1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AArch64 KGDB support
4 *
5 * Based on arch/arm/kernel/kgdb.c
6 *
7 * Copyright (C) 2013 Cavium Inc.
8 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
9 */
10
11 #include <linux/bug.h>
12 #include <linux/irq.h>
13 #include <linux/kdebug.h>
14 #include <linux/kgdb.h>
15 #include <linux/kprobes.h>
16 #include <linux/sched/task_stack.h>
17
18 #include <asm/debug-monitors.h>
19 #include <asm/insn.h>
20 #include <asm/patching.h>
21 #include <asm/traps.h>
22
23 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
24 { "x0", 8, offsetof(struct pt_regs, regs[0])},
25 { "x1", 8, offsetof(struct pt_regs, regs[1])},
26 { "x2", 8, offsetof(struct pt_regs, regs[2])},
27 { "x3", 8, offsetof(struct pt_regs, regs[3])},
28 { "x4", 8, offsetof(struct pt_regs, regs[4])},
29 { "x5", 8, offsetof(struct pt_regs, regs[5])},
30 { "x6", 8, offsetof(struct pt_regs, regs[6])},
31 { "x7", 8, offsetof(struct pt_regs, regs[7])},
32 { "x8", 8, offsetof(struct pt_regs, regs[8])},
33 { "x9", 8, offsetof(struct pt_regs, regs[9])},
34 { "x10", 8, offsetof(struct pt_regs, regs[10])},
35 { "x11", 8, offsetof(struct pt_regs, regs[11])},
36 { "x12", 8, offsetof(struct pt_regs, regs[12])},
37 { "x13", 8, offsetof(struct pt_regs, regs[13])},
38 { "x14", 8, offsetof(struct pt_regs, regs[14])},
39 { "x15", 8, offsetof(struct pt_regs, regs[15])},
40 { "x16", 8, offsetof(struct pt_regs, regs[16])},
41 { "x17", 8, offsetof(struct pt_regs, regs[17])},
42 { "x18", 8, offsetof(struct pt_regs, regs[18])},
43 { "x19", 8, offsetof(struct pt_regs, regs[19])},
44 { "x20", 8, offsetof(struct pt_regs, regs[20])},
45 { "x21", 8, offsetof(struct pt_regs, regs[21])},
46 { "x22", 8, offsetof(struct pt_regs, regs[22])},
47 { "x23", 8, offsetof(struct pt_regs, regs[23])},
48 { "x24", 8, offsetof(struct pt_regs, regs[24])},
49 { "x25", 8, offsetof(struct pt_regs, regs[25])},
50 { "x26", 8, offsetof(struct pt_regs, regs[26])},
51 { "x27", 8, offsetof(struct pt_regs, regs[27])},
52 { "x28", 8, offsetof(struct pt_regs, regs[28])},
53 { "x29", 8, offsetof(struct pt_regs, regs[29])},
54 { "x30", 8, offsetof(struct pt_regs, regs[30])},
55 { "sp", 8, offsetof(struct pt_regs, sp)},
56 { "pc", 8, offsetof(struct pt_regs, pc)},
57 /*
58 * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
59 * protocol disagrees. Therefore we must extract only the lower
60 * 32-bits. Look for the big comment in asm/kgdb.h for more
61 * detail.
