| 1 | #include <linux/module.h> |
| 2 | #include <linux/sched.h> |
| 3 | #include <linux/mutex.h> |
| 4 | #include <linux/list.h> |
| 5 | #include <linux/stringify.h> |
| 6 | #include <linux/kprobes.h> |
| 7 | #include <linux/mm.h> |
| 8 | #include <linux/vmalloc.h> |
| 9 | #include <linux/memory.h> |
| 10 | #include <linux/stop_machine.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <asm/alternative.h> |
| 13 | #include <asm/sections.h> |
| 14 | #include <asm/pgtable.h> |
| 15 | #include <asm/mce.h> |
| 16 | #include <asm/nmi.h> |
| 17 | #include <asm/vsyscall.h> |
| 18 | #include <asm/cacheflush.h> |
| 19 | #include <asm/tlbflush.h> |
| 20 | #include <asm/io.h> |
| 21 | #include <asm/fixmap.h> |
| 22 | |
| 23 | #define MAX_PATCH_LEN (255-1) |
| 24 | |
| 25 | #ifdef CONFIG_HOTPLUG_CPU |
| 26 | static int smp_alt_once; |
| 27 | |
| 28 | static int __init bootonly(char *str) |
| 29 | { |
| 30 | smp_alt_once = 1; |
| 31 | return 1; |
| 32 | } |
| 33 | __setup("smp-alt-boot", bootonly); |
| 34 | #else |
| 35 | #define smp_alt_once 1 |
| 36 | #endif |
| 37 | |
| 38 | static int __initdata_or_module debug_alternative; |
| 39 | |
| 40 | static int __init debug_alt(char *str) |
| 41 | { |
| 42 | debug_alternative = 1; |
| 43 | return 1; |
| 44 | } |
| 45 | __setup("debug-alternative", debug_alt); |
| 46 | |
| 47 | static int noreplace_smp; |
| 48 | |
| 49 | static int __init setup_noreplace_smp(char *str) |
| 50 | { |
| 51 | noreplace_smp = 1; |
| 52 | return 1; |
| 53 | } |
| 54 | __setup("noreplace-smp", setup_noreplace_smp); |
| 55 | |
| 56 | #ifdef CONFIG_PARAVIRT |
| 57 | static int __initdata_or_module noreplace_paravirt = 0; |
| 58 | |
| 59 | static int __init setup_noreplace_paravirt(char *str) |
| 60 | { |
| 61 | noreplace_paravirt = 1; |
| 62 | return 1; |
| 63 | } |
| 64 | __setup("noreplace-paravirt", setup_noreplace_paravirt); |
| 65 | #endif |
| 66 | |
| 67 | #define DPRINTK(fmt, args...) if (debug_alternative) \ |
| 68 | printk(KERN_DEBUG fmt, args) |
| 69 | |
| 70 | #if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64) |
| 71 | /* Use inline assembly to define this because the nops are defined |
| 72 | as inline assembly strings in the include files and we cannot |
| 73 | get them easily into strings. */ |
| 74 | asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nintelnops: " |
| 75 | GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6 |
| 76 | GENERIC_NOP7 GENERIC_NOP8 |
| 77 | "\t.previous"); |
| 78 | extern const unsigned char intelnops[]; |
| 79 | static const unsigned char *const __initconst_or_module |
| 80 | intel_nops[ASM_NOP_MAX+1] = { |
| 81 | NULL, |
| 82 | intelnops, |
| 83 | intelnops + 1, |
| 84 | intelnops + 1 + 2, |
| 85 | intelnops + 1 + 2 + 3, |
| 86 | intelnops + 1 + 2 + 3 + 4, |
| 87 | intelnops + 1 + 2 + 3 + 4 + 5, |
| 88 | intelnops + 1 + 2 + 3 + 4 + 5 + 6, |
| 89 | intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7, |
| 90 | }; |
| 91 | #endif |
| 92 | |
| 93 | #ifdef K8_NOP1 |
| 94 | asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk8nops: " |
| 95 | K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6 |
| 96 | K8_NOP7 K8_NOP8 |
