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