SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 <asm/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
  36 #include "pf_in.h"
  37
  38 #define NAME "mmiotrace: "
  39
  40 struct trap_reason {
  41         unsigned long addr;
  42         unsigned long ip;
  43         enum reason_type type;
  44         int active_traces;
  45 };
  46
  47 struct remap_trace {
  48         struct list_head list;
  49         struct kmmio_probe probe;
  50         unsigned long phys;
  51         unsigned long id;
  52 };
  53
  54 /* Accessed per-cpu. */
  55 static DEFINE_PER_CPU(struct trap_reason, pf_reason);
  56 static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);
  57
  58 #if 0 /* XXX: no way gather this info anymore */
  59 /* Access to this is not per-cpu. */
  60 static DEFINE_PER_CPU(atomic_t, dropped);
  61 #endif
  62
  63 static struct dentry *marker_file;
  64
  65 static DEFINE_MUTEX(mmiotrace_mutex);
  66 static DEFINE_SPINLOCK(trace_lock);
  67 static atomic_t mmiotrace_enabled;
  68 static LIST_HEAD(trace_list);           /* struct remap_trace */
  69
  70 /*
  71  * Locking in this file:
  72  * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections.
  73  * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex
  74  *   and trace_lock.
  75  * - Routines depending on is_enabled() must take trace_lock.
  76  * - trace_list users must hold trace_lock.
  77  * - is_enabled() guarantees that mmio_trace_record is allowed.
  78  * - pre/post callbacks assume the effect of is_enabled() being true.
  79  */
  80
  81 /* module parameters */
  82 static unsigned long    filter_offset;
  83 static int              nommiotrace;
  84 static int              trace_pc;
  85
  86 module_param(filter_offset, ulong, 0);
  87 module_param(nommiotrace, bool, 0);
  88 module_param(trace_pc, bool, 0);
  89
  90 MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
  91 MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
  92 MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
  93
  94 static bool is_enabled(void)
  95 {
  96         return atomic_read(&mmiotrace_enabled);
  97 }
  98
  99 #if 0 /* XXX: needs rewrite */
 100 /*
 101  * Write callback for the debugfs entry:
 102  * Read a marker and write it to the mmio trace log
 103  */
 104 static ssize_t write_marker(struct file *file, const char __user *buffer,
 105                                                 size_t count, loff_t *ppos)
 106 {
 107         char *event = NULL;
 108         struct mm_io_header *headp;
 109         ssize_t len = (count > 65535) ? 65535 : count;
 110
 111         event = kzalloc(sizeof(*headp) + len, GFP_KERNEL);
 112         if (!event)
 113                 return -ENOMEM;
 114
 115         headp = (struct mm_io_header *)event;
 116         headp->type = MMIO_MAGIC | (MMIO_MARKER << MMIO_OPCODE_SHIFT);
 117         headp->data_len = len;
 118
 119         if (copy_from_user(event + sizeof(*headp), buffer, len)) {
 120                 kfree(event);
 121                 return -EFAULT;
 122         }
 123
 124         spin_lock_irq(&trace_lock);
 125 #if 0 /* XXX: convert this to use tracing */
 126         if (is_enabled())
 127                 relay_write(chan, event, sizeof(*headp) + len);
 128         else
 129 #endif
 130                 len = -EINVAL;
 131         spin_unlock_irq(&trace_lock);
 132         kfree(event);
 133         return len;
 134 }
 135 #endif
 136
 137 static void print_pte(unsigned long address)
 138 {
 139         int level;
 140         pte_t *pte = lookup_address(address, &level);
 141
 142         if (!pte) {
 143                 pr_err(NAME "Error in %s: no pte for page 0x%08lx\n",
 144                                                         __func__, address);
 145                 return;
 146         }
 147
 148         if (level == PG_LEVEL_2M) {
 149                 pr_emerg(NAME "4MB pages are not currently supported: "
 150                                                         "0x%08lx\n", address);
 151                 BUG();
 152         }
 153         pr_info(NAME "pte for 0x%lx: 0x%llx 0x%llx\n", address,
 154                 (unsigned long long)pte_val(*pte),
 155                 (unsigned long long)pte_val(*pte) & _PAGE_PRESENT);
 156 }
 157
 158 /*
 159  * For some reason the pre/post pairs have been called in an
 160  * unmatched order. Report and die.
