1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License as published by 4 * the Free Software Foundation; either version 2 of the License, or 5 * (at your option) any later version. 6 * 7 * This program is distributed in the hope that it will be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 * GNU General Public License for more details. 11 * 12 * You should have received a copy of the GNU General Public License 13 * along with this program; if not, write to the Free Software 14 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 15 * 16 * Copyright (C) IBM Corporation, 2005 17 * Jeff Muizelaar, 2006, 2007 18 * Pekka Paalanen, 2008 <pq@iki.fi> 19 * 20 * Derived from the read-mod example from relay-examples by Tom Zanussi. 21 */ 22 23 #define pr_fmt(fmt) "mmiotrace: " fmt 24 25 #define DEBUG 1 26 27 #include <linux/module.h> 28 #include <linux/debugfs.h> 29 #include <linux/slab.h> 30 #include <linux/uaccess.h> 31 #include <linux/io.h> 32 #include <linux/version.h> 33 #include <linux/kallsyms.h> 34 #include <asm/pgtable.h> 35 #include <linux/mmiotrace.h> 36 #include <asm/e820.h> /* for ISA_START_ADDRESS */ 37 #include <linux/atomic.h> 38 #include <linux/percpu.h> 39 #include <linux/cpu.h> 40 41 #include "pf_in.h" 42 43 struct trap_reason { 44 unsigned long addr; 45 unsigned long ip; 46 enum reason_type type; 47 int active_traces; 48 }; 49 50 struct remap_trace { 51 struct list_head list; 52 struct kmmio_probe probe; 53 resource_size_t phys; 54 unsigned long id; 55 }; 56 57 /* Accessed per-cpu. */ 58 static DEFINE_PER_CPU(struct trap_reason, pf_reason); 59 static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace); 60 61 static DEFINE_MUTEX(mmiotrace_mutex); 62 static DEFINE_SPINLOCK(trace_lock); 63 static atomic_t mmiotrace_enabled; 64 static LIST_HEAD(trace_list); /* struct remap_trace */ 65 66 /* 67 * Locking in this file: 68 * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections. 69 * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex 70 * and trace_lock. 71 * - Routines depending on is_enabled() must take trace_lock. 72 * - trace_list users must hold trace_lock. 73 * - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed. 74 * - pre/post callbacks assume the effect of is_enabled() being true. 75 */ 76 77 /* module parameters */ 78 static unsigned long filter_offset; 79 static int nommiotrace; 80 static int trace_pc; 81 82 module_param(filter_offset, ulong, 0); 83 module_param(nommiotrace, bool, 0); 84 module_param(trace_pc, bool, 0); 85 86 MODULE_PARM_DESC(filter_offset, "Start address of traced mappings."); 87 MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing."); 88 MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions."); 89 90 static bool is_enabled(void) 91 { 92 return atomic_read(&mmiotrace_enabled); 93 } 94 95 static void print_pte(unsigned long address) 96 { 97 unsigned int level; 98 pte_t *pte = lookup_address(address, &level); 99 100 if (!pte) { 101 pr_err("Error in %s: no pte for page 0x%08lx\n", 102 __func__, address); 103 return; 104 } 105 106 if (level == PG_LEVEL_2M) { 107 pr_emerg("4MB pages are not currently supported: 0x%08lx\n", 108 address); 109 BUG(); 110 } 111 pr_info("pte for 0x%lx: 0x%llx 0x%llx\n", 112 address, 113 (unsigned long long)pte_val(*pte), 114 (unsigned long long)pte_val(*pte) & _PAGE_PRESENT); 115 } 116 117 /* 118 * For some reason the pre/post pairs have been called in an 119 * unmatched order. Report and die. 120 */ 121 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr) 122 { 123 const struct trap_reason *my_reason = &get_cpu_var(pf_reason); 124 pr_emerg("unexpected fault for address: 0x%08lx, last fault for address: 0x%08lx\n", 125 addr, my_reason->addr); 126 print_pte(addr); 127 print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip); 128 print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip); 129 #ifdef __i386__ 130 pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n", 131 regs->ax, regs->bx, regs->cx, regs->dx); 132 pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n", 133 regs->si, regs->di, regs->bp, regs->sp); 134 #else 135 pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n", 136 regs->ax, regs->cx, regs->dx); 137 pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n", 138 regs->si, regs->di, regs->bp, regs->sp); 139 #endif 140 put_cpu_var(pf_reason); 141 BUG(); 142 } 143 144 static void pre(struct kmmio_probe *p, struct pt_regs *regs, 145 unsigned long addr) 146 { 147 struct trap_reason *my_reason = &get_cpu_var(pf_reason); 148 struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); 149 const unsigned long instptr = instruction_pointer(regs); 150 const enum reason_type type = get_ins_type(instptr); 151 struct remap_trace *trace = p->private; 152 153 /* it doesn't make sense to have more than one active trace per cpu */ 154 if (my_reason->active_traces) 155 die_kmmio_nesting_error(regs, addr); 156 else 157 my_reason->active_traces++; 158 159 my_reason->type = type; 160 my_reason->addr = addr; 161 my_reason->ip = instptr; 162 163 my_trace->phys = addr - trace->probe.addr + trace->phys; 164 my_trace->map_id = trace->id; 165 166 /* 167 * Only record the program counter when requested. 168 * It may taint clean-room reverse engineering. 169 */ 170 if (trace_pc) 171 my_trace->pc = instptr; 172 else 173 my_trace->pc = 0; 174 175 /* 176 * XXX: the timestamp recorded will be *after* the tracing has been 177 * done, not at the time we hit the instruction. SMP implications 178 * on event ordering? 179 */ 180 181 switch (type) { 182 case REG_READ: 183 my_trace->opcode = MMIO_READ; 184 my_trace->width = get_ins_mem_width(instptr); 185 break; 186 case REG_WRITE: 187 my_trace->opcode = MMIO_WRITE; 188 my_trace->width = get_ins_mem_width(instptr); 189 my_trace->value = get_ins_reg_val(instptr, regs); 190 break; 191 case IMM_WRITE: 192 my_trace->opcode = MMIO_WRITE; 193 my_trace->width = get_ins_mem_width(instptr); 194 my_trace->value = get_ins_imm_val(instptr); 195 break; 196 default: 197 { 198 unsigned char *ip = (unsigned char *)instptr; 199 my_trace->opcode = MMIO_UNKNOWN_OP; 200 my_trace->width = 0; 201 my_trace->value = (*ip) << 16 | *(ip + 1) << 8 | 202 *(ip + 2); 203 } 204 } 205 put_cpu_var(cpu_trace); 206 put_cpu_var(pf_reason); 207 } 208 209 static void post(struct kmmio_probe *p, unsigned long condition, 210 struct pt_regs *regs) 211 { 212 struct trap_reason *my_reason = &get_cpu_var(pf_reason); 213 struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); 214 215 /* this should always return the active_trace count to 0 */ 216 my_reason->active_traces--; 217 if (my_reason->active_traces) { 218 pr_emerg("unexpected post handler"); 219 BUG(); 220 } 221 222 switch (my_reason->type) { 223 case REG_READ: 224 my_trace->value = get_ins_reg_val(my_reason->ip, regs); 225 break; 226 default: 227 break; 228 } 229 230 mmio_trace_rw(my_trace); 231 put_cpu_var(cpu_trace); 232 put_cpu_var(pf_reason); 233 } 234 235 static void ioremap_trace_core(resource_size_t offset, unsigned long size, 236 void __iomem *addr) 237 { 238 static atomic_t next_id; 239 struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL); 240 /* These are page-unaligned. */ 241 struct mmiotrace_map map = { 242 .phys = offset, 243 .virt = (unsigned long)addr, 244 .len = size, 245 .opcode = MMIO_PROBE 246 }; 247 248 if (!trace) { 249 pr_err("kmalloc failed in ioremap\n"); 250 return; 251 } 252 253 *trace = (struct remap_trace) { 254 .probe = { 255 .addr = (unsigned long)addr, 256 .len = size, 257 .pre_handler = pre, 258 .post_handler = post, 259 .private = trace 260 }, 261 .phys = offset, 262 .id = atomic_inc_return(&next_id) 263 }; 264 map.map_id = trace->id; 265 266 spin_lock_irq(&trace_lock); 267 if (!is_enabled()) { 268 kfree(trace); 269 goto not_enabled; 270 } 271 272 mmio_trace_mapping(&map); 273 list_add_tail(&trace->list, &trace_list); 274 if (!nommiotrace) 275 register_kmmio_probe(&trace->probe); 276 277 not_enabled: 278 spin_unlock_irq(&trace_lock); 279 } 280 281 void mmiotrace_ioremap(resource_size_t offset, unsigned long size, 282 void __iomem *addr) 283 { 284 if (!is_enabled()) /* recheck and proper locking in *_core() */ 285 return; 286 287 pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n", 288 (unsigned long long)offset, size, addr); 289 if ((filter_offset) && (offset != filter_offset)) 290 return; 291 ioremap_trace_core(offset, size, addr); 292 } 293 294 static void iounmap_trace_core(volatile void __iomem *addr) 295 { 296 struct mmiotrace_map map = { 297 .phys = 0, 298 .virt = (unsigned long)addr, 299 .len = 0, 300 .opcode = MMIO_UNPROBE 301 }; 302 struct remap_trace *trace; 303 struct remap_trace *tmp; 304 struct remap_trace *found_trace = NULL; 305 306 pr_debug("Unmapping %p.