1 /*-
2 * SPDX-License-Identifier: MIT-CMU
3 *
4 * Mach Operating System
5 * Copyright (c) 1991,1990 Carnegie Mellon University
6 * All Rights Reserved.
7 *
8 * Permission to use, copy, modify and distribute this software and its
9 * documentation is hereby granted, provided that both the copyright
10 * notice and this permission notice appear in all copies of the
11 * software, derivative works or modified versions, and any portions
12 * thereof, and that both notices appear in supporting documentation.
13 *
14 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
15 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
16 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17 *
18 * Carnegie Mellon requests users of this software to return to
19 *
20 * Software Distribution Coordinator or [email protected]
21 * School of Computer Science
22 * Carnegie Mellon University
23 * Pittsburgh PA 15213-3890
24 *
25 * any improvements or extensions that they make and grant Carnegie the
26 * rights to redistribute these changes.
27 */
28 /*
29 * Author: David B. Golub, Carnegie Mellon University
30 * Date: 7/90
31 */
32
33 /*
34 * Commands to run process.
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39
40 #include <sys/param.h>
41 #include <sys/kdb.h>
42 #include <sys/proc.h>
43 #include <sys/systm.h>
44
45 #include <machine/kdb.h>
46 #include <machine/pcb.h>
47
48 #include <vm/vm.h>
49
50 #include <ddb/ddb.h>
51 #include <ddb/db_access.h>
52 #include <ddb/db_break.h>
53 #include <ddb/db_command.h>
54
55 #define STEP_ONCE 1
56 #define STEP_RETURN 2
57 #define STEP_CALLT 3
58 #define STEP_CONTINUE 4
59 #define STEP_INVISIBLE 5
60 #define STEP_COUNT 6
61 static int db_run_mode = STEP_CONTINUE;
62
63 static bool db_sstep_multiple;
64 static bool db_sstep_print;
65 static int db_loop_count;
66 static int db_call_depth;
67
68 int db_inst_count;
69 int db_load_count;
70 int db_store_count;
71
72 #ifdef SOFTWARE_SSTEP
73 db_breakpoint_t db_not_taken_bkpt = 0;
74 db_breakpoint_t db_taken_bkpt = 0;
75 #endif
76
77 #ifndef db_set_single_step
78 void db_set_single_step(void);
79 #endif
80 #ifndef db_clear_single_step
81 void db_clear_single_step(void);
82 #endif
83 #ifndef db_pc_is_singlestep
84 static bool
db_pc_is_singlestep(db_addr_t pc)85 db_pc_is_singlestep(db_addr_t pc)
86 {
87 #ifdef SOFTWARE_SSTEP
88 if ((db_not_taken_bkpt != 0 && pc == db_not_taken_bkpt->address)
89 || (db_taken_bkpt != 0 && pc == db_taken_bkpt->address))
90 return (true);
91 #endif
92 return (false);
93 }
94 #endif
95
96 bool
db_stop_at_pc(int type,int code,bool * is_breakpoint,bool * is_watchpoint)97 db_stop_at_pc(int type, int code, bool *is_breakpoint, bool *is_watchpoint)
98 {
99 db_addr_t pc;
100 db_breakpoint_t bkpt;
101
102 *is_breakpoint = IS_BREAKPOINT_TRAP(type, code);
103 *is_watchpoint = IS_WATCHPOINT_TRAP(type, code);
104 pc = PC_REGS();
105 if (db_pc_is_singlestep(pc))
106 *is_breakpoint = false;
107
108 db_clear_single_step();
109 db_clear_breakpoints();
110 db_clear_watchpoints();
111
112 #ifdef FIXUP_PC_AFTER_BREAK
113 if (*is_breakpoint) {
114 /*
115 * Breakpoint trap. Fix up the PC if the
116 * machine requires it.
117 */
118 FIXUP_PC_AFTER_BREAK
119 pc = PC_REGS();
120 }
121 #endif
122
123 /*
124 * Now check for a breakpoint at this address.
125 */
126 bkpt = db_find_breakpoint_here(pc);
127 if (bkpt) {
128 if (--bkpt->count == 0) {
129 bkpt->count = bkpt->init_count;
130 *is_breakpoint = true;
131 return (true); /* stop here */
132 }
133 return (false); /* continue the countdown */
134 } else if (*is_breakpoint) {
135 #ifdef BKPT_SKIP
136 BKPT_SKIP;
137 #endif
138 }
139
140 *is_breakpoint = false; /* might be a breakpoint, but not ours */
141
142 /*
143 * If not stepping, then silently ignore single-step traps
144 * (except for clearing the single-step-flag above).
