1 /*
2  * This provides the callbacks and functions that KGDB needs to share between
3  * the core, I/O and arch-specific portions.
4  *
5  * Author: Amit Kale <amitkale@linsyssoft.com> and
6  *         Tom Rini <trini@kernel.crashing.org>
7  *
8  * 2001-2004 (c) Amit S. Kale and 2003-2005 (c) MontaVista Software, Inc.
9  * This file is licensed under the terms of the GNU General Public License
10  * version 2. This program is licensed "as is" without any warranty of any
11  * kind, whether express or implied.
12  */
13 #ifndef _KGDB_H_
14 #define _KGDB_H_
15 
16 #include <linux/linkage.h>
17 #include <linux/init.h>
18 #include <linux/atomic.h>
19 #include <linux/kprobes.h>
20 #ifdef CONFIG_HAVE_ARCH_KGDB
21 #include <asm/kgdb.h>
22 #endif
23 
24 #ifdef CONFIG_KGDB
25 struct pt_regs;
26 
27 /**
28  *	kgdb_skipexception - (optional) exit kgdb_handle_exception early
29  *	@exception: Exception vector number
30  *	@regs: Current &struct pt_regs.
31  *
32  *	On some architectures it is required to skip a breakpoint
33  *	exception when it occurs after a breakpoint has been removed.
34  *	This can be implemented in the architecture specific portion of kgdb.
35  */
36 extern int kgdb_skipexception(int exception, struct pt_regs *regs);
37 
38 struct tasklet_struct;
39 struct task_struct;
40 struct uart_port;
41 
42 /**
43  *	kgdb_breakpoint - compiled in breakpoint
44  *
45  *	This will be implemented as a static inline per architecture.  This
46  *	function is called by the kgdb core to execute an architecture
47  *	specific trap to cause kgdb to enter the exception processing.
48  *
49  */
50 void kgdb_breakpoint(void);
51 
52 extern int kgdb_connected;
53 extern int kgdb_io_module_registered;
54 
55 extern atomic_t			kgdb_setting_breakpoint;
56 extern atomic_t			kgdb_cpu_doing_single_step;
57 
58 extern struct task_struct	*kgdb_usethread;
59 extern struct task_struct	*kgdb_contthread;
60 
61 enum kgdb_bptype {
62 	BP_BREAKPOINT = 0,
63 	BP_HARDWARE_BREAKPOINT,
64 	BP_WRITE_WATCHPOINT,
65 	BP_READ_WATCHPOINT,
66 	BP_ACCESS_WATCHPOINT,
67 	BP_POKE_BREAKPOINT,
68 };
69 
70 enum kgdb_bpstate {
71 	BP_UNDEFINED = 0,
72 	BP_REMOVED,
73 	BP_SET,
74 	BP_ACTIVE
75 };
76 
77 struct kgdb_bkpt {
78 	unsigned long		bpt_addr;
79 	unsigned char		saved_instr[BREAK_INSTR_SIZE];
80 	enum kgdb_bptype	type;
81 	enum kgdb_bpstate	state;
82 };
83 
84 struct dbg_reg_def_t {
85 	char *name;
86 	int size;
87 	int offset;
88 };
89 
90 #ifndef DBG_MAX_REG_NUM
91 #define DBG_MAX_REG_NUM 0
92 #else
93 extern struct dbg_reg_def_t dbg_reg_def[];
94 extern char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs);
95 extern int dbg_set_reg(int regno, void *mem, struct pt_regs *regs);
96 #endif
97 #ifndef KGDB_MAX_BREAKPOINTS
98 # define KGDB_MAX_BREAKPOINTS	1000
99 #endif
100 
101 #define KGDB_HW_BREAKPOINT	1
102 
103 /*
104  * Functions each KGDB-supporting architecture must provide:
105  */
106 
107 /**
108  *	kgdb_arch_init - Perform any architecture specific initialization.
109  *
110  *	This function will handle the initialization of any architecture
111  *	specific callbacks.
112  */
113 extern int kgdb_arch_init(void);
114 
115 /**
116  *	kgdb_arch_exit - Perform any architecture specific uninitalization.
117  *
118  *	This function will handle the uninitalization of any architecture
119  *	specific callbacks, for dynamic registration and unregistration.
120  */
121 extern void kgdb_arch_exit(void);
122 
123 /**
124  *	pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
125  *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
126  *	@regs: The &struct pt_regs of the current process.
127  *
128  *	Convert the pt_regs in @regs into the format for registers that
129  *	GDB expects, stored in @gdb_regs.
130  */
131 extern void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs);
132 
133 /**
134  *	sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
135  *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
136  *	@p: The &struct task_struct of the desired process.
137  *
138  *	Convert the register values of the sleeping process in @p to
139  *	the format that GDB expects.
