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-rw-r--r--arch/arm/include/asm/hw_breakpoint.h123
-rw-r--r--arch/arm/kernel/hw_breakpoint.c849
2 files changed, 972 insertions, 0 deletions
diff --git a/arch/arm/include/asm/hw_breakpoint.h b/arch/arm/include/asm/hw_breakpoint.h
new file mode 100644
index 000000000000..33048c700caa
--- /dev/null
+++ b/arch/arm/include/asm/hw_breakpoint.h
@@ -0,0 +1,123 @@
1#ifndef _ARM_HW_BREAKPOINT_H
2#define _ARM_HW_BREAKPOINT_H
3
4#ifdef __KERNEL__
5struct arch_hw_breakpoint_ctrl {
6 u32 __reserved : 9,
7 mismatch : 1,
8 : 9,
9 len : 8,
10 type : 2,
11 privilege : 2,
12 enabled : 1;
13};
14
15struct arch_hw_breakpoint {
16 u32 address;
17 u32 trigger;
18 struct perf_event *suspended_wp;
19 struct arch_hw_breakpoint_ctrl ctrl;
20};
21
22static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
23{
24 return (ctrl.mismatch << 22) | (ctrl.len << 5) | (ctrl.type << 3) |
25 (ctrl.privilege << 1) | ctrl.enabled;
26}
27
28static inline void decode_ctrl_reg(u32 reg,
29 struct arch_hw_breakpoint_ctrl *ctrl)
30{
31 ctrl->enabled = reg & 0x1;
32 reg >>= 1;
33 ctrl->privilege = reg & 0x3;
34 reg >>= 2;
35 ctrl->type = reg & 0x3;
36 reg >>= 2;
37 ctrl->len = reg & 0xff;
38 reg >>= 17;
39 ctrl->mismatch = reg & 0x1;
40}
41
42/* Debug architecture numbers. */
43#define ARM_DEBUG_ARCH_RESERVED 0 /* In case of ptrace ABI updates. */
44#define ARM_DEBUG_ARCH_V6 1
45#define ARM_DEBUG_ARCH_V6_1 2
46#define ARM_DEBUG_ARCH_V7_ECP14 3
47#define ARM_DEBUG_ARCH_V7_MM 4
48
49/* Breakpoint */
50#define ARM_BREAKPOINT_EXECUTE 0
51
52/* Watchpoints */
53#define ARM_BREAKPOINT_LOAD 1
54#define ARM_BREAKPOINT_STORE 2
55
56/* Privilege Levels */
57#define ARM_BREAKPOINT_PRIV 1
58#define ARM_BREAKPOINT_USER 2
59
60/* Lengths */
61#define ARM_BREAKPOINT_LEN_1 0x1
62#define ARM_BREAKPOINT_LEN_2 0x3
63#define ARM_BREAKPOINT_LEN_4 0xf
64#define ARM_BREAKPOINT_LEN_8 0xff
65
66/* Limits */
67#define ARM_MAX_BRP 16
68#define ARM_MAX_WRP 16
69#define ARM_MAX_HBP_SLOTS (ARM_MAX_BRP + ARM_MAX_WRP)
70
71/* DSCR method of entry bits. */
72#define ARM_DSCR_MOE(x) ((x >> 2) & 0xf)
73#define ARM_ENTRY_BREAKPOINT 0x1
74#define ARM_ENTRY_ASYNC_WATCHPOINT 0x2
75#define ARM_ENTRY_SYNC_WATCHPOINT 0xa
76
77/* DSCR monitor/halting bits. */
78#define ARM_DSCR_HDBGEN (1 << 14)
79#define ARM_DSCR_MDBGEN (1 << 15)
80
81/* opcode2 numbers for the co-processor instructions. */
82#define ARM_OP2_BVR 4
83#define ARM_OP2_BCR 5
84#define ARM_OP2_WVR 6
85#define ARM_OP2_WCR 7
86
87/* Base register numbers for the debug registers. */
88#define ARM_BASE_BVR 64
89#define ARM_BASE_BCR 80
90#define ARM_BASE_WVR 96
91#define ARM_BASE_WCR 112
92
93/* Accessor macros for the debug registers. */
94#define ARM_DBG_READ(M, OP2, VAL) do {\
95 asm volatile("mrc p14, 0, %0, c0," #M ", " #OP2 : "=r" (VAL));\
96} while (0)
97
98#define ARM_DBG_WRITE(M, OP2, VAL) do {\
99 asm volatile("mcr p14, 0, %0, c0," #M ", " #OP2 : : "r" (VAL));\
100} while (0)
101
102struct notifier_block;
103struct perf_event;
104struct pmu;
105struct task_struct;
106
107extern struct pmu perf_ops_bp;
108extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
109 int *gen_len, int *gen_type);
110extern int arch_check_bp_in_kernelspace(struct perf_event *bp);
111extern int arch_validate_hwbkpt_settings(struct perf_event *bp);
112extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
113 unsigned long val, void *data);
114extern u8 arch_get_debug_arch(void);
115extern u8 arch_get_max_wp_len(void);
116
117int arch_install_hw_breakpoint(struct perf_event *bp);
118void arch_uninstall_hw_breakpoint(struct perf_event *bp);
119void hw_breakpoint_pmu_read(struct perf_event *bp);
120int hw_breakpoint_slots(int type);
121
122#endif /* __KERNEL__ */
123#endif /* _ARM_HW_BREAKPOINT_H */
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
new file mode 100644
index 000000000000..54593b0c241b
--- /dev/null
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -0,0 +1,849 @@
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 version 2 as
4 * published by the Free Software Foundation.
5 *
6 * This program is distributed in the hope that it will be useful,
7 * but WITHOUT ANY WARRANTY; without even the implied warranty of
8 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
9 * GNU General Public License for more details.
10 *
11 * You should have received a copy of the GNU General Public License
12 * along with this program; if not, write to the Free Software
13 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
14 *
15 * Copyright (C) 2009, 2010 ARM Limited
16 *
17 * Author: Will Deacon <will.deacon@arm.com>
18 */
19
20/*
21 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
22 * using the CPU's debug registers.
23 */
24#define pr_fmt(fmt) "hw-breakpoint: " fmt
25
26#include <linux/errno.h>
27#include <linux/perf_event.h>
28#include <linux/hw_breakpoint.h>
29#include <linux/smp.h>
30
31#include <asm/cacheflush.h>
32#include <asm/cputype.h>
33#include <asm/current.h>
34#include <asm/hw_breakpoint.h>
35#include <asm/kdebug.h>
36#include <asm/system.h>
37#include <asm/traps.h>
38
39/* Breakpoint currently in use for each BRP. */
40static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
41
42/* Watchpoint currently in use for each WRP. */
43static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
44
45/* Number of BRP/WRP registers on this CPU. */
46static int core_num_brps;
47static int core_num_wrps;
48
49/* Debug architecture version. */
50static u8 debug_arch;
51
52/* Maximum supported watchpoint length. */
53static u8 max_watchpoint_len;
54
55/* Determine number of BRP registers available. */
56static int get_num_brps(void)
57{
58 u32 didr;
59 ARM_DBG_READ(c0, 0, didr);
60 return ((didr >> 24) & 0xf) + 1;
61}
62
63/* Determine number of WRP registers available. */
64static int get_num_wrps(void)
65{
66 /*
67 * FIXME: When a watchpoint fires, the only way to work out which
68 * watchpoint it was is by disassembling the faulting instruction
69 * and working out the address of the memory access.
70 *
71 * Furthermore, we can only do this if the watchpoint was precise
72 * since imprecise watchpoints prevent us from calculating register
73 * based addresses.
74 *
75 * For the time being, we only report 1 watchpoint register so we
76 * always know which watchpoint fired. In the future we can either
77 * add a disassembler and address generation emulator, or we can
78 * insert a check to see if the DFAR is set on watchpoint exception
79 * entry [the ARM ARM states that the DFAR is UNKNOWN, but
80 * experience shows that it is set on some implementations].