145 *
146 * If stepping, then abort if the trap type is unexpected.
147 * Breakpoints owned by us are expected and were handled above.
148 * Single-steps are expected and are handled below. All others
149 * are unexpected.
150 *
151 * Only do either of these if the MD layer claims to classify
152 * single-step traps unambiguously (by defining IS_SSTEP_TRAP).
153 * Otherwise, fall through to the bad historical behaviour
154 * given by turning unexpected traps into expected traps: if not
155 * stepping, then expect only breakpoints and stop, and if
156 * stepping, then expect only single-steps and step.
157 */
158 #ifdef IS_SSTEP_TRAP
159 if (db_run_mode == STEP_CONTINUE && IS_SSTEP_TRAP(type, code))
160 return (false);
161 if (db_run_mode != STEP_CONTINUE && !IS_SSTEP_TRAP(type, code)) {
162 printf("Stepping aborted\n");
163 return (true);
164 }
165 #endif
166
167 if (db_run_mode == STEP_INVISIBLE) {
168 db_run_mode = STEP_CONTINUE;
169 return (false); /* continue */
170 }
171 if (db_run_mode == STEP_COUNT) {
172 return (false); /* continue */
173 }
174 if (db_run_mode == STEP_ONCE) {
175 if (--db_loop_count > 0) {
176 if (db_sstep_print) {
177 db_printf("\t\t");
178 db_print_loc_and_inst(pc);
179 }
180 return (false); /* continue */
181 }
182 }
183 if (db_run_mode == STEP_RETURN) {
184 /* continue until matching return */
185 db_expr_t ins;
186
187 ins = db_get_value(pc, sizeof(int), false);
188 if (!inst_trap_return(ins) &&
189 (!inst_return(ins) || --db_call_depth != 0)) {
190 if (db_sstep_print) {
191 if (inst_call(ins) || inst_return(ins)) {
192 int i;
193
194 db_printf("[after %6d] ", db_inst_count);
195 for (i = db_call_depth; --i > 0; )
196 db_printf(" ");
197 db_print_loc_and_inst(pc);
198 }
199 }
200 if (inst_call(ins))
201 db_call_depth++;
202 return (false); /* continue */
203 }
204 }
205 if (db_run_mode == STEP_CALLT) {
206 /* continue until call or return */
207 db_expr_t ins;
208
209 ins = db_get_value(pc, sizeof(int), false);
210 if (!inst_call(ins) &&
211 !inst_return(ins) &&
212 !inst_trap_return(ins)) {
213 return (false); /* continue */
214 }
215 }
216 return (true);
217 }
218
219 void
db_restart_at_pc(bool watchpt)220 db_restart_at_pc(bool watchpt)
221 {
222 db_addr_t pc = PC_REGS();
223
224 if ((db_run_mode == STEP_COUNT) ||
225 ((db_run_mode == STEP_ONCE) && db_sstep_multiple) ||
226 (db_run_mode == STEP_RETURN) ||
227 (db_run_mode == STEP_CALLT)) {
228 /*
229 * We are about to execute this instruction,
230 * so count it now.
231 */
232 #ifdef SOFTWARE_SSTEP
233 db_expr_t ins =
234 #endif
235 db_get_value(pc, sizeof(int), false);
236 db_inst_count++;
237 db_load_count += inst_load(ins);
238 db_store_count += inst_store(ins);
239 #ifdef SOFTWARE_SSTEP
240 /* XXX works on mips, but... */
241 if (inst_branch(ins) || inst_call(ins)) {
242 ins = db_get_value(next_instr_address(pc,1),
243 sizeof(int), false);
244 db_inst_count++;
245 db_load_count += inst_load(ins);
246 db_store_count += inst_store(ins);
247 }
248 #endif /* SOFTWARE_SSTEP */
249 }
250
251 if (db_run_mode == STEP_CONTINUE) {
252 if (watchpt || db_find_breakpoint_here(pc)) {
253 /*
254 * Step over breakpoint/watchpoint.
255 */
256 db_run_mode = STEP_INVISIBLE;
257 db_set_single_step();
258 } else {
259 db_set_breakpoints();
260 db_set_watchpoints();
261 }
262 } else {
263 db_set_single_step();
264 }
265 }
266
267 #ifdef SOFTWARE_SSTEP
268 /*
269 * Software implementation of single-stepping.
270 * If your machine does not have a trace mode
271 * similar to the vax or sun ones you can use
272 * this implementation, done for the mips.
