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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 | /* * Copyright 2008 Michael Ellerman, IBM Corporation. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/kernel.h> #include <linux/vmalloc.h> #include <linux/init.h> #include <linux/mm.h> #include <asm/page.h> #include <asm/code-patching.h> #include <asm/uaccess.h> #include <asm/setup.h> #include <asm/sections.h> int patch_instruction(unsigned int *addr, unsigned int instr) { int err; /* Make sure we aren't patching a freed init section */ if (*PTRRELOC(&init_mem_is_free) && init_section_contains(addr, 4)) { pr_debug("Skipping init section patching addr: 0x%px\n", addr); return 0; } __put_user_size(instr, addr, 4, err); if (err) return err; asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr)); return 0; } int patch_branch(unsigned int *addr, unsigned long target, int flags) { return patch_instruction(addr, create_branch(addr, target, flags)); } int patch_branch_site(s32 *site, unsigned long target, int flags) { unsigned int *addr; addr = (unsigned int *)((unsigned long)site + *site); return patch_instruction(addr, create_branch(addr, target, flags)); } int patch_instruction_site(s32 *site, unsigned int instr) { unsigned int *addr; addr = (unsigned int *)((unsigned long)site + *site); return patch_instruction(addr, instr); } unsigned int create_branch(const unsigned int *addr, unsigned long target, int flags) { unsigned int instruction; long offset; offset = target; if (! (flags & BRANCH_ABSOLUTE)) offset = offset - (unsigned long)addr; /* Check we can represent the target in the instruction format */ if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3) return 0; /* Mask out the flags and target, so they don't step on each other. */ instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC); return instruction; } unsigned int create_cond_branch(const unsigned int *addr, unsigned long target, int flags) { unsigned int instruction; long offset; offset = target; if (! (flags & BRANCH_ABSOLUTE)) offset = offset - (unsigned long)addr; /* Check we can represent the target in the instruction format */ if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3) return 0; /* Mask out the flags and target, so they don't step on each other. */ instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC); return instruction; } static unsigned int branch_opcode(unsigned int instr) { return (instr >> 26) & 0x3F; } static int instr_is_branch_iform(unsigned int instr) { return branch_opcode(instr) == 18; } static int instr_is_branch_bform(unsigned int instr) { return branch_opcode(instr) == 16; } int instr_is_relative_branch(unsigned int instr) { if (instr & BRANCH_ABSOLUTE) return 0; return instr_is_branch_iform(instr) || instr_is_branch_bform(instr); } int instr_is_relative_link_branch(unsigned int instr) { return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK); } static unsigned long branch_iform_target(const unsigned int *instr) { signed long imm; imm = *instr & 0x3FFFFFC; /* If the top bit of the immediate value is set this is negative */ if (imm & 0x2000000) imm -= 0x4000000; if ((*instr & BRANCH_ABSOLUTE) == 0) imm += (unsigned long)instr; return (unsigned long)imm; } static unsigned long branch_bform_target(const unsigned int *instr) { signed long imm; imm = *instr & 0xFFFC; /* If the top bit of the immediate value is set this is negative */ if (imm & 0x8000) imm -= 0x10000; if ((*instr & BRANCH_ABSOLUTE) == 0) imm += (unsigned long)instr; return (unsigned long)imm; } unsigned long branch_target(const unsigned int *instr) { if (instr_is_branch_iform(*instr)) return branch_iform_target(instr); else if (instr_is_branch_bform(*instr)) return branch_bform_target(instr); return 0; } int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr) { if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr)) return branch_target(instr) == addr; return 0; } unsigned int translate_branch(const unsigned int *dest, const unsigned int *src) { unsigned long target; target = branch_target(src); if (instr_is_branch_iform(*src)) return create_branch(dest, target, *src); else