81 */
82
83#if 0
84 u32 didr, wrps;
85 ARM_DBG_READ(c0, 0, didr);
86 return ((didr >> 28) & 0xf) + 1;
87#endif
88
89 return 1;
90}
91
92int hw_breakpoint_slots(int type)
93{
94 /*
95 * We can be called early, so don't rely on
96 * our static variables being initialised.
97 */
98 switch (type) {
99 case TYPE_INST:
100 return get_num_brps();
101 case TYPE_DATA:
102 return get_num_wrps();
103 default:
104 pr_warning("unknown slot type: %d\n", type);
105 return 0;
106 }
107}
108
109/* Determine debug architecture. */
110static u8 get_debug_arch(void)
111{
112 u32 didr;
113
114 /* Do we implement the extended CPUID interface? */
115 if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
116 pr_warning("CPUID feature registers not supported. "
117 "Assuming v6 debug is present.\n");
118 return ARM_DEBUG_ARCH_V6;
119 }
120
121 ARM_DBG_READ(c0, 0, didr);
122 return (didr >> 16) & 0xf;
123}
124
125/* Does this core support mismatch breakpoints? */
126static int core_has_mismatch_bps(void)
127{
128 return debug_arch >= ARM_DEBUG_ARCH_V7_ECP14 && core_num_brps > 1;
129}
130
131u8 arch_get_debug_arch(void)
132{
133 return debug_arch;
134}
135
136#define READ_WB_REG_CASE(OP2, M, VAL) \
137 case ((OP2 << 4) + M): \
138 ARM_DBG_READ(c ## M, OP2, VAL); \
139 break
140
141#define WRITE_WB_REG_CASE(OP2, M, VAL) \
142 case ((OP2 << 4) + M): \
143 ARM_DBG_WRITE(c ## M, OP2, VAL);\
144 break
145
146#define GEN_READ_WB_REG_CASES(OP2, VAL) \
147 READ_WB_REG_CASE(OP2, 0, VAL); \
148 READ_WB_REG_CASE(OP2, 1, VAL); \
149 READ_WB_REG_CASE(OP2, 2, VAL); \
150 READ_WB_REG_CASE(OP2, 3, VAL); \
151 READ_WB_REG_CASE(OP2, 4, VAL); \
152 READ_WB_REG_CASE(OP2, 5, VAL); \
153 READ_WB_REG_CASE(OP2, 6, VAL); \
154 READ_WB_REG_CASE(OP2, 7, VAL); \
155 READ_WB_REG_CASE(OP2, 8, VAL); \
156 READ_WB_REG_CASE(OP2, 9, VAL); \
157 READ_WB_REG_CASE(OP2, 10, VAL); \
158 READ_WB_REG_CASE(OP2, 11, VAL); \
159 READ_WB_REG_CASE(OP2, 12, VAL); \
160 READ_WB_REG_CASE(OP2, 13, VAL); \
161 READ_WB_REG_CASE(OP2, 14, VAL); \
162 READ_WB_REG_CASE(OP2, 15, VAL)
163
164#define GEN_WRITE_WB_REG_CASES(OP2, VAL) \
165 WRITE_WB_REG_CASE(OP2, 0, VAL); \
166 WRITE_WB_REG_CASE(OP2, 1, VAL); \
167 WRITE_WB_REG_CASE(OP2, 2, VAL); \
168 WRITE_WB_REG_CASE(OP2, 3, VAL); \
169 WRITE_WB_REG_CASE(OP2, 4, VAL); \
170 WRITE_WB_REG_CASE(OP2, 5, VAL); \
171 WRITE_WB_REG_CASE(OP2, 6, VAL); \
172 WRITE_WB_REG_CASE(OP2, 7, VAL); \
173 WRITE_WB_REG_CASE(OP2, 8, VAL); \
174 WRITE_WB_REG_CASE(OP2, 9, VAL); \
175 WRITE_WB_REG_CASE(OP2, 10, VAL); \
176 WRITE_WB_REG_CASE(OP2, 11, VAL); \
177 WRITE_WB_REG_CASE(OP2, 12, VAL); \
178 WRITE_WB_REG_CASE(OP2, 13, VAL); \
179 WRITE_WB_REG_CASE(OP2, 14, VAL); \
180 WRITE_WB_REG_CASE(OP2, 15, VAL)
181
182static u32 read_wb_reg(int n)
183{
184 u32 val = 0;
185
186 switch (n) {
187 GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val);
188 GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val);
189 GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val);
190 GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val);
191 default:
