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              ISA_trace;
  85 static int              trace_pc;
  86
  87 module_param(filter_offset, ulong, 0);
  88 module_param(nommiotrace, bool, 0);
  89 module_param(ISA_trace, bool, 0);
  90 module_param(trace_pc, bool, 0);
  91
  92 MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
  93 MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
  94 MODULE_PARM_DESC(ISA_trace, "Do not exclude the low ISA range.");
  95 MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
  96
  97 static bool is_enabled(void)
  98 {
  99         return atomic_read(&mmiotrace_enabled);
 100 }
 101
 102 #if 0 /* XXX: needs rewrite */
 103 /*
 104  * Write callback for the debugfs entry:
 105  * Read a marker and write it to the mmio trace log
 106  */
 107 static ssize_t write_marker(struct file *file, const char __user *buffer,
 108                                                 size_t count, loff_t *ppos)
 109 {
 110         char *event = NULL;
 111         struct mm_io_header *headp;
 112         ssize_t len = (count > 65535) ? 65535 : count;
 113
 114         event = kzalloc(sizeof(*headp) + len, GFP_KERNEL);
 115         if (!event)
 116                 return -ENOMEM;
 117
 118         headp = (struct mm_io_header *)event;
 119         headp->type = MMIO_MAGIC | (MMIO_MARKER << MMIO_OPCODE_SHIFT);
 120         headp->data_len = len;
 121
 122         if (copy_from_user(event + sizeof(*headp), buffer, len)) {
 123                 kfree(event);
 124                 return -EFAULT;
 125         }
 126
 127         spin_lock_irq(&trace_lock);
 128 #if 0 /* XXX: convert this to use tracing */
 129         if (is_enabled())
 130                 relay_write(chan, event, sizeof(*headp) + len);
 131         else
 132 #endif
 133                 len = -EINVAL;
 134         spin_unlock_irq(&trace_lock);
 135         kfree(event);
 136         return len;
 137 }
 138 #endif
 139
 140 static void print_pte(unsigned long address)
 141 {
 142         int level;
 143         pte_t *pte = lookup_address(address, &level);
 144
 145         if (!pte) {
 146                 pr_err(NAME "Error in %s: no pte for page 0x%08lx\n",
 147                                                         __func__, address);
 148                 return;
 149         }
 150
 151         if (level == PG_LEVEL_2M) {
 152                 pr_emerg(NAME "4MB pages are not currently supported: "
 153                                                         "0x%08lx\n", address);
 154                 BUG();
 155         }
 156         pr_info(NAME "pte for 0x%lx: 0x%lx 0x%lx\n", address, pte_val(*pte),
 157                                                 pte_val(*pte) & _PAGE_PRESENT);
 158 }
 159
 160 /*
 161  * For some reason the pre/post pairs have been called in an
 162  * unmatched order. Report and die.
 163  */
 164 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
 165 {
 166         const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 167         pr_emerg(NAME "unexpected fault for address: 0x%08lx, "
 168                                         "last fault for address: 0x%08lx\n",
 169                                         addr, my_reason->addr);
 170         print_pte(addr);
 171         print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
 172         print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip);
 173 #ifdef __i386__
 174         pr_emerg("eax: %08lx   ebx: %08lx   ecx: %08lx   edx: %08lx\n",
 175                         regs->ax, regs->bx, regs->cx, regs->dx);
 176         pr_emerg("esi: %08lx   edi: %08lx   ebp: %08lx   esp: %08lx\n",
 177                         regs->si, regs->di, regs->bp, regs->sp);
 178 #else
 179         pr_emerg("rax: %016lx   rcx: %016lx   rdx: %016lx\n",
 180                                         regs->ax, regs->cx, regs->dx);
 181         pr_emerg("rsi: %016lx   rdi: %016lx   rbp: %016lx   rsp: %016lx\n",
 182                                 regs->si, regs->di, regs->bp, regs->sp);
 183 #endif
 184         put_cpu_var(pf_reason);
 185         BUG();
 186 }
 187
 188 static void pre(struct kmmio_probe *p, struct pt_regs *regs,
 189                                                 unsigned long addr)
 190 {
 191         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 192         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 193         const unsigned long instptr = instruction_pointer(regs);
 194         const enum reason_type type = get_ins_type(instptr);
 195         struct remap_trace *trace = p->user_data;
 196
 197         /* it doesn't make sense to have more than one active trace per cpu */
 198         if (my_reason->active_traces)
 199                 die_kmmio_nesting_error(regs, addr);
 200         else
 201                 my_reason->active_traces++;
 202
 203         my_reason->type = type;
 204         my_reason->addr = addr;
 205         my_reason->ip = instptr;
 206
 207         my_trace->phys = addr - trace->probe.addr + trace->phys;
 208         my_trace->map_id = trace->id;
 209
 210         /*
 211          * Only record the program counter when requested.