140  *	This function is called when kgdb does not have access to the
141  *	&struct pt_regs and therefore it should fill the gdb registers
142  *	@gdb_regs with what has	been saved in &struct thread_struct
143  *	thread field during switch_to.
144  */
145 extern void
146 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p);
147 
148 /**
149  *	gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
150  *	@gdb_regs: A pointer to hold the registers we've received from GDB.
151  *	@regs: A pointer to a &struct pt_regs to hold these values in.
152  *
153  *	Convert the GDB regs in @gdb_regs into the pt_regs, and store them
154  *	in @regs.
155  */
156 extern void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs);
157 
158 /**
159  *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
160  *	@vector: The error vector of the exception that happened.
161  *	@signo: The signal number of the exception that happened.
162  *	@err_code: The error code of the exception that happened.
163  *	@remcom_in_buffer: The buffer of the packet we have read.
164  *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
165  *	@regs: The &struct pt_regs of the current process.
166  *
167  *	This function MUST handle the 'c' and 's' command packets,
168  *	as well packets to set / remove a hardware breakpoint, if used.
169  *	If there are additional packets which the hardware needs to handle,
170  *	they are handled here.  The code should return -1 if it wants to
171  *	process more packets, and a %0 or %1 if it wants to exit from the
172  *	kgdb callback.
173  */
174 extern int
175 kgdb_arch_handle_exception(int vector, int signo, int err_code,
176 			   char *remcom_in_buffer,
177 			   char *remcom_out_buffer,
178 			   struct pt_regs *regs);
179 
180 /**
181  *	kgdb_arch_handle_qxfer_pkt - Handle architecture specific GDB XML
182  *				     packets.
183  *	@remcom_in_buffer: The buffer of the packet we have read.
184  *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
185  */
186 
187 extern void
188 kgdb_arch_handle_qxfer_pkt(char *remcom_in_buffer,
189 			   char *remcom_out_buffer);
190 
191 /**
192  *	kgdb_call_nmi_hook - Call kgdb_nmicallback() on the current CPU
193  *	@ignored: This parameter is only here to match the prototype.
194  *
195  *	If you're using the default implementation of kgdb_roundup_cpus()
196  *	this function will be called per CPU.  If you don't implement
197  *	kgdb_call_nmi_hook() a default will be used.
198  */
199 
200 extern void kgdb_call_nmi_hook(void *ignored);
201 
202 /**
203  *	kgdb_roundup_cpus - Get other CPUs into a holding pattern
204  *
205  *	On SMP systems, we need to get the attention of the other CPUs
206  *	and get them into a known state.  This should do what is needed
207  *	to get the other CPUs to call kgdb_wait(). Note that on some arches,
208  *	the NMI approach is not used for rounding up all the CPUs.  Normally
209  *	those architectures can just not implement this and get the default.
210  *
211  *	On non-SMP systems, this is not called.
212  */
213 extern void kgdb_roundup_cpus(void);
214 
215 /**
216  *	kgdb_arch_set_pc - Generic call back to the program counter
217  *	@regs: Current &struct pt_regs.
218  *  @pc: The new value for the program counter
219  *
220  *	This function handles updating the program counter and requires an
221  *	architecture specific implementation.
222  */
223 extern void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc);
224 
225 
226 /* Optional functions. */
227 extern int kgdb_validate_break_address(unsigned long addr);
228 extern int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt);
229 extern int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt);
230 
231 /**
232  *	kgdb_arch_late - Perform any architecture specific initialization.
233  *
234  *	This function will handle the late initialization of any
235  *	architecture specific callbacks.  This is an optional function for
236  *	handling things like late initialization of hw breakpoints.  The
237  *	default implementation does nothing.
238  */
239 extern void kgdb_arch_late(void);
240 
241 
242 /**
243  * struct kgdb_arch - Describe architecture specific values.
244  * @gdb_bpt_instr: The instruction to trigger a breakpoint.
245  * @flags: Flags for the breakpoint, currently just %KGDB_HW_BREAKPOINT.
246  * @set_breakpoint: Allow an architecture to specify how to set a software
247  * breakpoint.
248  * @remove_breakpoint: Allow an architecture to specify how to remove a
249  * software breakpoint.
250  * @set_hw_breakpoint: Allow an architecture to specify how to set a hardware
251  * breakpoint.
252  * @remove_hw_breakpoint: Allow an architecture to specify how to remove a
253  * hardware breakpoint.
254  * @disable_hw_break: Allow an architecture to specify how to disable
255  * hardware breakpoints for a single cpu.
256  * @remove_all_hw_break: Allow an architecture to specify how to remove all
257  * hardware breakpoints.
258  * @correct_hw_break: Allow an architecture to specify how to correct the
259  * hardware debug registers.
