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09a07294 PM |
1 | /* |
2 | * arch/sh/kernel/hw_breakpoint.c | |
3 | * | |
4 | * Unified kernel/user-space hardware breakpoint facility for the on-chip UBC. | |
5 | * | |
6 | * Copyright (C) 2009 Paul Mundt | |
7 | * | |
8 | * This file is subject to the terms and conditions of the GNU General Public | |
9 | * License. See the file "COPYING" in the main directory of this archive | |
10 | * for more details. | |
11 | */ | |
12 | #include <linux/init.h> | |
13 | #include <linux/perf_event.h> | |
14 | #include <linux/hw_breakpoint.h> | |
15 | #include <linux/percpu.h> | |
16 | #include <linux/kallsyms.h> | |
17 | #include <linux/notifier.h> | |
18 | #include <linux/kprobes.h> | |
19 | #include <linux/kdebug.h> | |
20 | #include <linux/io.h> | |
21 | #include <asm/hw_breakpoint.h> | |
22 | #include <asm/mmu_context.h> | |
23 | ||
24 | struct ubc_context { | |
25 | unsigned long pc; | |
26 | unsigned long state; | |
27 | }; | |
28 | ||
29 | /* Per cpu ubc channel state */ | |
30 | static DEFINE_PER_CPU(struct ubc_context, ubc_ctx[HBP_NUM]); | |
31 | ||
32 | /* | |
33 | * Stores the breakpoints currently in use on each breakpoint address | |
34 | * register for each cpus | |
35 | */ | |
36 | static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); | |
37 | ||
38 | static int __init ubc_init(void) | |
39 | { | |
40 | __raw_writel(0, UBC_CAMR0); | |
41 | __raw_writel(0, UBC_CBR0); | |
42 | __raw_writel(0, UBC_CBCR); | |
43 | ||
44 | __raw_writel(UBC_CRR_BIE | UBC_CRR_PCB, UBC_CRR0); | |
45 | ||
46 | /* dummy read for write posting */ | |
47 | (void)__raw_readl(UBC_CRR0); | |
48 | ||
49 | return 0; | |
50 | } | |
51 | arch_initcall(ubc_init); | |
52 | ||
53 | /* | |
54 | * Install a perf counter breakpoint. | |
55 | * | |
56 | * We seek a free UBC channel and use it for this breakpoint. | |
57 | * | |
58 | * Atomic: we hold the counter->ctx->lock and we only handle variables | |
59 | * and registers local to this cpu. | |
60 | */ | |
61 | int arch_install_hw_breakpoint(struct perf_event *bp) | |
62 | { | |
63 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
64 | struct ubc_context *ubc_ctx; | |
65 | int i; | |
66 | ||
67 | for (i = 0; i < HBP_NUM; i++) { | |
68 | struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); | |
69 | ||
70 | if (!*slot) { | |
71 | *slot = bp; | |
72 | break; | |
73 | } | |
74 | } | |
75 | ||
76 | if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) | |
77 | return -EBUSY; | |
78 | ||
79 | ubc_ctx = &__get_cpu_var(ubc_ctx[i]); | |
80 | ||
81 | ubc_ctx->pc = info->address; | |
82 | ubc_ctx->state = info->len | info->type; | |
83 | ||
84 | __raw_writel(UBC_CBR_CE | ubc_ctx->state, UBC_CBR0); | |
85 | __raw_writel(ubc_ctx->pc, UBC_CAR0); | |
86 | ||
87 | return 0; | |
88 | } | |
89 | ||
90 | /* | |
91 | * Uninstall the breakpoint contained in the given counter. | |
92 | * | |
93 | * First we search the debug address register it uses and then we disable | |
94 | * it. | |
95 | * | |
96 | * Atomic: we hold the counter->ctx->lock and we only handle variables | |
