arch/mips/kernel/ptrace.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1992 Ross Biro
   7  * Copyright (C) Linus Torvalds
   8  * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
   9  * Copyright (C) 1996 David S. Miller
  10  * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
  11  * Copyright (C) 1999 MIPS Technologies, Inc.
  12  * Copyright (C) 2000 Ulf Carlsson
  13  *
  14  * At this time Linux/MIPS64 only supports syscall tracing, even for 32-bit
  15  * binaries.
  16  */
  17 #include <linux/config.h>
  18 #include <linux/compiler.h>
  19 #include <linux/kernel.h>
  20 #include <linux/sched.h>
  21 #include <linux/mm.h>
  22 #include <linux/errno.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/audit.h>
  25 #include <linux/smp.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/user.h>
  28 #include <linux/security.h>
  29 #include <linux/signal.h>
  30
  31 #include <asm/byteorder.h>
  32 #include <asm/cpu.h>
  33 #include <asm/dsp.h>
  34 #include <asm/fpu.h>
  35 #include <asm/mipsregs.h>
  36 #include <asm/pgtable.h>
  37 #include <asm/page.h>
  38 #include <asm/system.h>
  39 #include <asm/uaccess.h>
  40 #include <asm/bootinfo.h>
  41
  42 /*
  43  * Called by kernel/ptrace.c when detaching..
  44  *
  45  * Make sure single step bits etc are not set.
  46  */
  47 void ptrace_disable(struct task_struct *child)
  48 {
  49         /* Nothing to do.. */
  50 }
  51
  52 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
  53 {
  54         struct task_struct *child;
  55         int ret;
  56
  57 #if 0
  58         printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
  59                (int) request, (int) pid, (unsigned long) addr,
  60                (unsigned long) data);
  61 #endif
  62         lock_kernel();
  63         ret = -EPERM;
  64         if (request == PTRACE_TRACEME) {
  65                 /* are we already being traced? */
  66                 if (current->ptrace & PT_PTRACED)
  67                         goto out;
  68                 if ((ret = security_ptrace(current->parent, current)))
  69                         goto out;
  70                 /* set the ptrace bit in the process flags. */
  71                 current->ptrace |= PT_PTRACED;
  72                 ret = 0;
  73                 goto out;
  74         }
  75         ret = -ESRCH;
  76         read_lock(&tasklist_lock);
  77         child = find_task_by_pid(pid);
  78         if (child)
  79                 get_task_struct(child);
  80         read_unlock(&tasklist_lock);
  81         if (!child)
  82                 goto out;
  83
  84         ret = -EPERM;
  85         if (pid == 1)           /* you may not mess with init */
  86                 goto out_tsk;
  87
  88         if (request == PTRACE_ATTACH) {
  89                 ret = ptrace_attach(child);
  90                 goto out_tsk;
  91         }
  92
  93         ret = ptrace_check_attach(child, request == PTRACE_KILL);
  94         if (ret < 0)
  95                 goto out_tsk;
  96
  97         switch (request) {
  98         /* when I and D space are separate, these will need to be fixed. */
  99         case PTRACE_PEEKTEXT: /* read word at location addr. */
 100         case PTRACE_PEEKDATA: {
 101                 unsigned long tmp;
 102                 int copied;
 103
 104                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 105                 ret = -EIO;
 106                 if (copied != sizeof(tmp))
 107                         break;
 108                 ret = put_user(tmp,(unsigned long __user *) data);
 109                 break;
 110         }
 111
 112         /* Read the word at location addr in the USER area. */
 113         case PTRACE_PEEKUSR: {
 114                 struct pt_regs *regs;
 115                 unsigned long tmp = 0;
 116
 117                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 118                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 119                 ret = 0;  /* Default return value. */
 120
 121                 switch (addr) {
 122                 case 0 ... 31:
 123                         tmp = regs->regs[addr];
 124                         break;
 125                 case FPR_BASE ... FPR_BASE + 31:
 126                         if (tsk_used_math(child)) {
 127                                 fpureg_t *fregs = get_fpu_regs(child);
 128
 129 #ifdef CONFIG_32BIT
 130                                 /*
 131                                  * The odd registers are actually the high
 132                                  * order bits of the values stored in the even
 133                                  * registers - unless we're using r2k_switch.S.