260  * @enable_nmi: Manage NMI-triggered entry to KGDB
261  */
262 struct kgdb_arch {
263 	unsigned char		gdb_bpt_instr[BREAK_INSTR_SIZE];
264 	unsigned long		flags;
265 
266 	int	(*set_breakpoint)(unsigned long, char *);
267 	int	(*remove_breakpoint)(unsigned long, char *);
268 	int	(*set_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
269 	int	(*remove_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
270 	void	(*disable_hw_break)(struct pt_regs *regs);
271 	void	(*remove_all_hw_break)(void);
272 	void	(*correct_hw_break)(void);
273 
274 	void	(*enable_nmi)(bool on);
275 };
276 
277 /**
278  * struct kgdb_io - Describe the interface for an I/O driver to talk with KGDB.
279  * @name: Name of the I/O driver.
280  * @read_char: Pointer to a function that will return one char.
281  * @write_char: Pointer to a function that will write one char.
282  * @flush: Pointer to a function that will flush any pending writes.
283  * @init: Pointer to a function that will initialize the device.
284  * @deinit: Pointer to a function that will deinit the device. Implies that
285  * this I/O driver is temporary and expects to be replaced. Called when
286  * an I/O driver is replaced or explicitly unregistered.
287  * @pre_exception: Pointer to a function that will do any prep work for
288  * the I/O driver.
289  * @post_exception: Pointer to a function that will do any cleanup work
290  * for the I/O driver.
291  * @cons: valid if the I/O device is a console; else NULL.
292  */
293 struct kgdb_io {
294 	const char		*name;
295 	int			(*read_char) (void);
296 	void			(*write_char) (u8);
297 	void			(*flush) (void);
298 	int			(*init) (void);
299 	void			(*deinit) (void);
300 	void			(*pre_exception) (void);
301 	void			(*post_exception) (void);
302 	struct console		*cons;
303 };
304 
305 extern const struct kgdb_arch		arch_kgdb_ops;
306 
307 extern unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs);
308 
309 #ifdef CONFIG_SERIAL_KGDB_NMI
310 extern int kgdb_register_nmi_console(void);
311 extern int kgdb_unregister_nmi_console(void);
312 extern bool kgdb_nmi_poll_knock(void);
313 #else
kgdb_register_nmi_console(void)314 static inline int kgdb_register_nmi_console(void) { return 0; }
kgdb_unregister_nmi_console(void)315 static inline int kgdb_unregister_nmi_console(void) { return 0; }
kgdb_nmi_poll_knock(void)316 static inline bool kgdb_nmi_poll_knock(void) { return true; }
317 #endif
318 
319 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
320 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
321 extern struct kgdb_io *dbg_io_ops;
322 
323 extern int kgdb_hex2long(char **ptr, unsigned long *long_val);
324 extern char *kgdb_mem2hex(char *mem, char *buf, int count);
325 extern int kgdb_hex2mem(char *buf, char *mem, int count);
326 
327 extern int kgdb_isremovedbreak(unsigned long addr);
328 extern int kgdb_has_hit_break(unsigned long addr);
329 
330 extern int
331 kgdb_handle_exception(int ex_vector, int signo, int err_code,
332 		      struct pt_regs *regs);
333 extern int kgdb_nmicallback(int cpu, void *regs);
334 extern int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code,
335 			  atomic_t *snd_rdy);
336 extern void gdbstub_exit(int status);
337 
338 /*
339  * kgdb and kprobes both use the same (kprobe) blocklist (which makes sense
340  * given they are both typically hooked up to the same trap meaning on most
341  * architectures one cannot be used to debug the other)
342  *
343  * However on architectures where kprobes is not (yet) implemented we permit
344  * breakpoints everywhere rather than blocking everything by default.
345  */
kgdb_within_blocklist(unsigned long addr)346 static inline bool kgdb_within_blocklist(unsigned long addr)
347 {
348 #ifdef CONFIG_KGDB_HONOUR_BLOCKLIST
349 	return within_kprobe_blacklist(addr);
350 #else
351 	return false;
352 #endif
353 }
354 
355 extern int			kgdb_single_step;
356 extern atomic_t			kgdb_active;
357 #define in_dbg_master() \
358 	(irqs_disabled() && (smp_processor_id() == atomic_read(&kgdb_active)))
359 extern bool dbg_is_early;
360 extern void __init dbg_late_init(void);
361 extern void kgdb_panic(const char *msg);
362 extern void kgdb_free_init_mem(void);
363 #else /* ! CONFIG_KGDB */
364 #define in_dbg_master() (0)
365 #define dbg_late_init()
kgdb_panic(const char * msg)366 static inline void kgdb_panic(const char *msg) {}
kgdb_free_init_mem(void)367 static inline void kgdb_free_init_mem(void) { }
368 #endif /* ! CONFIG_KGDB */
369 #endif /* _KGDB_H_ */
370