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/errno.h> 14 #include <linux/ptrace.h> 15 #include <linux/user.h> 16 #include <linux/personality.h> 17 #include <linux/security.h> 18 #include <linux/compat.h> 19 #include <linux/signal.h> 20 21 #include <asm/uaccess.h> 22 #include <asm/pgtable.h> 23 #include <asm/system.h> 24 #include <asm/processor.h> 25 #include <asm/asm-offsets.h> 26 27 /* PSW bits we allow the debugger to modify */ 28 #define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB) 29 30 #undef DEBUG_PTRACE 31 32 #ifdef DEBUG_PTRACE 33 #define DBG(x...) printk(x) 34 #else 35 #define DBG(x...) 36 #endif 37 38 #ifdef CONFIG_64BIT 39 40 /* This function is needed to translate 32 bit pt_regs offsets in to 41 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel 42 * will request offset 12 if it wants gr3, but the lower 32 bits of 43 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4). 44 * This code relies on a 32 bit pt_regs being comprised of 32 bit values 45 * except for the fp registers which (a) are 64 bits, and (b) follow 46 * the gr registers at the start of pt_regs. The 32 bit pt_regs should 47 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[] 48 * being 64 bit in both cases. 49 */ 50 51 static long translate_usr_offset(long offset) 52 { 53 if (offset < 0) 54 return -1; 55 else if (offset <= 32*4) /* gr[0..31] */ 56 return offset * 2 + 4; 57 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */ 58 return offset + 32*4; 59 else if (offset < sizeof(struct pt_regs)/2 + 32*4) 60 return offset * 2 + 4 - 32*8; 61 else 62 return -1; 63 } 64 #endif 65 66 /* 67 * Called by kernel/ptrace.c when detaching.. 68 * 69 * Make sure single step bits etc are not set. 70 */ 71 void ptrace_disable(struct task_struct *child) 72 { 73 /* make sure the trap bits are not set */ 74 pa_psw(child)->r = 0; 75 pa_psw(child)->t = 0; 76 pa_psw(child)->h = 0; 77 pa_psw(child)->l = 0; 78 } 79 80 long arch_ptrace(struct task_struct *child, long request, long addr, long data) 81 { 82 long ret; 83 #ifdef DEBUG_PTRACE 84 long oaddr=addr, odata=data; 85 #endif 86 87 switch (request) { 88 case PTRACE_PEEKTEXT: /* read word at location addr. */ 89 case PTRACE_PEEKDATA: { 90 int copied; 91 92 #ifdef CONFIG_64BIT 93 if (__is_compat_task(child)) { 94 unsigned int tmp; 95 96 addr &= 0xffffffffL; 97 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 98 ret = -EIO; 99 if (copied != sizeof(tmp)) 100 goto out_tsk; 101 ret = put_user(tmp,(unsigned int *) data); 102 DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n", 103 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA", 104 pid, oaddr, odata, ret, tmp); 105 } 106 else 107 #endif 108 { 109 unsigned long tmp; 110 111 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); 112 ret = -EIO; 113 if (copied != sizeof(tmp)) 114 goto out_tsk; 115 ret = put_user(tmp,(unsigned long *) data); 116 } 117 goto out_tsk; 118 } 119 120 /* when I and D space are separate, this will have to be fixed. */ 121 case PTRACE_POKETEXT: /* write the word at location addr. */ 122 case PTRACE_POKEDATA: 123 ret = 0; 124 #ifdef CONFIG_64BIT 125 if (__is_compat_task(child)) { 126 unsigned int tmp = (unsigned int)data; 127 DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n", 128 request == PTRACE_POKETEXT ? "TEXT" : "DATA", 129 pid, oaddr, odata); 130 addr &= 0xffffffffL; 131 if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp)) 132 goto out_tsk; 133 } 134 else 135 #endif 136 { 137 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data)) 138 goto out_tsk; 139 } 140 ret = -EIO; 141 goto out_tsk; 142 143 /* Read the word at location addr in the USER area. For