 161  */
 162 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
 163 {
 164         const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 165         pr_emerg(NAME "unexpected fault for address: 0x%08lx, "
 166                                         "last fault for address: 0x%08lx\n",
 167                                         addr, my_reason->addr);
 168         print_pte(addr);
 169         print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
 170         print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip);
 171 #ifdef __i386__
 172         pr_emerg("eax: %08lx   ebx: %08lx   ecx: %08lx   edx: %08lx\n",
 173                         regs->ax, regs->bx, regs->cx, regs->dx);
 174         pr_emerg("esi: %08lx   edi: %08lx   ebp: %08lx   esp: %08lx\n",
 175                         regs->si, regs->di, regs->bp, regs->sp);
 176 #else
 177         pr_emerg("rax: %016lx   rcx: %016lx   rdx: %016lx\n",
 178                                         regs->ax, regs->cx, regs->dx);
 179         pr_emerg("rsi: %016lx   rdi: %016lx   rbp: %016lx   rsp: %016lx\n",
 180                                 regs->si, regs->di, regs->bp, regs->sp);
 181 #endif
 182         put_cpu_var(pf_reason);
 183         BUG();
 184 }
 185
 186 static void pre(struct kmmio_probe *p, struct pt_regs *regs,
 187                                                 unsigned long addr)
 188 {
 189         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 190         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 191         const unsigned long instptr = instruction_pointer(regs);
 192         const enum reason_type type = get_ins_type(instptr);
 193         struct remap_trace *trace = p->user_data;
 194
 195         /* it doesn't make sense to have more than one active trace per cpu */
 196         if (my_reason->active_traces)
 197                 die_kmmio_nesting_error(regs, addr);
 198         else
 199                 my_reason->active_traces++;
 200
 201         my_reason->type = type;
 202         my_reason->addr = addr;
 203         my_reason->ip = instptr;
 204
 205         my_trace->phys = addr - trace->probe.addr + trace->phys;
 206         my_trace->map_id = trace->id;
 207
 208         /*
 209          * Only record the program counter when requested.
 210          * It may taint clean-room reverse engineering.
 211          */
 212         if (trace_pc)
 213                 my_trace->pc = instptr;
 214         else
 215                 my_trace->pc = 0;
 216
 217         /*
 218          * XXX: the timestamp recorded will be *after* the tracing has been
 219          * done, not at the time we hit the instruction. SMP implications
 220          * on event ordering?
 221          */
 222
 223         switch (type) {
 224         case REG_READ:
 225                 my_trace->opcode = MMIO_READ;
 226                 my_trace->width = get_ins_mem_width(instptr);
 227                 break;
 228         case REG_WRITE:
 229                 my_trace->opcode = MMIO_WRITE;
 230                 my_trace->width = get_ins_mem_width(instptr);
 231                 my_trace->value = get_ins_reg_val(instptr, regs);
 232                 break;
 233         case IMM_WRITE:
 234                 my_trace->opcode = MMIO_WRITE;
 235                 my_trace->width = get_ins_mem_width(instptr);
 236                 my_trace->value = get_ins_imm_val(instptr);
 237                 break;
 238         default:
 239                 {
 240                         unsigned char *ip = (unsigned char *)instptr;
 241                         my_trace->opcode = MMIO_UNKNOWN_OP;
 242                         my_trace->width = 0;
 243                         my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
 244                                                                 *(ip + 2);
 245                 }
 246         }
 247         put_cpu_var(cpu_trace);
 248         put_cpu_var(pf_reason);
 249 }
 250
 251 static void post(struct kmmio_probe *p, unsigned long condition,
 252                                                         struct pt_regs *regs)
 253 {
 254         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 255         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 256
 257         /* this should always return the active_trace count to 0 */
 258         my_reason->active_traces--;
 259         if (my_reason->active_traces) {
 260                 pr_emerg(NAME "unexpected post handler");
 261                 BUG();
 262         }
 263
 264         switch (my_reason->type) {
 265         case REG_READ:
 266                 my_trace->value = get_ins_reg_val(my_reason->ip, regs);
 267                 break;
 268         default:
 269                 break;
 270         }
 271
 272         mmio_trace_rw(my_trace);
 273         put_cpu_var(cpu_trace);
 274         put_cpu_var(pf_reason);
 275 }
 276
 277 static void ioremap_trace_core(unsigned long offset, unsigned long size,
 278                                                         void __iomem *addr)
 279 {
 280         static atomic_t next_id;
 281         struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
 282         struct mmiotrace_map map = {
 283                 .phys = offset,
 284                 .virt = (unsigned long)addr,
 285                 .len = size,
 286                 .opcode = MMIO_PROBE
 287         };
 288
 289         if (!trace) {
 290                 pr_err(NAME "kmalloc failed in ioremap\n");
 291                 return;
 292         }
 293
 294         *trace = (struct remap_trace) {
