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c91e02bd MF |
1 | /* |
2 | * Xtensa hardware breakpoints/watchpoints handling functions | |
3 | * | |
4 | * This file is subject to the terms and conditions of the GNU General Public | |
5 | * License. See the file "COPYING" in the main directory of this archive | |
6 | * for more details. | |
7 | * | |
8 | * Copyright (C) 2016 Cadence Design Systems Inc. | |
9 | */ | |
10 | ||
11 | #include <linux/hw_breakpoint.h> | |
12 | #include <linux/log2.h> | |
13 | #include <linux/percpu.h> | |
14 | #include <linux/perf_event.h> | |
15 | #include <variant/core.h> | |
16 | ||
17 | /* Breakpoint currently in use for each IBREAKA. */ | |
18 | static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[XCHAL_NUM_IBREAK]); | |
19 | ||
20 | /* Watchpoint currently in use for each DBREAKA. */ | |
21 | static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[XCHAL_NUM_DBREAK]); | |
22 | ||
23 | int hw_breakpoint_slots(int type) | |
24 | { | |
25 | switch (type) { | |
26 | case TYPE_INST: | |
27 | return XCHAL_NUM_IBREAK; | |
28 | case TYPE_DATA: | |
29 | return XCHAL_NUM_DBREAK; | |
30 | default: | |
31 | pr_warn("unknown slot type: %d\n", type); | |
32 | return 0; | |
33 | } | |
34 | } | |
35 | ||
36 | int arch_check_bp_in_kernelspace(struct perf_event *bp) | |
37 | { | |
38 | unsigned int len; | |
39 | unsigned long va; | |
40 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
41 | ||
42 | va = info->address; | |
43 | len = bp->attr.bp_len; | |
44 | ||
45 | return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); | |
46 | } | |
47 | ||
48 | /* | |
49 | * Construct an arch_hw_breakpoint from a perf_event. | |
50 | */ | |
51 | static int arch_build_bp_info(struct perf_event *bp) | |
52 | { | |
53 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
54 | ||
55 | /* Type */ | |
56 | switch (bp->attr.bp_type) { | |
57 | case HW_BREAKPOINT_X: | |
58 | info->type = XTENSA_BREAKPOINT_EXECUTE; | |
59 | break; | |
60 | case HW_BREAKPOINT_R: | |
61 | info->type = XTENSA_BREAKPOINT_LOAD; | |
62 | break; | |
63 | case HW_BREAKPOINT_W: | |
64 | info->type = XTENSA_BREAKPOINT_STORE; | |
65 | break; | |
66 | case HW_BREAKPOINT_RW: | |
67 | info->type = XTENSA_BREAKPOINT_LOAD | XTENSA_BREAKPOINT_STORE; | |
68 | break; | |
69 | default: | |
70 | return -EINVAL; | |
71 | } | |
72 | ||
73 | /* Len */ | |
74 | info->len = bp->attr.bp_len; | |
75 | if (info->len < 1 || info->len > 64 || !is_power_of_2(info->len)) | |
76 | return -EINVAL; | |
77 | ||
78 | /* Address */ | |
79 | info->address = bp->attr.bp_addr; | |
80 | if (info->address & (info->len - 1)) | |
81 | return -EINVAL; | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | int arch_validate_hwbkpt_settings(struct perf_event *bp) | |
87 | { | |
88 | int ret; | |
89 | ||
90 | /* Build the arch_hw_breakpoint. */ | |
91 | ret = arch_build_bp_info(bp); | |
92 | return ret; | |
93 | } | |
94 | ||
95 | int hw_breakpoint_exceptions_notify(struct notifier_block *unused, | |
96 | unsigned long val, void *data) | |
97 | { | |
98 | return NOTIFY_DONE; | |
99 | } | |
100 | ||
101 | static void xtensa_wsr(unsigned long v, u8 sr) | |
102 | { | |
103 | /* We don't have indexed wsr and creating instruction dynamically | |
