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/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 arch_ptrace(struct task_struct *child, long request, long addr, long data) 82 { 83 long ret; 84 #ifdef DEBUG_PTRACE 85 long oaddr=addr, odata=data; 86 #endif 87 88 switch (request) { 89 case PTRACE_PEEKTEXT: /* read word at location addr. */ 90 case PTRACE_PEEKDATA: { 91 int copied; 92 93 #ifdef __LP64__ 94 if (is_compat_task(child)) { 95 unsigned int tmp; 96 97 addr &= 0xffffffffL; 98 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 99 ret = -EIO; 100 if (copied != sizeof(tmp)) 101 goto out_tsk; 102 ret = put_user(tmp,(unsigned int *) data); 103 DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n", 104 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA", 105 pid, oaddr, odata, ret, tmp); 106 } 107 else 108 #endif 109 { 110 unsigned long tmp; 111 112 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 113 ret = -EIO; 114 if (copied != sizeof(tmp)) 115 goto out_tsk; 116 ret = put_user(tmp,(unsigned long *) data); 117 } 118 goto out_tsk; 119 } 120 121 /* when I and D space are separate, this will have to be fixed. */ 122 case PTRACE_POKETEXT: /* write the word at location addr. */ 123 case PTRACE_POKEDATA: 124 ret = 0; 125 #ifdef __LP64__ 126 if (is_compat_task(child)) { 127 unsigned int tmp = (unsigned int)data; 128 DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n", 129 request == PTRACE_POKETEXT ? "TEXT" : "DATA", 130 pid, oaddr, odata); 131 addr &= 0xffffffffL; 132 if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp)) 133 goto out_tsk; 134 } 135 else 136 #endif 137 { 138 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data)) 139 goto out_tsk; 140 } 141 ret = -EIO; 142 goto out_tsk; 143 144 /* Read the word at location addr in the USER area. For ptraced 145 processes, the kernel saves all regs on a syscall. */ 146 case PTRACE_PEEKUSR: { 147 ret = -EIO; 148 #ifdef __LP64__ 149 if (is_compat_task(child)) { 150 unsigned int tmp; 151 152 if (addr & (sizeof(int)-1)) 153 goto out_tsk; 154 if ((addr = translate_usr_offset(addr)) < 0) 155 goto out_tsk; 156 157 tmp = *(unsigned int *) ((char *) task_regs(child) + addr); 158 ret = put_user(tmp, (unsigned int *) data); 159 DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n", 160 pid, oaddr, odata, ret, addr, tmp); 161 } 162 else 163 #endif 164 { 165 unsigned long tmp; 166 167 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 168 goto out_tsk; 169 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 170 ret = put_user(tmp, (unsigned long *) data); 171 } 172 goto out_tsk; 173 } 174 175 /* Write the word at location addr in the USER area. This will need 176 to change when the kernel no longer saves all regs on a syscall. 177 FIXME. There is a problem at the moment in that r3-r18 are only 178 saved if the process is ptraced on syscall entry, and even then 179 those values are overwritten by actual register values on syscall 180 exit. */ 181 case PTRACE_POKEUSR: 182 ret = -EIO; 183 /* Some register values written here may be ignored in 184 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 185 * r31/r31+4, and not with the values in pt_regs. 186 */ 187 /* PT_PSW=0, so this is valid for 32 bit processes under 64 188 * bit kernels. 189 */ 190 if (addr == PT_PSW) { 191 /* PT_PSW=0, so this is valid for 32 bit processes 192 * under 64 bit kernels. 193 * 194 * Allow writing to Nullify, Divide-step-correction, 195 * and carry/borrow bits. 196 * BEWARE, if you set N, and then single step, it won't 197 * stop on the nullified instruction. 198 */ 199 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n", 200 pid, oaddr, odata); 201 data &= USER_PSW_BITS; 202 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 203 task_regs(child)->gr[0] |= data; 204 ret = 0; 205 goto out_tsk; 206 } 207 #ifdef __LP64__ 208 if (is_compat_task(child)) { 209 if (addr & (sizeof(int)-1)) 210 goto out_tsk; 211 if ((addr = translate_usr_offset(addr)) < 0) 212 goto out_tsk; 213 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n", 214 pid, oaddr, odata, addr); 215 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 216 /* Special case, fp regs are 64 bits anyway */ 217 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 218 ret = 0; 219 } 220 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 221 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 222 addr == PT_SAR+4) { 223 /* Zero the top 32 bits */ 224 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0; 225 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 