192 pr_warning("attempt to read from unknown breakpoint "
193 "register %d\n", n);
194 }
195
196 return val;
197}
198
199static void write_wb_reg(int n, u32 val)
200{
201 switch (n) {
202 GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val);
203 GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val);
204 GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val);
205 GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val);
206 default:
207 pr_warning("attempt to write to unknown breakpoint "
208 "register %d\n", n);
209 }
210 isb();
211}
212
213/*
214 * In order to access the breakpoint/watchpoint control registers,
215 * we must be running in debug monitor mode. Unfortunately, we can
216 * be put into halting debug mode at any time by an external debugger
217 * but there is nothing we can do to prevent that.
218 */
219static int enable_monitor_mode(void)
220{
221 u32 dscr;
222 int ret = 0;
223
224 ARM_DBG_READ(c1, 0, dscr);
225
226 /* Ensure that halting mode is disabled. */
227 if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN, "halting debug mode enabled."
228 "Unable to access hardware resources.")) {
229 ret = -EPERM;
230 goto out;
231 }
232
233 /* Write to the corresponding DSCR. */
234 switch (debug_arch) {
235 case ARM_DEBUG_ARCH_V6:
236 case ARM_DEBUG_ARCH_V6_1:
237 ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
238 break;
239 case ARM_DEBUG_ARCH_V7_ECP14:
240 ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
241 break;
242 default:
243 ret = -ENODEV;
244 goto out;
245 }
246
247 /* Check that the write made it through. */
248 ARM_DBG_READ(c1, 0, dscr);
249 if (WARN_ONCE(!(dscr & ARM_DSCR_MDBGEN),
250 "failed to enable monitor mode.")) {
251 ret = -EPERM;
252 }
253
254out:
255 return ret;
256}
257
258/*
259 * Check if 8-bit byte-address select is available.
260 * This clobbers WRP 0.
261 */
262static u8 get_max_wp_len(void)
263{
264 u32 ctrl_reg;
265 struct arch_hw_breakpoint_ctrl ctrl;
266 u8 size = 4;
267
268 if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14)
269 goto out;
270
271 if (enable_monitor_mode())
272 goto out;
273
274 memset(&ctrl, 0, sizeof(ctrl));
275 ctrl.len = ARM_BREAKPOINT_LEN_8;
276 ctrl_reg = encode_ctrl_reg(ctrl);
277
278 write_wb_reg(ARM_BASE_WVR, 0);
279 write_wb_reg(ARM_BASE_WCR, ctrl_reg);
280 if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg)
281 size = 8;
282
283out:
284 return size;
285}
286
287u8 arch_get_max_wp_len(void)
288{
289 return max_watchpoint_len;
290}
291
292/*
293 * Handler for reactivating a suspended watchpoint when the single
294 * step `mismatch' breakpoint is triggered.
295 */
296static void wp_single_step_handler(struct perf_event *bp, int unused,
297 struct perf_sample_data *data,
298 struct pt_regs *regs)
299{
300 perf_event_enable(counter_arch_bp(bp)->suspended_wp);
301 unregister_hw_breakpoint(bp);
302}
303
304static int bp_is_single_step(struct perf_event *bp)
305{
306 return bp->overflow_handler == wp_single_step_handler;
307}
308
309/*
310 * Install a perf counter breakpoint.
