1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/arm/kernel/kgdb.c
4 *
5 * ARM KGDB support
6 *
7 * Copyright (c) 2002-2004 MontaVista Software, Inc
8 * Copyright (c) 2008 Wind River Systems, Inc.
9 *
10 * Authors: George Davis <davis_g@mvista.com>
11 * Deepak Saxena <dsaxena@plexity.net>
12 */
13 #include <linux/irq.h>
14 #include <linux/kdebug.h>
15 #include <linux/kgdb.h>
16 #include <linux/uaccess.h>
17
18 #include <asm/patch.h>
19 #include <asm/traps.h>
20
21 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
22 {
23 { "r0", 4, offsetof(struct pt_regs, ARM_r0)},
24 { "r1", 4, offsetof(struct pt_regs, ARM_r1)},
25 { "r2", 4, offsetof(struct pt_regs, ARM_r2)},
26 { "r3", 4, offsetof(struct pt_regs, ARM_r3)},
27 { "r4", 4, offsetof(struct pt_regs, ARM_r4)},
28 { "r5", 4, offsetof(struct pt_regs, ARM_r5)},
29 { "r6", 4, offsetof(struct pt_regs, ARM_r6)},
30 { "r7", 4, offsetof(struct pt_regs, ARM_r7)},
31 { "r8", 4, offsetof(struct pt_regs, ARM_r8)},
32 { "r9", 4, offsetof(struct pt_regs, ARM_r9)},
33 { "r10", 4, offsetof(struct pt_regs, ARM_r10)},
34 { "fp", 4, offsetof(struct pt_regs, ARM_fp)},
35 { "ip", 4, offsetof(struct pt_regs, ARM_ip)},
36 { "sp", 4, offsetof(struct pt_regs, ARM_sp)},
37 { "lr", 4, offsetof(struct pt_regs, ARM_lr)},
38 { "pc", 4, offsetof(struct pt_regs, ARM_pc)},
39 { "f0", 12, -1 },
40 { "f1", 12, -1 },
41 { "f2", 12, -1 },
42 { "f3", 12, -1 },
43 { "f4", 12, -1 },
44 { "f5", 12, -1 },
45 { "f6", 12, -1 },
46 { "f7", 12, -1 },
47 { "fps", 4, -1 },
48 { "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
49 };
50
51 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
52 {
53 if (regno >= DBG_MAX_REG_NUM || regno < 0)
54 return NULL;
55
56 if (dbg_reg_def[regno].offset != -1)
57 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
58 dbg_reg_def[regno].size);
59 else
60 memset(mem, 0, dbg_reg_def[regno].size);
61 return dbg_reg_def[regno].name;
62 }
63
64 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
65 {
66 if (regno >= DBG_MAX_REG_NUM || regno < 0)
67 return -EINVAL;
68
69 if (dbg_reg_def[regno].offset != -1)
70 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
71 dbg_reg_def[regno].size);
72 return 0;
73 }
74
75 void
76 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
77 {
78 struct thread_info *ti;
79 int regno;
80
81 /* Just making sure... */
82 if (task == NULL)
83 return;
84
85 /* Initialize to zero */
86 for (regno = 0; regno < GDB_MAX_REGS; regno++)
87 gdb_regs[regno] = 0;
88
89 /* Otherwise, we have only some registers from switch_to() */
90 ti = task_thread_info(task);
91 gdb_regs[_R4] = ti->cpu_context.r4;
92 gdb_regs[_R5] = ti->cpu_context.r5;
93 gdb_regs[_R6] = ti->cpu_context.r6;
94 gdb_regs[_R7] = ti->cpu_context.r7;
95 gdb_regs[_R8] = ti->cpu_context.r8;
96 gdb_regs[_R9] = ti->cpu_context.r9;
97 gdb_regs[_R10] = ti->cpu_context.sl;
98 gdb_regs[_FP] = ti->cpu_context.fp;
99 gdb_regs[_SPT] = ti->cpu_context.sp;
100 gdb_regs[_PC] = ti->cpu_context.pc;
101 }
102
103 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
104 {
105 regs->ARM_pc = pc;
106 }
107
108 static int compiled_break;
109
110 int kgdb_arch_handle_exception(int exception_vector, int signo,
111 int err_code, char *remcom_in_buffer,
112 char *remcom_out_buffer,
113 struct pt_regs *linux_regs)
114 {
115 unsigned long addr;
116 char *ptr;
117
118 switch (remcom_in_buffer[0]) {
119 case 'D':
120 case 'k':
121 case 'c':
122 /*
123 * Try to read optional parameter, pc unchanged if no parm.
124 * If this was a compiled breakpoint, we need to move
125 * to the next instruction or we will just breakpoint
126 * over and over again.
