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
  30 #include <asm/cpu.h>
  31 #include <asm/fpu.h>
  32 #include <asm/mipsregs.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/page.h>
  35 #include <asm/system.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/bootinfo.h>
  38
  39 /*
  40  * Called by kernel/ptrace.c when detaching..
  41  *
  42  * Make sure single step bits etc are not set.
  43  */
  44 void ptrace_disable(struct task_struct *child)
  45 {
  46         /* Nothing to do.. */
  47 }
  48
  49 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
  50 {
  51         struct task_struct *child;
  52         int ret;
  53
  54 #if 0
  55         printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
  56                (int) request, (int) pid, (unsigned long) addr,
  57                (unsigned long) data);
  58 #endif
  59         lock_kernel();
  60         ret = -EPERM;
  61         if (request == PTRACE_TRACEME) {
  62                 /* are we already being traced? */
  63                 if (current->ptrace & PT_PTRACED)
  64                         goto out;
  65                 if ((ret = security_ptrace(current->parent, current)))
  66                         goto out;
  67                 /* set the ptrace bit in the process flags. */
  68                 current->ptrace |= PT_PTRACED;
  69                 ret = 0;
  70                 goto out;
  71         }
  72         ret = -ESRCH;
  73         read_lock(&tasklist_lock);
  74         child = find_task_by_pid(pid);
  75         if (child)
  76                 get_task_struct(child);
  77         read_unlock(&tasklist_lock);
  78         if (!child)
  79                 goto out;
  80
  81         ret = -EPERM;
  82         if (pid == 1)           /* you may not mess with init */
  83                 goto out_tsk;
  84
  85         if (request == PTRACE_ATTACH) {
  86                 ret = ptrace_attach(child);
  87                 goto out_tsk;
  88         }
  89
  90         ret = ptrace_check_attach(child, request == PTRACE_KILL);
  91         if (ret < 0)
  92                 goto out_tsk;
  93
  94         switch (request) {
  95         /* when I and D space are separate, these will need to be fixed. */
  96         case PTRACE_PEEKTEXT: /* read word at location addr. */
  97         case PTRACE_PEEKDATA: {
  98                 unsigned long tmp;
  99                 int copied;
 100
 101                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 102                 ret = -EIO;
 103                 if (copied != sizeof(tmp))
 104                         break;
 105                 ret = put_user(tmp,(unsigned long *) data);
 106                 break;
 107         }
 108
 109         /* Read the word at location addr in the USER area. */
 110         case PTRACE_PEEKUSR: {
 111                 struct pt_regs *regs;
 112                 unsigned long tmp = 0;
 113
 114                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 115                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 116                 ret = 0;  /* Default return value. */
 117
 118                 switch (addr) {
 119                 case 0 ... 31:
 120                         tmp = regs->regs[addr];
 121                         break;
 122                 case FPR_BASE ... FPR_BASE + 31:
 123                         if (tsk_used_math(child)) {
 124                                 fpureg_t *fregs = get_fpu_regs(child);
 125
 126 #ifdef CONFIG_MIPS32
 127                                 /*
 128                                  * The odd registers are actually the high
 129                                  * order bits of the values stored in the even
 130                                  * registers - unless we're using r2k_switch.S.
 131                                  */
 132                                 if (addr & 1)
 133                                         tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
 134                                 else
 135                                         tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
 136 #endif
 137 #ifdef CONFIG_MIPS64
 138                                 tmp = fregs[addr - FPR_BASE];
 139 #endif
 140                         } else {
 141                                 tmp = -1;       /* FP not yet used  */
 142                         }
 143                         break;
 144                 case PC:
 145                         tmp = regs->cp0_epc;
 146                         break;
 147                 case CAUSE:
 148                         tmp = regs->cp0_cause;
 149                         break;
 150                 case BADVADDR:
 151                         tmp = regs->cp0_badvaddr;
 152                         break;
 153                 case MMHI:
 154                         tmp = regs->hi;
 155                         break;
 156                 case MMLO:
 157                         tmp = regs->lo;
 158                         break;
 159                 case FPC_CSR:
 160                         if (cpu_has_fpu)
 161                                 tmp = child->thread.fpu.hard.fcr31;
 162                         else
 163                                 tmp = child->thread.fpu.soft.fcr31;
 164                         break;
 165                 case FPC_EIR: { /* implementation / version register */
 166                         unsigned int flags;
 167
 168                         if (!cpu_has_fpu)
 169                                 break;
 170
 171                         flags = read_c0_status();
 172                         __enable_fpu();
 173                         __asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
 174                         write_c0_status(flags);
 175                         break;
 176                 }
 177                 default:
 178                         tmp = 0;
 179                         ret = -EIO;
 180                         goto out_tsk;
 181                 }
 182                 ret = put_user(tmp, (unsigned long *) data);
 183                 break;
 184         }
 185
 186         /* when I and D space are separate, this will have to be fixed. */
 187         case PTRACE_POKETEXT: /* write the word at location addr. */
 188         case PTRACE_POKEDATA:
 189                 ret = 0;
 190                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 191                     == sizeof(data))
 192                         break;
 193                 ret = -EIO;
 194                 break;
 195
 196         case PTRACE_POKEUSR: {
 197                 struct pt_regs *regs;
 198                 ret = 0;
 199                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 200                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 201
 202                 switch (addr) {
 203                 case 0 ... 31:
 204                         regs->regs[addr] = data;
 205                         break;
 206                 case FPR_BASE ... FPR_BASE + 31: {
 207                         fpureg_t *fregs = get_fpu_regs(child);
 208
 209                         if (!tsk_used_math(child)) {
 210                                 /* FP not yet used  */
 211                                 memset(&child->thread.fpu.hard, ~0,
 212                                        sizeof(child->thread.fpu.hard));
 213                                 child->thread.fpu.hard.fcr31 = 0;
 214                         }
 215 #ifdef CONFIG_MIPS32
 216                         /*
 217                          * The odd registers are actually the high order bits
 218                          * of the values stored in the even registers - unless
 219                          * we're using r2k_switch.S.
