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TOMOYO Linux Cross Reference
Linux/arch/x86/mm/mmio-mod.c

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

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