1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * |
4 | * Copyright (C) IBM Corporation, 2005 |
5 | * Jeff Muizelaar, 2006, 2007 |
6 | * Pekka Paalanen, 2008 <pq@iki.fi> |
7 | * |
8 | * Derived from the read-mod example from relay-examples by Tom Zanussi. |
9 | */ |
10 | |
11 | #define pr_fmt(fmt) "mmiotrace: " fmt |
12 | |
13 | #include <linux/moduleparam.h> |
14 | #include <linux/debugfs.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/uaccess.h> |
17 | #include <linux/io.h> |
18 | #include <linux/mmiotrace.h> |
19 | #include <linux/pgtable.h> |
20 | #include <asm/e820/api.h> /* for ISA_START_ADDRESS */ |
21 | #include <linux/atomic.h> |
22 | #include <linux/percpu.h> |
23 | #include <linux/cpu.h> |
24 | |
25 | #include "pf_in.h" |
26 | |
27 | struct trap_reason { |
28 | unsigned long addr; |
29 | unsigned long ip; |
30 | enum reason_type type; |
31 | int active_traces; |
32 | }; |
33 | |
34 | struct remap_trace { |
35 | struct list_head list; |
36 | struct kmmio_probe probe; |
37 | resource_size_t phys; |
38 | unsigned long id; |
39 | }; |
40 | |
41 | /* Accessed per-cpu. */ |
42 | static DEFINE_PER_CPU(struct trap_reason, pf_reason); |
43 | static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace); |
44 | |
45 | static DEFINE_MUTEX(mmiotrace_mutex); |
46 | static DEFINE_SPINLOCK(trace_lock); |
47 | static atomic_t mmiotrace_enabled; |
48 | static LIST_HEAD(trace_list); /* struct remap_trace */ |
49 | |
50 | /* |
51 | * Locking in this file: |
52 | * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections. |
53 | * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex |
54 | * and trace_lock. |
55 | * - Routines depending on is_enabled() must take trace_lock. |
56 | * - trace_list users must hold trace_lock. |
57 | * - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed. |
58 | * - pre/post callbacks assume the effect of is_enabled() being true. |
59 | */ |
60 | |
61 | /* module parameters */ |
62 | static unsigned long filter_offset; |
63 | static bool nommiotrace; |
64 | static bool trace_pc; |
65 | |
66 | module_param(filter_offset, ulong, 0); |
67 | module_param(nommiotrace, bool, 0); |
68 | module_param(trace_pc, bool, 0); |
69 | |
70 | MODULE_PARM_DESC(filter_offset, "Start address of traced mappings." ); |
71 | MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing." ); |
72 | MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions." ); |
73 | |
74 | static bool is_enabled(void) |
75 | { |
76 | return atomic_read(v: &mmiotrace_enabled); |
77 | } |
78 | |
79 | static void print_pte(unsigned long address) |
80 | { |
81 | unsigned int level; |
82 | pte_t *pte = lookup_address(address, level: &level); |
83 | |
84 | if (!pte) { |
85 | pr_err("Error in %s: no pte for page 0x%08lx\n" , |
86 | __func__, address); |
87 | return; |
88 | } |
89 | |
90 | if (level == PG_LEVEL_2M) { |
91 | pr_emerg("4MB pages are not currently supported: 0x%08lx\n" , |
92 | address); |
93 | BUG(); |
94 | } |
95 | pr_info("pte for 0x%lx: 0x%llx 0x%llx\n" , |
96 | address, |
97 | (unsigned long long)pte_val(*pte), |
98 | (unsigned long long)pte_val(*pte) & _PAGE_PRESENT); |
99 | } |
100 | |
101 | /* |
102 | * For some reason the pre/post pairs have been called in an |
103 | * unmatched order. Report and die. |
104 | */ |
105 | static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr) |
106 | { |
107 | const struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
108 | pr_emerg("unexpected fault for address: 0x%08lx, last fault for address: 0x%08lx\n" , |
109 | addr, my_reason->addr); |
110 | print_pte(address: addr); |
111 | pr_emerg("faulting IP is at %pS\n" , (void *)regs->ip); |