311 */
312int arch_install_hw_breakpoint(struct perf_event *bp)
313{
314 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
315 struct perf_event **slot, **slots;
316 int i, max_slots, ctrl_base, val_base, ret = 0;
317
318 /* Ensure that we are in monitor mode and halting mode is disabled. */
319 ret = enable_monitor_mode();
320 if (ret)
321 goto out;
322
323 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
324 /* Breakpoint */
325 ctrl_base = ARM_BASE_BCR;
326 val_base = ARM_BASE_BVR;
327 slots = __get_cpu_var(bp_on_reg);
328 max_slots = core_num_brps - 1;
329
330 if (bp_is_single_step(bp)) {
331 info->ctrl.mismatch = 1;
332 i = max_slots;
333 slots[i] = bp;
334 goto setup;
335 }
336 } else {
337 /* Watchpoint */
338 ctrl_base = ARM_BASE_WCR;
339 val_base = ARM_BASE_WVR;
340 slots = __get_cpu_var(wp_on_reg);
341 max_slots = core_num_wrps;
342 }
343
344 for (i = 0; i < max_slots; ++i) {
345 slot = &slots[i];
346
347 if (!*slot) {
348 *slot = bp;
349 break;
350 }
351 }
352
353 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot")) {
354 ret = -EBUSY;
355 goto out;
356 }
357
358setup:
359 /* Setup the address register. */
360 write_wb_reg(val_base + i, info->address);
361
362 /* Setup the control register. */
363 write_wb_reg(ctrl_base + i, encode_ctrl_reg(info->ctrl) | 0x1);
364
365out:
366 return ret;
367}
368
369void arch_uninstall_hw_breakpoint(struct perf_event *bp)
370{
371 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
372 struct perf_event **slot, **slots;
373 int i, max_slots, base;
374
375 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
376 /* Breakpoint */
377 base = ARM_BASE_BCR;
378 slots = __get_cpu_var(bp_on_reg);
379 max_slots = core_num_brps - 1;
380
381 if (bp_is_single_step(bp)) {
382 i = max_slots;
383 slots[i] = NULL;
384 goto reset;
385 }
386 } else {
387 /* Watchpoint */
388 base = ARM_BASE_WCR;
389 slots = __get_cpu_var(wp_on_reg);
390 max_slots = core_num_wrps;
391 }
392
393 /* Remove the breakpoint. */
394 for (i = 0; i < max_slots; ++i) {
395 slot = &slots[i];
396
397 if (*slot == bp) {
398 *slot = NULL;
399 break;
400 }
401 }
402
403 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
404 return;
405
406reset:
407 /* Reset the control register. */
408 write_wb_reg(base + i, 0);
409}
410
411static int get_hbp_len(u8 hbp_len)
412{
413 unsigned int len_in_bytes = 0;
414
415 switch (hbp_len) {
416 case ARM_BREAKPOINT_LEN_1:
417 len_in_bytes = 1;
418 break;
419 case ARM_BREAKPOINT_LEN_2:
420 len_in_bytes = 2;
421 break;
422 case ARM_BREAKPOINT_LEN_4:
423 len_in_bytes = 4;
424 break;
425 case ARM_BREAKPOINT_LEN_8:
426 len_in_bytes = 8;
427 break;
428 }
429
430 return len_in_bytes;
431}
432
433/*
434 * Check whether bp virtual address is in kernel space.
435 */
436int arch_check_bp_in_kernelspace(struct perf_event *bp)
437{
438 unsigned int len;
439 unsigned long va;
440 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
441
442 va = info->address;
443 len = get_hbp_len(info->ctrl.len);
444
445 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
446}
447
448/*
449 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
450 * Hopefully this will disappear when ptrace can bypass the conversion
451 * to generic breakpoint descriptions.