127 */
128 ptr = &remcom_in_buffer[1];
129 if (kgdb_hex2long(&ptr, &addr))
130 linux_regs->ARM_pc = addr;
131 else if (compiled_break == 1)
132 linux_regs->ARM_pc += 4;
133
134 compiled_break = 0;
135
136 return 0;
137 }
138
139 return -1;
140 }
141
142 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
143 {
144 kgdb_handle_exception(1, SIGTRAP, 0, regs);
145
146 return 0;
147 }
148
149 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
150 {
151 compiled_break = 1;
152 kgdb_handle_exception(1, SIGTRAP, 0, regs);
153
154 return 0;
155 }
156
157 static struct undef_hook kgdb_brkpt_arm_hook = {
158 .instr_mask = 0xffffffff,
159 .instr_val = KGDB_BREAKINST,
160 .cpsr_mask = PSR_T_BIT | MODE_MASK,
161 .cpsr_val = SVC_MODE,
162 .fn = kgdb_brk_fn
163 };
164
165 static struct undef_hook kgdb_brkpt_thumb_hook = {
166 .instr_mask = 0xffff,
167 .instr_val = KGDB_BREAKINST & 0xffff,
168 .cpsr_mask = PSR_T_BIT | MODE_MASK,
169 .cpsr_val = PSR_T_BIT | SVC_MODE,
170 .fn = kgdb_brk_fn
171 };
172
173 static struct undef_hook kgdb_compiled_brkpt_arm_hook = {
174 .instr_mask = 0xffffffff,
175 .instr_val = KGDB_COMPILED_BREAK,
176 .cpsr_mask = PSR_T_BIT | MODE_MASK,
177 .cpsr_val = SVC_MODE,
178 .fn = kgdb_compiled_brk_fn
179 };
180
181 static struct undef_hook kgdb_compiled_brkpt_thumb_hook = {
182 .instr_mask = 0xffff,
183 .instr_val = KGDB_COMPILED_BREAK & 0xffff,
184 .cpsr_mask = PSR_T_BIT | MODE_MASK,
185 .cpsr_val = PSR_T_BIT | SVC_MODE,
186 .fn = kgdb_compiled_brk_fn
187 };
188
189 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
190 {
191 struct pt_regs *regs = args->regs;
192
193 if (kgdb_handle_exception(1, args->signr, cmd, regs))
194 return NOTIFY_DONE;
195 return NOTIFY_STOP;
196 }
197 static int
198 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
199 {
200 unsigned long flags;
201 int ret;
202
203 local_irq_save(flags);
204 ret = __kgdb_notify(ptr, cmd);
205 local_irq_restore(flags);
206
207 return ret;
208 }
209
210 static struct notifier_block kgdb_notifier = {
211 .notifier_call = kgdb_notify,
212 .priority = -INT_MAX,
213 };
214
215
216 /**
217 * kgdb_arch_init - Perform any architecture specific initalization.
218 *
219 * This function will handle the initalization of any architecture
220 * specific callbacks.
221 */
222 int kgdb_arch_init(void)
223 {
224 int ret = register_die_notifier(&kgdb_notifier);
225
226 if (ret != 0)
227 return ret;
228
229 register_undef_hook(&kgdb_brkpt_arm_hook);
230 register_undef_hook(&kgdb_brkpt_thumb_hook);
231 register_undef_hook(&kgdb_compiled_brkpt_arm_hook);
232 register_undef_hook(&kgdb_compiled_brkpt_thumb_hook);
233
234 return 0;
235 }
236
237 /**
238 * kgdb_arch_exit - Perform any architecture specific uninitalization.
239 *
240 * This function will handle the uninitalization of any architecture
241 * specific callbacks, for dynamic registration and unregistration.
242 */
243 void kgdb_arch_exit(void)
244 {
245 unregister_undef_hook(&kgdb_brkpt_arm_hook);
246 unregister_undef_hook(&kgdb_brkpt_thumb_hook);
247 unregister_undef_hook(&kgdb_compiled_brkpt_arm_hook);
248 unregister_undef_hook(&kgdb_compiled_brkpt_thumb_hook);
249 unregister_die_notifier(&kgdb_notifier);
250 }
251
252 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
253 {
254 int err;
255
256 /* patch_text() only supports int-sized breakpoints */
257 BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
258
259 err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
260 BREAK_INSTR_SIZE);
261 if (err)
262 return err;
263
264 /* Machine is already stopped, so we can use __patch_text() directly */
265 __patch_text((void *)bpt->bpt_addr,
266 *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
267
268 return err;
269 }
270
271 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
272 {
273 /* Machine is already stopped, so we can use __patch_text() directly */
274 __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
275
276 return 0;
277 }
278
279 /*
280 * Register our undef instruction hooks with ARM undef core.
281 * We register a hook specifically looking for the KGB break inst
282 * and we handle the normal undef case within the do_undefinstr
283 * handler.
284 */
285 const struct kgdb_arch arch_kgdb_ops = {
286 #ifndef __ARMEB__
287 .gdb_bpt_instr = {0xfe, 0xde, 0xff, 0xe7}
288 #else /* ! __ARMEB__ */
289 .gdb_bpt_instr = {0xe7, 0xff, 0xde, 0xfe}
290 #endif
291 };
292
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