xref: /openbmc/linux/arch/arm64/kernel/kgdb.c (revision d7a3d85e)
1  /*
2   * AArch64 KGDB support
3   *
4   * Based on arch/arm/kernel/kgdb.c
5   *
6   * Copyright (C) 2013 Cavium Inc.
7   * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
8   *
9   * This program is free software; you can redistribute it and/or modify
10   * it under the terms of the GNU General Public License version 2 as
11   * published by the Free Software Foundation.
12   *
13   * This program is distributed in the hope that it will be useful,
14   * but WITHOUT ANY WARRANTY; without even the implied warranty of
15   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   * GNU General Public License for more details.
17   *
18   * You should have received a copy of the GNU General Public License
19   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
20   */
21  
22  #include <linux/irq.h>
23  #include <linux/kdebug.h>
24  #include <linux/kgdb.h>
25  #include <asm/traps.h>
26  
27  struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
28  	{ "x0", 8, offsetof(struct pt_regs, regs[0])},
29  	{ "x1", 8, offsetof(struct pt_regs, regs[1])},
30  	{ "x2", 8, offsetof(struct pt_regs, regs[2])},
31  	{ "x3", 8, offsetof(struct pt_regs, regs[3])},
32  	{ "x4", 8, offsetof(struct pt_regs, regs[4])},
33  	{ "x5", 8, offsetof(struct pt_regs, regs[5])},
34  	{ "x6", 8, offsetof(struct pt_regs, regs[6])},
35  	{ "x7", 8, offsetof(struct pt_regs, regs[7])},
36  	{ "x8", 8, offsetof(struct pt_regs, regs[8])},
37  	{ "x9", 8, offsetof(struct pt_regs, regs[9])},
38  	{ "x10", 8, offsetof(struct pt_regs, regs[10])},
39  	{ "x11", 8, offsetof(struct pt_regs, regs[11])},
40  	{ "x12", 8, offsetof(struct pt_regs, regs[12])},
41  	{ "x13", 8, offsetof(struct pt_regs, regs[13])},
42  	{ "x14", 8, offsetof(struct pt_regs, regs[14])},
43  	{ "x15", 8, offsetof(struct pt_regs, regs[15])},
44  	{ "x16", 8, offsetof(struct pt_regs, regs[16])},
45  	{ "x17", 8, offsetof(struct pt_regs, regs[17])},
46  	{ "x18", 8, offsetof(struct pt_regs, regs[18])},
47  	{ "x19", 8, offsetof(struct pt_regs, regs[19])},
48  	{ "x20", 8, offsetof(struct pt_regs, regs[20])},
49  	{ "x21", 8, offsetof(struct pt_regs, regs[21])},
50  	{ "x22", 8, offsetof(struct pt_regs, regs[22])},
51  	{ "x23", 8, offsetof(struct pt_regs, regs[23])},
52  	{ "x24", 8, offsetof(struct pt_regs, regs[24])},
53  	{ "x25", 8, offsetof(struct pt_regs, regs[25])},
54  	{ "x26", 8, offsetof(struct pt_regs, regs[26])},
55  	{ "x27", 8, offsetof(struct pt_regs, regs[27])},
56  	{ "x28", 8, offsetof(struct pt_regs, regs[28])},
57  	{ "x29", 8, offsetof(struct pt_regs, regs[29])},
58  	{ "x30", 8, offsetof(struct pt_regs, regs[30])},
59  	{ "sp", 8, offsetof(struct pt_regs, sp)},
60  	{ "pc", 8, offsetof(struct pt_regs, pc)},
61  	{ "pstate", 8, offsetof(struct pt_regs, pstate)},
62  	{ "v0", 16, -1 },
63  	{ "v1", 16, -1 },
64  	{ "v2", 16, -1 },
65  	{ "v3", 16, -1 },
66  	{ "v4", 16, -1 },
67  	{ "v5", 16, -1 },
68  	{ "v6", 16, -1 },
69  	{ "v7", 16, -1 },
70  	{ "v8", 16, -1 },
71  	{ "v9", 16, -1 },
72  	{ "v10", 16, -1 },
73  	{ "v11", 16, -1 },
74  	{ "v12", 16, -1 },
75  	{ "v13", 16, -1 },
76  	{ "v14", 16, -1 },
77  	{ "v15", 16, -1 },
78  	{ "v16", 16, -1 },
79  	{ "v17", 16, -1 },
