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                         if (!cpu_has_dsp) {
 182                                 tmp = 0;
 183                                 ret = -EIO;
 184                                 goto out_tsk;
 185                         }
 186                         if (child->thread.dsp.used_dsp) {
 187                                 dspreg_t *dregs = __get_dsp_regs(child);
 188                                 tmp = (unsigned long) (dregs[addr - DSP_BASE]);
 189                         } else {
 190                                 tmp = -1;       /* DSP registers yet used  */
 191                         }
 192                         break;
 193                 case DSP_CONTROL:
 194                         if (!cpu_has_dsp) {
 195                                 tmp = 0;
 196                                 ret = -EIO;
 197                                 goto out_tsk;
 198                         }
 199                         tmp = child->thread.dsp.dspcontrol;
 200                         break;
 201                 default:
 202                         tmp = 0;
 203                         ret = -EIO;
 204                         goto out_tsk;
 205                 }
 206                 ret = put_user(tmp, (unsigned long __user *) data);
 207                 break;
 208         }
 209
 210         /* when I and D space are separate, this will have to be fixed. */
 211         case PTRACE_POKETEXT: /* write the word at location addr. */
 212         case PTRACE_POKEDATA:
 213                 ret = 0;
 214                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 215                     == sizeof(data))
 216                         break;
 217                 ret = -EIO;
 218                 break;
 219
 220         case PTRACE_POKEUSR: {
 221                 struct pt_regs *regs;
 222                 ret = 0;
 223                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 224                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 225
 226                 switch (addr) {
 227                 case 0 ... 31:
 228                         regs->regs[addr] = data;
 229                         break;
 230                 case FPR_BASE ... FPR_BASE + 31: {
 231                         fpureg_t *fregs = get_fpu_regs(child);
 232
 233                         if (!tsk_used_math(child)) {
 234                                 /* FP not yet used  */
 235                                 memset(&child->thread.fpu.hard, ~0,
 236                                        sizeof(child->thread.fpu.hard));
 237                                 child->thread.fpu.hard.fcr31 = 0;
 238                         }
 239 #ifdef CONFIG_32BIT
 240                         /*
 241                          * The odd registers are actually the high order bits
 242                          * of the values stored in the even registers - unless
 243                          * we're using r2k_switch.S.
 244                          */
 245                         if (addr & 1) {
 246                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 247                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 248                         } else {
 249                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 250                                 fregs[addr - FPR_BASE] |= data;
 251                         }
 252 #endif
 253 #ifdef CONFIG_64BIT
 254                         fregs[addr - FPR_BASE] = data;
 255 #endif
 256                         break;
 257                 }
 258                 case PC:
 259                         regs->cp0_epc = data;
 260                         break;
 261                 case MMHI:
 262                         regs->hi = data;
 263                         break;
 264                 case MMLO:
 265                         regs->lo = data;
 266                         break;
 267                 case FPC_CSR:
 268                         if (cpu_has_fpu)
 269                                 child->thread.fpu.hard.fcr31 = data;
 270                         else
 271                                 child->thread.fpu.soft.fcr31 = data;
 272                         break;
 273                 case DSP_BASE ... DSP_BASE + 5:
 274                         if (!cpu_has_dsp) {
 275                                 ret = -EIO;
 276                                 break;
 277                         }
 278
 279                         dspreg_t *dregs = __get_dsp_regs(child);
 280                         dregs[addr - DSP_BASE] = data;
 281                         break;
 282                 case DSP_CONTROL:
 283                         if (!cpu_has_dsp) {
 284                                 ret = -EIO;
 285                                 break;
 286                         }
 287                         child->thread.dsp.dspcontrol = data;
 288                         break;
 289                 default:
 290                         /* The rest are not allowed. */
 291                         ret = -EIO;
 292                         break;
 293                 }
 294                 break;
 295                 }
 296
 297         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 298         case PTRACE_CONT: { /* restart after signal. */
 299                 ret = -EIO;
 300                 if (!valid_signal(data))
 301                         break;
 302                 if (request == PTRACE_SYSCALL) {
 303                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 304                 }
 305                 else {
 306                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 307                 }
 308                 child->exit_code = data;
 309                 wake_up_process(child);
 310                 ret = 0;
 311                 break;
 312         }
 313
 314         /*
 315          * make the child exit.  Best I can do is send it a sigkill.
 316          * perhaps it should be put in the status that it wants to
 317          * exit.
 318          */
 319         case PTRACE_KILL:
 320                 ret = 0;
 321                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 322                         break;
 323                 child->exit_code = SIGKILL;
 324                 wake_up_process(child);
 325                 break;
 326
 327         case PTRACE_DETACH: /* detach a process that was attached. */
 328                 ret = ptrace_detach(child, data);
 329                 break;
 330
 331         case PTRACE_GET_THREAD_AREA:
 332                 ret = put_user(child->thread_info->tp_value,
 333                                 (unsigned long __user *) data);
 334                 break;
 335
 336         default:
 337                 ret = ptrace_request(child, request, addr, data);
 338                 break;
 339         }
 340
 341 out_tsk:
 342         put_task_struct(child);
 343 out:
 344         unlock_kernel();
 345         return ret;
 346 }
 347
 348 static inline int audit_arch(void)
 349 {
 350         int arch = EM_MIPS;
 351 #ifdef CONFIG_64BIT
 352         arch |=  __AUDIT_ARCH_64BIT;
 353 #endif
 354 #if defined(__LITTLE_ENDIAN)
 355         arch |=  __AUDIT_ARCH_LE;
 356 #endif
 357         return arch;
 358 }
 359
 360 /*
 361  * Notification of system call entry/exit
 362  * - triggered by current->work.syscall_trace
 363  */
 364 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 365 {
 366         if (unlikely(current->audit_context) && entryexit)
 367                 audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]),
 368                                    regs->regs[2]);
 369
 370         if (!(current->ptrace & PT_PTRACED))
 371                 goto out;
 372         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 373                 goto out;
 374
 375         /* The 0x80 provides a way for the tracing parent to distinguish
 376            between a syscall stop and SIGTRAP delivery */
 377         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 378                                  0x80 : 0));
 379
 380         /*
 381          * this isn't the same as continuing with a signal, but it will do
 382          * for normal use.  strace only continues with a signal if the
 383          * stopping signal is not SIGTRAP.  -brl
 384          */
 385         if (current->exit_code) {
 386                 send_sig(current->exit_code, current, 1);
 387                 current->exit_code = 0;
 388         }
 389  out:
 390         if (unlikely(current->audit_context) && !entryexit)
 391                 audit_syscall_entry(current, audit_arch(), regs->regs[2],
 392                                     regs->regs[4], regs->regs[5],
 393                                     regs->regs[6], regs->regs[7]);
 394 }