62 */
63 { "pstate", 4, offsetof(struct pt_regs, pstate)
64 #ifdef CONFIG_CPU_BIG_ENDIAN
65 + 4
66 #endif
67 },
68 { "v0", 16, -1 },
69 { "v1", 16, -1 },
70 { "v2", 16, -1 },
71 { "v3", 16, -1 },
72 { "v4", 16, -1 },
73 { "v5", 16, -1 },
74 { "v6", 16, -1 },
75 { "v7", 16, -1 },
76 { "v8", 16, -1 },
77 { "v9", 16, -1 },
78 { "v10", 16, -1 },
79 { "v11", 16, -1 },
80 { "v12", 16, -1 },
81 { "v13", 16, -1 },
82 { "v14", 16, -1 },
83 { "v15", 16, -1 },
84 { "v16", 16, -1 },
85 { "v17", 16, -1 },
86 { "v18", 16, -1 },
87 { "v19", 16, -1 },
88 { "v20", 16, -1 },
89 { "v21", 16, -1 },
90 { "v22", 16, -1 },
91 { "v23", 16, -1 },
92 { "v24", 16, -1 },
93 { "v25", 16, -1 },
94 { "v26", 16, -1 },
95 { "v27", 16, -1 },
96 { "v28", 16, -1 },
97 { "v29", 16, -1 },
98 { "v30", 16, -1 },
99 { "v31", 16, -1 },
100 { "fpsr", 4, -1 },
101 { "fpcr", 4, -1 },
102 };
103
104 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
105 {
106 if (regno >= DBG_MAX_REG_NUM || regno < 0)
107 return NULL;
108
109 if (dbg_reg_def[regno].offset != -1)
110 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
111 dbg_reg_def[regno].size);
112 else
113 memset(mem, 0, dbg_reg_def[regno].size);
114 return dbg_reg_def[regno].name;
115 }
116
117 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
118 {
119 if (regno >= DBG_MAX_REG_NUM || regno < 0)
120 return -EINVAL;
121
122 if (dbg_reg_def[regno].offset != -1)
123 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
124 dbg_reg_def[regno].size);
125 return 0;
126 }
127
128 void
129 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
130 {
131 struct cpu_context *cpu_context = &task->thread.cpu_context;
132
133 /* Initialize to zero */
134 memset((char *)gdb_regs, 0, NUMREGBYTES);
135
136 gdb_regs[19] = cpu_context->x19;
137 gdb_regs[20] = cpu_context->x20;
138 gdb_regs[21] = cpu_context->x21;
139 gdb_regs[22] = cpu_context->x22;
140 gdb_regs[23] = cpu_context->x23;
141 gdb_regs[24] = cpu_context->x24;
142 gdb_regs[25] = cpu_context->x25;
143 gdb_regs[26] = cpu_context->x26;
144 gdb_regs[27] = cpu_context->x27;
145 gdb_regs[28] = cpu_context->x28;
146 gdb_regs[29] = cpu_context->fp;
147
148 gdb_regs[31] = cpu_context->sp;
149 gdb_regs[32] = cpu_context->pc;
150 }
151
152 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
153 {
154 regs->pc = pc;
155 }
156
157 static int compiled_break;
158
159 static void kgdb_arch_update_addr(struct pt_regs *regs,
160 char *remcom_in_buffer)
161 {
162 unsigned long addr;
163 char *ptr;
164
165 ptr = &remcom_in_buffer[1];
166 if (kgdb_hex2long(&ptr, &addr))
167 kgdb_arch_set_pc(regs, addr);
168 else if (compiled_break == 1)
169 kgdb_arch_set_pc(regs, regs->pc + 4);
170
171 compiled_break = 0;
172 }
173
174 int kgdb_arch_handle_exception(int exception_vector, int signo,
175 int err_code, char *remcom_in_buffer,
176 char *remcom_out_buffer,
177 struct pt_regs *linux_regs)
178 {
179 int err;
180
181 switch (remcom_in_buffer[0]) {
182 case 'D':
183 case 'k':
184 /*
185 * Packet D (Detach), k (kill). No special handling
186 * is required here. Handle same as c packet.
187 */
188 case 'c':
189 /*
190 * Packet c (Continue) to continue executing.
191 * Set pc to required address.
192 * Try to read optional parameter and set pc.
193 * If this was a compiled breakpoint, we need to move
194 * to the next instruction else we will just breakpoint
195 * over and over again.
196 */
197 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
198 atomic_set(&kgdb_cpu_doing_single_step, -1);
199 kgdb_single_step = 0;
200
201 /*
202 * Received continue command, disable single step
203 */
204 if (kernel_active_single_step())
205 kernel_disable_single_step();
206
207 err = 0;
208 break;
209 case 's':
210 /*
211 * Update step address value with address passed
212 * with step packet.
213 * On debug exception return PC is copied to ELR
214 * So just update PC.