80  	{ "v18", 16, -1 },
81  	{ "v19", 16, -1 },
82  	{ "v20", 16, -1 },
83  	{ "v21", 16, -1 },
84  	{ "v22", 16, -1 },
85  	{ "v23", 16, -1 },
86  	{ "v24", 16, -1 },
87  	{ "v25", 16, -1 },
88  	{ "v26", 16, -1 },
89  	{ "v27", 16, -1 },
90  	{ "v28", 16, -1 },
91  	{ "v29", 16, -1 },
92  	{ "v30", 16, -1 },
93  	{ "v31", 16, -1 },
94  	{ "fpsr", 4, -1 },
95  	{ "fpcr", 4, -1 },
96  };
97  
98  char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
99  {
100  	if (regno >= DBG_MAX_REG_NUM || regno < 0)
101  		return NULL;
102  
103  	if (dbg_reg_def[regno].offset != -1)
104  		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
105  		       dbg_reg_def[regno].size);
106  	else
107  		memset(mem, 0, dbg_reg_def[regno].size);
108  	return dbg_reg_def[regno].name;
109  }
110  
111  int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
112  {
113  	if (regno >= DBG_MAX_REG_NUM || regno < 0)
114  		return -EINVAL;
115  
116  	if (dbg_reg_def[regno].offset != -1)
117  		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
118  		       dbg_reg_def[regno].size);
119  	return 0;
120  }
121  
122  void
123  sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
124  {
125  	struct pt_regs *thread_regs;
126  
127  	/* Initialize to zero */
128  	memset((char *)gdb_regs, 0, NUMREGBYTES);
129  	thread_regs = task_pt_regs(task);
130  	memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
131  }
132  
133  void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
134  {
135  	regs->pc = pc;
136  }
137  
138  static int compiled_break;
139  
140  static void kgdb_arch_update_addr(struct pt_regs *regs,
141  				char *remcom_in_buffer)
142  {
143  	unsigned long addr;
144  	char *ptr;
145  
146  	ptr = &remcom_in_buffer[1];
147  	if (kgdb_hex2long(&ptr, &addr))
148  		kgdb_arch_set_pc(regs, addr);
149  	else if (compiled_break == 1)
150  		kgdb_arch_set_pc(regs, regs->pc + 4);
151  
152  	compiled_break = 0;
153  }
154  
155  int kgdb_arch_handle_exception(int exception_vector, int signo,
156  			       int err_code, char *remcom_in_buffer,
157  			       char *remcom_out_buffer,
158  			       struct pt_regs *linux_regs)
159  {
160  	int err;
161  
162  	switch (remcom_in_buffer[0]) {
163  	case 'D':
164  	case 'k':
165  		/*
166  		 * Packet D (Detach), k (kill). No special handling
167  		 * is required here. Handle same as c packet.
168  		 */
169  	case 'c':
170  		/*
171  		 * Packet c (Continue) to continue executing.
172  		 * Set pc to required address.
173  		 * Try to read optional parameter and set pc.
174  		 * If this was a compiled breakpoint, we need to move
175  		 * to the next instruction else we will just breakpoint
176  		 * over and over again.
177  		 */
178  		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
179  		atomic_set(&kgdb_cpu_doing_single_step, -1);
180  		kgdb_single_step =  0;
181  
182  		/*
183  		 * Received continue command, disable single step
184  		 */
185  		if (kernel_active_single_step())
186  			kernel_disable_single_step();
187  
188  		err = 0;
189  		break;
190  	case 's':
191  		/*
192  		 * Update step address value with address passed
193  		 * with step packet.
194  		 * On debug exception return PC is copied to ELR
195  		 * So just update PC.