452 */
453int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
454 int *gen_len, int *gen_type)
455{
456 /* Type */
457 switch (ctrl.type) {
458 case ARM_BREAKPOINT_EXECUTE:
459 *gen_type = HW_BREAKPOINT_X;
460 break;
461 case ARM_BREAKPOINT_LOAD:
462 *gen_type = HW_BREAKPOINT_R;
463 break;
464 case ARM_BREAKPOINT_STORE:
465 *gen_type = HW_BREAKPOINT_W;
466 break;
467 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
468 *gen_type = HW_BREAKPOINT_RW;
469 break;
470 default:
471 return -EINVAL;
472 }
473
474 /* Len */
475 switch (ctrl.len) {
476 case ARM_BREAKPOINT_LEN_1:
477 *gen_len = HW_BREAKPOINT_LEN_1;
478 break;
479 case ARM_BREAKPOINT_LEN_2:
480 *gen_len = HW_BREAKPOINT_LEN_2;
481 break;
482 case ARM_BREAKPOINT_LEN_4:
483 *gen_len = HW_BREAKPOINT_LEN_4;
484 break;
485 case ARM_BREAKPOINT_LEN_8:
486 *gen_len = HW_BREAKPOINT_LEN_8;
487 break;
488 default:
489 return -EINVAL;
490 }
491
492 return 0;
493}
494
495/*
496 * Construct an arch_hw_breakpoint from a perf_event.
497 */
498static int arch_build_bp_info(struct perf_event *bp)
499{
500 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
501
502 /* Type */
503 switch (bp->attr.bp_type) {
504 case HW_BREAKPOINT_X:
505 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
506 break;
507 case HW_BREAKPOINT_R:
508 info->ctrl.type = ARM_BREAKPOINT_LOAD;
509 break;
510 case HW_BREAKPOINT_W:
511 info->ctrl.type = ARM_BREAKPOINT_STORE;
512 break;
513 case HW_BREAKPOINT_RW:
514 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
515 break;
516 default:
517 return -EINVAL;
518 }
519
520 /* Len */
521 switch (bp->attr.bp_len) {
522 case HW_BREAKPOINT_LEN_1:
523 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
524 break;
525 case HW_BREAKPOINT_LEN_2:
526 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
527 break;
528 case HW_BREAKPOINT_LEN_4:
529 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
530 break;
531 case HW_BREAKPOINT_LEN_8:
532 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
533 if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
534 && max_watchpoint_len >= 8)
535 break;
536 default:
537 return -EINVAL;
538 }
539
540 /* Address */
541 info->address = bp->attr.bp_addr;
542
543 /* Privilege */
544 info->ctrl.privilege = ARM_BREAKPOINT_USER;
545 if (arch_check_bp_in_kernelspace(bp) && !bp_is_single_step(bp))
546 info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
547
548 /* Enabled? */
549 info->ctrl.enabled = !bp->attr.disabled;
550
551 /* Mismatch */
552 info->ctrl.mismatch = 0;
553
554 return 0;
555}
556
557/*
558 * Validate the arch-specific HW Breakpoint register settings.
559 */
560int arch_validate_hwbkpt_settings(struct perf_event *bp)
561{
562 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
563 int ret = 0;
564 u32 bytelen, max_len, offset, alignment_mask = 0x3;
565
566 /* Build the arch_hw_breakpoint. */
567 ret = arch_build_bp_info(bp);
568 if (ret)
569 goto out;
570
571 /* Check address alignment. */
572 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
573 alignment_mask = 0x7;
574 if (info->address & alignment_mask) {
575 /*
576 * Try to fix the alignment. This may result in a length
577 * that is too large, so we must check for that.
578 */
579 bytelen = get_hbp_len(info->ctrl.len);
580 max_len = info->ctrl.type == ARM_BREAKPOINT_EXECUTE ? 4 :
581 max_watchpoint_len;
582
583 if (max_len >= 8)
584 offset = info->address & 0x7;
585 else
586 offset = info->address & 0x3;
587
588 if (bytelen > (1 << ((max_len - (offset + 1)) >> 1))) {
589 ret = -EFBIG;
590 goto out;
591 }
592
593 info->ctrl.len <<= offset;
594 info->address &= ~offset;
595
596 pr_debug("breakpoint alignment fixup: length = 0x%x, "
597 "address = 0x%x\n", info->ctrl.len, info->address);
598 }
599
600 /*
601 * Currently we rely on an overflow handler to take
602 * care of single-stepping the breakpoint when it fires.