 295                 .probe = {
 296                         .addr = (unsigned long)addr,
 297                         .len = size,
 298                         .pre_handler = pre,
 299                         .post_handler = post,
 300                         .user_data = trace
 301                 },
 302                 .phys = offset,
 303                 .id = atomic_inc_return(&next_id)
 304         };
 305         map.map_id = trace->id;
 306
 307         spin_lock_irq(&trace_lock);
 308         if (!is_enabled())
 309                 goto not_enabled;
 310
 311         mmio_trace_mapping(&map);
 312         list_add_tail(&trace->list, &trace_list);
 313         if (!nommiotrace)
 314                 register_kmmio_probe(&trace->probe);
 315
 316 not_enabled:
 317         spin_unlock_irq(&trace_lock);
 318 }
 319
 320 void
 321 mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr)
 322 {
 323         if (!is_enabled()) /* recheck and proper locking in *_core() */
 324                 return;
 325
 326         pr_debug(NAME "ioremap_*(0x%lx, 0x%lx) = %p\n", offset, size, addr);
 327         if ((filter_offset) && (offset != filter_offset))
 328                 return;
 329         ioremap_trace_core(offset, size, addr);
 330 }
 331
 332 static void iounmap_trace_core(volatile void __iomem *addr)
 333 {
 334         struct mmiotrace_map map = {
 335                 .phys = 0,
 336                 .virt = (unsigned long)addr,
 337                 .len = 0,
 338                 .opcode = MMIO_UNPROBE
 339         };
 340         struct remap_trace *trace;
 341         struct remap_trace *tmp;
 342         struct remap_trace *found_trace = NULL;
 343
 344         pr_debug(NAME "Unmapping %p.\n", addr);
 345
 346         spin_lock_irq(&trace_lock);
 347         if (!is_enabled())
 348                 goto not_enabled;
 349
 350         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 351                 if ((unsigned long)addr == trace->probe.addr) {
 352                         if (!nommiotrace)
 353                                 unregister_kmmio_probe(&trace->probe);
 354                         list_del(&trace->list);
 355                         found_trace = trace;
 356                         break;
 357                 }
 358         }
 359         map.map_id = (found_trace) ? found_trace->id : -1;
 360         mmio_trace_mapping(&map);
 361
 362 not_enabled:
 363         spin_unlock_irq(&trace_lock);
 364         if (found_trace) {
 365                 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 366                 kfree(found_trace);
 367         }
 368 }
 369
 370 void mmiotrace_iounmap(volatile void __iomem *addr)
 371 {
 372         might_sleep();
 373         if (is_enabled()) /* recheck and proper locking in *_core() */
 374                 iounmap_trace_core(addr);
 375 }
 376
 377 static void clear_trace_list(void)
 378 {
 379         struct remap_trace *trace;
 380         struct remap_trace *tmp;
 381
 382         /*
 383          * No locking required, because the caller ensures we are in a
 384          * critical section via mutex, and is_enabled() is false,
 385          * i.e. nothing can traverse or modify this list.
 386          * Caller also ensures is_enabled() cannot change.
 387          */
 388         list_for_each_entry(trace, &trace_list, list) {
 389                 pr_notice(NAME "purging non-iounmapped "
 390                                         "trace @0x%08lx, size 0x%lx.\n",
 391                                         trace->probe.addr, trace->probe.len);
 392                 if (!nommiotrace)
 393                         unregister_kmmio_probe(&trace->probe);
 394         }
 395         synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 396
 397         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 398                 list_del(&trace->list);
 399                 kfree(trace);
 400         }
 401 }
 402
 403 #if 0 /* XXX: out of order */
 404 static struct file_operations fops_marker = {
 405         .owner =        THIS_MODULE,
 406         .write =        write_marker
 407 };
 408 #endif
 409
 410 void enable_mmiotrace(void)
 411 {
 412         mutex_lock(&mmiotrace_mutex);
 413         if (is_enabled())
 414                 goto out;
 415
 416 #if 0 /* XXX: tracing does not support text entries */
 417         marker_file = debugfs_create_file("marker", 0660, dir, NULL,
 418                                                                 &fops_marker);
 419         if (!marker_file)
 420                 pr_err(NAME "marker file creation failed.\n");
 421 #endif
 422
 423         if (nommiotrace)
 424                 pr_info(NAME "MMIO tracing disabled.\n");
 425         spin_lock_irq(&trace_lock);
 426         atomic_inc(&mmiotrace_enabled);
 427         spin_unlock_irq(&trace_lock);
 428         pr_info(NAME "enabled.\n");
 429 out:
 430         mutex_unlock(&mmiotrace_mutex);
 431 }
 432
 433 void disable_mmiotrace(void)
 434 {
 435         mutex_lock(&mmiotrace_mutex);
 436         if (!is_enabled())
 437                 goto out;
 438
 439         spin_lock_irq(&trace_lock);
 440         atomic_dec(&mmiotrace_enabled);
 441         BUG_ON(is_enabled());
 442         spin_unlock_irq(&trace_lock);
 443
 444         clear_trace_list(); /* guarantees: no more kmmio callbacks */
 445         if (marker_file) {
 446                 debugfs_remove(marker_file);
 447                 marker_file = NULL;
 448         }
 449
 450         pr_info(NAME "disabled.\n");
 451 out:
 452         mutex_unlock(&mmiotrace_mutex);
 453 }