1 /* 2 * Kernel support for the ptrace() and syscall tracing interfaces. 3 * 4 * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc. 5 * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx> 6 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org> 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/sched.h> 11 #include <linux/mm.h> 12 #include <linux/smp.h> 13 #include <linux/smp_lock.h> 14 #include <linux/errno.h> 15 #include <linux/ptrace.h> 16 #include <linux/user.h> 17 #include <linux/personality.h> 18 #include <linux/security.h> 19 #include <linux/compat.h> 20 #include <linux/signal.h> 21 22 #include <asm/uaccess.h> 23 #include <asm/pgtable.h> 24 #include <asm/system.h> 25 #include <asm/processor.h> 26 #include <asm/offsets.h> 27 28 /* PSW bits we allow the debugger to modify */ 29 #define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB) 30 31 #undef DEBUG_PTRACE 32 33 #ifdef DEBUG_PTRACE 34 #define DBG(x...) printk(x) 35 #else 36 #define DBG(x...) 37 #endif 38 39 #ifdef __LP64__ 40 41 /* This function is needed to translate 32 bit pt_regs offsets in to 42 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel 43 * will request offset 12 if it wants gr3, but the lower 32 bits of 44 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4). 45 * This code relies on a 32 bit pt_regs being comprised of 32 bit values 46 * except for the fp registers which (a) are 64 bits, and (b) follow 47 * the gr registers at the start of pt_regs. The 32 bit pt_regs should 48 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[] 49 * being 64 bit in both cases. 50 */ 51 52 static long translate_usr_offset(long offset) 53 { 54 if (offset < 0) 55 return -1; 56 else if (offset <= 32*4) /* gr[0..31] */ 57 return offset * 2 + 4; 58 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */ 59 return offset + 32*4; 60 else if (offset < sizeof(struct pt_regs)/2 + 32*4) 61 return offset * 2 + 4 - 32*8; 62 else 63 return -1; 64 } 65 #endif 66 67 /* 68 * Called by kernel/ptrace.c when detaching.. 69 * 70 * Make sure single step bits etc are not set. 71 */ 72 void ptrace_disable(struct task_struct *child) 73 { 74 /* make sure the trap bits are not set */ 75 pa_psw(child)->r = 0; 76 pa_psw(child)->t = 0; 77 pa_psw(child)->h = 0; 78 pa_psw(child)->l = 0; 79 } 80 81 long sys_ptrace(long request, pid_t pid, long addr, long data) 82 { 83 struct task_struct *child; 84 long ret; 85 #ifdef DEBUG_PTRACE 86 long oaddr=addr, odata=data; 87 #endif 88 89 lock_kernel(); 90 ret = -EPERM; 91 if (request == PTRACE_TRACEME) { 92 /* are we already being traced? */ 93 if (current->ptrace & PT_PTRACED) 94 goto out; 95 96 ret = security_ptrace(current->parent, current); 97 if (ret) 98 goto out; 99 100 /* set the ptrace bit in the process flags. */ 101 current->ptrace |= PT_PTRACED; 102 ret = 0; 103 goto out; 104 } 105 106 ret = -ESRCH; 107 read_lock(&tasklist_lock); 108 child = find_task_by_pid(pid); 109 if (child) 110 get_task_struct(child); 111 read_unlock(&tasklist_lock); 112 if (!child) 113 goto out; 114 ret = -EPERM; 115 if (pid == 1) /* no messing around with init! */ 116 goto out_tsk; 117 118 if (request == PTRACE_ATTACH) { 119 ret = ptrace_attach(child); 120 goto out_tsk; 121 } 122 123 ret = ptrace_check_attach(child, request == PTRACE_KILL); 124 if (ret < 0) 125 goto out_tsk; 126 127 switch (request) { 128 case PTRACE_PEEKTEXT: /* read word at location addr. */ 129 case PTRACE_PEEKDATA: { 130 int copied; 131 132 #ifdef __LP64__ 133 if (is_compat_task(child)) { 134 unsigned int tmp; 135 136 addr &= 0xffffffffL; 137 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 138 ret = -EIO; 139 if (copied != sizeof(tmp)) 140 goto out_tsk; 141 ret = put_user(tmp,(unsigned int *) data); 142 DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n", 143 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA", 144 pid, oaddr, odata, ret, tmp); 145 } 146 else 147 #endif 148 { 149 unsigned long tmp; 150 151 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 152 ret = -EIO; 153 if (copied != sizeof(tmp)) 154 goto out_tsk; 155 