tools/testing/selftests/breakpoints/breakpoint_test.c

   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
  20 #include "../kselftest.h"
  21
  22
  23 /* Breakpoint access modes */
  24 enum {
  25         BP_X = 1,
  26         BP_RW = 2,
  27         BP_W = 4,
  28 };
  29
  30 static pid_t child_pid;
  31
  32 /*
  33  * Ensures the child and parent are always "talking" about
  34  * the same test sequence. (ie: that we haven't forgotten
  35  * to call check_trapped() somewhere).
  36  */
  37 static int nr_tests;
  38
  39 static void set_breakpoint_addr(void *addr, int n)
  40 {
  41         int ret;
  42
  43         ret = ptrace(PTRACE_POKEUSER, child_pid,
  44                      offsetof(struct user, u_debugreg[n]), addr);
  45         if (ret) {
  46                 perror("Can't set breakpoint addr\n");
  47                 ksft_exit_fail();
  48         }
  49 }
  50
  51 static void toggle_breakpoint(int n, int type, int len,
  52                               int local, int global, int set)
  53 {
  54         int ret;
  55
  56         int xtype, xlen;
  57         unsigned long vdr7, dr7;
  58
  59         switch (type) {
  60         case BP_X:
  61                 xtype = 0;
  62                 break;
  63         case BP_W:
  64                 xtype = 1;
  65                 break;
  66         case BP_RW:
  67                 xtype = 3;
  68                 break;
  69         }
  70
  71         switch (len) {
  72         case 1:
  73                 xlen = 0;
  74                 break;
  75         case 2:
  76                 xlen = 4;
  77                 break;
  78         case 4:
  79                 xlen = 0xc;
  80                 break;
  81         case 8:
  82                 xlen = 8;
  83                 break;
  84         }
  85
  86         dr7 = ptrace(PTRACE_PEEKUSER, child_pid,
  87                      offsetof(struct user, u_debugreg[7]), 0);
  88
  89         vdr7 = (xlen | xtype) << 16;
  90         vdr7 <<= 4 * n;
  91
  92         if (local) {
  93                 vdr7 |= 1 << (2 * n);
  94                 vdr7 |= 1 << 8;
  95         }
  96         if (global) {
  97                 vdr7 |= 2 << (2 * n);
  98                 vdr7 |= 1 << 9;
  99         }
 100
 101         if (set)
 102                 dr7 |= vdr7;
 103         else
 104                 dr7 &= ~vdr7;
 105
 106         ret = ptrace(PTRACE_POKEUSER, child_pid,
 107                      offsetof(struct user, u_debugreg[7]), dr7);
 108         if (ret) {
 109                 perror("Can't set dr7");
 110                 ksft_exit_fail();
 111         }
 112 }
 113
 114 /* Dummy variables to test read/write accesses */
 115 static unsigned long long dummy_var[4];
 116
 117 /* Dummy functions to test execution accesses */
 118 static void dummy_func(void) { }
 119 static void dummy_func1(void) { }
 120 static void dummy_func2(void) { }
 121 static void dummy_func3(void) { }
 122
 123 static void (*dummy_funcs[])(void) = {
 124         dummy_func,
 125         dummy_func1,
 126         dummy_func2,
 127         dummy_func3,
 128 };
 129
 130 static int trapped;
 131
 132 static void check_trapped(void)
 133 {
 134         /*
 135          * If we haven't trapped, wake up the parent
 136          * so that it notices the failure.
 137          */
 138         if (!trapped)
 139                 kill(getpid(), SIGUSR1);
 140         trapped = 0;
 141
 142         nr_tests++;
 143 }
 144
 145 static void write_var(int len)
 146 {
 147         char *pcval; short *psval; int *pival; long long *plval;
 148         int i;
 149
 150         for (i = 0; i < 4; i++) {
 151                 switch (len) {
 152                 case 1:
 153                         pcval = (char *)&dummy_var[i];
 154                         *pcval = 0xff;
 155                         break;
 156                 case 2:
 157                         psval = (short *)&dummy_var[i];
 158                         *psval = 0xffff;
 159                         break;
 160                 case 4:
 161                         pival = (int *)&dummy_var[i];
 162                         *pival = 0xffffffff;
 163                         break;
 164                 case 8:
 165                         plval = (long long *)&dummy_var[i];
 166                         *plval = 0xffffffffffffffffLL;
 167                         break;
 168                 }
 169                 check_trapped();
 170         }
 171 }
 172
 173 static void read_var(int len)
 174 {
 175         char cval; short sval; int ival; long long lval;
 176         int i;
 177
 178         for (i = 0; i < 4; i++) {
 179                 switch (len) {
 180                 case 1:
 181                         cval = *(char *)&dummy_var[i];
 182                         break;
 183                 case 2:
 184                         sval = *(short *)&dummy_var[i];
 185                         break;
 186                 case 4:
 187                         ival = *(int *)&dummy_var[i];
 188                         break;
 189                 case 8:
 190                         lval = *(long long *)&dummy_var[i];
 191                         break;
 192                 }
 193                 check_trapped();
 194         }
 195 }
 196
 197 /*
 198  * Do the r/w/x accesses to trigger the breakpoints. And run
 199  * the usual traps.
