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 <linux/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 #include <linux/cpu.h>
36
37 #include "pf_in.h"
38
39 #define NAME "mmiotrace: "
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 int nommiotrace;
78 static int 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(NAME "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(NAME "4MB pages are not currently supported: "
106 "0x%08lx\n", address);
107 BUG();
108 }
109 pr_info(NAME "pte for 0x%lx: 0x%llx 0x%llx\n", address,
110 (unsigned long long)pte_val(*pte),
111 (unsigned long long)pte_val(*pte) & _PAGE_PRESENT);
112 }
113
114 /*
115 * For some reason the pre/post pairs have been called in an
116 * unmatched order. Report and die.
117 */
118 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
119 {
120 const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
121 pr_emerg(NAME "unexpected fault for address: 0x%08lx, "
122 "last fault for address: 0x%08lx\n",
123 addr, my_reason->addr);
124 print_pte(addr);
125 print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
126 print_symbol(KERN_EMERG "last faulting IP was at %s\n", 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(NAME "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(NAME "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(NAME "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(NAME "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(NAME "purging non-iounmapped "
367 "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(NAME "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(NAME "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(NAME "CPU%d is down.\n", cpu);
405 else
406 pr_err(NAME "Error taking CPU%d down: %d\n", cpu, err);
407 }
408 out:
409 if (num_online_cpus() > 1)
410 pr_warning(NAME "multiple CPUs still online, "
411 "may miss events.\n");
412 }
413
414 /* __ref because leave_uniprocessor calls cpu_up which is __cpuinit,
415 but this whole function is ifdefed CONFIG_HOTPLUG_CPU */
416 static void __ref leave_uniprocessor(void)
417 {
418 int cpu;
419 int err;
420
421 if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
422 return;
423 pr_notice(NAME "Re-enabling CPUs...\n");
424 for_each_cpu(cpu, downed_cpus) {
425 err = cpu_up(cpu);
426 if (!err)
427 pr_info(NAME "enabled CPU%d.\n", cpu);
428 else
429 pr_err(NAME "cannot re-enable CPU%d: %d\n", cpu, err);
430 }
431 }
432
433 #else /* !CONFIG_HOTPLUG_CPU */
434 static void enter_uniprocessor(void)
435 {
436 if (num_online_cpus() > 1)
437 pr_warning(NAME "multiple CPUs are online, may miss events. "
438 "Suggest booting with maxcpus=1 kernel argument.\n");
439 }
440
441 static void leave_uniprocessor(void)
442 {
443 }
444 #endif
445
446 void enable_mmiotrace(void)
447 {
448 mutex_lock(&mmiotrace_mutex);
449 if (is_enabled())
450 goto out;
451
452 if (nommiotrace)
453 pr_info(NAME "MMIO tracing disabled.\n");
454 kmmio_init();
455 enter_uniprocessor();
456 spin_lock_irq(&trace_lock);
457 atomic_inc(&mmiotrace_enabled);
458 spin_unlock_irq(&trace_lock);
459 pr_info(NAME "enabled.\n");
460 out:
461 mutex_unlock(&mmiotrace_mutex);
462 }
463
464 void disable_mmiotrace(void)
465 {
466 mutex_lock(&mmiotrace_mutex);
467 if (!is_enabled())
468 goto out;
469
470 spin_lock_irq(&trace_lock);
471 atomic_dec(&mmiotrace_enabled);
472 BUG_ON(is_enabled());
473 spin_unlock_irq(&trace_lock);
474
475 clear_trace_list(); /* guarantees: no more kmmio callbacks */
476 leave_uniprocessor();
477 kmmio_cleanup();
478 pr_info(NAME "disabled.\n");
479 out:
480 mutex_unlock(&mmiotrace_mutex);
481 }
482
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