 134                                  */
 135                                 if (addr & 1)
 136                                         tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
 137                                 else
 138                                         tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
 139 #endif
 140 #ifdef CONFIG_64BIT
 141                                 tmp = fregs[addr - FPR_BASE];
 142 #endif
 143                         } else {
 144                                 tmp = -1;       /* FP not yet used  */
 145                         }
 146                         break;
 147                 case PC:
 148                         tmp = regs->cp0_epc;
 149                         break;
 150                 case CAUSE:
 151                         tmp = regs->cp0_cause;
 152                         break;
 153                 case BADVADDR:
 154                         tmp = regs->cp0_badvaddr;
 155                         break;
 156                 case MMHI:
 157                         tmp = regs->hi;
 158                         break;
 159                 case MMLO:
 160                         tmp = regs->lo;
 161                         break;
 162                 case FPC_CSR:
 163                         if (cpu_has_fpu)
 164                                 tmp = child->thread.fpu.hard.fcr31;
 165                         else
 166                                 tmp = child->thread.fpu.soft.fcr31;
 167                         break;
 168                 case FPC_EIR: { /* implementation / version register */
 169                         unsigned int flags;
 170
 171                         if (!cpu_has_fpu)
 172                                 break;
 173
 174                         flags = read_c0_status();
 175                         __enable_fpu();
 176                         __asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
 177                         write_c0_status(flags);
 178                         break;
 179                 }
 180                 case DSP_BASE ... DSP_BASE + 5: {
 181                         dspreg_t *dregs;
 182
 183                         if (!cpu_has_dsp) {
 184                                 tmp = 0;
 185                                 ret = -EIO;
 186                                 goto out_tsk;
 187                         }
 188                         if (child->thread.dsp.used_dsp) {
 189                                 dregs = __get_dsp_regs(child);
 190                                 tmp = (unsigned long) (dregs[addr - DSP_BASE]);
 191                         } else {
 192                                 tmp = -1;       /* DSP registers yet used  */
 193                         }
 194                         break;
 195                 }
 196                 case DSP_CONTROL:
 197                         if (!cpu_has_dsp) {
 198                                 tmp = 0;
 199                                 ret = -EIO;
 200                                 goto out_tsk;
 201                         }
 202                         tmp = child->thread.dsp.dspcontrol;
 203                         break;
 204                 default:
 205                         tmp = 0;
 206                         ret = -EIO;
 207                         goto out_tsk;
 208                 }
 209                 ret = put_user(tmp, (unsigned long __user *) data);
 210                 break;
 211         }
 212
 213         /* when I and D space are separate, this will have to be fixed. */
 214         case PTRACE_POKETEXT: /* write the word at location addr. */
 215         case PTRACE_POKEDATA:
 216                 ret = 0;
 217                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 218                     == sizeof(data))
 219                         break;
 220                 ret = -EIO;
 221                 break;
 222
 223         case PTRACE_POKEUSR: {
 224                 struct pt_regs *regs;
 225                 ret = 0;
 226                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 227                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 228
 229                 switch (addr) {
 230                 case 0 ... 31:
 231                         regs->regs[addr] = data;
 232                         break;
 233                 case FPR_BASE ... FPR_BASE + 31: {
 234                         fpureg_t *fregs = get_fpu_regs(child);
 235
 236                         if (!tsk_used_math(child)) {
 237                                 /* FP not yet used  */
 238                                 memset(&child->thread.fpu.hard, ~0,
 239                                        sizeof(child->thread.fpu.hard));
 240                                 child->thread.fpu.hard.fcr31 = 0;
 241                         }
 242 #ifdef CONFIG_32BIT
 243                         /*
 244                          * The odd registers are actually the high order bits
 245                          * of the values stored in the even registers - unless
 246                          * we're using r2k_switch.S.