104 | * doesn't seem worth it given how small XCHAL_NUM_IBREAK and | |
105 | * XCHAL_NUM_DBREAK are. Thus the switch. In case build breaks here | |
106 | * the switch below needs to be extended. | |
107 | */ | |
108 | BUILD_BUG_ON(XCHAL_NUM_IBREAK > 2); | |
109 | BUILD_BUG_ON(XCHAL_NUM_DBREAK > 2); | |
110 | ||
111 | switch (sr) { | |
112 | #if XCHAL_NUM_IBREAK > 0 | |
113 | case SREG_IBREAKA + 0: | |
114 | WSR(v, SREG_IBREAKA + 0); | |
115 | break; | |
116 | #endif | |
117 | #if XCHAL_NUM_IBREAK > 1 | |
118 | case SREG_IBREAKA + 1: | |
119 | WSR(v, SREG_IBREAKA + 1); | |
120 | break; | |
121 | #endif | |
122 | ||
123 | #if XCHAL_NUM_DBREAK > 0 | |
124 | case SREG_DBREAKA + 0: | |
125 | WSR(v, SREG_DBREAKA + 0); | |
126 | break; | |
127 | case SREG_DBREAKC + 0: | |
128 | WSR(v, SREG_DBREAKC + 0); | |
129 | break; | |
130 | #endif | |
131 | #if XCHAL_NUM_DBREAK > 1 | |
132 | case SREG_DBREAKA + 1: | |
133 | WSR(v, SREG_DBREAKA + 1); | |
134 | break; | |
135 | ||
136 | case SREG_DBREAKC + 1: | |
137 | WSR(v, SREG_DBREAKC + 1); | |
138 | break; | |
139 | #endif | |
140 | } | |
141 | } | |
142 | ||
143 | static int alloc_slot(struct perf_event **slot, size_t n, | |
144 | struct perf_event *bp) | |
145 | { | |
146 | size_t i; | |
147 | ||
148 | for (i = 0; i < n; ++i) { | |
149 | if (!slot[i]) { | |
150 | slot[i] = bp; | |
151 | return i; | |
152 | } | |
153 | } | |
154 | return -EBUSY; | |
155 | } | |
156 | ||
157 | static void set_ibreak_regs(int reg, struct perf_event *bp) | |
158 | { | |
159 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
160 | unsigned long ibreakenable; | |
161 | ||
162 | xtensa_wsr(info->address, SREG_IBREAKA + reg); | |
163 | RSR(ibreakenable, SREG_IBREAKENABLE); | |
164 | WSR(ibreakenable | (1 << reg), SREG_IBREAKENABLE); | |
165 | } | |
166 | ||
167 | static void set_dbreak_regs(int reg, struct perf_event *bp) | |
168 | { | |
169 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
170 | unsigned long dbreakc = DBREAKC_MASK_MASK & -info->len; | |
171 | ||
172 | if (info->type & XTENSA_BREAKPOINT_LOAD) | |
173 | dbreakc |= DBREAKC_LOAD_MASK; | |
174 | if (info->type & XTENSA_BREAKPOINT_STORE) | |
175 | dbreakc |= DBREAKC_STOR_MASK; | |
176 | ||
177 | xtensa_wsr(info->address, SREG_DBREAKA + reg); | |
178 | xtensa_wsr(dbreakc, SREG_DBREAKC + reg); | |
179 | } | |
180 | ||
181 | int arch_install_hw_breakpoint(struct perf_event *bp) | |
182 | { | |
183 | int i; | |
184 | ||
185 | if (counter_arch_bp(bp)->type == XTENSA_BREAKPOINT_EXECUTE) { | |
186 | /* Breakpoint */ | |
187 | i = alloc_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp); | |
188 | if (i < 0) | |
189 | return i; | |
190 | set_ibreak_regs(i, bp); | |
191 | ||
192 | } else { | |
193 | /* Watchpoint */ | |
194 | i = alloc_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp); | |
195 | if (i < 0) | |
196 | return i; | |
197 | set_dbreak_regs(i, bp); | |
198 | } | |
199 | return 0; | |
200 | } | |
201 | ||
202 | static int free_slot(struct perf_event **slot, size_t n, | |
203 | struct perf_event *bp) | |
204 | { | |
205 | size_t i; | |
206 | ||
207 | for (i = 0; i < n; ++i) { | |
208 | if (slot[i] == bp) { | |
209 | slot[i] = NULL; | |
210 | return i; | |
211 | } | |
212 | } | |
213 | return -EBUSY; | |
214 | } | |
215 | ||
216 | void arch_uninstall_hw_breakpoint(struct perf_event *bp) | |