ptraced 144 processes, the kernel saves all regs on a syscall. */ 145 case PTRACE_PEEKUSR: { 146 ret = -EIO; 147 #ifdef CONFIG_64BIT 148 if (__is_compat_task(child)) { 149 unsigned int tmp; 150 151 if (addr & (sizeof(int)-1)) 152 goto out_tsk; 153 if ((addr = translate_usr_offset(addr)) < 0) 154 goto out_tsk; 155 156 tmp = *(unsigned int *) ((char *) task_regs(child) + addr); 157 ret = put_user(tmp, (unsigned int *) data); 158 DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n", 159 pid, oaddr, odata, ret, addr, tmp); 160 } 161 else 162 #endif 163 { 164 unsigned long tmp; 165 166 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 167 goto out_tsk; 168 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 169 ret = put_user(tmp, (unsigned long *) data); 170 } 171 goto out_tsk; 172 } 173 174 /* Write the word at location addr in the USER area. This will need 175 to change when the kernel no longer saves all regs on a syscall. 176 FIXME. There is a problem at the moment in that r3-r18 are only 177 saved if the process is ptraced on syscall entry, and even then 178 those values are overwritten by actual register values on syscall 179 exit. */ 180 case PTRACE_POKEUSR: 181 ret = -EIO; 182 /* Some register values written here may be ignored in 183 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 184 * r31/r31+4, and not with the values in pt_regs. 185 */ 186 /* PT_PSW=0, so this is valid for 32 bit processes under 64 187 * bit kernels. 188 */ 189 if (addr == PT_PSW) { 190 /* PT_PSW=0, so this is valid for 32 bit processes 191 * under 64 bit kernels. 192 * 193 * Allow writing to Nullify, Divide-step-correction, 194 * and carry/borrow bits. 195 * BEWARE, if you set N, and then single step, it won't 196 * stop on the nullified instruction. 197 */ 198 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n", 199 pid, oaddr, odata); 200 data &= USER_PSW_BITS; 201 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 202 task_regs(child)->gr[0] |= data; 203 ret = 0; 204 goto out_tsk; 205 } 206 #ifdef CONFIG_64BIT 207 if (__is_compat_task(child)) { 208 if (addr & (sizeof(int)-1)) 209 goto out_tsk; 210 if ((addr = translate_usr_offset(addr)) < 0) 211 goto out_tsk; 212 DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n", 213 pid, oaddr, odata, addr); 214 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 215 /* Special case, fp regs are 64 bits anyway */ 216 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 217 ret = 0; 218 } 219 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 220 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 221 addr == PT_SAR+4) { 222 /* Zero the top 32 bits */ 223 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0; 224 *(unsigned int *) ((char *) task_regs(child) + addr) = data; 225 ret = 0; 226 } 227 goto out_tsk; 228 } 229 else 230 #endif 231 { 232 if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs)) 233 goto out_tsk; 234 if ((addr >= PT_GR1 && addr <= PT_GR31) || 235 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 236 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 237 addr == PT_SAR) { 238 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 239 ret = 0; 240 } 241 goto out_tsk; 242 } 243 244 case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ 245 case PTRACE_CONT: 246 ret = -EIO; 247 DBG("sys_ptrace(%s)\n", 248 request == PTRACE_SYSCALL ? "SYSCALL" : "CONT"); 249 if (!valid_signal(data)) 250 goto out_tsk; 251 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP); 252 if (request == PTRACE_SYSCALL) { 253 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 254 } else { 255 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 