603 * In the case of userspace breakpoints on a core with V7 debug,
604 * we can use the mismatch feature as a poor-man's hardware single-step.
605 */
606 if (WARN_ONCE(!bp->overflow_handler &&
607 (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_bps()),
608 "overflow handler required but none found")) {
609 ret = -EINVAL;
610 goto out;
611 }
612out:
613 return ret;
614}
615
616static void update_mismatch_flag(int idx, int flag)
617{
618 struct perf_event *bp = __get_cpu_var(bp_on_reg[idx]);
619 struct arch_hw_breakpoint *info;
620
621 if (bp == NULL)
622 return;
623
624 info = counter_arch_bp(bp);
625
626 /* Update the mismatch field to enter/exit `single-step' mode */
627 if (!bp->overflow_handler && info->ctrl.mismatch != flag) {
628 info->ctrl.mismatch = flag;
629 write_wb_reg(ARM_BASE_BCR + idx, encode_ctrl_reg(info->ctrl) | 0x1);
630 }
631}
632
633static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs)
634{
635 int i;
636 struct perf_event *bp, **slots = __get_cpu_var(wp_on_reg);
637 struct arch_hw_breakpoint *info;
638 struct perf_event_attr attr;
639
640 /* Without a disassembler, we can only handle 1 watchpoint. */
641 BUG_ON(core_num_wrps > 1);
642
643 hw_breakpoint_init(&attr);
644 attr.bp_addr = regs->ARM_pc & ~0x3;
645 attr.bp_len = HW_BREAKPOINT_LEN_4;
646 attr.bp_type = HW_BREAKPOINT_X;
647
648 for (i = 0; i < core_num_wrps; ++i) {
649 rcu_read_lock();
650
651 if (slots[i] == NULL) {
652 rcu_read_unlock();
653 continue;
654 }
655
656 /*
657 * The DFAR is an unknown value. Since we only allow a
658 * single watchpoint, we can set the trigger to the lowest
659 * possible faulting address.
660 */
661 info = counter_arch_bp(slots[i]);
662 info->trigger = slots[i]->attr.bp_addr;
663 pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
664 perf_bp_event(slots[i], regs);
665
666 /*
667 * If no overflow handler is present, insert a temporary
668 * mismatch breakpoint so we can single-step over the
669 * watchpoint trigger.
670 */
671 if (!slots[i]->overflow_handler) {
672 bp = register_user_hw_breakpoint(&attr,
673 wp_single_step_handler,
674 current);
675 counter_arch_bp(bp)->suspended_wp = slots[i];
676 perf_event_disable(slots[i]);
677 }
678
679 rcu_read_unlock();
680 }
681}
682
683static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
684{
685 int i;
686 int mismatch;
687 u32 ctrl_reg, val, addr;
688 struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg);
689 struct arch_hw_breakpoint *info;
690 struct arch_hw_breakpoint_ctrl ctrl;
691
692 /* The exception entry code places the amended lr in the PC. */
693 addr = regs->ARM_pc;
694
695 for (i = 0; i < core_num_brps; ++i) {
696 rcu_read_lock();
697
698 bp = slots[i];
699
700 if (bp == NULL) {
701 rcu_read_unlock();
702 continue;
703 }
704
705 mismatch = 0;
706
707 /* Check if the breakpoint value matches. */
708 val = read_wb_reg(ARM_BASE_BVR + i);
709 if (val != (addr & ~0x3))
710 goto unlock;
711
712 /* Possible match, check the byte address select to confirm. */
713 ctrl_reg = read_wb_reg(ARM_BASE_BCR + i);
714 decode_ctrl_reg(ctrl_reg, &ctrl);
715 if ((1 << (addr & 0x3)) & ctrl.len) {
716 mismatch = 1;
717 info = counter_arch_bp(bp);
718 info->trigger = addr;
719 }
720
721unlock:
722 if ((mismatch && !info->ctrl.mismatch) || bp_is_single_step(bp)) {
723 pr_debug("breakpoint fired: address = 0x%x\n", addr);
724 perf_bp_event(bp, regs);
725 }
726
727 update_mismatch_flag(i, mismatch);
728 rcu_read_unlock();
729 }
730}
731
732/*
733 * Called from either the Data Abort Handler [watchpoint] or the
734 * Prefetch Abort Handler [breakpoint].
