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10#include <linux/extable.h>
11#include <linux/kasan.h>
12#include <linux/kernel.h>
13#include <linux/kprobes.h>
14#include <linux/sched/debug.h>
15#include <linux/set_memory.h>
16#include <linux/slab.h>
17#include <linux/stop_machine.h>
18#include <linux/stringify.h>
19#include <linux/uaccess.h>
20#include <linux/vmalloc.h>
21
22#include <asm/cacheflush.h>
23#include <asm/daifflags.h>
24#include <asm/debug-monitors.h>
25#include <asm/insn.h>
26#include <asm/irq.h>
27#include <asm/patching.h>
28#include <asm/ptrace.h>
29#include <asm/sections.h>
30#include <asm/system_misc.h>
31#include <asm/traps.h>
32
33#include "decode-insn.h"
34
35DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
36DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
37
38static void __kprobes
39post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *);
40
41static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
42{
43 kprobe_opcode_t *addr = p->ainsn.api.insn;
44 void *addrs[] = {addr, addr + 1};
45 u32 insns[] = {p->opcode, BRK64_OPCODE_KPROBES_SS};
46
47
48 aarch64_insn_patch_text(addrs, insns, 2);
49
50 flush_icache_range((uintptr_t)addr, (uintptr_t)(addr + MAX_INSN_SIZE));
51
52
53
54
55 p->ainsn.api.restore = (unsigned long) p->addr +
56 sizeof(kprobe_opcode_t);
57}
58
59static void __kprobes arch_prepare_simulate(struct kprobe *p)
60{
61
62 p->ainsn.api.restore = 0;
63}
64
65static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
66{
67 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
68
69 if (p->ainsn.api.handler)
70 p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs);
71
72
73 post_kprobe_handler(p, kcb, regs);
74}
75
76int __kprobes arch_prepare_kprobe(struct kprobe *p)
77{
78 unsigned long probe_addr = (unsigned long)p->addr;
79
80 if (probe_addr & 0x3)
81 return -EINVAL;
82
83
84 p->opcode = le32_to_cpu(*p->addr);
85
86 if (search_exception_tables(probe_addr))
87 return -EINVAL;
88
89
90 switch (arm_kprobe_decode_insn(p->addr, &p->ainsn)) {
91 case INSN_REJECTED:
92 return -EINVAL;
93
94 case INSN_GOOD_NO_SLOT:
95 p->ainsn.api.insn = NULL;
96 break;
97
98 case INSN_GOOD:
99 p->ainsn.api.insn = get_insn_slot();
100 if (!p->ainsn.api.insn)
101 return -ENOMEM;
102 break;
103 }
104
105
106 if (p->ainsn.api.insn)
107 arch_prepare_ss_slot(p);
108 else
109 arch_prepare_simulate(p);
110
111 return 0;
112}
113
114void *alloc_insn_page(void)
115{
116 return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
117 GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS,
118 NUMA_NO_NODE, __builtin_return_address(0));
119}
120
121
122void __kprobes arch_arm_kprobe(struct kprobe *p)
123{
124 void *addr = p->addr;
125 u32 insn = BRK64_OPCODE_KPROBES;
126
127 aarch64_insn_patch_text(&addr, &insn, 1);
128}
129
130
131void __kprobes arch_disarm_kprobe(struct kprobe *p)
132{
133 void *addr = p->addr;
134
135 aarch64_insn_patch_text(&addr, &p->opcode, 1);
136}
137
138void __kprobes arch_remove_kprobe(struct kprobe *p)
139{
140 if (p->ainsn.api.insn) {
141 free_insn_slot(p->ainsn.api.insn, 0);
142 p->ainsn.api.insn = NULL;
143 }
144}
145
146static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
147{
148 kcb->prev_kprobe.kp = kprobe_running();
149 kcb->prev_kprobe.status = kcb->kprobe_status;
150}
151
152static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
153{
154 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
155 kcb->kprobe_status = kcb->prev_kprobe.status;
156}
157
158static void __kprobes set_current_kprobe(struct kprobe *p)
159{
160 __this_cpu_write(current_kprobe, p);
161}
162
163
164
165
166
167
168static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb,
169 struct pt_regs *regs)
170{
171 kcb->saved_irqflag = regs->pstate & DAIF_MASK;
172 regs->pstate |= DAIF_MASK;
173}
174
175static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb,
176 struct pt_regs *regs)
177{
178 regs->pstate &= ~DAIF_MASK;
179 regs->pstate |= kcb->saved_irqflag;
180}
181
182static void __kprobes setup_singlestep(struct kprobe *p,
183 struct pt_regs *regs,
184 struct kprobe_ctlblk *kcb, int reenter)
185{
186 unsigned long slot;
187
188 if (reenter) {
189 save_previous_kprobe(kcb);
190 set_current_kprobe(p);
191 kcb->kprobe_status = KPROBE_REENTER;
192 } else {
193 kcb->kprobe_status = KPROBE_HIT_SS;
194 }
195
196
197 if (p->ainsn.api.insn) {
198
199 slot = (unsigned long)p->ainsn.api.insn;
200
201 kprobes_save_local_irqflag(kcb, regs);
202 instruction_pointer_set(regs, slot);
203 } else {
204
205 arch_simulate_insn(p, regs);
206 }
207}
208
209static int __kprobes reenter_kprobe(struct kprobe *p,
210 struct pt_regs *regs,
211 struct kprobe_ctlblk *kcb)
212{
213 switch (kcb->kprobe_status) {