| 97 | "\t.previous"); |
| 98 | extern const unsigned char k8nops[]; |
| 99 | static const unsigned char *const __initconst_or_module |
| 100 | k8_nops[ASM_NOP_MAX+1] = { |
| 101 | NULL, |
| 102 | k8nops, |
| 103 | k8nops + 1, |
| 104 | k8nops + 1 + 2, |
| 105 | k8nops + 1 + 2 + 3, |
| 106 | k8nops + 1 + 2 + 3 + 4, |
| 107 | k8nops + 1 + 2 + 3 + 4 + 5, |
| 108 | k8nops + 1 + 2 + 3 + 4 + 5 + 6, |
| 109 | k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, |
| 110 | }; |
| 111 | #endif |
| 112 | |
| 113 | #if defined(K7_NOP1) && !defined(CONFIG_X86_64) |
| 114 | asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk7nops: " |
| 115 | K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6 |
| 116 | K7_NOP7 K7_NOP8 |
| 117 | "\t.previous"); |
| 118 | extern const unsigned char k7nops[]; |
| 119 | static const unsigned char *const __initconst_or_module |
| 120 | k7_nops[ASM_NOP_MAX+1] = { |
| 121 | NULL, |
| 122 | k7nops, |
| 123 | k7nops + 1, |
| 124 | k7nops + 1 + 2, |
| 125 | k7nops + 1 + 2 + 3, |
| 126 | k7nops + 1 + 2 + 3 + 4, |
| 127 | k7nops + 1 + 2 + 3 + 4 + 5, |
| 128 | k7nops + 1 + 2 + 3 + 4 + 5 + 6, |
| 129 | k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, |
| 130 | }; |
| 131 | #endif |
| 132 | |
| 133 | #ifdef P6_NOP1 |
| 134 | asm("\t" __stringify(__INITRODATA_OR_MODULE) "\np6nops: " |
| 135 | P6_NOP1 P6_NOP2 P6_NOP3 P6_NOP4 P6_NOP5 P6_NOP6 |
| 136 | P6_NOP7 P6_NOP8 |
| 137 | "\t.previous"); |
| 138 | extern const unsigned char p6nops[]; |
| 139 | static const unsigned char *const __initconst_or_module |
| 140 | p6_nops[ASM_NOP_MAX+1] = { |
| 141 | NULL, |
| 142 | p6nops, |
| 143 | p6nops + 1, |
| 144 | p6nops + 1 + 2, |
| 145 | p6nops + 1 + 2 + 3, |
| 146 | p6nops + 1 + 2 + 3 + 4, |
| 147 | p6nops + 1 + 2 + 3 + 4 + 5, |
| 148 | p6nops + 1 + 2 + 3 + 4 + 5 + 6, |
| 149 | p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, |
| 150 | }; |
| 151 | #endif |
| 152 | |
| 153 | #ifdef CONFIG_X86_64 |
| 154 | |
| 155 | extern char __vsyscall_0; |
| 156 | static const unsigned char *const *__init_or_module find_nop_table(void) |
| 157 | { |
| 158 | if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && |
| 159 | boot_cpu_has(X86_FEATURE_NOPL)) |
| 160 | return p6_nops; |
| 161 | else |
| 162 | return k8_nops; |
| 163 | } |
| 164 | |
| 165 | #else /* CONFIG_X86_64 */ |
| 166 | |
| 167 | static const unsigned char *const *__init_or_module find_nop_table(void) |
| 168 | { |
| 169 | if (boot_cpu_has(X86_FEATURE_K8)) |
| 170 | return k8_nops; |
| 171 | else if (boot_cpu_has(X86_FEATURE_K7)) |
| 172 | return k7_nops; |
| 173 | else if (boot_cpu_has(X86_FEATURE_NOPL)) |
| 174 | return p6_nops; |
| 175 | else |
| 176 | return intel_nops; |
| 177 | } |
| 178 | |
| 179 | #endif /* CONFIG_X86_64 */ |
| 180 | |
| 181 | /* Use this to add nops to a buffer, then text_poke the whole buffer. */ |
| 182 | static void __init_or_module add_nops(void *insns, unsigned int len) |
| 183 | { |
| 184 | const unsigned char *const *noptable = find_nop_table(); |
| 185 | |
| 186 | while (len > 0) { |
| 187 | unsigned int noplen = len; |
| 188 | if (noplen > ASM_NOP_MAX) |
| 189 | noplen = ASM_NOP_MAX; |