if (instr_is_branch_bform(*src)) return create_cond_branch(dest, target, *src); return 0; } #ifdef CONFIG_PPC_BOOK3E_64 void __patch_exception(int exc, unsigned long addr) { extern unsigned int interrupt_base_book3e; unsigned int *ibase = &interrupt_base_book3e; /* Our exceptions vectors start with a NOP and -then- a branch * to deal with single stepping from userspace which stops on * the second instruction. Thus we need to patch the second * instruction of the exception, not the first one */ patch_branch(ibase + (exc / 4) + 1, addr, 0); } #endif #ifdef CONFIG_CODE_PATCHING_SELFTEST static void __init test_trampoline(void) { asm ("nop;\n"); } #define check(x) \ if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__); static void __init test_branch_iform(void) { unsigned int instr; unsigned long addr; addr = (unsigned long)&instr; /* The simplest case, branch to self, no flags */ check(instr_is_branch_iform(0x48000000)); /* All bits of target set, and flags */ check(instr_is_branch_iform(0x4bffffff)); /* High bit of opcode set, which is wrong */ check(!instr_is_branch_iform(0xcbffffff)); /* Middle bits of opcode set, which is wrong */ check(!instr_is_branch_iform(0x7bffffff)); /* Simplest case, branch to self with link */ check(instr_is_branch_iform(0x48000001)); /* All bits of targets set */ check(instr_is_branch_iform(0x4bfffffd)); /* Some bits of targets set */ check(instr_is_branch_iform(0x4bff00fd)); /* Must be a valid branch to start with */ check(!instr_is_branch_iform(0x7bfffffd)); /* Absolute branch to 0x100 */ instr = 0x48000103; check(instr_is_branch_to_addr(&instr, 0x100)); /* Absolute branch to 0x420fc */ instr = 0x480420ff; check(instr_is_branch_to_addr(&instr, 0x420fc)); /* Maximum positive relative branch, + 20MB - 4B */ instr = 0x49fffffc; check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC)); /* Smallest negative relative branch, - 4B */ instr = 0x4bfffffc; check(instr_is_branch_to_addr(&instr, addr - 4)); /* Largest negative relative branch, - 32 MB */ instr = 0x4a000000; check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); /* Branch to self, with link */ instr = create_branch(&instr, addr, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr)); /* Branch to self - 0x100, with link */ instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr - 0x100)); /* Branch to self + 0x100, no link */ instr = create_branch(&instr, addr + 0x100, 0); check(instr_is_branch_to_addr(&instr, addr + 0x100)); /* Maximum relative negative offset, - 32 MB */ instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); /* Out of range relative negative offset, - 32 MB + 4*/ instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK); check(instr == 0); /* Out of range relative positive offset, + 32 MB */ instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK); check(instr == 0); /* Unaligned target */ instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK); check(instr == 0); /* Check flags are masked correctly */ instr = create_branch(&instr, addr, 0xFFFFFFFC); check(instr_is_branch_to_addr(&instr, addr)); check(instr == 0x48000000); } static void __init test_create_function_call(void) { unsigned int *iptr; unsigned long dest; /* Check we can create a function call */ iptr = (unsigned int *)ppc_function_entry(test_trampoline); dest = ppc_function_entry(test_create_function_call); patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK)); check(instr_is_branch_to_addr(iptr, dest)); } static void __init test_branch_bform(void) { unsigned long addr; unsigned int *iptr, instr, flags; iptr = &instr; addr = (unsigned long)iptr; /* The simplest case, branch to self, no flags */ check(instr_is_branch_bform(0x40000000)); /* All bits of target set, and flags */ check(instr_is_branch_bform(0x43ffffff)); /* High bit of opcode set, which is wrong */ check(!instr_is_branch_bform(0xc3ffffff)); /* Middle bits of opcode set, which is wrong */ check(!instr_is_branch_bform(0x7bffffff)); /* Absolute conditional branch to 0x100 */ instr = 0x43ff0103; check(instr_is_branch_to_addr(&instr, 0x100)); /* Absolute conditional branch to 0x20fc */ instr = 0x43ff20ff; check(instr_is_branch_to_addr(&instr, 0x20fc)); /* Maximum positive relative conditional branch, + 32 KB - 4B */ instr = 0x43ff7ffc; check(instr_is_branch_to_addr(&instr, addr + 0x7FFC)); /* Smallest negative relative conditional branch, - 4B */ instr = 0x43fffffc; check(instr_is_branch_to_addr(&instr, addr - 4)); /* Largest negative relative conditional branch, - 32 KB */ instr = 0x43ff8000; check(instr_is_branch_to_addr(&instr, addr - 0x8000)); /* All condition code bits set & link */ flags = 0x3ff000 | BRANCH_SET_LINK; /* Branch to self */ instr = create_cond_branch(iptr, addr, flags); check(instr_is_branch_to_addr(&instr, addr)); /* Branch to self - 0x100 */ instr = create_cond_branch(iptr, addr - 0x100, flags); check(instr_is_branch_to_addr(&instr, addr - 0x100)); /* Branch to self + 0x100 */ instr = create_cond_branch(iptr, addr + 0x100, flags); check(instr_is_branch_to_addr(&instr, addr + 0x100)); /* Maximum relative negative offset, - 32 KB */ instr = create_cond_branch(iptr, addr - 0x8000, flags); check(instr_is_branch_to_addr(&instr, addr - 0x8000)); /* Out of range relative negative offset, - 32 KB + 4*/ instr = create_cond_branch(iptr, addr - 0x8004, flags); check(instr == 0); /* Out of range relative positive offset, + 32 KB */ instr = create_cond_branch(iptr, addr + 0x8000, flags); check(instr == 0); /* Unaligned target */ instr = create_cond_branch(iptr, addr + 3, flags); check(instr == 0); /* Check flags are masked correctly */ instr = create_cond_branch(iptr, addr, 0xFFFFFFFC); check(instr_is_branch_to_addr(&instr, addr)); check(instr == 0x43FF0000); } static void __init test_translate_branch(void) { unsigned long addr; unsigned int *p, *q; void *buf; buf = vmalloc(PAGE_ALIGN(0x2000000 + 1)); check(buf); if (!buf) return; /* Simple case, branch to self moved a little */ p = buf; addr = (unsigned long)p; patch_branch(p, addr, 0); check(instr_is_branch_to_addr(p, addr)); q = p + 1; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(q, addr)); /* Maximum negative case, move b . to addr + 32 MB */ p = buf; addr = (unsigned long)p; patch_branch(p, addr, 0); q = buf + 0x2000000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x4a000000); /* Maximum positive case, move x to x - 32 MB + 4 */ p = buf + 0x2000000; addr = (unsigned long)p; patch_branch(p, addr, 0); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x49fffffc); /* Jump to x + 16 MB moved to x + 20 MB */ p = buf; addr = 0x1000000 + (unsigned long)buf; patch_branch(p, addr, BRANCH_SET_LINK); q = buf + 0x1400000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Jump to x + 16 MB moved to x - 16 MB + 4 */ p = buf + 0x1000000; addr = 0x2000000 + (unsigned long)buf; patch_branch(p, addr, 0); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Conditional branch tests */ /* Simple case, branch to self moved a little */ p = buf; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0)); check(instr_is_branch_to_addr(p, addr)); q = p + 1; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(q, addr)); /* Maximum negative case, move b . to addr + 32 KB */ p = buf; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); q = buf + 0x8000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x43ff8000); /* Maximum positive case, move x to x - 32 KB + 4 */ p = buf + 0x8000; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x43ff7ffc); /* Jump to x + 12 KB moved to x + 20 KB */ p = buf; addr = 0x3000 + (unsigned long)buf; patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK)); q = buf + 0x5000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Jump to x + 8 KB moved to x - 8 KB + 4 */ p = buf + 0x2000; addr = 0x4000 + (unsigned long)buf; patch_instruction(p, create_cond_branch(p, addr, 0)); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Free the buffer we were using */ vfree(buf); } static int __init test_code_patching(void) { printk(KERN_DEBUG "Running code patching self-tests ...\n"); test_branch_iform(); test_branch_bform(); test_create_function_call(); test_translate_branch(); return 0; } late_initcall(test_code_patching); #endif /* CONFIG_CODE_PATCHING_SELFTEST */ |