 200  */
 201 static void trigger_tests(void)
 202 {
 203         int len, local, global, i;
 204         char val;
 205         int ret;
 206
 207         ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
 208         if (ret) {
 209                 perror("Can't be traced?\n");
 210                 return;
 211         }
 212
 213         /* Wake up father so that it sets up the first test */
 214         kill(getpid(), SIGUSR1);
 215
 216         /* Test instruction breakpoints */
 217         for (local = 0; local < 2; local++) {
 218                 for (global = 0; global < 2; global++) {
 219                         if (!local && !global)
 220                                 continue;
 221
 222                         for (i = 0; i < 4; i++) {
 223                                 dummy_funcs[i]();
 224                                 check_trapped();
 225                         }
 226                 }
 227         }
 228
 229         /* Test write watchpoints */
 230         for (len = 1; len <= sizeof(long); len <<= 1) {
 231                 for (local = 0; local < 2; local++) {
 232                         for (global = 0; global < 2; global++) {
 233                                 if (!local && !global)
 234                                         continue;
 235                                 write_var(len);
 236                         }
 237                 }
 238         }
 239
 240         /* Test read/write watchpoints (on read accesses) */
 241         for (len = 1; len <= sizeof(long); len <<= 1) {
 242                 for (local = 0; local < 2; local++) {
 243                         for (global = 0; global < 2; global++) {
 244                                 if (!local && !global)
 245                                         continue;
 246                                 read_var(len);
 247                         }
 248                 }
 249         }
 250
 251         /* Icebp trap */
 252         asm(".byte 0xf1\n");
 253         check_trapped();
 254
 255         /* Int 3 trap */
 256         asm("int $3\n");
 257         check_trapped();
 258
 259         kill(getpid(), SIGUSR1);
 260 }
 261
 262 static void check_success(const char *msg)
 263 {
 264         const char *msg2;
 265         int child_nr_tests;
 266         int status;
 267
 268         /* Wait for the child to SIGTRAP */
 269         wait(&status);
 270
 271         msg2 = "Failed";
 272
 273         if (WSTOPSIG(status) == SIGTRAP) {
 274                 child_nr_tests = ptrace(PTRACE_PEEKDATA, child_pid,
 275                                         &nr_tests, 0);
 276                 if (child_nr_tests == nr_tests)
 277                         msg2 = "Ok";
 278                 if (ptrace(PTRACE_POKEDATA, child_pid, &trapped, 1)) {
 279                         perror("Can't poke\n");
 280                         ksft_exit_fail();
 281                 }
 282         }
 283
 284         nr_tests++;
 285
 286         printf("%s [%s]\n", msg, msg2);
 287 }
 288
 289 static void launch_instruction_breakpoints(char *buf, int local, int global)
 290 {
 291         int i;
 292
 293         for (i = 0; i < 4; i++) {
 294                 set_breakpoint_addr(dummy_funcs[i], i);
 295                 toggle_breakpoint(i, BP_X, 1, local, global, 1);
 296                 ptrace(PTRACE_CONT, child_pid, NULL, 0);
 297                 sprintf(buf, "Test breakpoint %d with local: %d global: %d",
 298                         i, local, global);
 299                 check_success(buf);
 300                 toggle_breakpoint(i, BP_X, 1, local, global, 0);
 301         }
 302 }
 303
 304 static void launch_watchpoints(char *buf, int mode, int len,
 305                                int local, int global)
 306 {
 307         const char *mode_str;
 308         int i;
 309
 310         if (mode == BP_W)
 311                 mode_str = "write";
 312         else
 313                 mode_str = "read";
 314
 315         for (i = 0; i < 4; i++) {
 316                 set_breakpoint_addr(&dummy_var[i], i);
 317                 toggle_breakpoint(i, mode, len, local, global, 1);
 318                 ptrace(PTRACE_CONT, child_pid, NULL, 0);
 319                 sprintf(buf, "Test %s watchpoint %d with len: %d local: "
 320                         "%d global: %d", mode_str, i, len, local, global);
 321                 check_success(buf);
 322                 toggle_breakpoint(i, mode, len, local, global, 0);
 323         }
 324 }
 325
 326 /* Set the breakpoints and check the child successfully trigger them */
 327 static void launch_tests(void)
 328 {
 329         char buf[1024];
 330         int len, local, global, i;
 331
 332         /* Instruction breakpoints */
 333         for (local = 0; local < 2; local++) {
 334                 for (global = 0; global < 2; global++) {
 335                         if (!local && !global)
 336                                 continue;
 337                         launch_instruction_breakpoints(buf, local, global);
 338                 }
 339         }
 340
 341         /* Write watchpoint */
 342         for (len = 1; len <= sizeof(long); len <<= 1) {
 343                 for (local = 0; local < 2; local++) {
 344                         for (global = 0; global < 2; global++) {
 345                                 if (!local && !global)
 346                                         continue;
 347                                 launch_watchpoints(buf, BP_W, len,
 348                                                    local, global);
 349                         }
 350                 }
 351         }
 352
 353         /* Read-Write watchpoint */
 354         for (len = 1; len <= sizeof(long); len <<= 1) {
 355                 for (local = 0; local < 2; local++) {
 356                         for (global = 0; global < 2; global++) {
 357                                 if (!local && !global)
 358                                         continue;
 359                                 launch_watchpoints(buf, BP_RW, len,
 360                                                    local, global);
 361                         }
 362                 }
 363         }
 364
 365         /* Icebp traps */
 366         ptrace(PTRACE_CONT, child_pid, NULL, 0);
 367         check_success("Test icebp");
 368
 369         /* Int 3 traps */
 370         ptrace(PTRACE_CONT, child_pid, NULL, 0);
 371         check_success("Test int 3 trap");
 372
 373         ptrace(PTRACE_CONT, child_pid, NULL, 0);
 374 }
 375
 376 int main(int argc, char **argv)
 377 {
 378         pid_t pid;
 379         int ret;
 380
 381         pid = fork();
 382         if (!pid) {
 383                 trigger_tests();
 384                 return 0;
 385         }
 386
 387         child_pid = pid;
 388
 389         wait(NULL);
 390
 391         launch_tests();
 392
 393         wait(NULL);
 394
 395         return ksft_exit_pass();
 396 }