| 190 | memcpy(insns, noptable[noplen], noplen); |
| 191 | insns += noplen; |
| 192 | len -= noplen; |
| 193 | } |
| 194 | } |
| 195 | |
| 196 | extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; |
| 197 | extern s32 __smp_locks[], __smp_locks_end[]; |
| 198 | void *text_poke_early(void *addr, const void *opcode, size_t len); |
| 199 | |
| 200 | /* Replace instructions with better alternatives for this CPU type. |
| 201 | This runs before SMP is initialized to avoid SMP problems with |
| 202 | self modifying code. This implies that assymetric systems where |
| 203 | APs have less capabilities than the boot processor are not handled. |
| 204 | Tough. Make sure you disable such features by hand. */ |
| 205 | |
| 206 | void __init_or_module apply_alternatives(struct alt_instr *start, |
| 207 | struct alt_instr *end) |
| 208 | { |
| 209 | struct alt_instr *a; |
| 210 | u8 insnbuf[MAX_PATCH_LEN]; |
| 211 | |
| 212 | DPRINTK("%s: alt table %p -> %p\n", __func__, start, end); |
| 213 | for (a = start; a < end; a++) { |
| 214 | u8 *instr = a->instr; |
| 215 | BUG_ON(a->replacementlen > a->instrlen); |
| 216 | BUG_ON(a->instrlen > sizeof(insnbuf)); |
| 217 | BUG_ON(a->cpuid >= NCAPINTS*32); |
| 218 | if (!boot_cpu_has(a->cpuid)) |
| 219 | continue; |
| 220 | #ifdef CONFIG_X86_64 |
| 221 | /* vsyscall code is not mapped yet. resolve it manually. */ |
| 222 | if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) { |
| 223 | instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0)); |
| 224 | DPRINTK("%s: vsyscall fixup: %p => %p\n", |
| 225 | __func__, a->instr, instr); |
| 226 | } |
| 227 | #endif |
| 228 | memcpy(insnbuf, a->replacement, a->replacementlen); |
| 229 | if (*insnbuf == 0xe8 && a->replacementlen == 5) |
| 230 | *(s32 *)(insnbuf + 1) += a->replacement - a->instr; |
| 231 | add_nops(insnbuf + a->replacementlen, |
| 232 | a->instrlen - a->replacementlen); |
| 233 | text_poke_early(instr, insnbuf, a->instrlen); |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | #ifdef CONFIG_SMP |
| 238 | |
| 239 | static void alternatives_smp_lock(const s32 *start, const s32 *end, |
| 240 | u8 *text, u8 *text_end) |
| 241 | { |
| 242 | const s32 *poff; |
| 243 | |
| 244 | mutex_lock(&text_mutex); |
| 245 | for (poff = start; poff < end; poff++) { |
| 246 | u8 *ptr = (u8 *)poff + *poff; |
| 247 | |
| 248 | if (!*poff || ptr < text || ptr >= text_end) |
| 249 | continue; |
| 250 | /* turn DS segment override prefix into lock prefix */ |
| 251 | if (*ptr == 0x3e) |
| 252 | text_poke(ptr, ((unsigned char []){0xf0}), 1); |
| 253 | }; |
| 254 | mutex_unlock(&text_mutex); |
| 255 | } |
| 256 | |
| 257 | static void alternatives_smp_unlock(const s32 *start, const s32 *end, |
| 258 | u8 *text, u8 *text_end) |
| 259 | { |
| 260 | const s32 *poff; |
| 261 | |
| 262 | if (noreplace_smp) |
| 263 | return; |
| 264 | |
| 265 | mutex_lock(&text_mutex); |
| 266 | for (poff = start; poff < end; poff++) { |
| 267 | u8 *ptr = (u8 *)poff + *poff; |
| 268 | |
| 269 | if (!*poff || ptr < text || ptr >= text_end) |
| 270 | continue; |
| 271 | /* turn lock prefix into DS segment override prefix */ |