97 | * and registers local to this cpu. | |
98 | */ | |
99 | void arch_uninstall_hw_breakpoint(struct perf_event *bp) | |
100 | { | |
101 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
102 | struct ubc_context *ubc_ctx; | |
103 | int i; | |
104 | ||
105 | for (i = 0; i < HBP_NUM; i++) { | |
106 | struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); | |
107 | ||
108 | if (*slot == bp) { | |
109 | *slot = NULL; | |
110 | break; | |
111 | } | |
112 | } | |
113 | ||
114 | if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) | |
115 | return; | |
116 | ||
117 | ubc_ctx = &__get_cpu_var(ubc_ctx[i]); | |
118 | ubc_ctx->pc = 0; | |
119 | ubc_ctx->state &= ~(info->len | info->type); | |
120 | ||
121 | __raw_writel(ubc_ctx->pc, UBC_CBR0); | |
122 | __raw_writel(ubc_ctx->state, UBC_CAR0); | |
123 | } | |
124 | ||
125 | static int get_hbp_len(u16 hbp_len) | |
126 | { | |
127 | unsigned int len_in_bytes = 0; | |
128 | ||
129 | switch (hbp_len) { | |
130 | case SH_BREAKPOINT_LEN_1: | |
131 | len_in_bytes = 1; | |
132 | break; | |
133 | case SH_BREAKPOINT_LEN_2: | |
134 | len_in_bytes = 2; | |
135 | break; | |
136 | case SH_BREAKPOINT_LEN_4: | |
137 | len_in_bytes = 4; | |
138 | break; | |
139 | case SH_BREAKPOINT_LEN_8: | |
140 | len_in_bytes = 8; | |
141 | break; | |
142 | } | |
143 | return len_in_bytes; | |
144 | } | |
145 | ||
146 | /* | |
147 | * Check for virtual address in user space. | |
148 | */ | |
149 | int arch_check_va_in_userspace(unsigned long va, u16 hbp_len) | |
150 | { | |
151 | unsigned int len; | |
152 | ||
153 | len = get_hbp_len(hbp_len); | |
154 | ||
155 | return (va <= TASK_SIZE - len); | |
156 | } | |
157 | ||
158 | /* | |
159 | * Check for virtual address in kernel space. | |
160 | */ | |
161 | static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len) | |
162 | { | |
163 | unsigned int len; | |
164 | ||
165 | len = get_hbp_len(hbp_len); | |
166 | ||
167 | return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); | |
168 | } | |
169 | ||
170 | /* | |
171 | * Store a breakpoint's encoded address, length, and type. | |
172 | */ | |
173 | static int arch_store_info(struct perf_event *bp) | |
174 | { | |
175 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
176 | ||
177 | /* | |
178 | * User-space requests will always have the address field populated | |
179 | * For kernel-addresses, either the address or symbol name can be | |
180 | * specified. | |
181 | */ | |
182 | if (info->name) | |
183 | info->address = (unsigned long)kallsyms_lookup_name(info->name); | |
184 | if (info->address) { | |
185 | info->asid = get_asid(); | |
186 | return 0; | |
187 | } | |
188 | ||
189 | return -EINVAL; | |
190 | } | |
191 | ||
192 | int arch_bp_generic_fields(int sh_len, int sh_type, | |
193 | int *gen_len, int *gen_type) | |
194 | { | |
195 | /* Len */ | |
196 | switch (sh_len) { | |
197 | case SH_BREAKPOINT_LEN_1: | |
198 | *gen_len = HW_BREAKPOINT_LEN_1; | |
199 | break; | |
200 | case SH_BREAKPOINT_LEN_2: | |
201 | *gen_len = HW_BREAKPOINT_LEN_2; | |
202 | break; | |
203 | case SH_BREAKPOINT_LEN_4: | |