215 * If no step address is passed, resume from the address
216 * pointed by PC. Do not update PC
217 */
218 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
219 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
220 kgdb_single_step = 1;
221
222 /*
223 * Enable single step handling
224 */
225 if (!kernel_active_single_step())
226 kernel_enable_single_step(linux_regs);
227 else
228 kernel_rewind_single_step(linux_regs);
229 err = 0;
230 break;
231 default:
232 err = -1;
233 }
234 return err;
235 }
236
237 static int kgdb_brk_fn(struct pt_regs *regs, unsigned long esr)
238 {
239 kgdb_handle_exception(1, SIGTRAP, 0, regs);
240 return DBG_HOOK_HANDLED;
241 }
242 NOKPROBE_SYMBOL(kgdb_brk_fn)
243
244 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned long esr)
245 {
246 compiled_break = 1;
247 kgdb_handle_exception(1, SIGTRAP, 0, regs);
248
249 return DBG_HOOK_HANDLED;
250 }
251 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
252
253 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned long esr)
254 {
255 if (!kgdb_single_step)
256 return DBG_HOOK_ERROR;
257
258 kgdb_handle_exception(0, SIGTRAP, 0, regs);
259 return DBG_HOOK_HANDLED;
260 }
261 NOKPROBE_SYMBOL(kgdb_step_brk_fn);
262
263 static struct break_hook kgdb_brkpt_hook = {
264 .fn = kgdb_brk_fn,
265 .imm = KGDB_DYN_DBG_BRK_IMM,
266 };
267
268 static struct break_hook kgdb_compiled_brkpt_hook = {
269 .fn = kgdb_compiled_brk_fn,
270 .imm = KGDB_COMPILED_DBG_BRK_IMM,
271 };
272
273 static struct step_hook kgdb_step_hook = {
274 .fn = kgdb_step_brk_fn
275 };
276
277 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
278 {
279 struct pt_regs *regs = args->regs;
280
281 if (kgdb_handle_exception(1, args->signr, cmd, regs))
282 return NOTIFY_DONE;
283 return NOTIFY_STOP;
284 }
285
286 static int
287 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
288 {
289 unsigned long flags;
290 int ret;
291
292 local_irq_save(flags);
293 ret = __kgdb_notify(ptr, cmd);
294 local_irq_restore(flags);
295
296 return ret;
297 }
298
299 static struct notifier_block kgdb_notifier = {
300 .notifier_call = kgdb_notify,
301 /*
302 * Want to be lowest priority
303 */
304 .priority = -INT_MAX,
305 };
306
307 /*
308 * kgdb_arch_init - Perform any architecture specific initialization.
309 * This function will handle the initialization of any architecture
310 * specific callbacks.
311 */
312 int kgdb_arch_init(void)
313 {
314 int ret = register_die_notifier(&kgdb_notifier);
315
316 if (ret != 0)
317 return ret;
318
319 register_kernel_break_hook(&kgdb_brkpt_hook);
320 register_kernel_break_hook(&kgdb_compiled_brkpt_hook);
321 register_kernel_step_hook(&kgdb_step_hook);
322 return 0;
323 }
324
325 /*
326 * kgdb_arch_exit - Perform any architecture specific uninitalization.
327 * This function will handle the uninitalization of any architecture
328 * specific callbacks, for dynamic registration and unregistration.
329 */
330 void kgdb_arch_exit(void)
331 {
332 unregister_kernel_break_hook(&kgdb_brkpt_hook);
333 unregister_kernel_break_hook(&kgdb_compiled_brkpt_hook);
334 unregister_kernel_step_hook(&kgdb_step_hook);
335 unregister_die_notifier(&kgdb_notifier);
336 }
337
338 const struct kgdb_arch arch_kgdb_ops;
339
340 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
341 {
342 int err;
343
344 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE);
345
346 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr);
347 if (err)
348 return err;
349
350 return aarch64_insn_write((void *)bpt->bpt_addr,
351 (u32)AARCH64_BREAK_KGDB_DYN_DBG);
352 }
353
354 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
355 {
356 return aarch64_insn_write((void *)bpt->bpt_addr,
357 *(u32 *)bpt->saved_instr);
358 }
359
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