\n", addr); 307 308 spin_lock_irq(&trace_lock); 309 if (!is_enabled()) 310 goto not_enabled; 311 312 list_for_each_entry_safe(trace, tmp, &trace_list, list) { 313 if ((unsigned long)addr == trace->probe.addr) { 314 if (!nommiotrace) 315 unregister_kmmio_probe(&trace->probe); 316 list_del(&trace->list); 317 found_trace = trace; 318 break; 319 } 320 } 321 map.map_id = (found_trace) ? found_trace->id : -1; 322 mmio_trace_mapping(&map); 323 324 not_enabled: 325 spin_unlock_irq(&trace_lock); 326 if (found_trace) { 327 synchronize_rcu(); /* unregister_kmmio_probe() requirement */ 328 kfree(found_trace); 329 } 330 } 331 332 void mmiotrace_iounmap(volatile void __iomem *addr) 333 { 334 might_sleep(); 335 if (is_enabled()) /* recheck and proper locking in *_core() */ 336 iounmap_trace_core(addr); 337 } 338 339 int mmiotrace_printk(const char *fmt, ...) 340 { 341 int ret = 0; 342 va_list args; 343 unsigned long flags; 344 va_start(args, fmt); 345 346 spin_lock_irqsave(&trace_lock, flags); 347 if (is_enabled()) 348 ret = mmio_trace_printk(fmt, args); 349 spin_unlock_irqrestore(&trace_lock, flags); 350 351 va_end(args); 352 return ret; 353 } 354 EXPORT_SYMBOL(mmiotrace_printk); 355 356 static void clear_trace_list(void) 357 { 358 struct remap_trace *trace; 359 struct remap_trace *tmp; 360 361 /* 362 * No locking required, because the caller ensures we are in a 363 * critical section via mutex, and is_enabled() is false, 364 * i.e. nothing can traverse or modify this list. 365 * Caller also ensures is_enabled() cannot change. 366 */ 367 list_for_each_entry(trace, &trace_list, list) { 368 pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n", 369 trace->probe.addr, trace->probe.len); 370 if (!nommiotrace) 371 unregister_kmmio_probe(&trace->probe); 372 } 373 synchronize_rcu(); /* unregister_kmmio_probe() requirement */ 374 375 list_for_each_entry_safe(trace, tmp, &trace_list, list) { 376 list_del(&trace->list); 377 kfree(trace); 378 } 379 } 380 381 #ifdef CONFIG_HOTPLUG_CPU 382 static cpumask_var_t downed_cpus; 383 384 static void enter_uniprocessor(void) 385 { 386 int cpu; 387 int err; 388 389 if (downed_cpus == NULL && 390 !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) { 391 pr_notice("Failed to allocate mask\n"); 392 goto out; 393 } 394 395 get_online_cpus(); 396 cpumask_copy(downed_cpus, cpu_online_mask); 397 cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus); 398 if (num_online_cpus() > 1) 399 pr_notice("Disabling non-boot CPUs...\n"); 400 put_online_cpus(); 401 402 for_each_cpu(cpu, downed_cpus) { 403 err = cpu_down(cpu); 404 if (!err) 405 pr_info("CPU%d is down.\n", cpu); 406 else 407 pr_err("Error taking CPU%d down: %d\n", cpu, err); 408 } 409 out: 410 if (num_online_cpus() > 1) 411 pr_warning("multiple CPUs still online, may miss events.\n"); 412 } 413 414 /* __ref because leave_uniprocessor calls cpu_up which is __cpuinit, 415 but this whole function is ifdefed CONFIG_HOTPLUG_CPU */ 416 static void __ref leave_uniprocessor(void) 417 { 418 int cpu; 419 int err; 420 421 if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0) 422 return; 423 pr_notice("Re-enabling CPUs...\n"); 424 for_each_cpu(cpu, downed_cpus) { 425 err = cpu_up(cpu); 426 if (!err) 427 pr_info("enabled CPU%d.\n", cpu); 428 else 429 pr_err("cannot re-enable CPU%d: %d\n", cpu, err); 430 } 431 } 432 433 #else /* !CONFIG_HOTPLUG_CPU */ 434 static void enter_uniprocessor(void) 435 { 436 if (num_online_cpus() > 1) 437 pr_warning("multiple CPUs are online, may miss events. " 438 "Suggest booting with maxcpus=1 kernel argument.\n"); 439 } 440 441 static void leave_uniprocessor(void) 442 { 443 } 444 #endif 445 446 void enable_mmiotrace(void) 447 { 448 mutex_lock(&mmiotrace_mutex); 449 if (is_enabled()) 450 goto out; 451 452 if (nommiotrace) 453 pr_info("MMIO tracing disabled.\n"); 454 kmmio_init(); 455 enter_uniprocessor(); 456 spin_lock_irq(&trace_lock); 457 atomic_inc(&mmiotrace_enabled); 458 spin_unlock_irq(&trace_lock); 459 pr_info("enabled.\n"); 460 out: 461 mutex_unlock(&mmiotrace_mutex); 462 } 463 464 void disable_mmiotrace(void) 465 { 466 mutex_lock(&mmiotrace_mutex); 467 if (!is_enabled()) 468 goto out; 469 470 spin_lock_irq(&trace_lock); 471 atomic_dec(&mmiotrace_enabled); 472 BUG_ON(is_enabled()); 473 spin_unlock_irq(&trace_lock); 474 475 clear_trace_list(); /* guarantees: no more kmmio callbacks */ 476 leave_uniprocessor(); 477 kmmio_cleanup(); 478 pr_info("disabled.\n"); 479 out: 480 mutex_unlock(&mmiotrace_mutex); 481 } 482