arch/x86/mm/mmio-mod.c

   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 #define DEBUG 1
  23
  24 #include <linux/module.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/io.h>
  28 #include <linux/version.h>
  29 #include <linux/kallsyms.h>
  30 #include <asm/pgtable.h>
  31 #include <linux/mmiotrace.h>
  32 #include <asm/e820.h> /* for ISA_START_ADDRESS */
  33 #include <asm/atomic.h>
  34 #include <linux/percpu.h>
  35 #include <linux/cpu.h>
  36
  37 #include "pf_in.h"
  38
  39 #define NAME "mmiotrace: "
  40
  41 struct trap_reason {
  42         unsigned long addr;
  43         unsigned long ip;
  44         enum reason_type type;
  45         int active_traces;
  46 };
  47
  48 struct remap_trace {
  49         struct list_head list;
  50         struct kmmio_probe probe;
  51         resource_size_t phys;
  52         unsigned long id;
  53 };
  54
  55 /* Accessed per-cpu. */
  56 static DEFINE_PER_CPU(struct trap_reason, pf_reason);
  57 static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);
  58
  59 #if 0 /* XXX: no way gather this info anymore */
  60 /* Access to this is not per-cpu. */
  61 static DEFINE_PER_CPU(atomic_t, dropped);
  62 #endif
  63
  64 static struct dentry *marker_file;
  65
  66 static DEFINE_MUTEX(mmiotrace_mutex);
  67 static DEFINE_SPINLOCK(trace_lock);
  68 static atomic_t mmiotrace_enabled;
  69 static LIST_HEAD(trace_list);           /* struct remap_trace */
  70
  71 /*
  72  * Locking in this file:
  73  * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections.
  74  * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex
  75  *   and trace_lock.
  76  * - Routines depending on is_enabled() must take trace_lock.
  77  * - trace_list users must hold trace_lock.
  78  * - is_enabled() guarantees that mmio_trace_record is allowed.
  79  * - pre/post callbacks assume the effect of is_enabled() being true.
  80  */
  81
  82 /* module parameters */
  83 static unsigned long    filter_offset;
  84 static int              nommiotrace;
  85 static int              trace_pc;
  86
  87 module_param(filter_offset, ulong, 0);
  88 module_param(nommiotrace, bool, 0);
  89 module_param(trace_pc, bool, 0);
  90
  91 MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
  92 MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
  93 MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
  94
  95 static bool is_enabled(void)
  96 {
  97         return atomic_read(&mmiotrace_enabled);
  98 }
  99
 100 #if 0 /* XXX: needs rewrite */
 101 /*
 102  * Write callback for the debugfs entry:
 103  * Read a marker and write it to the mmio trace log
 104  */
 105 static ssize_t write_marker(struct file *file, const char __user *buffer,
 106                                                 size_t count, loff_t *ppos)
 107 {
 108         char *event = NULL;
 109         struct mm_io_header *headp;
 110         ssize_t len = (count > 65535) ? 65535 : count;
 111
 112         event = kzalloc(sizeof(*headp) + len, GFP_KERNEL);
 113         if (!event)
 114                 return -ENOMEM;
 115
 116         headp = (struct mm_io_header *)event;
 117         headp->type = MMIO_MAGIC | (MMIO_MARKER << MMIO_OPCODE_SHIFT);
 118         headp->data_len = len;
 119
 120         if (copy_from_user(event + sizeof(*headp), buffer, len)) {
 121                 kfree(event);
 122                 return -EFAULT;
 123         }
 124
 125         spin_lock_irq(&trace_lock);
 126 #if 0 /* XXX: convert this to use tracing */
 127         if (is_enabled())
 128                 relay_write(chan, event, sizeof(*headp) + len);
 129         else
 130 #endif
 131                 len = -EINVAL;
 132         spin_unlock_irq(&trace_lock);
 133         kfree(event);
 134         return len;
 135 }
 136 #endif
 137
 138 static void print_pte(unsigned long address)
 139 {
 140         unsigned int level;
 141         pte_t *pte = lookup_address(address, &level);
 142
 143         if (!pte) {
 144                 pr_err(NAME "Error in %s: no pte for page 0x%08lx\n",
 145                                                         __func__, address);
 146                 return;
 147         }
 148
 149         if (level == PG_LEVEL_2M) {
 150                 pr_emerg(NAME "4MB pages are not currently supported: "
 151                                                         "0x%08lx\n", address);
 152                 BUG();
 153         }
 154         pr_info(NAME "pte for 0x%lx: 0x%llx 0x%llx\n", address,
 155                 (unsigned long long)pte_val(*pte),
 156                 (unsigned long long)pte_val(*pte) & _PAGE_PRESENT);
 157 }
 158
 159 /*
 160  * For some reason the pre/post pairs have been called in an
 161  * unmatched order. Report and die.