256 } 257 child->exit_code = data; 258 goto out_wake_notrap; 259 260 case PTRACE_KILL: 261 /* 262 * make the child exit. Best I can do is send it a 263 * sigkill. perhaps it should be put in the status 264 * that it wants to exit. 265 */ 266 ret = 0; 267 DBG("sys_ptrace(KILL)\n"); 268 if (child->exit_state == EXIT_ZOMBIE) /* already dead */ 269 goto out_tsk; 270 child->exit_code = SIGKILL; 271 goto out_wake_notrap; 272 273 case PTRACE_SINGLEBLOCK: 274 DBG("sys_ptrace(SINGLEBLOCK)\n"); 275 ret = -EIO; 276 if (!valid_signal(data)) 277 goto out_tsk; 278 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 279 child->ptrace &= ~PT_SINGLESTEP; 280 child->ptrace |= PT_BLOCKSTEP; 281 child->exit_code = data; 282 283 /* Enable taken branch trap. */ 284 pa_psw(child)->r = 0; 285 pa_psw(child)->t = 1; 286 pa_psw(child)->h = 0; 287 pa_psw(child)->l = 0; 288 goto out_wake; 289 290 case PTRACE_SINGLESTEP: 291 DBG("sys_ptrace(SINGLESTEP)\n"); 292 ret = -EIO; 293 if (!valid_signal(data)) 294 goto out_tsk; 295 296 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 297 child->ptrace &= ~PT_BLOCKSTEP; 298 child->ptrace |= PT_SINGLESTEP; 299 child->exit_code = data; 300 301 if (pa_psw(child)->n) { 302 struct siginfo si; 303 304 /* Nullified, just crank over the queue. */ 305 task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1]; 306 task_regs(child)->iasq[0] = task_regs(child)->iasq[1]; 307 task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4; 308 pa_psw(child)->n = 0; 309 pa_psw(child)->x = 0; 310 pa_psw(child)->y = 0; 311 pa_psw(child)->z = 0; 312 pa_psw(child)->b = 0; 313 ptrace_disable(child); 314 /* Don't wake up the child, but let the 315 parent know something happened. */ 316 si.si_code = TRAP_TRACE; 317 si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3); 318 si.si_signo = SIGTRAP; 319 si.si_errno = 0; 320 force_sig_info(SIGTRAP, &si, child); 321 //notify_parent(child, SIGCHLD); 322 //ret = 0; 323 goto out_wake; 324 } 325 326 /* Enable recovery counter traps. The recovery counter 327 * itself will be set to zero on a task switch. If the 328 * task is suspended on a syscall then the syscall return 329 * path will overwrite the recovery counter with a suitable 330 * value such that it traps once back in user space. We 331 * disable interrupts in the childs PSW here also, to avoid 332 * interrupts while the recovery counter is decrementing. 333 */ 334 pa_psw(child)->r = 1; 335 pa_psw(child)->t = 0; 336 pa_psw(child)->h = 0; 337 pa_psw(child)->l = 0; 338 /* give it a chance to run. */ 339 goto out_wake; 340 341 case PTRACE_DETACH: 342 ret = ptrace_detach(child, data); 343 goto out_tsk; 344 345 case PTRACE_GETEVENTMSG: 346 ret = put_user(child->ptrace_message, (unsigned int __user *) data); 347 goto out_tsk; 348 349 default: 350 ret = ptrace_request(child, request, addr, data); 351 goto out_tsk; 352 } 353 354 out_wake_notrap: 355 ptrace_disable(child); 356 out_wake: 357 wake_up_process(child); 358 ret = 0; 359 out_tsk: 360 DBG("arch_ptrace(%ld, %d, %lx, %lx) returning %ld\n", 361 request, pid, oaddr, odata, ret); 362 return ret; 363 } 364 365 void syscall_trace(void) 366 { 367 if (!test_thread_flag(TIF_SYSCALL_TRACE)) 368 return; 369 if (!(current->ptrace & PT_PTRACED)) 370 return; 371 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) 372 ? 0x80 : 0)); 373 /* 374 * this isn't the same as continuing with a signal, but it will do 375 * for normal use. strace only continues with a signal if the 376 * stopping signal is not SIGTRAP. -brl 377 */ 378 if (current->exit_code) { 379 send_sig(current->exit_code, current, 1); 380 current->exit_code = 0; 381 } 382 } 383