1 // SPDX-License-Identifier: GPL-2.0-or-later
4 * Copyright (C) IBM Corporation, 2005
5 * Jeff Muizelaar, 2006, 2007
6 * Pekka Paalanen, 2008 <pq@iki.fi>
8 * Derived from the read-mod example from relay-examples by Tom Zanussi.
11 #define pr_fmt(fmt) "mmiotrace: " fmt
15 #include <linux/moduleparam.h>
16 #include <linux/debugfs.h>
17 #include <linux/slab.h>
18 #include <linux/uaccess.h>
20 #include <asm/pgtable.h>
21 #include <linux/mmiotrace.h>
22 #include <asm/e820/api.h> /* for ISA_START_ADDRESS */
23 #include <linux/atomic.h>
24 #include <linux/percpu.h>
25 #include <linux/cpu.h>
32 enum reason_type type;
37 struct list_head list;
38 struct kmmio_probe probe;
43 /* Accessed per-cpu. */
44 static DEFINE_PER_CPU(struct trap_reason, pf_reason);
45 static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);
47 static DEFINE_MUTEX(mmiotrace_mutex);
48 static DEFINE_SPINLOCK(trace_lock);
49 static atomic_t mmiotrace_enabled;
50 static LIST_HEAD(trace_list); /* struct remap_trace */
53 * Locking in this file:
54 * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections.
55 * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex
57 * - Routines depending on is_enabled() must take trace_lock.
58 * - trace_list users must hold trace_lock.
59 * - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed.
60 * - pre/post callbacks assume the effect of is_enabled() being true.
63 /* module parameters */
64 static unsigned long filter_offset;
65 static bool nommiotrace;
68 module_param(filter_offset, ulong, 0);
69 module_param(nommiotrace, bool, 0);
70 module_param(trace_pc, bool, 0);
72 MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
73 MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
74 MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
76 static bool is_enabled(void)
78 return atomic_read(&mmiotrace_enabled);
81 static void print_pte(unsigned long address)
84 pte_t *pte = lookup_address(address, &level);
87 pr_err("Error in %s: no pte for page 0x%08lx\n",
92 if (level == PG_LEVEL_2M) {
93 pr_emerg("4MB pages are not currently supported: 0x%08lx\n",
97 pr_info("pte for 0x%lx: 0x%llx 0x%llx\n",
99 (unsigned long long)pte_val(*pte),
100 (unsigned long long)pte_val(*pte) & _PAGE_PRESENT);
104 * For some reason the pre/post pairs have been called in an
105 * unmatched order. Report and die.
107 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
109 const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
110 pr_emerg("unexpected fault for address: 0x%08lx, last fault for address: 0x%08lx\n",
111 addr, my_reason->addr);
113 pr_emerg("faulting IP is at %pS\n", (void *)regs->ip);
114 pr_emerg("last faulting IP was at %pS\n", (void *)my_reason->ip);
116 pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
117 regs->ax, regs->bx, regs->cx, regs->dx);
118 pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n",
119 regs->si, regs->di, regs->bp, regs->sp);
121 pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n",
122 regs->ax, regs->cx, regs->dx);
123 pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n",
124 regs->si, regs->di, regs->bp, regs->sp);
126 put_cpu_var(pf_reason);
130 static void pre(struct kmmio_probe *p, struct pt_regs *regs,
133 struct trap_reason *my_reason = &get_cpu_var(pf_reason);
134 struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
135 const unsigned long instptr = instruction_pointer(regs);
136 const enum reason_type type = get_ins_type(instptr);
137 struct remap_trace *trace = p->private;
139 /* it doesn't make sense to have more than one active trace per cpu */
140 if (my_reason->active_traces)
141 die_kmmio_nesting_error(regs, addr);
143 my_reason->active_traces++;
145 my_reason->type = type;
146 my_reason->addr = addr;
147 my_reason->ip = instptr;
149 my_trace->phys = addr - trace->probe.addr + trace->phys;
150 my_trace->map_id = trace->id;
153 * Only record the program counter when requested.
154 * It may taint clean-room reverse engineering.