 162  */
 163 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
 164 {
 165         const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 166         pr_emerg(NAME "unexpected fault for address: 0x%08lx, "
 167                                         "last fault for address: 0x%08lx\n",
 168                                         addr, my_reason->addr);
 169         print_pte(addr);
 170         print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
 171         print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip);
 172 #ifdef __i386__
 173         pr_emerg("eax: %08lx   ebx: %08lx   ecx: %08lx   edx: %08lx\n",
 174                         regs->ax, regs->bx, regs->cx, regs->dx);
 175         pr_emerg("esi: %08lx   edi: %08lx   ebp: %08lx   esp: %08lx\n",
 176                         regs->si, regs->di, regs->bp, regs->sp);
 177 #else
 178         pr_emerg("rax: %016lx   rcx: %016lx   rdx: %016lx\n",
 179                                         regs->ax, regs->cx, regs->dx);
 180         pr_emerg("rsi: %016lx   rdi: %016lx   rbp: %016lx   rsp: %016lx\n",
 181                                 regs->si, regs->di, regs->bp, regs->sp);
 182 #endif
 183         put_cpu_var(pf_reason);
 184         BUG();
 185 }
 186
 187 static void pre(struct kmmio_probe *p, struct pt_regs *regs,
 188                                                 unsigned long addr)
 189 {
 190         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 191         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 192         const unsigned long instptr = instruction_pointer(regs);
 193         const enum reason_type type = get_ins_type(instptr);
 194         struct remap_trace *trace = p->private;
 195
 196         /* it doesn't make sense to have more than one active trace per cpu */
 197         if (my_reason->active_traces)
 198                 die_kmmio_nesting_error(regs, addr);
 199         else
 200                 my_reason->active_traces++;
 201
 202         my_reason->type = type;
 203         my_reason->addr = addr;
 204         my_reason->ip = instptr;
 205
 206         my_trace->phys = addr - trace->probe.addr + trace->phys;
 207         my_trace->map_id = trace->id;
 208
 209         /*
 210          * Only record the program counter when requested.
 211          * It may taint clean-room reverse engineering.
 212          */
 213         if (trace_pc)
 214                 my_trace->pc = instptr;
 215         else
 216                 my_trace->pc = 0;
 217
 218         /*
 219          * XXX: the timestamp recorded will be *after* the tracing has been
 220          * done, not at the time we hit the instruction. SMP implications
 221          * on event ordering?
 222          */
 223
 224         switch (type) {
 225         case REG_READ:
 226                 my_trace->opcode = MMIO_READ;
 227                 my_trace->width = get_ins_mem_width(instptr);
 228                 break;
 229         case REG_WRITE:
 230                 my_trace->opcode = MMIO_WRITE;
 231                 my_trace->width = get_ins_mem_width(instptr);
 232                 my_trace->value = get_ins_reg_val(instptr, regs);
 233                 break;
 234         case IMM_WRITE:
 235                 my_trace->opcode = MMIO_WRITE;
 236                 my_trace->width = get_ins_mem_width(instptr);
 237                 my_trace->value = get_ins_imm_val(instptr);
 238                 break;
 239         default:
 240                 {
 241                         unsigned char *ip = (unsigned char *)instptr;
 242                         my_trace->opcode = MMIO_UNKNOWN_OP;
 243                         my_trace->width = 0;
 244                         my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
 245                                                                 *(ip + 2);
 246                 }
 247         }
 248         put_cpu_var(cpu_trace);
 249         put_cpu_var(pf_reason);
 250 }
 251
 252 static void post(struct kmmio_probe *p, unsigned long condition,
 253                                                         struct pt_regs *regs)
 254 {
 255         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 256         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 257
 258         /* this should always return the active_trace count to 0 */
 259         my_reason->active_traces--;
 260         if (my_reason->active_traces) {
 261                 pr_emerg(NAME "unexpected post handler");
 262                 BUG();
 263         }
