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