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/cpu.h>
  32 #include <asm/fpu.h>
  33 #include <asm/mipsregs.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/page.h>
  36 #include <asm/system.h>
  37 #include <asm/uaccess.h>
  38 #include <asm/bootinfo.h>
  39
  40 /*
  41  * Called by kernel/ptrace.c when detaching..
  42  *
  43  * Make sure single step bits etc are not set.
  44  */
  45 void ptrace_disable(struct task_struct *child)
  46 {
  47         /* Nothing to do.. */
  48 }
  49
  50 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
  51 {
  52         struct task_struct *child;
  53         int ret;
  54
  55 #if 0
  56         printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
  57                (int) request, (int) pid, (unsigned long) addr,
  58                (unsigned long) data);
  59 #endif
  60         lock_kernel();
  61         ret = -EPERM;
  62         if (request == PTRACE_TRACEME) {
  63                 /* are we already being traced? */
  64                 if (current->ptrace & PT_PTRACED)
  65                         goto out;
  66                 if ((ret = security_ptrace(current->parent, current)))
  67                         goto out;
  68                 /* set the ptrace bit in the process flags. */
  69                 current->ptrace |= PT_PTRACED;
  70                 ret = 0;
  71                 goto out;
  72         }
  73         ret = -ESRCH;
  74         read_lock(&tasklist_lock);
  75         child = find_task_by_pid(pid);
  76         if (child)
  77                 get_task_struct(child);
  78         read_unlock(&tasklist_lock);
  79         if (!child)
  80                 goto out;
  81
  82         ret = -EPERM;
  83         if (pid == 1)           /* you may not mess with init */
  84                 goto out_tsk;
  85
  86         if (request == PTRACE_ATTACH) {
  87                 ret = ptrace_attach(child);
  88                 goto out_tsk;
  89         }
  90
  91         ret = ptrace_check_attach(child, request == PTRACE_KILL);
  92         if (ret < 0)
  93                 goto out_tsk;
  94
  95         switch (request) {
  96         /* when I and D space are separate, these will need to be fixed. */
  97         case PTRACE_PEEKTEXT: /* read word at location addr. */
  98         case PTRACE_PEEKDATA: {
  99                 unsigned long tmp;
 100                 int copied;
 101
 102                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 103                 ret = -EIO;
 104                 if (copied != sizeof(tmp))
 105                         break;
 106                 ret = put_user(tmp,(unsigned long *) data);
 107                 break;
 108         }
 109
 110         /* Read the word at location addr in the USER area. */
 111         case PTRACE_PEEKUSR: {
 112                 struct pt_regs *regs;
 113                 unsigned long tmp = 0;
 114
 115                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 116                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 117                 ret = 0;  /* Default return value. */
 118
 119                 switch (addr) {
 120                 case 0 ... 31:
 121                         tmp = regs->regs[addr];
 122                         break;
 123                 case FPR_BASE ... FPR_BASE + 31:
 124                         if (tsk_used_math(child)) {
 125                                 fpureg_t *fregs = get_fpu_regs(child);
 126
 127 #ifdef CONFIG_32BIT
 128                                 /*
 129                                  * The odd registers are actually the high
 130                                  * order bits of the values stored in the even
 131                                  * registers - unless we're using r2k_switch.S.
 132                                  */
 133                                 if (addr & 1)
 134                                         tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
 135                                 else
 136                                         tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
 137 #endif
 138 #ifdef CONFIG_64BIT
 139                                 tmp = fregs[addr - FPR_BASE];
 140 #endif
 141                         } else {
 142                                 tmp = -1;       /* FP not yet used  */
 143                         }
 144                         break;
 145                 case PC:
 146                         tmp = regs->cp0_epc;
 147                         break;
 148                 case CAUSE:
 149                         tmp = regs->cp0_cause;
 150                         break;
 151                 case BADVADDR:
 152                         tmp = regs->cp0_badvaddr;
 153                         break;
 154                 case MMHI:
 155                         tmp = regs->hi;
 156                         break;
 157                 case MMLO:
 158                         tmp = regs->lo;
 159                         break;
 160                 case FPC_CSR:
 161                         if (cpu_has_fpu)
 162                                 tmp = child->thread.fpu.hard.fcr31;
 163                         else
 164                                 tmp = child->thread.fpu.soft.fcr31;
 165                         break;
 166                 case FPC_EIR: { /* implementation / version register */
 167                         unsigned int flags;
 168
 169                         if (!cpu_has_fpu)
 170                                 break;
 171
 172                         flags = read_c0_status();
 173                         __enable_fpu();
 174                         __asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
 175                         write_c0_status(flags);
 176                         break;
 177                 }
 178                 default:
 179                         tmp = 0;
 180                         ret = -EIO;
 181                         goto out_tsk;
 182                 }
 183                 ret = put_user(tmp, (unsigned long *) data);
 184                 break;
 185         }
 186
 187         /* when I and D space are separate, this will have to be fixed. */
 188         case PTRACE_POKETEXT: /* write the word at location addr. */
 189         case PTRACE_POKEDATA:
 190                 ret = 0;
 191                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 192                     == sizeof(data))
 193                         break;
 194                 ret = -EIO;
 195                 break;
 196
 197         case PTRACE_POKEUSR: {
 198                 struct pt_regs *regs;
 199                 ret = 0;
 200                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 201                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 202
 203                 switch (addr) {
 204                 case 0 ... 31:
 205                         regs->regs[addr] = data;
 206                         break;
 207                 case FPR_BASE ... FPR_BASE + 31: {
 208                         fpureg_t *fregs = get_fpu_regs(child);
 209
 210                         if (!tsk_used_math(child)) {
 211                                 /* FP not yet used  */
 212                                 memset(&child->thread.fpu.hard, ~0,
 213                                        sizeof(child->thread.fpu.hard));
 214                                 child->thread.fpu.hard.fcr31 = 0;
 215                         }
 216 #ifdef CONFIG_32BIT
 217                         /*
 218                          * The odd registers are actually the high order bits
 219                          * of the values stored in the even registers - unless
 220                          * we're using r2k_switch.S.
