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

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