| 272 | if (*ptr == 0xf0) |
| 273 | text_poke(ptr, ((unsigned char []){0x3E}), 1); |
| 274 | }; |
| 275 | mutex_unlock(&text_mutex); |
| 276 | } |
| 277 | |
| 278 | struct smp_alt_module { |
| 279 | /* what is this ??? */ |
| 280 | struct module *mod; |
| 281 | char *name; |
| 282 | |
| 283 | /* ptrs to lock prefixes */ |
| 284 | const s32 *locks; |
| 285 | const s32 *locks_end; |
| 286 | |
| 287 | /* .text segment, needed to avoid patching init code ;) */ |
| 288 | u8 *text; |
| 289 | u8 *text_end; |
| 290 | |
| 291 | struct list_head next; |
| 292 | }; |
| 293 | static LIST_HEAD(smp_alt_modules); |
| 294 | static DEFINE_MUTEX(smp_alt); |
| 295 | static int smp_mode = 1; /* protected by smp_alt */ |
| 296 | |
| 297 | void __init_or_module alternatives_smp_module_add(struct module *mod, |
| 298 | char *name, |
| 299 | void *locks, void *locks_end, |
| 300 | void *text, void *text_end) |
| 301 | { |
| 302 | struct smp_alt_module *smp; |
| 303 | |
| 304 | if (noreplace_smp) |
| 305 | return; |
| 306 | |
| 307 | if (smp_alt_once) { |
| 308 | if (boot_cpu_has(X86_FEATURE_UP)) |
| 309 | alternatives_smp_unlock(locks, locks_end, |
| 310 | text, text_end); |
| 311 | return; |
| 312 | } |
| 313 | |
| 314 | smp = kzalloc(sizeof(*smp), GFP_KERNEL); |
| 315 | if (NULL == smp) |
| 316 | return; /* we'll run the (safe but slow) SMP code then ... */ |
| 317 | |
| 318 | smp->mod = mod; |
| 319 | smp->name = name; |
| 320 | smp->locks = locks; |
| 321 | smp->locks_end = locks_end; |
| 322 | smp->text = text; |
| 323 | smp->text_end = text_end; |
| 324 | DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n", |
| 325 | __func__, smp->locks, smp->locks_end, |
| 326 | smp->text, smp->text_end, smp->name); |
| 327 | |
| 328 | mutex_lock(&smp_alt); |
| 329 | list_add_tail(&smp->next, &smp_alt_modules); |
| 330 | if (boot_cpu_has(X86_FEATURE_UP)) |
| 331 | alternatives_smp_unlock(smp->locks, smp->locks_end, |
| 332 | smp->text, smp->text_end); |
| 333 | mutex_unlock(&smp_alt); |
| 334 | } |
| 335 | |
| 336 | void __init_or_module alternatives_smp_module_del(struct module *mod) |
| 337 | { |
| 338 | struct smp_alt_module *item; |
| 339 | |
| 340 | if (smp_alt_once || noreplace_smp) |
| 341 | return; |
| 342 | |
| 343 | mutex_lock(&smp_alt); |
| 344 | list_for_each_entry(item, &smp_alt_modules, next) { |
| 345 | if (mod != item->mod) |
| 346 | continue; |
| 347 | list_del(&item->next); |
| 348 | mutex_unlock(&smp_alt); |
| 349 | DPRINTK("%s: %s\n", __func__, item->name); |
| 350 | kfree(item); |
| 351 | return; |
| 352 | } |
| 353 | mutex_unlock(&smp_alt); |
| 354 | } |
| 355 | |
| 356 | void alternatives_smp_switch(int smp) |
| 357 | { |
| 358 | struct smp_alt_module *mod; |
| 359 | |
| 360 | #ifdef CONFIG_LOCKDEP |
| 361 | /* |
| 362 | * Older binutils section handling bug prevented |
| 363 | * alternatives-replacement from working reliably. |
| 364 | * |
| 365 | * If this still occurs then you should see a hang |
| 366 | * or crash shortly after this line: |
| 367 | */ |
| 368 | printk("lockdep: fixing up alternatives.\n"); |
| 369 | #endif |
| 370 | |
| 371 | if (noreplace_smp || smp_alt_once) |
| 372 | return; |
