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