 220                          */
 221                         if (addr & 1) {
 222                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 223                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 224                         } else {
 225                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 226                                 fregs[addr - FPR_BASE] |= data;
 227                         }
 228 #endif
 229 #ifdef CONFIG_MIPS64
 230                         fregs[addr - FPR_BASE] = data;
 231 #endif
 232                         break;
 233                 }
 234                 case PC:
 235                         regs->cp0_epc = data;
 236                         break;
 237                 case MMHI:
 238                         regs->hi = data;
 239                         break;
 240                 case MMLO:
 241                         regs->lo = data;
 242                         break;
 243                 case FPC_CSR:
 244                         if (cpu_has_fpu)
 245                                 child->thread.fpu.hard.fcr31 = data;
 246                         else
 247                                 child->thread.fpu.soft.fcr31 = data;
 248                         break;
 249                 default:
 250                         /* The rest are not allowed. */
 251                         ret = -EIO;
 252                         break;
 253                 }
 254                 break;
 255                 }
 256
 257         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 258         case PTRACE_CONT: { /* restart after signal. */
 259                 ret = -EIO;
 260                 if ((unsigned long) data > _NSIG)
 261                         break;
 262                 if (request == PTRACE_SYSCALL) {
 263                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 264                 }
 265                 else {
 266                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 267                 }
 268                 child->exit_code = data;
 269                 wake_up_process(child);
 270                 ret = 0;
 271                 break;
 272         }
 273
 274         /*
 275          * make the child exit.  Best I can do is send it a sigkill.
 276          * perhaps it should be put in the status that it wants to
 277          * exit.
 278          */
 279         case PTRACE_KILL:
 280                 ret = 0;
 281                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 282                         break;
 283                 child->exit_code = SIGKILL;
 284                 wake_up_process(child);
 285                 break;
 286
 287         case PTRACE_DETACH: /* detach a process that was attached. */
 288                 ret = ptrace_detach(child, data);
 289                 break;
 290
 291         default:
 292                 ret = ptrace_request(child, request, addr, data);
 293                 break;
 294         }
 295
 296 out_tsk:
 297         put_task_struct(child);
 298 out:
 299         unlock_kernel();
 300         return ret;
 301 }
 302
 303 /*
 304  * Notification of system call entry/exit
 305  * - triggered by current->work.syscall_trace
 306  */
 307 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 308 {
 309         if (unlikely(current->audit_context)) {
 310                 if (!entryexit)
 311                         audit_syscall_entry(current, regs->regs[2],
 312                                             regs->regs[4], regs->regs[5],
 313                                             regs->regs[6], regs->regs[7]);
 314                 else
 315                         audit_syscall_exit(current, regs->regs[2]);
 316         }
 317
 318         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 319                 return;
 320         if (!(current->ptrace & PT_PTRACED))
 321                 return;
 322
 323         /* The 0x80 provides a way for the tracing parent to distinguish
 324            between a syscall stop and SIGTRAP delivery */
 325         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 326                                  0x80 : 0));
 327
 328         /*
 329          * this isn't the same as continuing with a signal, but it will do
 330          * for normal use.  strace only continues with a signal if the
 331          * stopping signal is not SIGTRAP.  -brl
 332          */
 333         if (current->exit_code) {
 334                 send_sig(current->exit_code, current, 1);
 335                 current->exit_code = 0;
 336         }
 337 }