217 | { | |
218 | struct arch_hw_breakpoint *info = counter_arch_bp(bp); | |
219 | int i; | |
220 | ||
221 | if (info->type == XTENSA_BREAKPOINT_EXECUTE) { | |
222 | unsigned long ibreakenable; | |
223 | ||
224 | /* Breakpoint */ | |
225 | i = free_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp); | |
226 | if (i >= 0) { | |
227 | RSR(ibreakenable, SREG_IBREAKENABLE); | |
228 | WSR(ibreakenable & ~(1 << i), SREG_IBREAKENABLE); | |
229 | } | |
230 | } else { | |
231 | /* Watchpoint */ | |
232 | i = free_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp); | |
233 | if (i >= 0) | |
234 | xtensa_wsr(0, SREG_DBREAKC + i); | |
235 | } | |
236 | } | |
237 | ||
238 | void hw_breakpoint_pmu_read(struct perf_event *bp) | |
239 | { | |
240 | } | |
241 | ||
242 | void flush_ptrace_hw_breakpoint(struct task_struct *tsk) | |
243 | { | |
244 | int i; | |
245 | struct thread_struct *t = &tsk->thread; | |
246 | ||
247 | for (i = 0; i < XCHAL_NUM_IBREAK; ++i) { | |
248 | if (t->ptrace_bp[i]) { | |
249 | unregister_hw_breakpoint(t->ptrace_bp[i]); | |
250 | t->ptrace_bp[i] = NULL; | |
251 | } | |
252 | } | |
253 | for (i = 0; i < XCHAL_NUM_DBREAK; ++i) { | |
254 | if (t->ptrace_wp[i]) { | |
255 | unregister_hw_breakpoint(t->ptrace_wp[i]); | |
256 | t->ptrace_wp[i] = NULL; | |
257 | } | |
258 | } | |
259 | } | |
260 | ||
261 | /* | |
262 | * Set ptrace breakpoint pointers to zero for this task. | |
263 | * This is required in order to prevent child processes from unregistering | |
264 | * breakpoints held by their parent. | |
265 | */ | |
266 | void clear_ptrace_hw_breakpoint(struct task_struct *tsk) | |
267 | { | |
268 | memset(tsk->thread.ptrace_bp, 0, sizeof(tsk->thread.ptrace_bp)); | |
269 | memset(tsk->thread.ptrace_wp, 0, sizeof(tsk->thread.ptrace_wp)); | |
270 | } | |
271 | ||
272 | void restore_dbreak(void) | |
273 | { | |
274 | int i; | |
275 | ||
276 | for (i = 0; i < XCHAL_NUM_DBREAK; ++i) { | |
277 | struct perf_event *bp = this_cpu_ptr(wp_on_reg)[i]; | |
278 | ||
279 | if (bp) | |
280 | set_dbreak_regs(i, bp); | |
281 | } | |
282 | clear_thread_flag(TIF_DB_DISABLED); | |
283 | } | |
284 | ||
285 | int check_hw_breakpoint(struct pt_regs *regs) | |
286 | { | |
287 | if (regs->debugcause & BIT(DEBUGCAUSE_IBREAK_BIT)) { | |
288 | int i; | |
289 | struct perf_event **bp = this_cpu_ptr(bp_on_reg); | |
290 | ||
291 | for (i = 0; i < XCHAL_NUM_IBREAK; ++i) { | |
292 | if (bp[i] && !bp[i]->attr.disabled && | |
293 | regs->pc == bp[i]->attr.bp_addr) | |
294 | perf_bp_event(bp[i], regs); | |
295 | } | |
296 | return 0; | |
297 | } else if (regs->debugcause & BIT(DEBUGCAUSE_DBREAK_BIT)) { | |
298 | struct perf_event **bp = this_cpu_ptr(wp_on_reg); | |
299 | int dbnum = (regs->debugcause & DEBUGCAUSE_DBNUM_MASK) >> | |
300 | DEBUGCAUSE_DBNUM_SHIFT; | |
301 | ||
302 | if (dbnum < XCHAL_NUM_DBREAK && bp[dbnum]) { | |
303 | if (user_mode(regs)) { | |
304 | perf_bp_event(bp[dbnum], regs); | |
305 | } else { | |
306 | set_thread_flag(TIF_DB_DISABLED); | |
307 | xtensa_wsr(0, SREG_DBREAKC + dbnum); | |
308 | } | |
309 | } else { | |
310 | WARN_ONCE(1, | |
311 | "Wrong/unconfigured DBNUM reported in DEBUGCAUSE: %d\n", | |
312 | dbnum); | |
313 | } | |
314 | return 0; | |
315 | } | |
316 | return -ENOENT; | |
317 | } |