 212          * It may taint clean-room reverse engineering.
 213          */
 214         if (trace_pc)
 215                 my_trace->pc = instptr;
 216         else
 217                 my_trace->pc = 0;
 218
 219         /*
 220          * XXX: the timestamp recorded will be *after* the tracing has been
 221          * done, not at the time we hit the instruction. SMP implications
 222          * on event ordering?
 223          */
 224
 225         switch (type) {
 226         case REG_READ:
 227                 my_trace->opcode = MMIO_READ;
 228                 my_trace->width = get_ins_mem_width(instptr);
 229                 break;
 230         case REG_WRITE:
 231                 my_trace->opcode = MMIO_WRITE;
 232                 my_trace->width = get_ins_mem_width(instptr);
 233                 my_trace->value = get_ins_reg_val(instptr, regs);
 234                 break;
 235         case IMM_WRITE:
 236                 my_trace->opcode = MMIO_WRITE;
 237                 my_trace->width = get_ins_mem_width(instptr);
 238                 my_trace->value = get_ins_imm_val(instptr);
 239                 break;
 240         default:
 241                 {
 242                         unsigned char *ip = (unsigned char *)instptr;
 243                         my_trace->opcode = MMIO_UNKNOWN_OP;
 244                         my_trace->width = 0;
 245                         my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
 246                                                                 *(ip + 2);
 247                 }
 248         }
 249         put_cpu_var(cpu_trace);
 250         put_cpu_var(pf_reason);
 251 }
 252
 253 static void post(struct kmmio_probe *p, unsigned long condition,
 254                                                         struct pt_regs *regs)
 255 {
 256         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 257         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 258
 259         /* this should always return the active_trace count to 0 */
 260         my_reason->active_traces--;
 261         if (my_reason->active_traces) {
 262                 pr_emerg(NAME "unexpected post handler");
 263                 BUG();
 264         }
 265
 266         switch (my_reason->type) {
 267         case REG_READ:
 268                 my_trace->value = get_ins_reg_val(my_reason->ip, regs);
 269                 break;
 270         default:
 271                 break;
 272         }
 273
 274         mmio_trace_rw(my_trace);
 275         put_cpu_var(cpu_trace);
 276         put_cpu_var(pf_reason);
 277 }
 278
 279 static void ioremap_trace_core(unsigned long offset, unsigned long size,
 280                                                         void __iomem *addr)
 281 {
 282         static atomic_t next_id;
 283         struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
 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                         .user_data = 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
 323 mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr)
 324 {
 325         if (!is_enabled()) /* recheck and proper locking in *_core() */
 326                 return;
 327
 328         pr_debug(NAME "ioremap_*(0x%lx, 0x%lx) = %p\n", offset, size, addr);
 329         if ((filter_offset) && (offset != filter_offset))
 330                 return;
 331         ioremap_trace_core(offset, size, addr);
 332 }
 333
 334 static void iounmap_trace_core(volatile void __iomem *addr)
 335 {
 336         struct mmiotrace_map map = {
 337                 .phys = 0,
 338                 .virt = (unsigned long)addr,
 339                 .len = 0,
 340                 .opcode = MMIO_UNPROBE
 341         };
 342         struct remap_trace *trace;
 343         struct remap_trace *tmp;
 344         struct remap_trace *found_trace = NULL;
 345
 346         pr_debug(NAME "Unmapping %p.\n", addr);
 347
 348         spin_lock_irq(&trace_lock);