204 | *gen_len = HW_BREAKPOINT_LEN_4; | |
205 | break; | |
206 | case SH_BREAKPOINT_LEN_8: | |
207 | *gen_len = HW_BREAKPOINT_LEN_8; | |
208 | break; | |
209 | default: | |
210 | return -EINVAL; | |
211 | } | |
212 | ||
213 | /* Type */ | |
214 | switch (sh_type) { | |
215 | case SH_BREAKPOINT_READ: | |
216 | *gen_type = HW_BREAKPOINT_R; | |
217 | case SH_BREAKPOINT_WRITE: | |
218 | *gen_type = HW_BREAKPOINT_W; | |
219 | break; | |
220 | case SH_BREAKPOINT_RW: | |
221 | *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; | |
222 | break; | |
223 | default: | |
224 | return -EINVAL; | |
225 | } | |
226 | ||
227 | return 0; | |
228 | } | |
229 | ||
230 | static int arch_build_bp_info(struct perf_event *bp) | |
231 | { | |
232 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
233 | ||
234 | info->address = bp->attr.bp_addr; | |
235 | ||
236 | /* Len */ | |
237 | switch (bp->attr.bp_len) { | |
238 | case HW_BREAKPOINT_LEN_1: | |
239 | info->len = SH_BREAKPOINT_LEN_1; | |
240 | break; | |
241 | case HW_BREAKPOINT_LEN_2: | |
242 | info->len = SH_BREAKPOINT_LEN_2; | |
243 | break; | |
244 | case HW_BREAKPOINT_LEN_4: | |
245 | info->len = SH_BREAKPOINT_LEN_4; | |
246 | break; | |
247 | case HW_BREAKPOINT_LEN_8: | |
248 | info->len = SH_BREAKPOINT_LEN_8; | |
249 | break; | |
250 | default: | |
251 | return -EINVAL; | |
252 | } | |
253 | ||
254 | /* Type */ | |
255 | switch (bp->attr.bp_type) { | |
256 | case HW_BREAKPOINT_R: | |
257 | info->type = SH_BREAKPOINT_READ; | |
258 | break; | |
259 | case HW_BREAKPOINT_W: | |
260 | info->type = SH_BREAKPOINT_WRITE; | |
261 | break; | |
262 | case HW_BREAKPOINT_W | HW_BREAKPOINT_R: | |
263 | info->type = SH_BREAKPOINT_RW; | |
264 | break; | |
265 | default: | |
266 | return -EINVAL; | |
267 | } | |
268 | ||
269 | return 0; | |
270 | } | |
271 | ||
272 | /* | |
273 | * Validate the arch-specific HW Breakpoint register settings | |
274 | */ | |
275 | int arch_validate_hwbkpt_settings(struct perf_event *bp, | |
276 | struct task_struct *tsk) | |
277 | { | |
278 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
279 | unsigned int align; | |
280 | int ret; | |
281 | ||
282 | ret = arch_build_bp_info(bp); | |
283 | if (ret) | |
284 | return ret; | |
285 | ||
286 | ret = -EINVAL; | |
287 | ||
288 | switch (info->len) { | |
289 | case SH_BREAKPOINT_LEN_1: | |
290 | align = 0; | |
291 | break; | |
292 | case SH_BREAKPOINT_LEN_2: | |
293 | align = 1; | |
294 | break; | |
295 | case SH_BREAKPOINT_LEN_4: | |
296 | align = 3; | |
297 | break; | |
298 | case SH_BREAKPOINT_LEN_8: | |
299 | align = 7; | |
300 | break; | |
301 | default: | |
302 | return ret; | |
303 | } | |
304 | ||
a28b460e | 305 | ret = arch_store_info(bp); |
09a07294 PM |
306 | |
307 | if (ret < 0) | |
308 | return ret; | |
309 | ||
310 | /* | |
311 | * Check that the low-order bits of the address are appropriate | |
312 | * for the alignment implied by len. | |
313 | */ | |
314 | if (info->address & align) | |
315 | return -EINVAL; | |
316 | ||
317 | /* Check that the virtual address is in the proper range */ | |
318 | if (tsk) { | |