ret = put_user(tmp,(unsigned long *) data); 156 } 157 goto out_tsk; 158 } 159 160 /* when I and D space are separate, this will have to be fixed. */ 161 case PTRACE_POKETEXT: /* write the word at location addr. */ 162 case PTRACE_POKEDATA: 163 ret = 0; 164 #ifdef __LP64__ 165 if (is_compat_task(child)) { 166 unsigned int tmp = (unsigned int)data; 167 DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n", 168 request == PTRACE_POKETEXT ? "TEXT" : "DATA", 169 pid, oaddr, odata); 170 addr &= 0xffffffffL; 171 if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp)) 172 goto out_tsk; 173 } 174 else 175 #endif 176 { 177 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data)) 178 goto out_tsk; 179 } 180 ret = -EIO; 181 goto out_tsk; 182 183 /* Read the word at location addr in the USER area. For ptraced 184 processes, the kernel saves all regs on a syscall. */ 185 case PTRACE_PEEKUSR: { 186 ret = -EIO; 187 #ifdef __LP64__ 188 if (is_compat_task(child)) { 189 unsigned int tmp; 190 191 if (addr & (sizeof(int)-1)) 192 goto out_tsk; 193 if ((addr = translate_usr_offset(addr)) < 0) 194 goto out_tsk; 195 196 tmp = *(unsigned int *) ((char *) task_regs(child) + addr); 197 ret = put_user(tmp, (unsigned int *) data); 198 DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n", 199 pid, oaddr, odata, ret, addr, tmp); 200 } 201 else 202 #endif 203 { 204 unsigned long tmp; 205 206 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 207 goto out_tsk; 208 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 209 ret = put_user(tmp, (unsigned long *) data); 210 } 211 goto out_tsk; 212 } 213 214 /* Write the word at location addr in the USER area. This will need 215 to change when the kernel no longer saves all regs on a syscall. 216 FIXME. There is a problem at the moment in that r3-r18 are only 217 saved if the process is ptraced on syscall entry, and even then 218 those values are overwritten by actual register values on syscall 219 exit. */ 220 case PTRACE_POKEUSR: 221 ret = -EIO; 222 /* Some register values written here may be ignored in 223 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 224 * r31/r31+4, and not with the values in pt_regs. 225 */ 226 /* PT_PSW=0, so this is valid for 32 bit processes under 64 227 * bit kernels. 228 */ 229 if (addr == PT_PSW) { 230 /* PT_PSW=0, so this is valid for 32 bit processes 231 * under 64 bit kernels. 232 * 233 * Allow writing to Nullify, Divide-step-correction, 234 * and carry/borrow bits. 235 * BEWARE, if you set N, and then single step, it won't 236 * stop on the nullified instruction. 237 */ 238 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n", 239 pid, oaddr, odata); 240 data &= USER_PSW_BITS; 241 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 242 task_regs(child)->gr[0] |= data; 243 ret = 0; 244 goto out_tsk; 245 } 246 #ifdef __LP64__ 247 if (is_compat_task(child)) { 248 if (addr & (sizeof(int)-1)) 249 goto out_tsk; 250 if ((addr = translate_usr_offset(addr)) < 0) 251 goto out_tsk; 252 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n", 253 pid, oaddr, odata, addr); 254 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 255 /* Special case, fp regs are 64 bits anyway */ 256 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 257 ret = 0; 258 } 259 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 260 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 261 addr == PT_SAR+4) { 262 /* Zero the top 32 bits */ 263 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0; 264 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 265 ret = 0; 266 } 267 goto out_tsk; 268 } 269 else 270 #endif 271 { 272 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 273 goto out_tsk; 274 if ((addr >= PT_GR1 && addr <= PT_GR31) || 275 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 276 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 277 addr == PT_SAR) { 278 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 279 ret = 0; 280 } 281 goto out_tsk; 282 } 283 284 case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ 285 case