 221                          */
 222                         if (addr & 1) {
 223                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 224                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 225                         } else {
 226                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 227                                 fregs[addr - FPR_BASE] |= data;
 228                         }
 229 #endif
 230 #ifdef CONFIG_64BIT
 231                         fregs[addr - FPR_BASE] = data;
 232 #endif
 233                         break;
 234                 }
 235                 case PC:
 236                         regs->cp0_epc = data;
 237                         break;
 238                 case MMHI:
 239                         regs->hi = data;
 240                         break;
 241                 case MMLO:
 242                         regs->lo = data;
 243                         break;
 244                 case FPC_CSR:
 245                         if (cpu_has_fpu)
 246                                 child->thread.fpu.hard.fcr31 = data;
 247                         else
 248                                 child->thread.fpu.soft.fcr31 = data;
 249                         break;
 250                 default:
 251                         /* The rest are not allowed. */
 252                         ret = -EIO;
 253                         break;
 254                 }
 255                 break;
 256                 }
 257
 258         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 259         case PTRACE_CONT: { /* restart after signal. */
 260                 ret = -EIO;
 261                 if (!valid_signal(data))
 262                         break;
 263                 if (request == PTRACE_SYSCALL) {
 264                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 265                 }
 266                 else {
 267                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 268                 }
 269                 child->exit_code = data;
 270                 wake_up_process(child);
 271                 ret = 0;
 272                 break;
 273         }
 274
 275         /*
 276          * make the child exit.  Best I can do is send it a sigkill.
 277          * perhaps it should be put in the status that it wants to
 278          * exit.
 279          */
 280         case PTRACE_KILL:
 281                 ret = 0;
 282                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 283                         break;
 284                 child->exit_code = SIGKILL;
 285                 wake_up_process(child);
 286                 break;
 287
 288         case PTRACE_DETACH: /* detach a process that was attached. */
 289                 ret = ptrace_detach(child, data);
 290                 break;
 291
 292         default:
 293                 ret = ptrace_request(child, request, addr, data);
 294                 break;
 295         }
 296
 297 out_tsk:
 298         put_task_struct(child);
 299 out:
 300         unlock_kernel();
 301         return ret;
 302 }
 303
 304 static inline int audit_arch(void)
 305 {
 306 #ifdef CONFIG_CPU_LITTLE_ENDIAN
 307 #ifdef CONFIG_64BIT
 308         if (!(current->thread.mflags & MF_32BIT_REGS))
 309                 return AUDIT_ARCH_MIPSEL64;
 310 #endif /* MIPS64 */
 311         return AUDIT_ARCH_MIPSEL;
 312
 313 #else /* big endian... */
 314 #ifdef CONFIG_64BIT
 315         if (!(current->thread.mflags & MF_32BIT_REGS))
 316                 return AUDIT_ARCH_MIPS64;
 317 #endif /* MIPS64 */
 318         return AUDIT_ARCH_MIPS;
 319
 320 #endif /* endian */
 321 }
 322
 323 /*
 324  * Notification of system call entry/exit
 325  * - triggered by current->work.syscall_trace
 326  */
 327 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 328 {
 329         if (unlikely(current->audit_context) && entryexit)
 330                 audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]), regs->regs[2]);
 331
 332         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 333                 goto out;
 334         if (!(current->ptrace & PT_PTRACED))
 335                 goto out;
 336
 337         /* The 0x80 provides a way for the tracing parent to distinguish
 338            between a syscall stop and SIGTRAP delivery */
 339         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 340                                  0x80 : 0));
 341
 342         /*
 343          * this isn't the same as continuing with a signal, but it will do
 344          * for normal use.  strace only continues with a signal if the
 345          * stopping signal is not SIGTRAP.  -brl
 346          */
 347         if (current->exit_code) {
 348                 send_sig(current->exit_code, current, 1);
 349                 current->exit_code = 0;
 350         }
 351  out:
 352         if (unlikely(current->audit_context) && !entryexit)
 353                 audit_syscall_entry(current, audit_arch(), regs->regs[2],
 354                                     regs->regs[4], regs->regs[5],
 355                                     regs->regs[6], regs->regs[7]);
 356 }