 247                          */
 248                         if (addr & 1) {
 249                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 250                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 251                         } else {
 252                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 253                                 fregs[addr - FPR_BASE] |= data;
 254                         }
 255 #endif
 256 #ifdef CONFIG_64BIT
 257                         fregs[addr - FPR_BASE] = data;
 258 #endif
 259                         break;
 260                 }
 261                 case PC:
 262                         regs->cp0_epc = data;
 263                         break;
 264                 case MMHI:
 265                         regs->hi = data;
 266                         break;
 267                 case MMLO:
 268                         regs->lo = data;
 269                         break;
 270                 case FPC_CSR:
 271                         if (cpu_has_fpu)
 272                                 child->thread.fpu.hard.fcr31 = data;
 273                         else
 274                                 child->thread.fpu.soft.fcr31 = data;
 275                         break;
 276                 case DSP_BASE ... DSP_BASE + 5: {
 277                         dspreg_t *dregs;
 278
 279                         if (!cpu_has_dsp) {
 280                                 ret = -EIO;
 281                                 break;
 282                         }
 283
 284                         dregs = __get_dsp_regs(child);
 285                         dregs[addr - DSP_BASE] = data;
 286                         break;
 287                 }
 288                 case DSP_CONTROL:
 289                         if (!cpu_has_dsp) {
 290                                 ret = -EIO;
 291                                 break;
 292                         }
 293                         child->thread.dsp.dspcontrol = data;
 294                         break;
 295                 default:
 296                         /* The rest are not allowed. */
 297                         ret = -EIO;
 298                         break;
 299                 }
 300                 break;
 301                 }
 302
 303         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 304         case PTRACE_CONT: { /* restart after signal. */
 305                 ret = -EIO;
 306                 if (!valid_signal(data))
 307                         break;
 308                 if (request == PTRACE_SYSCALL) {
 309                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 310                 }
 311                 else {
 312                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 313                 }
 314                 child->exit_code = data;
 315                 wake_up_process(child);
 316                 ret = 0;
 317                 break;
 318         }
 319
 320         /*
 321          * make the child exit.  Best I can do is send it a sigkill.
 322          * perhaps it should be put in the status that it wants to
 323          * exit.
 324          */
 325         case PTRACE_KILL:
 326                 ret = 0;
 327                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 328                         break;
 329                 child->exit_code = SIGKILL;
 330                 wake_up_process(child);
 331                 break;
 332
 333         case PTRACE_DETACH: /* detach a process that was attached. */
 334                 ret = ptrace_detach(child, data);
 335                 break;
 336
 337         case PTRACE_GET_THREAD_AREA:
 338                 ret = put_user(child->thread_info->tp_value,
 339                                 (unsigned long __user *) data);
 340                 break;
 341
 342         default:
 343                 ret = ptrace_request(child, request, addr, data);
 344                 break;
 345         }
 346
 347 out_tsk:
 348         put_task_struct(child);
 349 out:
 350         unlock_kernel();
 351         return ret;
 352 }
 353
 354 static inline int audit_arch(void)
 355 {
 356         int arch = EM_MIPS;
 357 #ifdef CONFIG_64BIT
 358         arch |=  __AUDIT_ARCH_64BIT;
 359 #endif
 360 #if defined(__LITTLE_ENDIAN)
 361         arch |=  __AUDIT_ARCH_LE;
 362 #endif
 363         return arch;
 364 }
 365
 366 /*
 367  * Notification of system call entry/exit
 368  * - triggered by current->work.syscall_trace
 369  */
 370 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 371 {
 372         if (unlikely(current->audit_context) && entryexit)
 373                 audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]),
 374                                    regs->regs[2]);
 375
 376         if (!(current->ptrace & PT_PTRACED))
 377                 goto out;
 378         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 379                 goto out;
 380
 381         /* The 0x80 provides a way for the tracing parent to distinguish
 382            between a syscall stop and SIGTRAP delivery */
 383         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 384                                  0x80 : 0));
 385
 386         /*
 387          * this isn't the same as continuing with a signal, but it will do
 388          * for normal use.  strace only continues with a signal if the
 389          * stopping signal is not SIGTRAP.  -brl
 390          */
 391         if (current->exit_code) {
 392                 send_sig(current->exit_code, current, 1);
 393                 current->exit_code = 0;
 394         }
 395  out:
 396         if (unlikely(current->audit_context) && !entryexit)
 397                 audit_syscall_entry(current, audit_arch(), regs->regs[2],
 398                                     regs->regs[4], regs->regs[5],
 399                                     regs->regs[6], regs->regs[7]);
 400 }