 264
 265         switch (my_reason->type) {
 266         case REG_READ:
 267                 my_trace->value = get_ins_reg_val(my_reason->ip, regs);
 268                 break;
 269         default:
 270                 break;
 271         }
 272
 273         mmio_trace_rw(my_trace);
 274         put_cpu_var(cpu_trace);
 275         put_cpu_var(pf_reason);
 276 }
 277
 278 static void ioremap_trace_core(resource_size_t offset, unsigned long size,
 279                                                         void __iomem *addr)
 280 {
 281         static atomic_t next_id;
 282         struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
 283         /* These are page-unaligned. */
 284         struct mmiotrace_map map = {
 285                 .phys = offset,
 286                 .virt = (unsigned long)addr,
 287                 .len = size,
 288                 .opcode = MMIO_PROBE
 289         };
 290
 291         if (!trace) {
 292                 pr_err(NAME "kmalloc failed in ioremap\n");
 293                 return;
 294         }
 295
 296         *trace = (struct remap_trace) {
 297                 .probe = {
 298                         .addr = (unsigned long)addr,
 299                         .len = size,
 300                         .pre_handler = pre,
 301                         .post_handler = post,
 302                         .private = trace
 303                 },
 304                 .phys = offset,
 305                 .id = atomic_inc_return(&next_id)
 306         };
 307         map.map_id = trace->id;
 308
 309         spin_lock_irq(&trace_lock);
 310         if (!is_enabled())
 311                 goto not_enabled;
 312
 313         mmio_trace_mapping(&map);
 314         list_add_tail(&trace->list, &trace_list);
 315         if (!nommiotrace)
 316                 register_kmmio_probe(&trace->probe);
 317
 318 not_enabled:
 319         spin_unlock_irq(&trace_lock);
 320 }
 321
 322 void mmiotrace_ioremap(resource_size_t offset, unsigned long size,
 323                                                 void __iomem *addr)
 324 {
 325         if (!is_enabled()) /* recheck and proper locking in *_core() */
 326                 return;
 327
 328         pr_debug(NAME "ioremap_*(0x%llx, 0x%lx) = %p\n",
 329                                 (unsigned long long)offset, size, addr);
 330         if ((filter_offset) && (offset != filter_offset))
 331                 return;
 332         ioremap_trace_core(offset, size, addr);
 333 }
 334
 335 static void iounmap_trace_core(volatile void __iomem *addr)
 336 {
 337         struct mmiotrace_map map = {
 338                 .phys = 0,
 339                 .virt = (unsigned long)addr,
 340                 .len = 0,
 341                 .opcode = MMIO_UNPROBE
 342         };
 343         struct remap_trace *trace;
 344         struct remap_trace *tmp;
 345         struct remap_trace *found_trace = NULL;
 346
 347         pr_debug(NAME "Unmapping %p.\n", addr);
 348
 349         spin_lock_irq(&trace_lock);
 350         if (!is_enabled())
 351                 goto not_enabled;
 352
 353         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 354                 if ((unsigned long)addr == trace->probe.addr) {
 355                         if (!nommiotrace)
 356                                 unregister_kmmio_probe(&trace->probe);
 357                         list_del(&trace->list);
 358                         found_trace = trace;
 359                         break;
 360                 }
 361         }
 362         map.map_id = (found_trace) ? found_trace->id : -1;
 363         mmio_trace_mapping(&map);
 364
 365 not_enabled:
 366         spin_unlock_irq(&trace_lock);
 367         if (found_trace) {
 368                 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 369                 kfree(found_trace);
 370         }
 371 }
 372
 373 void mmiotrace_iounmap(volatile void __iomem *addr)
 374 {
 375         might_sleep();
 376         if (is_enabled()) /* recheck and proper locking in *_core() */
 377                 iounmap_trace_core(addr);
 378 }
 379
 380 static void clear_trace_list(void)
 381 {
 382         struct remap_trace *trace;
 383         struct remap_trace *tmp;
 384
 385         /*
 386          * No locking required, because the caller ensures we are in a
 387          * critical section via mutex, and is_enabled() is false,
 388          * i.e. nothing can traverse or modify this list.
 389          * Caller also ensures is_enabled() cannot change.