112 | pr_emerg("last faulting IP was at %pS\n" , (void *)my_reason->ip); |
113 | #ifdef __i386__ |
114 | pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n" , |
115 | regs->ax, regs->bx, regs->cx, regs->dx); |
116 | pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n" , |
117 | regs->si, regs->di, regs->bp, regs->sp); |
118 | #else |
119 | pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n" , |
120 | regs->ax, regs->cx, regs->dx); |
121 | pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n" , |
122 | regs->si, regs->di, regs->bp, regs->sp); |
123 | #endif |
124 | put_cpu_var(pf_reason); |
125 | BUG(); |
126 | } |
127 | |
128 | static void pre(struct kmmio_probe *p, struct pt_regs *regs, |
129 | unsigned long addr) |
130 | { |
131 | struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
132 | struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); |
133 | const unsigned long instptr = instruction_pointer(regs); |
134 | const enum reason_type type = get_ins_type(ins_addr: instptr); |
135 | struct remap_trace *trace = p->private; |
136 | |
137 | /* it doesn't make sense to have more than one active trace per cpu */ |
138 | if (my_reason->active_traces) |
139 | die_kmmio_nesting_error(regs, addr); |
140 | else |
141 | my_reason->active_traces++; |
142 | |
143 | my_reason->type = type; |
144 | my_reason->addr = addr; |
145 | my_reason->ip = instptr; |
146 | |
147 | my_trace->phys = addr - trace->probe.addr + trace->phys; |
148 | my_trace->map_id = trace->id; |
149 | |
150 | /* |
151 | * Only record the program counter when requested. |
152 | * It may taint clean-room reverse engineering. |
153 | */ |
154 | if (trace_pc) |
155 | my_trace->pc = instptr; |
156 | else |
157 | my_trace->pc = 0; |
158 | |
159 | /* |
160 | * XXX: the timestamp recorded will be *after* the tracing has been |
161 | * done, not at the time we hit the instruction. SMP implications |
162 | * on event ordering? |
163 | */ |
164 | |
165 | switch (type) { |
166 | case REG_READ: |
167 | my_trace->opcode = MMIO_READ; |
168 | my_trace->width = get_ins_mem_width(ins_addr: instptr); |
169 | break; |
170 | case REG_WRITE: |
171 | my_trace->opcode = MMIO_WRITE; |
172 | my_trace->width = get_ins_mem_width(ins_addr: instptr); |
173 | my_trace->value = get_ins_reg_val(ins_addr: instptr, regs); |
174 | break; |
175 | case IMM_WRITE: |
176 | my_trace->opcode = MMIO_WRITE; |
177 | my_trace->width = get_ins_mem_width(ins_addr: instptr); |
178 | my_trace->value = get_ins_imm_val(ins_addr: instptr); |
179 | break; |
180 | default: |
181 | { |
182 | unsigned char *ip = (unsigned char *)instptr; |
183 | my_trace->opcode = MMIO_UNKNOWN_OP; |
184 | my_trace->width = 0; |
185 | my_trace->value = (*ip) << 16 | *(ip + 1) << 8 | |
186 | *(ip + 2); |
187 | } |
188 | } |
189 | put_cpu_var(cpu_trace); |
190 | put_cpu_var(pf_reason); |
191 | } |
192 | |
193 | static void post(struct kmmio_probe *p, unsigned long condition, |
194 | struct pt_regs *regs) |
195 | { |
196 | struct trap_reason *my_reason = &get_cpu_var(pf_reason); |
197 | struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace); |
198 | |
199 | /* this should always return the active_trace count to 0 */ |
200 | my_reason->active_traces--; |
201 | if (my_reason->active_traces) { |
202 | pr_emerg("unexpected post handler" ); |
203 | BUG(); |
204 | } |
205 | |
206 | switch (my_reason->type) { |
207 | case REG_READ: |
208 | my_trace->value = get_ins_reg_val(ins_addr: my_reason->ip, regs); |
209 | break; |
210 | default: |
211 | break; |
212 | } |
213 | |
214 | mmio_trace_rw(rw: my_trace); |
215 | put_cpu_var(cpu_trace); |
216 | put_cpu_var(pf_reason); |
217 | } |
218 | |