196  		 * If no step address is passed, resume from the address
197  		 * pointed by PC. Do not update PC
198  		 */
199  		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
200  		atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
201  		kgdb_single_step =  1;
202  
203  		/*
204  		 * Enable single step handling
205  		 */
206  		if (!kernel_active_single_step())
207  			kernel_enable_single_step(linux_regs);
208  		err = 0;
209  		break;
210  	default:
211  		err = -1;
212  	}
213  	return err;
214  }
215  
216  static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
217  {
218  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
219  	return 0;
220  }
221  
222  static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
223  {
224  	compiled_break = 1;
225  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
226  
227  	return 0;
228  }
229  
230  static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
231  {
232  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
233  	return 0;
234  }
235  
236  static struct break_hook kgdb_brkpt_hook = {
237  	.esr_mask	= 0xffffffff,
238  	.esr_val	= DBG_ESR_VAL_BRK(KGDB_DYN_DBG_BRK_IMM),
239  	.fn		= kgdb_brk_fn
240  };
241  
242  static struct break_hook kgdb_compiled_brkpt_hook = {
243  	.esr_mask	= 0xffffffff,
244  	.esr_val	= DBG_ESR_VAL_BRK(KGDB_COMPILED_DBG_BRK_IMM),
245  	.fn		= kgdb_compiled_brk_fn
246  };
247  
248  static struct step_hook kgdb_step_hook = {
249  	.fn		= kgdb_step_brk_fn
250  };
251  
252  static void kgdb_call_nmi_hook(void *ignored)
253  {
254  	kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
255  }
256  
257  void kgdb_roundup_cpus(unsigned long flags)
258  {
259  	local_irq_enable();
260  	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
261  	local_irq_disable();
262  }
263  
264  static int __kgdb_notify(struct die_args *args, unsigned long cmd)
265  {
266  	struct pt_regs *regs = args->regs;
267  
268  	if (kgdb_handle_exception(1, args->signr, cmd, regs))
269  		return NOTIFY_DONE;
270  	return NOTIFY_STOP;
271  }
272  
273  static int
274  kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
275  {
276  	unsigned long flags;
277  	int ret;
278  
279  	local_irq_save(flags);
280  	ret = __kgdb_notify(ptr, cmd);
281  	local_irq_restore(flags);
282  
283  	return ret;
284  }
285  
286  static struct notifier_block kgdb_notifier = {
287  	.notifier_call	= kgdb_notify,
288  	/*
289  	 * Want to be lowest priority
290  	 */
291  	.priority	= -INT_MAX,
292  };
293  
294  /*
295   * kgdb_arch_init - Perform any architecture specific initalization.
296   * This function will handle the initalization of any architecture
297   * specific callbacks.
298   */
299  int kgdb_arch_init(void)
300  {
301  	int ret = register_die_notifier(&kgdb_notifier);
302  
303  	if (ret != 0)
304  		return ret;
305  
306  	register_break_hook(&kgdb_brkpt_hook);
307  	register_break_hook(&kgdb_compiled_brkpt_hook);
308  	register_step_hook(&kgdb_step_hook);
309  	return 0;
310  }
311  
312  /*
313   * kgdb_arch_exit - Perform any architecture specific uninitalization.
314   * This function will handle the uninitalization of any architecture
315   * specific callbacks, for dynamic registration and unregistration.
316   */
317  void kgdb_arch_exit(void)
318  {
319  	unregister_break_hook(&kgdb_brkpt_hook);
320  	unregister_break_hook(&kgdb_compiled_brkpt_hook);
321  	unregister_step_hook(&kgdb_step_hook);
322  	unregister_die_notifier(&kgdb_notifier);
323  }
324  
325  /*
326   * ARM instructions are always in LE.
327   * Break instruction is encoded in LE format
328   */
329  struct kgdb_arch arch_kgdb_ops = {
330  	.gdb_bpt_instr = {
331  		KGDB_DYN_BRK_INS_BYTE0,
332  		KGDB_DYN_BRK_INS_BYTE1,
333  		KGDB_DYN_BRK_INS_BYTE2,
334  		KGDB_DYN_BRK_INS_BYTE3,
335  	}
336  };
337