 390          */
 391         list_for_each_entry(trace, &trace_list, list) {
 392                 pr_notice(NAME "purging non-iounmapped "
 393                                         "trace @0x%08lx, size 0x%lx.\n",
 394                                         trace->probe.addr, trace->probe.len);
 395                 if (!nommiotrace)
 396                         unregister_kmmio_probe(&trace->probe);
 397         }
 398         synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 399
 400         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 401                 list_del(&trace->list);
 402                 kfree(trace);
 403         }
 404 }
 405
 406 #ifdef CONFIG_HOTPLUG_CPU
 407 static cpumask_t downed_cpus;
 408
 409 static void enter_uniprocessor(void)
 410 {
 411         int cpu;
 412         int err;
 413
 414         get_online_cpus();
 415         downed_cpus = cpu_online_map;
 416         cpu_clear(first_cpu(cpu_online_map), downed_cpus);
 417         if (num_online_cpus() > 1)
 418                 pr_notice(NAME "Disabling non-boot CPUs...\n");
 419         put_online_cpus();
 420
 421         for_each_cpu_mask(cpu, downed_cpus) {
 422                 err = cpu_down(cpu);
 423                 if (!err)
 424                         pr_info(NAME "CPU%d is down.\n", cpu);
 425                 else
 426                         pr_err(NAME "Error taking CPU%d down: %d\n", cpu, err);
 427         }
 428         if (num_online_cpus() > 1)
 429                 pr_warning(NAME "multiple CPUs still online, "
 430                                                 "may miss events.\n");
 431 }
 432
 433 static void leave_uniprocessor(void)
 434 {
 435         int cpu;
 436         int err;
 437
 438         if (cpus_weight(downed_cpus) == 0)
 439                 return;
 440         pr_notice(NAME "Re-enabling CPUs...\n");
 441         for_each_cpu_mask(cpu, downed_cpus) {
 442                 err = cpu_up(cpu);
 443                 if (!err)
 444                         pr_info(NAME "enabled CPU%d.\n", cpu);
 445                 else
 446                         pr_err(NAME "cannot re-enable CPU%d: %d\n", cpu, err);
 447         }
 448 }
 449
 450 #else /* !CONFIG_HOTPLUG_CPU */
 451 static void enter_uniprocessor(void)
 452 {
 453         if (num_online_cpus() > 1)
 454                 pr_warning(NAME "multiple CPUs are online, may miss events. "
 455                         "Suggest booting with maxcpus=1 kernel argument.\n");
 456 }
 457
 458 static void leave_uniprocessor(void)
 459 {
 460 }
 461 #endif
 462
 463 #if 0 /* XXX: out of order */
 464 static struct file_operations fops_marker = {
 465         .owner =        THIS_MODULE,
 466         .write =        write_marker
 467 };
 468 #endif
 469
 470 void enable_mmiotrace(void)
 471 {
 472         mutex_lock(&mmiotrace_mutex);
 473         if (is_enabled())
 474                 goto out;
 475
 476 #if 0 /* XXX: tracing does not support text entries */
 477         marker_file = debugfs_create_file("marker", 0660, dir, NULL,
 478                                                                 &fops_marker);
 479         if (!marker_file)
 480                 pr_err(NAME "marker file creation failed.\n");
 481 #endif
 482
 483         if (nommiotrace)
 484                 pr_info(NAME "MMIO tracing disabled.\n");
 485         enter_uniprocessor();
 486         spin_lock_irq(&trace_lock);
 487         atomic_inc(&mmiotrace_enabled);
 488         spin_unlock_irq(&trace_lock);
 489         pr_info(NAME "enabled.\n");
 490 out:
 491         mutex_unlock(&mmiotrace_mutex);
 492 }
 493
 494 void disable_mmiotrace(void)
 495 {
 496         mutex_lock(&mmiotrace_mutex);
 497         if (!is_enabled())
 498                 goto out;
 499
 500         spin_lock_irq(&trace_lock);
 501         atomic_dec(&mmiotrace_enabled);
 502         BUG_ON(is_enabled());
 503         spin_unlock_irq(&trace_lock);
 504
 505         clear_trace_list(); /* guarantees: no more kmmio callbacks */
 506         leave_uniprocessor();
 507         if (marker_file) {
 508                 debugfs_remove(marker_file);
 509                 marker_file = NULL;
 510         }
 511
 512         pr_info(NAME "disabled.\n");
 513 out:
 514         mutex_unlock(&mmiotrace_mutex);
 515 }