release/src-rt-6.x.4708/linux/linux-2.6.36/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
  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 <asm/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         switch (type) {
 177         case REG_READ:
 178                 my_trace->opcode = MMIO_READ;
 179                 my_trace->width = get_ins_mem_width(instptr);
 180                 break;
 181         case REG_WRITE:
 182                 my_trace->opcode = MMIO_WRITE;
 183                 my_trace->width = get_ins_mem_width(instptr);
 184                 my_trace->value = get_ins_reg_val(instptr, regs);
 185                 break;
 186         case IMM_WRITE:
 187                 my_trace->opcode = MMIO_WRITE;
 188                 my_trace->width = get_ins_mem_width(instptr);
 189                 my_trace->value = get_ins_imm_val(instptr);
 190                 break;
 191         default:
 192                 {
 193                         unsigned char *ip = (unsigned char *)instptr;
 194                         my_trace->opcode = MMIO_UNKNOWN_OP;
 195                         my_trace->width = 0;
 196                         my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
 197                                                                 *(ip + 2);
 198                 }
 199         }
 200         put_cpu_var(cpu_trace);
 201         put_cpu_var(pf_reason);
 202 }
 203
 204 static void post(struct kmmio_probe *p, unsigned long condition,
 205                                                         struct pt_regs *regs)
 206 {
 207         struct trap_reason *my_reason = &get_cpu_var(pf_reason);
 208         struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
 209
 210         /* this should always return the active_trace count to 0 */
 211         my_reason->active_traces--;
 212         if (my_reason->active_traces) {
 213                 pr_emerg("unexpected post handler");
 214                 BUG();
 215         }
 216
 217         switch (my_reason->type) {
 218         case REG_READ:
 219                 my_trace->value = get_ins_reg_val(my_reason->ip, regs);
 220                 break;
 221         default:
 222                 break;
 223         }
 224
 225         mmio_trace_rw(my_trace);
 226         put_cpu_var(cpu_trace);
 227         put_cpu_var(pf_reason);
 228 }
 229
 230 static void ioremap_trace_core(resource_size_t offset, unsigned long size,
 231                                                         void __iomem *addr)
 232 {
 233         static atomic_t next_id;
 234         struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
 235         /* These are page-unaligned. */
 236         struct mmiotrace_map map = {
 237                 .phys = offset,
 238                 .virt = (unsigned long)addr,
 239                 .len = size,
 240                 .opcode = MMIO_PROBE
 241         };
 242
 243         if (!trace) {
 244                 pr_err("kmalloc failed in ioremap\n");
 245                 return;
 246         }
 247
 248         *trace = (struct remap_trace) {
 249                 .probe = {
 250                         .addr = (unsigned long)addr,
 251                         .len = size,
 252                         .pre_handler = pre,
 253                         .post_handler = post,
 254                         .private = trace
 255                 },
 256                 .phys = offset,
 257                 .id = atomic_inc_return(&next_id)
 258         };
 259         map.map_id = trace->id;
 260
 261         spin_lock_irq(&trace_lock);
 262         if (!is_enabled()) {
 263                 kfree(trace);
 264                 goto not_enabled;
 265         }
 266
 267         mmio_trace_mapping(&map);
 268         list_add_tail(&trace->list, &trace_list);
 269         if (!nommiotrace)
 270                 register_kmmio_probe(&trace->probe);
 271
 272 not_enabled:
 273         spin_unlock_irq(&trace_lock);
 274 }
 275
 276 void mmiotrace_ioremap(resource_size_t offset, unsigned long size,
 277                                                 void __iomem *addr)
 278 {
 279         if (!is_enabled()) /* recheck and proper locking in *_core() */
 280                 return;
 281
 282         pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n",
 283                  (unsigned long long)offset, size, addr);
 284         if ((filter_offset) && (offset != filter_offset))
 285                 return;
 286         ioremap_trace_core(offset, size, addr);
 287 }
 288
 289 static void iounmap_trace_core(volatile void __iomem *addr)
 290 {
 291         struct mmiotrace_map map = {
 292                 .phys = 0,
 293                 .virt = (unsigned long)addr,
 294                 .len = 0,
 295                 .opcode = MMIO_UNPROBE
 296         };
 297         struct remap_trace *trace;
 298         struct remap_trace *tmp;
 299         struct remap_trace *found_trace = NULL;
 300
 301         pr_debug("Unmapping %p.\n", addr);
 302
 303         spin_lock_irq(&trace_lock);
 304         if (!is_enabled())
 305                 goto not_enabled;
 306
 307         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 308                 if ((unsigned long)addr == trace->probe.addr) {
 309                         if (!nommiotrace)
 310                                 unregister_kmmio_probe(&trace->probe);
 311                         list_del(&trace->list);
 312                         found_trace = trace;
 313                         break;
 314                 }
 315         }
 316         map.map_id = (found_trace) ? found_trace->id : -1;
 317         mmio_trace_mapping(&map);
 318
 319 not_enabled:
 320         spin_unlock_irq(&trace_lock);
 321         if (found_trace) {
 322                 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 323                 kfree(found_trace);
 324         }
 325 }
 326
 327 void mmiotrace_iounmap(volatile void __iomem *addr)
 328 {
 329         might_sleep();
 330         if (is_enabled()) /* recheck and proper locking in *_core() */
 331                 iounmap_trace_core(addr);
 332 }
 333
 334 int mmiotrace_printk(const char *fmt, ...)
