1 /* ptrace.c */ 2 /* By Ross Biro 1/23/92 */ 3 /* edited by Linus Torvalds */ 4 /* mangled further by Bob Manson (manson@santafe.edu) */ 5 /* more mutilation by David Mosberger (davidm@azstarnet.com) */ 6 7 #include <linux/kernel.h> 8 #include <linux/sched.h> 9 #include <linux/mm.h> 10 #include <linux/smp.h> 11 #include <linux/smp_lock.h> 12 #include <linux/errno.h> 13 #include <linux/ptrace.h> 14 #include <linux/user.h> 15 #include <linux/slab.h> 16 #include <linux/security.h> 17 18 #include <asm/uaccess.h> 19 #include <asm/pgtable.h> 20 #include <asm/system.h> 21 #include <asm/fpu.h> 22 23 #include "proto.h" 24 25 #define DEBUG DBG_MEM 26 #undef DEBUG 27 28 #ifdef DEBUG 29 enum { 30 DBG_MEM = (1<<0), 31 DBG_BPT = (1<<1), 32 DBG_MEM_ALL = (1<<2) 33 }; 34 #define DBG(fac,args) {if ((fac) & DEBUG) printk args;} 35 #else 36 #define DBG(fac,args) 37 #endif 38 39 #define BREAKINST 0x00000080 /* call_pal bpt */ 40 41 /* 42 * does not yet catch signals sent when the child dies. 43 * in exit.c or in signal.c. 44 */ 45 46 /* 47 * Processes always block with the following stack-layout: 48 * 49 * +================================+ <---- task + 2*PAGE_SIZE 50 * | PALcode saved frame (ps, pc, | ^ 51 * | gp, a0, a1, a2) | | 52 * +================================+ | struct pt_regs 53 * | | | 54 * | frame generated by SAVE_ALL | | 55 * | | v 56 * +================================+ 57 * | | ^ 58 * | frame saved by do_switch_stack | | struct switch_stack 59 * | | v 60 * +================================+ 61 */ 62 63 /* 64 * The following table maps a register index into the stack offset at 65 * which the register is saved. Register indices are 0-31 for integer 66 * regs, 32-63 for fp regs, and 64 for the pc. Notice that sp and 67 * zero have no stack-slot and need to be treated specially (see 68 * get_reg/put_reg below). 69 */ 70 enum { 71 REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64 72 }; 73 74 static int regoff[] = { 75 PT_REG( r0), PT_REG( r1), PT_REG( r2), PT_REG( r3), 76 PT_REG( r4), PT_REG( r5), PT_REG( r6), PT_REG( r7), 77 PT_REG( r8), SW_REG( r9), SW_REG( r10), SW_REG( r11), 78 SW_REG( r12), SW_REG( r13), SW_REG( r14), SW_REG( r15), 79 PT_REG( r16), PT_REG( r17), PT_REG( r18), PT_REG( r19), 80 PT_REG( r20), PT_REG( r21), PT_REG( r22), PT_REG( r23), 81 PT_REG( r24), PT_REG( r25), PT_REG( r26), PT_REG( r27), 82 PT_REG( r28), PT_REG( gp), -1, -1, 83 SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]), 84 SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]), 85 SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]), 86 SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]), 87 SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]), 88 SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]), 89 SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]), 90 SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]), 91 PT_REG( pc) 92 }; 93 94 static unsigned long zero; 95 96 /* 97 * Get address of register REGNO in task TASK. 98 */ 99 static unsigned long * 100 get_reg_addr(struct task_struct * task, unsigned long regno) 101 { 102 unsigned long *addr; 103 104 if (regno == 30) { 105 addr = &task->thread_info->pcb.usp; 106 } else if (regno == 65) { 107 addr = &task->thread_info->pcb.unique; 108 } else if (regno == 31 || regno > 65) { 109 zero = 0; 110 addr = &zero; 111 } else { 112 addr = (void *)task->thread_info + regoff[regno]; 113 } 114 return addr; 115 } 116 117 /* 118 * Get contents of register REGNO in task TASK. 119 */ 120 static unsigned long 121 get_reg(struct task_struct * task, unsigned long regno) 122 { 123 /* Special hack for fpcr -- combine hardware and software bits. */ 124 if (regno == 63) { 125 unsigned long fpcr = *get_reg_addr(task, regno); 126 unsigned long swcr 127 = task->thread_info->ieee_state & IEEE_SW_MASK; 128 swcr = swcr_update_status(swcr, fpcr); 129 return fpcr | swcr; 130 } 131 return *get_reg_addr(task, regno); 132 } 133 134 /* 135 * Write contents