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