 335 {
 336         int ret = 0;
 337         va_list args;
 338         unsigned long flags;
 339         va_start(args, fmt);
 340
 341         spin_lock_irqsave(&trace_lock, flags);
 342         if (is_enabled())
 343                 ret = mmio_trace_printk(fmt, args);
 344         spin_unlock_irqrestore(&trace_lock, flags);
 345
 346         va_end(args);
 347         return ret;
 348 }
 349 EXPORT_SYMBOL(mmiotrace_printk);
 350
 351 static void clear_trace_list(void)
 352 {
 353         struct remap_trace *trace;
 354         struct remap_trace *tmp;
 355
 356         /*
 357          * No locking required, because the caller ensures we are in a
 358          * critical section via mutex, and is_enabled() is false,
 359          * i.e. nothing can traverse or modify this list.
 360          * Caller also ensures is_enabled() cannot change.
 361          */
 362         list_for_each_entry(trace, &trace_list, list) {
 363                 pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n",
 364                           trace->probe.addr, trace->probe.len);
 365                 if (!nommiotrace)
 366                         unregister_kmmio_probe(&trace->probe);
 367         }
 368         synchronize_rcu(); /* unregister_kmmio_probe() requirement */
 369
 370         list_for_each_entry_safe(trace, tmp, &trace_list, list) {
 371                 list_del(&trace->list);
 372                 kfree(trace);
 373         }
 374 }
 375
 376 #ifdef CONFIG_HOTPLUG_CPU
 377 static cpumask_var_t downed_cpus;
 378
 379 static void enter_uniprocessor(void)
 380 {
 381         int cpu;
 382         int err;
 383
 384         if (downed_cpus == NULL &&
 385             !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
 386                 pr_notice("Failed to allocate mask\n");
 387                 goto out;
 388         }
 389
 390         get_online_cpus();
 391         cpumask_copy(downed_cpus, cpu_online_mask);
 392         cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus);
 393         if (num_online_cpus() > 1)
 394                 pr_notice("Disabling non-boot CPUs...\n");
 395         put_online_cpus();
 396
 397         for_each_cpu(cpu, downed_cpus) {
 398                 err = cpu_down(cpu);
 399                 if (!err)
 400                         pr_info("CPU%d is down.\n", cpu);
 401                 else
 402                         pr_err("Error taking CPU%d down: %d\n", cpu, err);
 403         }
 404 out:
 405         if (num_online_cpus() > 1)
 406                 pr_warning("multiple CPUs still online, may miss events.\n");
 407 }
 408
 409 /* __ref because leave_uniprocessor calls cpu_up which is __cpuinit,
 410    but this whole function is ifdefed CONFIG_HOTPLUG_CPU */
 411 static void __ref leave_uniprocessor(void)
 412 {
 413         int cpu;
 414         int err;
 415
 416         if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
 417                 return;
 418         pr_notice("Re-enabling CPUs...\n");
 419         for_each_cpu(cpu, downed_cpus) {
 420                 err = cpu_up(cpu);
 421                 if (!err)
 422                         pr_info("enabled CPU%d.\n", cpu);
 423                 else
 424                         pr_err("cannot re-enable CPU%d: %d\n", cpu, err);
 425         }
 426 }
 427
 428 #else /* !CONFIG_HOTPLUG_CPU */
 429 static void enter_uniprocessor(void)
 430 {
 431         if (num_online_cpus() > 1)
 432                 pr_warning("multiple CPUs are online, may miss events. "
 433                            "Suggest booting with maxcpus=1 kernel argument.\n");
 434 }
 435
 436 static void leave_uniprocessor(void)
 437 {
 438 }
 439 #endif
 440
 441 void enable_mmiotrace(void)
 442 {
 443         mutex_lock(&mmiotrace_mutex);
 444         if (is_enabled())
 445                 goto out;
 446
 447         if (nommiotrace)
 448                 pr_info("MMIO tracing disabled.\n");
 449         kmmio_init();
 450         enter_uniprocessor();
 451         spin_lock_irq(&trace_lock);
 452         atomic_inc(&mmiotrace_enabled);
 453         spin_unlock_irq(&trace_lock);
 454         pr_info("enabled.\n");
 455 out:
 456         mutex_unlock(&mmiotrace_mutex);
 457 }
 458
 459 void disable_mmiotrace(void)
 460 {
 461         mutex_lock(&mmiotrace_mutex);
 462         if (!is_enabled())
 463                 goto out;
 464
 465         spin_lock_irq(&trace_lock);
 466         atomic_dec(&mmiotrace_enabled);
 467         BUG_ON(is_enabled());
 468         spin_unlock_irq(&trace_lock);
 469
 470         clear_trace_list(); /* guarantees: no more kmmio callbacks */
 471         leave_uniprocessor();
 472         kmmio_cleanup();
 473         pr_info("disabled.\n");
 474 out:
 475         mutex_unlock(&mmiotrace_mutex);
 476 }