| 373 | BUG_ON(!smp && (num_online_cpus() > 1)); |
| 374 | |
| 375 | mutex_lock(&smp_alt); |
| 376 | |
| 377 | /* |
| 378 | * Avoid unnecessary switches because it forces JIT based VMs to |
| 379 | * throw away all cached translations, which can be quite costly. |
| 380 | */ |
| 381 | if (smp == smp_mode) { |
| 382 | /* nothing */ |
| 383 | } else if (smp) { |
| 384 | printk(KERN_INFO "SMP alternatives: switching to SMP code\n"); |
| 385 | clear_cpu_cap(&boot_cpu_data, X86_FEATURE_UP); |
| 386 | clear_cpu_cap(&cpu_data(0), X86_FEATURE_UP); |
| 387 | list_for_each_entry(mod, &smp_alt_modules, next) |
| 388 | alternatives_smp_lock(mod->locks, mod->locks_end, |
| 389 | mod->text, mod->text_end); |
| 390 | } else { |
| 391 | printk(KERN_INFO "SMP alternatives: switching to UP code\n"); |
| 392 | set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP); |
| 393 | set_cpu_cap(&cpu_data(0), X86_FEATURE_UP); |
| 394 | list_for_each_entry(mod, &smp_alt_modules, next) |
| 395 | alternatives_smp_unlock(mod->locks, mod->locks_end, |
| 396 | mod->text, mod->text_end); |
| 397 | } |
| 398 | smp_mode = smp; |
| 399 | mutex_unlock(&smp_alt); |
| 400 | } |
| 401 | |
| 402 | /* Return 1 if the address range is reserved for smp-alternatives */ |
| 403 | int alternatives_text_reserved(void *start, void *end) |
| 404 | { |
| 405 | struct smp_alt_module *mod; |
| 406 | const s32 *poff; |
| 407 | u8 *text_start = start; |
| 408 | u8 *text_end = end; |
| 409 | |
| 410 | list_for_each_entry(mod, &smp_alt_modules, next) { |
| 411 | if (mod->text > text_end || mod->text_end < text_start) |
| 412 | continue; |
| 413 | for (poff = mod->locks; poff < mod->locks_end; poff++) { |
| 414 | const u8 *ptr = (const u8 *)poff + *poff; |
| 415 | |
| 416 | if (text_start <= ptr && text_end > ptr) |
| 417 | return 1; |
| 418 | } |
| 419 | } |
| 420 | |
| 421 | return 0; |
| 422 | } |
| 423 | #endif |
| 424 | |
| 425 | #ifdef CONFIG_PARAVIRT |
| 426 | void __init_or_module apply_paravirt(struct paravirt_patch_site *start, |
| 427 | struct paravirt_patch_site *end) |
| 428 | { |
| 429 | struct paravirt_patch_site *p; |
| 430 | char insnbuf[MAX_PATCH_LEN]; |
| 431 | |
| 432 | if (noreplace_paravirt) |
| 433 | return; |
| 434 | |
| 435 | for (p = start; p < end; p++) { |
| 436 | unsigned int used; |
| 437 | |
| 438 | BUG_ON(p->len > MAX_PATCH_LEN); |
| 439 | /* prep the buffer with the original instructions */ |
| 440 | memcpy(insnbuf, p->instr, p->len); |
| 441 | used = pv_init_ops.patch(p->instrtype, p->clobbers, insnbuf, |
| 442 | (unsigned long)p->instr, p->len); |
| 443 | |
| 444 | BUG_ON(used > p->len); |
| 445 | |
| 446 | /* Pad the rest with nops */ |
| 447 | add_nops(insnbuf + used, p->len - used); |
| 448 | text_poke_early(p->instr, insnbuf, p->len); |
| 449 | } |
| 450 | } |
| 451 | extern struct paravirt_patch_site __start_parainstructions[], |
| 452 | __stop_parainstructions[]; |
| 453 | #endif /* CONFIG_PARAVIRT */ |
| 454 | |
| 455 | void __init alternative_instructions(void) |
| 456 | { |
| 457 | /* The patching is not fully atomic, so try to avoid local interruptions |
| 458 | that might execute the to be patched code. |