319 | if (!arch_check_va_in_userspace(info->address, info->len)) | |
320 | return -EFAULT; | |
321 | } else { | |
322 | if (!arch_check_va_in_kernelspace(info->address, info->len)) | |
323 | return -EFAULT; | |
324 | } | |
325 | ||
326 | return 0; | |
327 | } | |
328 | ||
329 | /* | |
330 | * Release the user breakpoints used by ptrace | |
331 | */ | |
332 | void flush_ptrace_hw_breakpoint(struct task_struct *tsk) | |
333 | { | |
334 | int i; | |
335 | struct thread_struct *t = &tsk->thread; | |
336 | ||
337 | for (i = 0; i < HBP_NUM; i++) { | |
338 | unregister_hw_breakpoint(t->ptrace_bps[i]); | |
339 | t->ptrace_bps[i] = NULL; | |
340 | } | |
341 | } | |
342 | ||
343 | static int __kprobes hw_breakpoint_handler(struct die_args *args) | |
344 | { | |
345 | int cpu, i, rc = NOTIFY_STOP; | |
346 | struct perf_event *bp; | |
347 | unsigned long val; | |
348 | ||
349 | val = __raw_readl(UBC_CBR0); | |
350 | __raw_writel(val & ~UBC_CBR_CE, UBC_CBR0); | |
351 | ||
352 | cpu = get_cpu(); | |
353 | for (i = 0; i < HBP_NUM; i++) { | |
354 | /* | |
355 | * The counter may be concurrently released but that can only | |
356 | * occur from a call_rcu() path. We can then safely fetch | |
357 | * the breakpoint, use its callback, touch its counter | |
358 | * while we are in an rcu_read_lock() path. | |
359 | */ | |
360 | rcu_read_lock(); | |
361 | ||
362 | bp = per_cpu(bp_per_reg[i], cpu); | |
363 | if (bp) { | |
364 | rc = NOTIFY_DONE; | |
365 | } else { | |
366 | rcu_read_unlock(); | |
367 | break; | |
368 | } | |
369 | ||
a28b460e | 370 | perf_bp_event(bp, args->regs); |
09a07294 PM |
371 | |
372 | rcu_read_unlock(); | |
373 | } | |
374 | ||
375 | if (bp) { | |
376 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
377 | ||
378 | __raw_writel(UBC_CBR_CE | info->len | info->type, UBC_CBR0); | |
379 | __raw_writel(info->address, UBC_CAR0); | |
380 | } | |
381 | ||
382 | put_cpu(); | |
383 | ||
384 | return rc; | |
385 | } | |
386 | ||
387 | BUILD_TRAP_HANDLER(breakpoint) | |
388 | { | |
389 | unsigned long ex = lookup_exception_vector(); | |
390 | TRAP_HANDLER_DECL; | |
391 | ||
392 | notify_die(DIE_BREAKPOINT, "breakpoint", regs, 0, ex, SIGTRAP); | |
393 | } | |
394 | ||
395 | /* | |
396 | * Handle debug exception notifications. | |
397 | */ | |
398 | int __kprobes hw_breakpoint_exceptions_notify(struct notifier_block *unused, | |
399 | unsigned long val, void *data) | |
400 | { | |
b74ab703 PM |
401 | struct die_args *args = data; |
402 | ||
09a07294 PM |
403 | if (val != DIE_BREAKPOINT) |
404 | return NOTIFY_DONE; | |
405 | ||
b74ab703 PM |
406 | /* |
407 | * If the breakpoint hasn't been triggered by the UBC, it's | |
408 | * probably from a debugger, so don't do anything more here. | |
409 | */ | |
410 | if (args->trapnr != 0x1e0) | |
411 | return NOTIFY_DONE; | |
412 | ||
09a07294 PM |
413 | return hw_breakpoint_handler(data); |
414 | } | |
415 | ||
416 | void hw_breakpoint_pmu_read(struct perf_event *bp) | |
417 | { | |
418 | /* TODO */ | |
419 | } | |
420 | ||
421 | void hw_breakpoint_pmu_unthrottle(struct perf_event *bp) | |
422 | { | |
423 | /* TODO */ | |
424 | } |