214 case KPROBE_HIT_SSDONE:
215 case KPROBE_HIT_ACTIVE:
216 kprobes_inc_nmissed_count(p);
217 setup_singlestep(p, regs, kcb, 1);
218 break;
219 case KPROBE_HIT_SS:
220 case KPROBE_REENTER:
221 pr_warn("Unrecoverable kprobe detected.\n");
222 dump_kprobe(p);
223 BUG();
224 break;
225 default:
226 WARN_ON(1);
227 return 0;
228 }
229
230 return 1;
231}
232
233static void __kprobes
234post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs)
235{
236
237 if (cur->ainsn.api.restore != 0)
238 instruction_pointer_set(regs, cur->ainsn.api.restore);
239
240
241 if (kcb->kprobe_status == KPROBE_REENTER) {
242 restore_previous_kprobe(kcb);
243 return;
244 }
245
246 kcb->kprobe_status = KPROBE_HIT_SSDONE;
247 if (cur->post_handler)
248 cur->post_handler(cur, regs, 0);
249
250 reset_current_kprobe();
251}
252
253int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
254{
255 struct kprobe *cur = kprobe_running();
256 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
257
258 switch (kcb->kprobe_status) {
259 case KPROBE_HIT_SS:
260 case KPROBE_REENTER:
261
262
263
264
265
266
267
268 instruction_pointer_set(regs, (unsigned long) cur->addr);
269 BUG_ON(!instruction_pointer(regs));
270
271 if (kcb->kprobe_status == KPROBE_REENTER) {
272 restore_previous_kprobe(kcb);
273 } else {
274 kprobes_restore_local_irqflag(kcb, regs);
275 reset_current_kprobe();
276 }
277
278 break;
279 case KPROBE_HIT_ACTIVE:
280 case KPROBE_HIT_SSDONE:
281
282
283
284
285 if (fixup_exception(regs))
286 return 1;
287 }
288 return 0;
289}
290
291static void __kprobes kprobe_handler(struct pt_regs *regs)
292{
293 struct kprobe *p, *cur_kprobe;
294 struct kprobe_ctlblk *kcb;
295 unsigned long addr = instruction_pointer(regs);
296
297 kcb = get_kprobe_ctlblk();
298 cur_kprobe = kprobe_running();
299
300 p = get_kprobe((kprobe_opcode_t *) addr);
301
302 if (p) {
303 if (cur_kprobe) {
304 if (reenter_kprobe(p, regs, kcb))
305 return;
306 } else {
307
308 set_current_kprobe(p);
309 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
310
311
312
313
314
315
316
317
318 if (!p->pre_handler || !p->pre_handler(p, regs)) {
319 setup_singlestep(p, regs, kcb, 0);
320 } else
321 reset_current_kprobe();
322 }
323 }
324
325
326
327
328
329
330
331
332}
333
334static int __kprobes
335kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned int esr)
336{
337 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
338 unsigned long addr = instruction_pointer(regs);
339 struct kprobe *cur = kprobe_running();
340
341 if (cur && (kcb->kprobe_status & (KPROBE_HIT_SS | KPROBE_REENTER)) &&
342 ((unsigned long)&cur->ainsn.api.insn[1] == addr)) {
343 kprobes_restore_local_irqflag(kcb, regs);
344 post_kprobe_handler(cur, kcb, regs);
345
346 return DBG_HOOK_HANDLED;
347 }
348
349
350 return DBG_HOOK_ERROR;
351}
352
353static struct break_hook kprobes_break_ss_hook = {
354 .imm = KPROBES_BRK_SS_IMM,
355 .fn = kprobe_breakpoint_ss_handler,
356};
357
358static int __kprobes
359kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
360{
361 kprobe_handler(regs);
362 return DBG_HOOK_HANDLED;
363}
364
365static struct break_hook kprobes_break_hook = {
366 .imm = KPROBES_BRK_IMM,
367 .fn = kprobe_breakpoint_handler,
368};
369
370
371
372
373
374int __init arch_populate_kprobe_blacklist(void)
375{
376 int ret;
377
378 ret = kprobe_add_area_blacklist((unsigned long)__entry_text_start,
379 (unsigned long)__entry_text_end);
380 if (ret)
381 return ret;
382 ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
383 (unsigned long)__irqentry_text_end);
384 if (ret)
385 return ret;
386 ret = kprobe_add_area_blacklist((unsigned long)__idmap_text_start,
387 (unsigned long)__idmap_text_end);
388 if (ret)
389 return ret;
390 ret = kprobe_add_area_blacklist((unsigned long)__hyp_text_start,
391 (unsigned long)__hyp_text_end);
392 if (ret || is_kernel_in_hyp_mode())
393 return ret;
394 ret = kprobe_add_area_blacklist((unsigned long)__hyp_idmap_text_start,
395 (unsigned long)__hyp_idmap_text_end);
396 return ret;
397}
398
399void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
400{
401 return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline,
402 (void *)kernel_stack_pointer(regs));
403}
404
405void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
406 struct pt_regs *regs)
407{
408 ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
409 ri->fp = (void *)kernel_stack_pointer(regs);
410
411
412 regs->regs[30] = (long)&kretprobe_trampoline;
413}
414
415int __kprobes arch_trampoline_kprobe(struct kprobe *p)
416{
417 return 0;
418}
419
420int __init arch_init_kprobes(void)
421{
422 register_kernel_break_hook(&kprobes_break_hook);
423 register_kernel_break_hook(&kprobes_break_ss_hook);
424
425 return 0;
426}
427