219 | static void ioremap_trace_core(resource_size_t offset, unsigned long size, |
220 | void __iomem *addr) |
221 | { |
222 | static atomic_t next_id; |
223 | struct remap_trace *trace = kmalloc(size: sizeof(*trace), GFP_KERNEL); |
224 | /* These are page-unaligned. */ |
225 | struct mmiotrace_map map = { |
226 | .phys = offset, |
227 | .virt = (unsigned long)addr, |
228 | .len = size, |
229 | .opcode = MMIO_PROBE |
230 | }; |
231 | |
232 | if (!trace) { |
233 | pr_err("kmalloc failed in ioremap\n" ); |
234 | return; |
235 | } |
236 | |
237 | *trace = (struct remap_trace) { |
238 | .probe = { |
239 | .addr = (unsigned long)addr, |
240 | .len = size, |
241 | .pre_handler = pre, |
242 | .post_handler = post, |
243 | .private = trace |
244 | }, |
245 | .phys = offset, |
246 | .id = atomic_inc_return(v: &next_id) |
247 | }; |
248 | map.map_id = trace->id; |
249 | |
250 | spin_lock_irq(lock: &trace_lock); |
251 | if (!is_enabled()) { |
252 | kfree(objp: trace); |
253 | goto not_enabled; |
254 | } |
255 | |
256 | mmio_trace_mapping(map: &map); |
257 | list_add_tail(new: &trace->list, head: &trace_list); |
258 | if (!nommiotrace) |
259 | register_kmmio_probe(p: &trace->probe); |
260 | |
261 | not_enabled: |
262 | spin_unlock_irq(lock: &trace_lock); |
263 | } |
264 | |
265 | void mmiotrace_ioremap(resource_size_t offset, unsigned long size, |
266 | void __iomem *addr) |
267 | { |
268 | if (!is_enabled()) /* recheck and proper locking in *_core() */ |
269 | return; |
270 | |
271 | pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n" , |
272 | (unsigned long long)offset, size, addr); |
273 | if ((filter_offset) && (offset != filter_offset)) |
274 | return; |
275 | ioremap_trace_core(offset, size, addr); |
276 | } |
277 | |
278 | static void iounmap_trace_core(volatile void __iomem *addr) |
279 | { |
280 | struct mmiotrace_map map = { |
281 | .phys = 0, |
282 | .virt = (unsigned long)addr, |
283 | .len = 0, |
284 | .opcode = MMIO_UNPROBE |
285 | }; |
286 | struct remap_trace *trace; |
287 | struct remap_trace *tmp; |
288 | struct remap_trace *found_trace = NULL; |
289 | |
290 | pr_debug("Unmapping %p.\n" , addr); |
291 | |
292 | spin_lock_irq(lock: &trace_lock); |
293 | if (!is_enabled()) |
294 | goto not_enabled; |
295 | |
296 | list_for_each_entry_safe(trace, tmp, &trace_list, list) { |
297 | if ((unsigned long)addr == trace->probe.addr) { |
298 | if (!nommiotrace) |
299 | unregister_kmmio_probe(p: &trace->probe); |
300 | list_del(entry: &trace->list); |
301 | found_trace = trace; |
302 | break; |
303 | } |
304 | } |
305 | map.map_id = (found_trace) ? found_trace->id : -1; |
306 | mmio_trace_mapping(map: &map); |
307 | |
308 | not_enabled: |
309 | spin_unlock_irq(lock: &trace_lock); |
310 | if (found_trace) { |
311 | synchronize_rcu(); /* unregister_kmmio_probe() requirement */ |
312 | kfree(objp: found_trace); |
313 | } |
314 | } |
315 | |
316 | void mmiotrace_iounmap(volatile void __iomem *addr) |
317 | { |
318 | might_sleep(); |
319 | if (is_enabled()) /* recheck and proper locking in *_core() */ |
320 | iounmap_trace_core(addr); |
321 | } |
322 | |
323 | int mmiotrace_printk(const char *fmt, ...) |
324 | { |
325 | int ret = 0; |
326 | va_list args; |
327 | unsigned long flags; |
328 | va_start(args, fmt); |
329 | |
330 | spin_lock_irqsave(&trace_lock, flags); |
331 | if (is_enabled()) |
332 | ret = mmio_trace_printk(fmt, args); |
333 | spin_unlock_irqrestore(lock: &trace_lock, flags); |
334 | |
335 | va_end(args); |
336 | return ret; |
337 | } |
338 | EXPORT_SYMBOL(mmiotrace_printk); |
339 | |
340 | static void clear_trace_list(void) |
341 | { |
342 | struct remap_trace *trace; |
343 | struct remap_trace *tmp; |
