1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2011 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
4 *
5 * Selftests for breakpoints (and more generally the do_debug() path) in x86.
6 */
7
8
9 #include <sys/ptrace.h>
10 #include <unistd.h>
11 #include <stddef.h>
12 #include <sys/user.h>
13 #include <stdio.h>
14 #include <stdlib.h>
15 #include <signal.h>
16 #include <sys/types.h>
17 #include <sys/wait.h>
18 #include <errno.h>
19 #include <string.h>
20
21 #include "../kselftest.h"
22
23 #define COUNT_ISN_BPS 4
24 #define COUNT_WPS 4
25
26 /* Breakpoint access modes */
27 enum {
28 BP_X = 1,
29 BP_RW = 2,
30 BP_W = 4,
31 };
32
33 static pid_t child_pid;
34
35 /*
36 * Ensures the child and parent are always "talking" about
37 * the same test sequence. (ie: that we haven't forgotten
38 * to call check_trapped() somewhere).
39 */
40 static int nr_tests;
41
set_breakpoint_addr(void * addr,int n)42 static void set_breakpoint_addr(void *addr, int n)
43 {
44 int ret;
45
46 ret = ptrace(PTRACE_POKEUSER, child_pid,
47 offsetof(struct user, u_debugreg[n]), addr);
48 if (ret)
49 ksft_exit_fail_msg("Can't set breakpoint addr: %s\n",
50 strerror(errno));
51 }
52
toggle_breakpoint(int n,int type,int len,int local,int global,int set)53 static void toggle_breakpoint(int n, int type, int len,
54 int local, int global, int set)
55 {
56 int ret;
57
58 int xtype, xlen;
59 unsigned long vdr7, dr7;
60
61 switch (type) {
62 case BP_X:
63 xtype = 0;
64 break;
65 case BP_W:
66 xtype = 1;
67 break;
68 case BP_RW:
69 xtype = 3;
70 break;
71 }
72
73 switch (len) {
74 case 1:
75 xlen = 0;
76 break;
77 case 2:
78 xlen = 4;
79 break;
80 case 4:
81 xlen = 0xc;
82 break;
83 case 8:
84 xlen = 8;
85 break;
86 }
87
88 dr7 = ptrace(PTRACE_PEEKUSER, child_pid,
89 offsetof(struct user, u_debugreg[7]), 0);
90
91 vdr7 = (xlen | xtype) << 16;
92 vdr7 <<= 4 * n;
93
94 if (local) {
95 vdr7 |= 1 << (2 * n);
96 vdr7 |= 1 << 8;
97 }
98 if (global) {
99 vdr7 |= 2 << (2 * n);
100 vdr7 |= 1 << 9;
101 }
102
103 if (set)
104 dr7 |= vdr7;
105 else
106 dr7 &= ~vdr7;
107
108 ret = ptrace(PTRACE_POKEUSER, child_pid,
109 offsetof(struct user, u_debugreg[7]), dr7);
110 if (ret) {
111 ksft_print_msg("Can't set dr7: %s\n", strerror(errno));
112 exit(-1);
113 }
114 }
115
116 /* Dummy variables to test read/write accesses */
117 static unsigned long long dummy_var[4];
118
119 /* Dummy functions to test execution accesses */
dummy_func(void)120 static void dummy_func(void) { }
dummy_func1(void)121 static void dummy_func1(void) { }
dummy_func2(void)122 static void dummy_func2(void) { }
dummy_func3(void)123 static void dummy_func3(void) { }
124
125 static void (*dummy_funcs[])(void) = {
126 dummy_func,
127 dummy_func1,
128 dummy_func2,
129 dummy_func3,
130 };
131
132 static int trapped;
133
check_trapped(void)134 static void check_trapped(void)
135 {
136 /*
137 * If we haven't trapped, wake up the parent
138 * so that it notices the failure.