| 459 | Other CPUs are not running. */ |
| 460 | stop_nmi(); |
| 461 | |
| 462 | /* |
| 463 | * Don't stop machine check exceptions while patching. |
| 464 | * MCEs only happen when something got corrupted and in this |
| 465 | * case we must do something about the corruption. |
| 466 | * Ignoring it is worse than a unlikely patching race. |
| 467 | * Also machine checks tend to be broadcast and if one CPU |
| 468 | * goes into machine check the others follow quickly, so we don't |
| 469 | * expect a machine check to cause undue problems during to code |
| 470 | * patching. |
| 471 | */ |
| 472 | |
| 473 | apply_alternatives(__alt_instructions, __alt_instructions_end); |
| 474 | |
| 475 | /* switch to patch-once-at-boottime-only mode and free the |
| 476 | * tables in case we know the number of CPUs will never ever |
| 477 | * change */ |
| 478 | #ifdef CONFIG_HOTPLUG_CPU |
| 479 | if (num_possible_cpus() < 2) |
| 480 | smp_alt_once = 1; |
| 481 | #endif |
| 482 | |
| 483 | #ifdef CONFIG_SMP |
| 484 | if (smp_alt_once) { |
| 485 | if (1 == num_possible_cpus()) { |
| 486 | printk(KERN_INFO "SMP alternatives: switching to UP code\n"); |
| 487 | set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP); |
| 488 | set_cpu_cap(&cpu_data(0), X86_FEATURE_UP); |
| 489 | |
| 490 | alternatives_smp_unlock(__smp_locks, __smp_locks_end, |
| 491 | _text, _etext); |
| 492 | } |
| 493 | } else { |
| 494 | alternatives_smp_module_add(NULL, "core kernel", |
| 495 | __smp_locks, __smp_locks_end, |
| 496 | _text, _etext); |
| 497 | |
| 498 | /* Only switch to UP mode if we don't immediately boot others */ |
| 499 | if (num_present_cpus() == 1 || setup_max_cpus <= 1) |
| 500 | alternatives_smp_switch(0); |
| 501 | } |
| 502 | #endif |
| 503 | apply_paravirt(__parainstructions, __parainstructions_end); |
| 504 | |
| 505 | if (smp_alt_once) |
| 506 | free_init_pages("SMP alternatives", |
| 507 | (unsigned long)__smp_locks, |
| 508 | (unsigned long)__smp_locks_end); |
| 509 | |
| 510 | restart_nmi(); |
| 511 | } |
| 512 | |
| 513 | /** |
| 514 | * text_poke_early - Update instructions on a live kernel at boot time |
| 515 | * @addr: address to modify |
| 516 | * @opcode: source of the copy |
| 517 | * @len: length to copy |
| 518 | * |
| 519 | * When you use this code to patch more than one byte of an instruction |
| 520 | * you need to make sure that other CPUs cannot execute this code in parallel. |
| 521 | * Also no thread must be currently preempted in the middle of these |
| 522 | * instructions. And on the local CPU you need to be protected again NMI or MCE |
| 523 | * handlers seeing an inconsistent instruction while you patch. |
| 524 | */ |
| 525 | void *__init_or_module text_poke_early(void *addr, const void *opcode, |
| 526 | size_t len) |
| 527 | { |
| 528 | unsigned long flags; |
| 529 | local_irq_save(flags); |
| 530 | memcpy(addr, opcode, len); |
| 531 | sync_core(); |
| 532 | local_irq_restore(flags); |
| 533 | /* Could also do a CLFLUSH here to speed up CPU recovery; but |
| 534 | that causes hangs on some VIA CPUs. */ |
| 535 | return addr; |
| 536 | } |
| 537 | |
| 538 | /** |