 349         if (!is_enabled())
 350                 goto not_enabled;
 351
 352         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 353                 if ((unsigned long)addr == trace->probe.addr) {
 354                         if (!nommiotrace)
 355                                 unregister_kmmio_probe(&trace->probe);
 356                         list_del(&trace->list);
 357                         found_trace = trace;
 358                         break;
 359                 }
 360         }
 361         map.map_id = (found_trace) ? found_trace->id : -1;
 362         mmio_trace_mapping(&map);
 363
 364 not_enabled:
 365         spin_unlock_irq(&trace_lock);
 366         if (found_trace) {
 367                 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 368                 kfree(found_trace);
 369         }
 370 }
 371
 372 void mmiotrace_iounmap(volatile void __iomem *addr)
 373 {
 374         might_sleep();
 375         if (is_enabled()) /* recheck and proper locking in *_core() */
 376                 iounmap_trace_core(addr);
 377 }
 378
 379 static void clear_trace_list(void)
 380 {
 381         struct remap_trace *trace;
 382         struct remap_trace *tmp;
 383
 384         /*
 385          * No locking required, because the caller ensures we are in a
 386          * critical section via mutex, and is_enabled() is false,
 387          * i.e. nothing can traverse or modify this list.
 388          * Caller also ensures is_enabled() cannot change.
 389          */
 390         list_for_each_entry(trace, &trace_list, list) {
 391                 pr_notice(NAME "purging non-iounmapped "
 392                                         "trace @0x%08lx, size 0x%lx.\n",
 393                                         trace->probe.addr, trace->probe.len);
 394                 if (!nommiotrace)
 395                         unregister_kmmio_probe(&trace->probe);
 396         }
 397         synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 398
 399         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 400                 list_del(&trace->list);
 401                 kfree(trace);
 402         }
 403 }
 404
 405 #if 0 /* XXX: out of order */
 406 static struct file_operations fops_marker = {
 407         .owner =        THIS_MODULE,
 408         .write =        write_marker
 409 };
 410 #endif
 411
 412 void enable_mmiotrace(void)
 413 {
 414         mutex_lock(&mmiotrace_mutex);
 415         if (is_enabled())
 416                 goto out;
 417
 418 #if 0 /* XXX: tracing does not support text entries */
 419         marker_file = debugfs_create_file("marker", 0660, dir, NULL,
 420                                                                 &fops_marker);
 421         if (!marker_file)
 422                 pr_err(NAME "marker file creation failed.\n");
 423 #endif
 424
 425         if (nommiotrace)
 426                 pr_info(NAME "MMIO tracing disabled.\n");
 427         if (ISA_trace)
 428                 pr_warning(NAME "Warning! low ISA range will be traced.\n");
 429         spin_lock_irq(&trace_lock);
 430         atomic_inc(&mmiotrace_enabled);
 431         spin_unlock_irq(&trace_lock);
 432         pr_info(NAME "enabled.\n");
 433 out:
 434         mutex_unlock(&mmiotrace_mutex);
 435 }
 436
 437 void disable_mmiotrace(void)
 438 {
 439         mutex_lock(&mmiotrace_mutex);
 440         if (!is_enabled())
 441                 goto out;
 442
 443         spin_lock_irq(&trace_lock);
 444         atomic_dec(&mmiotrace_enabled);
 445         BUG_ON(is_enabled());
 446         spin_unlock_irq(&trace_lock);
 447
 448         clear_trace_list(); /* guarantees: no more kmmio callbacks */
 449         if (marker_file) {
 450                 debugfs_remove(marker_file);
 451                 marker_file = NULL;
 452         }
 453
 454         pr_info(NAME "disabled.\n");
 455 out:
 456         mutex_unlock(&mmiotrace_mutex);
 457 }