PTRACE_CONT: 286 ret = -EIO; 287 DBG("sys_ptrace(%s)\n", 288 request == PTRACE_SYSCALL ? "SYSCALL" : "CONT"); 289 if (!valid_signal(data)) 290 goto out_tsk; 291 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP); 292 if (request == PTRACE_SYSCALL) { 293 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 294 } else { 295 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 296 } 297 child->exit_code = data; 298 goto out_wake_notrap; 299 300 case PTRACE_KILL: 301 /* 302 * make the child exit. Best I can do is send it a 303 * sigkill. perhaps it should be put in the status 304 * that it wants to exit. 305 */ 306 DBG("sys_ptrace(KILL)\n"); 307 if (child->exit_state == EXIT_ZOMBIE) /* already dead */ 308 goto out_tsk; 309 child->exit_code = SIGKILL; 310 goto out_wake_notrap; 311 312 case PTRACE_SINGLEBLOCK: 313 DBG("sys_ptrace(SINGLEBLOCK)\n"); 314 ret = -EIO; 315 if (!valid_signal(data)) 316 goto out_tsk; 317 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 318 child->ptrace &= ~PT_SINGLESTEP; 319 child->ptrace |= PT_BLOCKSTEP; 320 child->exit_code = data; 321 322 /* Enable taken branch trap. */ 323 pa_psw(child)->r = 0; 324 pa_psw(child)->t = 1; 325 pa_psw(child)->h = 0; 326 pa_psw(child)->l = 0; 327 goto out_wake; 328 329 case PTRACE_SINGLESTEP: 330 DBG("sys_ptrace(SINGLESTEP)\n"); 331 ret = -EIO; 332 if (!valid_signal(data)) 333 goto out_tsk; 334 335 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 336 child->ptrace &= ~PT_BLOCKSTEP; 337 child->ptrace |= PT_SINGLESTEP; 338 child->exit_code = data; 339 340 if (pa_psw(child)->n) { 341 struct siginfo si; 342 343 /* Nullified, just crank over the queue. */ 344 task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1]; 345 task_regs(child)->iasq[0] = task_regs(child)->iasq[1]; 346 task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4; 347 pa_psw(child)->n = 0; 348 pa_psw(child)->x = 0; 349 pa_psw(child)->y = 0; 350 pa_psw(child)->z = 0; 351 pa_psw(child)->b = 0; 352 ptrace_disable(child); 353 /* Don't wake up the child, but let the 354 parent know something happened. */ 355 si.si_code = TRAP_TRACE; 356 si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3); 357 si.si_signo = SIGTRAP; 358 si.si_errno = 0; 359 force_sig_info(SIGTRAP, &si, child); 360 //notify_parent(child, SIGCHLD); 361 //ret = 0; 362 goto out_wake; 363 } 364 365 /* Enable recovery counter traps. The recovery counter 366 * itself will be set to zero on a task switch. If the 367 * task is suspended on a syscall then the syscall return 368 * path will overwrite the recovery counter with a suitable 369 * value such that it traps once back in user space. We 370 * disable interrupts in the childs PSW here also, to avoid 371 * interrupts while the recovery counter is decrementing. 372 */ 373 pa_psw(child)->r = 1; 374 pa_psw(child)->t = 0; 375 pa_psw(child)->h = 0; 376 pa_psw(child)->l = 0; 377 /* give it a chance to run. */ 378 goto out_wake; 379 380 case PTRACE_DETACH: 381 ret = ptrace_detach(child, data); 382 goto out_tsk; 383 384 case PTRACE_GETEVENTMSG: 385 ret = put_user(child->ptrace_message, (unsigned int __user *) data); 386 goto out_tsk; 387 388 default: 389 ret = ptrace_request(child, request, addr, data); 390 goto out_tsk; 391 } 392 393 out_wake_notrap: 394 ptrace_disable(child); 395 out_wake: 396 wake_up_process(child); 397 ret = 0; 398 out_tsk: 399 put_task_struct(child); 400 out: 401 unlock_kernel(); 402 DBG("sys_ptrace(%ld, %d, %lx, %lx) returning %ld\n", 403 request, pid, oaddr, odata, ret); 404 return ret; 405 } 406 407 void syscall_trace(void) 408 { 409 if (!test_thread_flag(TIF_SYSCALL_TRACE)) 410 return; 411 if (!(current->ptrace & PT_PTRACED)) 412 return; 413 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) 414 ? 0x80 : 0)); 415 /* 416 * this isn't the same as continuing with a signal, but it will do 417 * for normal use. strace only continues with a signal if the 418 * stopping signal is not SIGTRAP. -brl 419 */ 420 if (current->exit_code) { 421 send_sig(current->exit_code, current, 1); 422 current->exit_code = 0; 423 } 424 } 425