735 */
736static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
737 struct pt_regs *regs)
738{
739 int ret = 1; /* Unhandled fault. */
740 u32 dscr;
741
742 /* We only handle watchpoints and hardware breakpoints. */
743 ARM_DBG_READ(c1, 0, dscr);
744
745 /* Perform perf callbacks. */
746 switch (ARM_DSCR_MOE(dscr)) {
747 case ARM_ENTRY_BREAKPOINT:
748 breakpoint_handler(addr, regs);
749 break;
750 case ARM_ENTRY_ASYNC_WATCHPOINT:
751 WARN_ON("Asynchronous watchpoint exception taken. "
752 "Debugging results may be unreliable");
753 case ARM_ENTRY_SYNC_WATCHPOINT:
754 watchpoint_handler(addr, regs);
755 break;
756 default:
757 goto out;
758 }
759
760 ret = 0;
761out:
762 return ret;
763}
764
765/*
766 * One-time initialisation.
767 */
768static void __init reset_ctrl_regs(void *unused)
769{
770 int i;
771
772 if (enable_monitor_mode())
773 return;
774
775 for (i = 0; i < core_num_brps; ++i) {
776 write_wb_reg(ARM_BASE_BCR + i, 0UL);
777 write_wb_reg(ARM_BASE_BVR + i, 0UL);
778 }
779
780 for (i = 0; i < core_num_wrps; ++i) {
781 write_wb_reg(ARM_BASE_WCR + i, 0UL);
782 write_wb_reg(ARM_BASE_WVR + i, 0UL);
783 }
784}
785
786static int __init arch_hw_breakpoint_init(void)
787{
788 int ret = 0;
789 u32 dscr;
790
791 debug_arch = get_debug_arch();
792
793 if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) {
794 pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
795 ret = -ENODEV;
796 goto out;
797 }
798
799 /* Determine how many BRPs/WRPs are available. */
800 core_num_brps = get_num_brps();
801 core_num_wrps = get_num_wrps();
802
803 pr_info("found %d breakpoint and %d watchpoint registers.\n",
804 core_num_brps, core_num_wrps);
805
806 if (core_has_mismatch_bps())
807 pr_info("1 breakpoint reserved for watchpoint single-step.\n");
808
809 ARM_DBG_READ(c1, 0, dscr);
810 if (dscr & ARM_DSCR_HDBGEN) {
811 pr_warning("halting debug mode enabled. Assuming maximum "
812 "watchpoint size of 4 bytes.");
813 } else {
814 /* Work out the maximum supported watchpoint length. */
815 max_watchpoint_len = get_max_wp_len();
816 pr_info("maximum watchpoint size is %u bytes.\n",
817 max_watchpoint_len);
818
819 /*
820 * Reset the breakpoint resources. We assume that a halting
821 * debugger will leave the world in a nice state for us.
822 */
823 smp_call_function(reset_ctrl_regs, NULL, 1);
824 reset_ctrl_regs(NULL);
825 }
826
827 /* Register debug fault handler. */
828 hook_fault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
829 "watchpoint debug exception");
830 hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
831 "breakpoint debug exception");
832
833out:
834 return ret;
835}
836arch_initcall(arch_hw_breakpoint_init);
837
838void hw_breakpoint_pmu_read(struct perf_event *bp)
839{
840}
841
842/*
843 * Dummy function to register with die_notifier.
844 */
845int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
846 unsigned long val, void *data)
847{
848 return NOTIFY_DONE;
849}
generated by cgit v1.2.2 (git 2.25.0) at 2025-11-13 05:29:33 -0500