| 539 | * text_poke - Update instructions on a live kernel |
| 540 | * @addr: address to modify |
| 541 | * @opcode: source of the copy |
| 542 | * @len: length to copy |
| 543 | * |
| 544 | * Only atomic text poke/set should be allowed when not doing early patching. |
| 545 | * It means the size must be writable atomically and the address must be aligned |
| 546 | * in a way that permits an atomic write. It also makes sure we fit on a single |
| 547 | * page. |
| 548 | * |
| 549 | * Note: Must be called under text_mutex. |
| 550 | */ |
| 551 | void *__kprobes text_poke(void *addr, const void *opcode, size_t len) |
| 552 | { |
| 553 | unsigned long flags; |
| 554 | char *vaddr; |
| 555 | struct page *pages[2]; |
| 556 | int i; |
| 557 | |
| 558 | if (!core_kernel_text((unsigned long)addr)) { |
| 559 | pages[0] = vmalloc_to_page(addr); |
| 560 | pages[1] = vmalloc_to_page(addr + PAGE_SIZE); |
| 561 | } else { |
| 562 | pages[0] = virt_to_page(addr); |
| 563 | WARN_ON(!PageReserved(pages[0])); |
| 564 | pages[1] = virt_to_page(addr + PAGE_SIZE); |
| 565 | } |
| 566 | BUG_ON(!pages[0]); |
| 567 | local_irq_save(flags); |
| 568 | set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0])); |
| 569 | if (pages[1]) |
| 570 | set_fixmap(FIX_TEXT_POKE1, page_to_phys(pages[1])); |
| 571 | vaddr = (char *)fix_to_virt(FIX_TEXT_POKE0); |
| 572 | memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); |
| 573 | clear_fixmap(FIX_TEXT_POKE0); |
| 574 | if (pages[1]) |
| 575 | clear_fixmap(FIX_TEXT_POKE1); |
| 576 | local_flush_tlb(); |
| 577 | sync_core(); |
| 578 | /* Could also do a CLFLUSH here to speed up CPU recovery; but |
| 579 | that causes hangs on some VIA CPUs. */ |
| 580 | for (i = 0; i < len; i++) |
| 581 | BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]); |
| 582 | local_irq_restore(flags); |
| 583 | return addr; |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * Cross-modifying kernel text with stop_machine(). |
| 588 | * This code originally comes from immediate value. |
| 589 | */ |
| 590 | static atomic_t stop_machine_first; |
| 591 | static int wrote_text; |
| 592 | |
| 593 | struct text_poke_params { |
| 594 | void *addr; |
| 595 | const void *opcode; |
| 596 | size_t len; |
| 597 | }; |
| 598 | |
| 599 | static int __kprobes stop_machine_text_poke(void *data) |
| 600 | { |
| 601 | struct text_poke_params *tpp = data; |
| 602 | |
| 603 | if (atomic_dec_and_test(&stop_machine_first)) { |
| 604 | text_poke(tpp->addr, tpp->opcode, tpp->len); |
| 605 | smp_wmb(); /* Make sure other cpus see that this has run */ |
| 606 | wrote_text = 1; |
| 607 | } else { |
| 608 | while (!wrote_text) |
| 609 | cpu_relax(); |
| 610 | smp_mb(); /* Load wrote_text before following execution */ |
| 611 | } |
| 612 | |
| 613 | flush_icache_range((unsigned long)tpp->addr, |
| 614 | (unsigned long)tpp->addr + tpp->len); |
| 615 | return 0; |
| 616 | } |
| 617 | |
| 618 | /** |
| 619 | * text_poke_smp - Update instructions on a live kernel on SMP |
| 620 | * @addr: address to modify |
| 621 | * @opcode: source of the copy |
| 622 | * @len: length to copy |
| 623 | * |
| 624 | * Modify multi-byte instruction by using stop_machine() on SMP. This allows |