344 | |
345 | /* |
346 | * No locking required, because the caller ensures we are in a |
347 | * critical section via mutex, and is_enabled() is false, |
348 | * i.e. nothing can traverse or modify this list. |
349 | * Caller also ensures is_enabled() cannot change. |
350 | */ |
351 | list_for_each_entry(trace, &trace_list, list) { |
352 | pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n" , |
353 | trace->probe.addr, trace->probe.len); |
354 | if (!nommiotrace) |
355 | unregister_kmmio_probe(p: &trace->probe); |
356 | } |
357 | synchronize_rcu(); /* unregister_kmmio_probe() requirement */ |
358 | |
359 | list_for_each_entry_safe(trace, tmp, &trace_list, list) { |
360 | list_del(entry: &trace->list); |
361 | kfree(objp: trace); |
362 | } |
363 | } |
364 | |
365 | #ifdef CONFIG_HOTPLUG_CPU |
366 | static cpumask_var_t downed_cpus; |
367 | |
368 | static void enter_uniprocessor(void) |
369 | { |
370 | int cpu; |
371 | int err; |
372 | |
373 | if (!cpumask_available(mask: downed_cpus) && |
374 | !alloc_cpumask_var(mask: &downed_cpus, GFP_KERNEL)) { |
375 | pr_notice("Failed to allocate mask\n" ); |
376 | goto out; |
377 | } |
378 | |
379 | cpus_read_lock(); |
380 | cpumask_copy(dstp: downed_cpus, cpu_online_mask); |
381 | cpumask_clear_cpu(cpu: cpumask_first(cpu_online_mask), dstp: downed_cpus); |
382 | if (num_online_cpus() > 1) |
383 | pr_notice("Disabling non-boot CPUs...\n" ); |
384 | cpus_read_unlock(); |
385 | |
386 | for_each_cpu(cpu, downed_cpus) { |
387 | err = remove_cpu(cpu); |
388 | if (!err) |
389 | pr_info("CPU%d is down.\n" , cpu); |
390 | else |
391 | pr_err("Error taking CPU%d down: %d\n" , cpu, err); |
392 | } |
393 | out: |
394 | if (num_online_cpus() > 1) |
395 | pr_warn("multiple CPUs still online, may miss events.\n" ); |
396 | } |
397 | |
398 | static void leave_uniprocessor(void) |
399 | { |
400 | int cpu; |
401 | int err; |
402 | |
403 | if (!cpumask_available(mask: downed_cpus) || cpumask_empty(srcp: downed_cpus)) |
404 | return; |
405 | pr_notice("Re-enabling CPUs...\n" ); |
406 | for_each_cpu(cpu, downed_cpus) { |
407 | err = add_cpu(cpu); |
408 | if (!err) |
409 | pr_info("enabled CPU%d.\n" , cpu); |
410 | else |
411 | pr_err("cannot re-enable CPU%d: %d\n" , cpu, err); |
412 | } |
413 | } |
414 | |
415 | #else /* !CONFIG_HOTPLUG_CPU */ |
416 | static void enter_uniprocessor(void) |
417 | { |
418 | if (num_online_cpus() > 1) |
419 | pr_warn("multiple CPUs are online, may miss events. " |
420 | "Suggest booting with maxcpus=1 kernel argument.\n" ); |
421 | } |
422 | |
423 | static void leave_uniprocessor(void) |
424 | { |
425 | } |
426 | #endif |
427 | |
428 | void enable_mmiotrace(void) |
429 | { |
430 | mutex_lock(&mmiotrace_mutex); |
431 | if (is_enabled()) |
432 | goto out; |
433 | |
434 | if (nommiotrace) |
435 | pr_info("MMIO tracing disabled.\n" ); |
436 | kmmio_init(); |
437 | enter_uniprocessor(); |
438 | spin_lock_irq(lock: &trace_lock); |
439 | atomic_inc(v: &mmiotrace_enabled); |
440 | spin_unlock_irq(lock: &trace_lock); |
441 | pr_info("enabled.\n" ); |
442 | out: |
443 | mutex_unlock(lock: &mmiotrace_mutex); |
444 | } |
445 | |
446 | void disable_mmiotrace(void) |
447 | { |
448 | mutex_lock(&mmiotrace_mutex); |
449 | if (!is_enabled()) |
450 | goto out; |
451 | |
452 | spin_lock_irq(lock: &trace_lock); |
453 | atomic_dec(v: &mmiotrace_enabled); |
454 | BUG_ON(is_enabled()); |
455 | spin_unlock_irq(lock: &trace_lock); |
456 | |
457 | clear_trace_list(); /* guarantees: no more kmmio callbacks */ |
458 | leave_uniprocessor(); |
459 | kmmio_cleanup(); |
460 | pr_info("disabled.\n" ); |
461 | out: |
462 | mutex_unlock(lock: &mmiotrace_mutex); |
463 | } |
464 | |