139 */
140 if (!trapped)
141 kill(getpid(), SIGUSR1);
142 trapped = 0;
143
144 nr_tests++;
145 }
146
write_var(int len)147 static void write_var(int len)
148 {
149 char *pcval; short *psval; int *pival; long long *plval;
150 int i;
151
152 for (i = 0; i < 4; i++) {
153 switch (len) {
154 case 1:
155 pcval = (char *)&dummy_var[i];
156 *pcval = 0xff;
157 break;
158 case 2:
159 psval = (short *)&dummy_var[i];
160 *psval = 0xffff;
161 break;
162 case 4:
163 pival = (int *)&dummy_var[i];
164 *pival = 0xffffffff;
165 break;
166 case 8:
167 plval = (long long *)&dummy_var[i];
168 *plval = 0xffffffffffffffffLL;
169 break;
170 }
171 check_trapped();
172 }
173 }
174
read_var(int len)175 static void read_var(int len)
176 {
177 char cval; short sval; int ival; long long lval;
178 int i;
179
180 for (i = 0; i < 4; i++) {
181 switch (len) {
182 case 1:
183 cval = *(char *)&dummy_var[i];
184 break;
185 case 2:
186 sval = *(short *)&dummy_var[i];
187 break;
188 case 4:
189 ival = *(int *)&dummy_var[i];
190 break;
191 case 8:
192 lval = *(long long *)&dummy_var[i];
193 break;
194 }
195 check_trapped();
196 }
197 }
198
199 /*
200 * Do the r/w/x accesses to trigger the breakpoints. And run
201 * the usual traps.
202 */
trigger_tests(void)203 static void trigger_tests(void)
204 {
205 int len, local, global, i;
206 char val;
207 int ret;
208
209 ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
210 if (ret) {
211 ksft_print_msg("Can't be traced? %s\n", strerror(errno));
212 return;
213 }
214
215 /* Wake up father so that it sets up the first test */
216 kill(getpid(), SIGUSR1);
217
218 /* Test instruction breakpoints */
219 for (local = 0; local < 2; local++) {
220 for (global = 0; global < 2; global++) {
221 if (!local && !global)
222 continue;
223
224 for (i = 0; i < COUNT_ISN_BPS; i++) {
225 dummy_funcs[i]();
226 check_trapped();
227 }
228 }
229 }
230
231 /* Test write watchpoints */
232 for (len = 1; len <= sizeof(long); len <<= 1) {
233 for (local = 0; local < 2; local++) {
234 for (global = 0; global < 2; global++) {
235 if (!local && !global)
236 continue;
237 write_var(len);
238 }
239 }
240 }
241
242 /* Test read/write watchpoints (on read accesses) */
243 for (len = 1; len <= sizeof(long); len <<= 1) {
244 for (local = 0; local < 2; local++) {
245 for (global = 0; global < 2; global++) {
246 if (!local && !global)
247 continue;
248 read_var(len);
249 }
250 }
251 }
252
253 /* Icebp trap */
254 asm(".byte 0xf1\n");
255 check_trapped();
256
257 /* Int 3 trap */
258 asm("int $3\n");
259 check_trapped();
260
261 kill(getpid(), SIGUSR1);
262 }
263
check_success(const char * msg)264 static void check_success(const char *msg)
265 {
266 int child_nr_tests;
267 int status;
268 int ret;
269
270 /* Wait for the child to SIGTRAP */
271 wait(&status);
272
273 ret = 0;
274
275 if (WSTOPSIG(status) == SIGTRAP) {
276 child_nr_tests = ptrace(PTRACE_PEEKDATA, child_pid,
277 &nr_tests, 0);
278 if (child_nr_tests == nr_tests)
279 ret = 1;
280 if (ptrace(PTRACE_POKEDATA, child_pid, &trapped, 1))
281 ksft_exit_fail_msg("Can't poke: %s\n", strerror(errno));
282 }
283
284 nr_tests++;
285
286 if (ret)
