p = buf + 0x8000; | |
412 | addr = (unsigned long)p; | |
413 | patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); | |
414 | q = buf + 4; | |
415 | patch_instruction(q, translate_branch(q, p)); | |
416 | check(instr_is_branch_to_addr(p, addr)); | |
417 | check(instr_is_branch_to_addr(q, addr)); | |
418 | check(*q == 0x43ff7ffc); | |
419 | ||
420 | /* Jump to x + 12 KB moved to x + 20 KB */ | |
421 | p = buf; | |
422 | addr = 0x3000 + (unsigned long)buf; | |
423 | patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK)); | |
424 | q = buf + 0x5000; | |
425 | patch_instruction(q, translate_branch(q, p)); | |
426 | check(instr_is_branch_to_addr(p, addr)); | |
427 | check(instr_is_branch_to_addr(q, addr)); | |
428 | ||
429 | /* Jump to x + 8 KB moved to x - 8 KB + 4 */ | |
430 | p = buf + 0x2000; | |
431 | addr = 0x4000 + (unsigned long)buf; | |
432 | patch_instruction(p, create_cond_branch(p, addr, 0)); | |
433 | q = buf + 4; | |
434 | patch_instruction(q, translate_branch(q, p)); | |
435 | check(instr_is_branch_to_addr(p, addr)); | |
436 | check(instr_is_branch_to_addr(q, addr)); | |
437 | ||
438 | /* Free the buffer we were using */ | |
439 | vfree(buf); | |
440 | } | |
441 | ||
442 | static int __init test_code_patching(void) | |
443 | { | |
444 | printk(KERN_DEBUG "Running code patching self-tests ...\n"); | |
445 | ||
446 | test_branch_iform(); | |
447 | test_branch_bform(); | |
448 | test_create_function_call(); | |
449 | test_translate_branch(); | |
450 | ||
451 | return 0; | |
452 | } | |
453 | late_initcall(test_code_patching); | |
454 | ||
455 | #endif /* CONFIG_CODE_PATCHING_SELFTEST */ |