of register REGNO in task TASK. 136 */ 137 static int 138 put_reg(struct task_struct *task, unsigned long regno, unsigned long data) 139 { 140 if (regno == 63) { 141 task->thread_info->ieee_state 142 = ((task->thread_info->ieee_state & ~IEEE_SW_MASK) 143 | (data & IEEE_SW_MASK)); 144 data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data); 145 } 146 *get_reg_addr(task, regno) = data; 147 return 0; 148 } 149 150 static inline int 151 read_int(struct task_struct *task, unsigned long addr, int * data) 152 { 153 int copied = access_process_vm(task, addr, data, sizeof(int), 0); 154 return (copied == sizeof(int)) ? 0 : -EIO; 155 } 156 157 static inline int 158 write_int(struct task_struct *task, unsigned long addr, int data) 159 { 160 int copied = access_process_vm(task, addr, &data, sizeof(int), 1); 161 return (copied == sizeof(int)) ? 0 : -EIO; 162 } 163 164 /* 165 * Set breakpoint. 166 */ 167 int 168 ptrace_set_bpt(struct task_struct * child) 169 { 170 int displ, i, res, reg_b, nsaved = 0; 171 unsigned int insn, op_code; 172 unsigned long pc; 173 174 pc = get_reg(child, REG_PC); 175 res = read_int(child, pc, (int *) &insn); 176 if (res < 0) 177 return res; 178 179 op_code = insn >> 26; 180 if (op_code >= 0x30) { 181 /* 182 * It's a branch: instead of trying to figure out 183 * whether the branch will be taken or not, we'll put 184 * a breakpoint at either location. This is simpler, 185 * more reliable, and probably not a whole lot slower 186 * than the alternative approach of emulating the 187 * branch (emulation can be tricky for fp branches). 188 */ 189 displ = ((s32)(insn << 11)) >> 9; 190 child->thread_info->bpt_addr[nsaved++] = pc + 4; 191 if (displ) /* guard against unoptimized code */ 192 child->thread_info->bpt_addr[nsaved++] 193 = pc + 4 + displ; 194 DBG(DBG_BPT, ("execing branch\n")); 195 } else if (op_code == 0x1a) { 196 reg_b = (insn >> 16) & 0x1f; 197 child->thread_info->bpt_addr[nsaved++] = get_reg(child, reg_b); 198 DBG(DBG_BPT, ("execing jump\n")); 199 } else { 200 child->thread_info->bpt_addr[nsaved++] = pc + 4; 201 DBG(DBG_BPT, ("execing normal insn\n")); 202 } 203 204 /* install breakpoints: */ 205 for (i = 0; i < nsaved; ++i) { 206 res = read_int(child, child->thread_info->bpt_addr[i], 207 (int *) &insn); 208 if (res < 0) 209 return res; 210 child->thread_info->bpt_insn[i] = insn; 211 DBG(DBG_BPT, (" -> next_pc=%lx\n", 212 child->thread_info->bpt_addr[i])); 213 res = write_int(child, child->thread_info->bpt_addr[i], 214 BREAKINST); 215 if (res < 0) 216 return res; 217 } 218 child->thread_info->bpt_nsaved = nsaved; 219 return 0; 220 } 221 222 /* 223 * Ensure no single-step breakpoint is pending. Returns non-zero 224 * value if child was being single-stepped. 225 */ 226 int 227 ptrace_cancel_bpt(struct task_struct * child) 228 { 229 int i, nsaved = child->thread_info->bpt_nsaved; 230 231 child->thread_info->bpt_nsaved = 0; 232 233 if (nsaved > 2) { 234 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved); 235 nsaved = 2; 236 } 237 238 for (i = 0; i < nsaved; ++i) { 239 write_int(child, child->thread_info->bpt_addr[i], 240 child->thread_info->bpt_insn[i]); 241 } 242 return (nsaved != 0); 243 } 244 245 /* 246 * Called by kernel/ptrace.c when detaching.. 247 * 248 * Make sure the single step bit is not set. 249 */ 250 void ptrace_disable(struct task_struct *child) 251 { 252 ptrace_cancel_bpt(child); 253 } 254 255 asmlinkage long 256 do_sys_ptrace(long request, long pid, long addr, long data, 257 struct pt_regs *regs) 258 { 259 struct task_struct *child; 260 unsigned long tmp; 261 size_t copied; 262 long ret; 263 264 lock_kernel(); 265 DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n", 266 request, pid, addr, data)); 267 ret = -EPERM; 268 if (request == PTRACE_TRACEME) { 269 /* are we already being traced? */ 270 if (current->ptrace & PT_PTRACED) 271 goto out_notsk; 272 ret = security_ptrace(current->parent, current); 273 if (ret) 274 goto out_notsk; 275 /* set the ptrace bit in the process ptrace flags. */ 276 current->ptrace |= PT_PTRACED; 277 ret = 0; 278 goto out_notsk; 279 } 280 if (pid == 1) /* you may not mess with init */ 281 goto out_notsk; 282 283 ret = -ESRCH; 284 read_lock(&tasklist_lock); 285 child = find_task_by_pid(pid); 286 if (child) 287 get_task_struct(child); 288 read_unlock(&tasklist_lock); 289 if (!child) 290 goto out_notsk; 291 292 if (request == PTRACE_ATTACH) { 293 ret = ptrace_attach(child); 294 goto out; 295 } 296 297 ret = ptrace_check_attach(child, request == PTRACE_KILL); 298 if (ret < 0) 299 goto out; 300 301 switch (request) { 302 /* When I and D space are separate, these will need to be fixed. */ 303 case PTRACE_PEEKTEXT: /* read word at location addr. */ 304 case PTRACE_PEEKDATA: 305 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 306 ret = -EIO; 307 if (copied != sizeof(tmp)) 308 break; 309 310 regs->r0 = 0; /* special return: no errors */ 311 ret = tmp; 312 break; 313 314 /* Read register number ADDR. */ 315 case PTRACE_PEEKUSR: 316 regs->r0 = 0; /* special return: no errors */ 317 ret = get_reg(child, addr); 318 DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret)); 319 break; 320 321 /* When I and D space are separate, this will have to be fixed. */ 322 case PTRACE_POKETEXT: /* write the word at location addr. */ 323 case PTRACE_POKEDATA: 324 tmp = data; 325 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1); 326 ret = (copied == sizeof(tmp)) ? 0 : -EIO; 327 break; 328 329 case PTRACE_POKEUSR: /* write the specified register */ 330 DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data)); 331 ret = put_reg(child, addr, data); 332 break; 333 334 case PTRACE_SYSCALL: 335 /* continue and stop at next (return from) syscall */ 336 case PTRACE_CONT: /* restart after signal. */ 337 ret = -EIO; 338 if ((unsigned long) data > _NSIG) 339 break; 340 if (request == PTRACE_SYSCALL) 341 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 342 else 343 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 344 child->exit_code = data; 345 /* make sure single-step breakpoint is gone. */ 346 ptrace_cancel_bpt(child); 347 wake_up_process(child); 348 ret = 0; 349 break; 350 351 /* 352 * Make the child exit. Best I can do is send it a sigkill. 353 * perhaps it should be put in the status that it wants to 354 * exit. 355 */ 356 case PTRACE_KILL: 357 ret = 0; 358 if (child->exit_state == EXIT_ZOMBIE) 359 break; 360 child->exit_code = SIGKILL; 361 /* make sure single-step breakpoint is gone. */ 362 ptrace_cancel_bpt(child); 363 wake_up_process(child); 364 goto out; 365 366 case PTRACE_SINGLESTEP: /* execute single instruction. */ 367 ret = -EIO; 368 if ((unsigned long) data > _NSIG) 369 break; 370 /* Mark single stepping. */ 371 child->thread_info->bpt_nsaved = -1; 372 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 373 child->exit_code = data; 374 wake_up_process(child); 375 /* give it a chance to run. */ 376 ret = 0; 377 goto out; 378 379 case PTRACE_DETACH: /* detach a process that was attached. */ 380 ret = ptrace_detach(child, data); 381 goto out; 382 383 default: 384 ret = ptrace_request(child, request, addr, data); 385 goto out; 386 } 387 out: 388 put_task_struct(child); 389 out_notsk: 390 unlock_kernel(); 391 return ret; 392 } 393 394 asmlinkage void 395 syscall_trace(void) 396 { 397 if (!test_thread_flag(TIF_SYSCALL_TRACE)) 398 return; 399 if (!(current->ptrace & PT_PTRACED)) 400 return; 401 /* The 0x80 provides a way for the tracing parent to distinguish 402 between a syscall stop and SIGTRAP delivery */ 403 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) 404 ? 0x80 : 0)); 405 406 /* 407 * This isn't the same as continuing with a signal, but it will do 408 * for normal use. strace only continues with a signal if the 409 * stopping signal is not SIGTRAP. -brl 410 */ 411 if (current->exit_code) { 412 send_sig(current->exit_code, current, 1); 413 current->exit_code = 0; 414 } 415 } 416