287 ksft_test_result_pass("%s", msg);
288 else
289 ksft_test_result_fail("%s", msg);
290 }
291
launch_instruction_breakpoints(char * buf,int local,int global)292 static void launch_instruction_breakpoints(char *buf, int local, int global)
293 {
294 int i;
295
296 for (i = 0; i < COUNT_ISN_BPS; i++) {
297 set_breakpoint_addr(dummy_funcs[i], i);
298 toggle_breakpoint(i, BP_X, 1, local, global, 1);
299 ptrace(PTRACE_CONT, child_pid, NULL, 0);
300 sprintf(buf, "Test breakpoint %d with local: %d global: %d\n",
301 i, local, global);
302 check_success(buf);
303 toggle_breakpoint(i, BP_X, 1, local, global, 0);
304 }
305 }
306
launch_watchpoints(char * buf,int mode,int len,int local,int global)307 static void launch_watchpoints(char *buf, int mode, int len,
308 int local, int global)
309 {
310 const char *mode_str;
311 int i;
312
313 if (mode == BP_W)
314 mode_str = "write";
315 else
316 mode_str = "read";
317
318 for (i = 0; i < COUNT_WPS; i++) {
319 set_breakpoint_addr(&dummy_var[i], i);
320 toggle_breakpoint(i, mode, len, local, global, 1);
321 ptrace(PTRACE_CONT, child_pid, NULL, 0);
322 sprintf(buf,
323 "Test %s watchpoint %d with len: %d local: %d global: %d\n",
324 mode_str, i, len, local, global);
325 check_success(buf);
326 toggle_breakpoint(i, mode, len, local, global, 0);
327 }
328 }
329
330 /* Set the breakpoints and check the child successfully trigger them */
launch_tests(void)331 static void launch_tests(void)
332 {
333 char buf[1024];
334 unsigned int tests = 0;
335 int len, local, global, i;
336
337 tests += 3 * COUNT_ISN_BPS;
338 tests += sizeof(long) / 2 * 3 * COUNT_WPS;
339 tests += sizeof(long) / 2 * 3 * COUNT_WPS;
340 tests += 2;
341 ksft_set_plan(tests);
342
343 /* Instruction breakpoints */
344 for (local = 0; local < 2; local++) {
345 for (global = 0; global < 2; global++) {
346 if (!local && !global)
347 continue;
348 launch_instruction_breakpoints(buf, local, global);
349 }
350 }
351
352 /* Write watchpoint */
353 for (len = 1; len <= sizeof(long); len <<= 1) {
354 for (local = 0; local < 2; local++) {
355 for (global = 0; global < 2; global++) {
356 if (!local && !global)
357 continue;
358 launch_watchpoints(buf, BP_W, len,
359 local, global);
360 }
361 }
362 }
363
364 /* Read-Write watchpoint */
365 for (len = 1; len <= sizeof(long); len <<= 1) {
366 for (local = 0; local < 2; local++) {
367 for (global = 0; global < 2; global++) {
368 if (!local && !global)
369 continue;
370 launch_watchpoints(buf, BP_RW, len,
371 local, global);
372 }
373 }
374 }
375
376 /* Icebp traps */
377 ptrace(PTRACE_CONT, child_pid, NULL, 0);
378 check_success("Test icebp\n");
379
380 /* Int 3 traps */
381 ptrace(PTRACE_CONT, child_pid, NULL, 0);
382 check_success("Test int 3 trap\n");
383
384 ptrace(PTRACE_CONT, child_pid, NULL, 0);
385 }
386
main(int argc,char ** argv)387 int main(int argc, char **argv)
388 {
389 pid_t pid;
390 int ret;
391
392 ksft_print_header();
393
394 pid = fork();
395 if (!pid) {
396 trigger_tests();
397 exit(0);
398 }
399
400 child_pid = pid;
401
402 wait(NULL);
403
404 launch_tests();
405
406 wait(NULL);
407
408 ksft_exit_pass();
409 }
410