157 my_trace->pc = instptr;
162 * XXX: the timestamp recorded will be *after* the tracing has been
163 * done, not at the time we hit the instruction. SMP implications
169 my_trace->opcode = MMIO_READ;
170 my_trace->width = get_ins_mem_width(instptr);
173 my_trace->opcode = MMIO_WRITE;
174 my_trace->width = get_ins_mem_width(instptr);
175 my_trace->value = get_ins_reg_val(instptr, regs);
178 my_trace->opcode = MMIO_WRITE;
179 my_trace->width = get_ins_mem_width(instptr);
180 my_trace->value = get_ins_imm_val(instptr);
184 unsigned char *ip = (unsigned char *)instptr;
185 my_trace->opcode = MMIO_UNKNOWN_OP;
187 my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
191 put_cpu_var(cpu_trace);
192 put_cpu_var(pf_reason);
195 static void post(struct kmmio_probe *p, unsigned long condition,
196 struct pt_regs *regs)
198 struct trap_reason *my_reason = &get_cpu_var(pf_reason);
199 struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
201 /* this should always return the active_trace count to 0 */
202 my_reason->active_traces--;
203 if (my_reason->active_traces) {
204 pr_emerg("unexpected post handler");
208 switch (my_reason->type) {
210 my_trace->value = get_ins_reg_val(my_reason->ip, regs);
216 mmio_trace_rw(my_trace);
217 put_cpu_var(cpu_trace);
218 put_cpu_var(pf_reason);
221 static void ioremap_trace_core(resource_size_t offset, unsigned long size,
224 static atomic_t next_id;
225 struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
226 /* These are page-unaligned. */
227 struct mmiotrace_map map = {
229 .virt = (unsigned long)addr,
235 pr_err("kmalloc failed in ioremap\n");
239 *trace = (struct remap_trace) {
241 .addr = (unsigned long)addr,
244 .post_handler = post,
248 .id = atomic_inc_return(&next_id)
250 map.map_id = trace->id;
252 spin_lock_irq(&trace_lock);
258 mmio_trace_mapping(&map);
259 list_add_tail(&trace->list, &trace_list);
261 register_kmmio_probe(&trace->probe);
264 spin_unlock_irq(&trace_lock);
267 void mmiotrace_ioremap(resource_size_t offset, unsigned long size,
270 if (!is_enabled()) /* recheck and proper locking in *_core() */
273 pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n",
274 (unsigned long long)offset, size, addr);
275 if ((filter_offset) && (offset != filter_offset))
277 ioremap_trace_core(offset, size, addr);
280 static void iounmap_trace_core(volatile void __iomem *addr)
282 struct mmiotrace_map map = {
284 .virt = (unsigned long)addr,
286 .opcode = MMIO_UNPROBE
288 struct remap_trace *trace;
289 struct remap_trace *tmp;
290 struct remap_trace *found_trace = NULL;
292 pr_debug("Unmapping %p.\n", addr);
294 spin_lock_irq(&trace_lock);
298 list_for_each_entry_safe(trace, tmp, &trace_list, list) {
299 if ((unsigned long)addr == trace->probe.addr) {
301 unregister_kmmio_probe(&trace->probe);
302 list_del(&trace->list);
307 map.map_id = (found_trace) ? found_trace->id : -1;
308 mmio_trace_mapping(&map);
311 spin_unlock_irq(&trace_lock);
313 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
318 void mmiotrace_iounmap(volatile void __iomem *addr)
321 if (is_enabled()) /* recheck and proper locking in *_core() */
322 iounmap_trace_core(addr);
325 int mmiotrace_printk(const char *fmt, ...)
332 spin_lock_irqsave(&trace_lock, flags);
334 ret = mmio_trace_printk(fmt, args);
335 spin_unlock_irqrestore(&trace_lock, flags);
340 EXPORT_SYMBOL(mmiotrace_printk);
342 static void clear_trace_list(void)
344 struct remap_trace *trace;
345 struct remap_trace *tmp;
348 * No locking required, because the caller ensures we are in a
349 * critical section via mutex, and is_enabled() is false,
350 * i.e. nothing can traverse or modify this list.
351 * Caller also ensures is_enabled() cannot change.
353 list_for_each_entry(trace, &trace_list, list) {
354 pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n",
355 trace->probe.addr, trace->probe.len);
357 unregister_kmmio_probe(&trace->probe);
359 synchronize_rcu(); /* unregister_kmmio_probe() requirement */
361 list_for_each_entry_safe(trace, tmp, &trace_list, list) {
362 list_del(&trace->list);
367 #ifdef CONFIG_HOTPLUG_CPU
368 static cpumask_var_t downed_cpus;
370 static void enter_uniprocessor(void)
375 if (downed_cpus == NULL &&
376 !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
377 pr_notice("Failed to allocate mask\n");
382 cpumask_copy(downed_cpus, cpu_online_mask);
383 cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus);
384 if (num_online_cpus() > 1)
385 pr_notice("Disabling non-boot CPUs...\n");
388 for_each_cpu(cpu, downed_cpus) {
389 err = remove_cpu(cpu);
391 pr_info("CPU%d is down.\n", cpu);
393 pr_err("Error taking CPU%d down: %d\n", cpu, err);
396 if (num_online_cpus() > 1)
397 pr_warn("multiple CPUs still online, may miss events.\n");
400 static void leave_uniprocessor(void)
405 if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
407 pr_notice("Re-enabling CPUs...\n");
408 for_each_cpu(cpu, downed_cpus) {
411 pr_info("enabled CPU%d.\n", cpu);
413 pr_err("cannot re-enable CPU%d: %d\n", cpu, err);
417 #else /* !CONFIG_HOTPLUG_CPU */
418 static void enter_uniprocessor(void)
420 if (num_online_cpus() > 1)
421 pr_warn("multiple CPUs are online, may miss events. "
422 "Suggest booting with maxcpus=1 kernel argument.\n");
425 static void leave_uniprocessor(void)
430 void enable_mmiotrace(void)
432 mutex_lock(&mmiotrace_mutex);
437 pr_info("MMIO tracing disabled.\n");
439 enter_uniprocessor();
440 spin_lock_irq(&trace_lock);
441 atomic_inc(&mmiotrace_enabled);
442 spin_unlock_irq(&trace_lock);
443 pr_info("enabled.\n");
445 mutex_unlock(&mmiotrace_mutex);
448 void disable_mmiotrace(void)
450 mutex_lock(&mmiotrace_mutex);
454 spin_lock_irq(&trace_lock);
455 atomic_dec(&mmiotrace_enabled);
456 BUG_ON(is_enabled());
457 spin_unlock_irq(&trace_lock);
459 clear_trace_list(); /* guarantees: no more kmmio callbacks */
460 leave_uniprocessor();
462 pr_info("disabled.\n");
464 mutex_unlock(&mmiotrace_mutex);