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