273 * Just define the above conditional and provide
274 * the functions/macros defined below.
275 *
276 * extern bool
277 * inst_branch(), returns true if the instruction might branch
278 * extern unsigned
279 * branch_taken(), return the address the instruction might
280 * branch to
281 * db_getreg_val(); return the value of a user register,
282 * as indicated in the hardware instruction
283 * encoding, e.g. 8 for r8
284 *
285 * next_instr_address(pc,bd) returns the address of the first
286 * instruction following the one at "pc",
287 * which is either in the taken path of
288 * the branch (bd==1) or not. This is
289 * for machines (mips) with branch delays.
290 *
291 * A single-step may involve at most 2 breakpoints -
292 * one for branch-not-taken and one for branch taken.
293 * If one of these addresses does not already have a breakpoint,
294 * we allocate a breakpoint and save it here.
295 * These breakpoints are deleted on return.
296 */
297
298 void
db_set_single_step(void)299 db_set_single_step(void)
300 {
301 db_addr_t pc = PC_REGS(), brpc;
302 unsigned inst;
303
304 /*
305 * User was stopped at pc, e.g. the instruction
306 * at pc was not executed.
307 */
308 inst = db_get_value(pc, sizeof(int), false);
309 if (inst_branch(inst) || inst_call(inst) || inst_return(inst)) {
310 brpc = branch_taken(inst, pc);
311 if (brpc != pc) { /* self-branches are hopeless */
312 db_taken_bkpt = db_set_temp_breakpoint(brpc);
313 }
314 pc = next_instr_address(pc, 1);
315 }
316 pc = next_instr_address(pc, 0);
317 db_not_taken_bkpt = db_set_temp_breakpoint(pc);
318 }
319
320 void
db_clear_single_step(void)321 db_clear_single_step(void)
322 {
323
324 if (db_not_taken_bkpt != 0) {
325 db_delete_temp_breakpoint(db_not_taken_bkpt);
326 db_not_taken_bkpt = 0;
327 }
328 if (db_taken_bkpt != 0) {
329 db_delete_temp_breakpoint(db_taken_bkpt);
330 db_taken_bkpt = 0;
331 }
332 }
333
334 #endif /* SOFTWARE_SSTEP */
335
336 /* single-step */
337 /*ARGSUSED*/
338 void
db_single_step_cmd(db_expr_t addr,bool have_addr,db_expr_t count,char * modif)339 db_single_step_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
340 {
341 bool print = false;
342
343 if (count == -1)
344 count = 1;
345
346 if (modif[0] == 'p')
347 print = true;
348
349 db_run_mode = STEP_ONCE;
350 db_loop_count = count;
351 db_sstep_multiple = (count != 1);
352 db_sstep_print = print;
353 db_inst_count = 0;
354 db_load_count = 0;
355 db_store_count = 0;
356
357 db_cmd_loop_done = 1;
358 }
359
360 /* trace and print until call/return */
361 /*ARGSUSED*/
362 void
db_trace_until_call_cmd(db_expr_t addr,bool have_addr,db_expr_t count,char * modif)363 db_trace_until_call_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
364 char *modif)
365 {
366 bool print = false;
367
368 if (modif[0] == 'p')
369 print = true;
370
371 db_run_mode = STEP_CALLT;
372 db_sstep_print = print;
373 db_inst_count = 0;
374 db_load_count = 0;
375 db_store_count = 0;
376
377 db_cmd_loop_done = 1;
378 }
379
380 /*ARGSUSED*/
381 void
db_trace_until_matching_cmd(db_expr_t addr,bool have_addr,db_expr_t count,char * modif)382 db_trace_until_matching_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
383 char *modif)
384 {
385 bool print = false;
386
387 if (modif[0] == 'p')
388 print = true;
389
390 db_run_mode = STEP_RETURN;
391 db_call_depth = 1;
392 db_sstep_print = print;
393 db_inst_count = 0;
394 db_load_count = 0;
395 db_store_count = 0;
396
397 db_cmd_loop_done = 1;
398 }
399
400 /* continue */
401 /*ARGSUSED*/
402 void
db_continue_cmd(db_expr_t addr,bool have_addr,db_expr_t count,char * modif)403 db_continue_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
404 {
405 if (modif[0] == 'c')
406 db_run_mode = STEP_COUNT;
407 else
408 db_run_mode = STEP_CONTINUE;
409 db_inst_count = 0;
410 db_load_count = 0;
411 db_store_count = 0;
412
413 db_cmd_loop_done = 1;
414 }
415