226 ret = 0; 227 } 228 goto out_tsk; 229 } 230 else 231 #endif 232 { 233 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 234 goto out_tsk; 235 if ((addr >= PT_GR1 && addr <= PT_GR31) || 236 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 237 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 238 addr == PT_SAR) { 239 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 240 ret = 0; 241 } 242 goto out_tsk; 243 } 244 245 case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ 246 case PTRACE_CONT: 247 ret = -EIO; 248 DBG("sys_ptrace(%s)\n", 249 request == PTRACE_SYSCALL ? "SYSCALL" : "CONT"); 250 if (!valid_signal(data)) 251 goto out_tsk; 252 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP); 253 if (request == PTRACE_SYSCALL) { 254 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 255 } else { 256 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 257 } 258 child->exit_code = data; 259 goto out_wake_notrap; 260 261 case PTRACE_KILL: 262 /* 263 * make the child exit. Best I can do is send it a 264 * sigkill. perhaps it should be put in the status 265 * that it wants to exit. 266 */ 267 ret = 0; 268 DBG("sys_ptrace(KILL)\n"); 269 if (child->exit_state == EXIT_ZOMBIE) /* already dead */ 270 goto out_tsk; 271 child->exit_code = SIGKILL; 272 goto out_wake_notrap; 273 274 case PTRACE_SINGLEBLOCK: 275 DBG("sys_ptrace(SINGLEBLOCK)\n"); 276 ret = -EIO; 277 if (!valid_signal(data)) 278 goto out_tsk; 279 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 280 child->ptrace &= ~PT_SINGLESTEP; 281 child->ptrace |= PT_BLOCKSTEP; 282 child->exit_code = data; 283 284 /* Enable taken branch trap. */ 285 pa_psw(child)->r = 0; 286 pa_psw(child)->t = 1; 287 pa_psw(child)->h = 0; 288 pa_psw(child)->l = 0; 289 goto out_wake; 290 291 case PTRACE_SINGLESTEP: 292 DBG("sys_ptrace(SINGLESTEP)\n"); 293 ret = -EIO; 294 if (!valid_signal(data)) 295 goto out_tsk; 296 297 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 298 child->ptrace &= ~PT_BLOCKSTEP; 299 child->ptrace |= PT_SINGLESTEP; 300 child->exit_code = data; 301 302 if (pa_psw(child)->n) { 303 struct siginfo si; 304 305 /* Nullified, just crank over the queue. */ 306 task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1]; 307 task_regs(child)->iasq[0] = task_regs(child)->iasq[1]; 308 task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4; 309 pa_psw(child)->n = 0; 310 pa_psw(child)->x = 0; 311 pa_psw(child)->y = 0; 312 pa_psw(child)->z = 0; 313 pa_psw(child)->b = 0; 314 ptrace_disable(child); 315 /* Don't wake up the child, but let the 316 parent know something happened. */ 317 si.si_code = TRAP_TRACE; 318 si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3); 319 si.si_signo = SIGTRAP; 320 si.si_errno = 0; 321 force_sig_info(SIGTRAP, &si, child); 322 //notify_parent(child, SIGCHLD); 323 //ret = 0; 324 goto out_wake; 325 } 326 327 /* Enable recovery counter traps. The recovery counter 328 * itself will be set to zero on a task switch. If the 329 * task is suspended on a syscall then the syscall return 330 * path will overwrite the recovery counter with a suitable 331 * value such that it traps once back in user space. We 332 * disable interrupts in the childs PSW here also, to avoid 333 * interrupts while the recovery counter is decrementing. 334 */ 335 pa_psw(child)->r = 1; 336 pa_psw(child)->t = 0; 337 pa_psw(child)->h = 0; 338 pa_psw(child)->l = 0; 339 /* give it a chance to run. */ 340 goto out_wake; 341 342 case PTRACE_DETACH: 343 ret = ptrace_detach(child, data); 344 goto out_tsk; 345 346 case PTRACE_GETEVENTMSG: 347 ret = put_user(child->ptrace_message, (unsigned int __user *) data); 348 goto out_tsk; 349 350 default: 351 ret = ptrace_request(child, request, addr, data); 352 goto out_tsk; 353 } 354 355 out_wake_notrap: 356 ptrace_disable(child); 357 out_wake: 358 wake_up_process(child); 359 ret = 0; 360 out_tsk: 361 DBG("arch_ptrace(%ld, %d, %lx, %lx) returning %ld\n", 362 request, pid, oaddr, odata, ret); 363 return ret; 364 } 365 366 void syscall_trace(void) 367 { 368 if (!test_thread_flag(TIF_SYSCALL_TRACE)) 369 return; 370 if (!(current->ptrace & PT_PTRACED)) 371 return; 372 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) 373 ? 0x80 : 0)); 374 /* 375 * this isn't the same as continuing with a signal, but it will do 376 * for normal use. strace only continues with a signal if the 377 * stopping signal is not SIGTRAP. -brl 378 */ 379 if (current->exit_code) { 380 send_sig(current->exit_code, current, 1); 381 current->exit_code = 0; 382 } 383 } 384