| 625 | * user to poke/set multi-byte text on SMP. Only non-NMI/MCE code modifying |
| 626 | * should be allowed, since stop_machine() does _not_ protect code against |
| 627 | * NMI and MCE. |
| 628 | * |
| 629 | * Note: Must be called under get_online_cpus() and text_mutex. |
| 630 | */ |
| 631 | void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) |
| 632 | { |
| 633 | struct text_poke_params tpp; |
| 634 | |
| 635 | tpp.addr = addr; |
| 636 | tpp.opcode = opcode; |
| 637 | tpp.len = len; |
| 638 | atomic_set(&stop_machine_first, 1); |
| 639 | wrote_text = 0; |
| 640 | /* Use __stop_machine() because the caller already got online_cpus. */ |
| 641 | __stop_machine(stop_machine_text_poke, (void *)&tpp, NULL); |
| 642 | return addr; |
| 643 | } |
| 644 | |
| 645 | #if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) |
| 646 | |
| 647 | unsigned char ideal_nop5[IDEAL_NOP_SIZE_5]; |
| 648 | |
| 649 | void __init arch_init_ideal_nop5(void) |
| 650 | { |
| 651 | extern const unsigned char ftrace_test_p6nop[]; |
| 652 | extern const unsigned char ftrace_test_nop5[]; |
| 653 | extern const unsigned char ftrace_test_jmp[]; |
| 654 | int faulted = 0; |
| 655 | |
| 656 | /* |
| 657 | * There is no good nop for all x86 archs. |
| 658 | * We will default to using the P6_NOP5, but first we |
| 659 | * will test to make sure that the nop will actually |
| 660 | * work on this CPU. If it faults, we will then |
| 661 | * go to a lesser efficient 5 byte nop. If that fails |
| 662 | * we then just use a jmp as our nop. This isn't the most |
| 663 | * efficient nop, but we can not use a multi part nop |
| 664 | * since we would then risk being preempted in the middle |
| 665 | * of that nop, and if we enabled tracing then, it might |
| 666 | * cause a system crash. |
| 667 | * |
| 668 | * TODO: check the cpuid to determine the best nop. |
| 669 | */ |
| 670 | asm volatile ( |
| 671 | "ftrace_test_jmp:" |
| 672 | "jmp ftrace_test_p6nop\n" |
| 673 | "nop\n" |
| 674 | "nop\n" |
| 675 | "nop\n" /* 2 byte jmp + 3 bytes */ |
| 676 | "ftrace_test_p6nop:" |
| 677 | P6_NOP5 |
| 678 | "jmp 1f\n" |
| 679 | "ftrace_test_nop5:" |
| 680 | ".byte 0x66,0x66,0x66,0x66,0x90\n" |
| 681 | "1:" |
| 682 | ".section .fixup, \"ax\"\n" |
| 683 | "2: movl $1, %0\n" |
| 684 | " jmp ftrace_test_nop5\n" |
| 685 | "3: movl $2, %0\n" |
| 686 | " jmp 1b\n" |
| 687 | ".previous\n" |
| 688 | _ASM_EXTABLE(ftrace_test_p6nop, 2b) |
| 689 | _ASM_EXTABLE(ftrace_test_nop5, 3b) |
| 690 | : "=r"(faulted) : "0" (faulted)); |
| 691 | |
| 692 | switch (faulted) { |
| 693 | case 0: |
| 694 | pr_info("converting mcount calls to 0f 1f 44 00 00\n"); |
| 695 | memcpy(ideal_nop5, ftrace_test_p6nop, IDEAL_NOP_SIZE_5); |
| 696 | break; |
| 697 | case 1: |
| 698 | pr_info("converting mcount calls to 66 66 66 66 90\n"); |
| 699 | memcpy(ideal_nop5, ftrace_test_nop5, IDEAL_NOP_SIZE_5); |
| 700 | break; |
| 701 | case 2: |
| 702 | pr_info("converting mcount calls to jmp . + 5\n"); |
| 703 | memcpy(ideal_nop5, ftrace_test_jmp, IDEAL_NOP_SIZE_5); |
| 704 | break; |
| 705 | } |
| 706 | |
| 707 | } |
| 708 | #endif |