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         if (!vx_check(vx_task_xid(child), VX_WATCH|VX_IDENT))
  82                 goto out_tsk;
  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 *) 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_MIPS32
 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_MIPS64
 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                 default:
 181                         tmp = 0;
 182                         ret = -EIO;
 183                         goto out_tsk;
 184                 }
 185                 ret = put_user(tmp, (unsigned long *) data);
 186                 break;
 187         }
 188
 189         /* when I and D space are separate, this will have to be fixed. */
 190         case PTRACE_POKETEXT: /* write the word at location addr. */
 191         case PTRACE_POKEDATA:
 192                 ret = 0;
 193                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 194                     == sizeof(data))
 195                         break;
 196                 ret = -EIO;
 197                 break;
 198
 199         case PTRACE_POKEUSR: {
 200                 struct pt_regs *regs;
 201                 ret = 0;
 202                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 203                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 204
 205                 switch (addr) {
 206                 case 0 ... 31:
 207                         regs->regs[addr] = data;
 208                         break;
 209                 case FPR_BASE ... FPR_BASE + 31: {
 210                         fpureg_t *fregs = get_fpu_regs(child);
 211
 212                         if (!tsk_used_math(child)) {
 213                                 /* FP not yet used  */
 214                                 memset(&child->thread.fpu.hard, ~0,
 215                                        sizeof(child->thread.fpu.hard));
 216                                 child->thread.fpu.hard.fcr31 = 0;
 217                         }
 218 #ifdef CONFIG_MIPS32
 219                         /*
 220                          * The odd registers are actually the high order bits
 221                          * of the values stored in the even registers - unless
 222                          * we're using r2k_switch.S.
 223                          */
 224                         if (addr & 1) {
 225                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 226                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 227                         } else {
 228                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 229                                 fregs[addr - FPR_BASE] |= data;
 230                         }
 231 #endif
 232 #ifdef CONFIG_MIPS64
 233                         fregs[addr - FPR_BASE] = data;
 234 #endif
 235                         break;
 236                 }
 237                 case PC:
 238                         regs->cp0_epc = data;
 239                         break;
 240                 case MMHI:
 241                         regs->hi = data;
 242                         break;
 243                 case MMLO:
 244                         regs->lo = data;
 245                         break;
 246                 case FPC_CSR:
 247                         if (cpu_has_fpu)
 248                                 child->thread.fpu.hard.fcr31 = data;
 249                         else
 250                                 child->thread.fpu.soft.fcr31 = data;
 251                         break;
 252                 default:
 253                         /* The rest are not allowed. */
 254                         ret = -EIO;
 255                         break;
 256                 }
 257                 break;
 258                 }
 259
 260         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 261         case PTRACE_CONT: { /* restart after signal. */
 262                 ret = -EIO;
 263                 if (!valid_signal(data))
 264                         break;
 265                 if (request == PTRACE_SYSCALL) {
 266                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 267                 }
 268                 else {
 269                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 270                 }
 271                 child->exit_code = data;
 272                 wake_up_process(child);
 273                 ret = 0;
 274                 break;
 275         }
 276
 277         /*
 278          * make the child exit.  Best I can do is send it a sigkill.
 279          * perhaps it should be put in the status that it wants to
 280          * exit.
 281          */
 282         case PTRACE_KILL:
 283                 ret = 0;
 284                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 285                         break;
 286                 child->exit_code = SIGKILL;
 287                 wake_up_process(child);
 288                 break;
 289
 290         case PTRACE_DETACH: /* detach a process that was attached. */
 291                 ret = ptrace_detach(child, data);
 292                 break;
 293
 294         default:
 295                 ret = ptrace_request(child, request, addr, data);
 296                 break;
 297         }
 298
 299 out_tsk:
 300         put_task_struct(child);
 301 out:
 302         unlock_kernel();
 303         return ret;
 304 }
 305
 306 static inline int audit_arch(void)
 307 {
 308 #ifdef CONFIG_CPU_LITTLE_ENDIAN
 309 #ifdef CONFIG_MIPS64
 310         if (!(current->thread.mflags & MF_32BIT_REGS))
 311                 return AUDIT_ARCH_MIPSEL64;
 312 #endif /* MIPS64 */
 313         return AUDIT_ARCH_MIPSEL;
 314
 315 #else /* big endian... */
 316 #ifdef CONFIG_MIPS64
 317         if (!(current->thread.mflags & MF_32BIT_REGS))
 318                 return AUDIT_ARCH_MIPS64;
 319 #endif /* MIPS64 */
 320         return AUDIT_ARCH_MIPS;
 321
 322 #endif /* endian */
 323 }
 324
 325 /*
 326  * Notification of system call entry/exit
 327  * - triggered by current->work.syscall_trace
 328  */
 329 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 330 {
 331         if (unlikely(current->audit_context) && entryexit)
 332                 audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]), regs->regs[2]);
 333
 334         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 335                 goto out;
 336         if (!(current->ptrace & PT_PTRACED))
 337                 goto out;
 338
 339         /* The 0x80 provides a way for the tracing parent to distinguish
 340            between a syscall stop and SIGTRAP delivery */
 341         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 342                                  0x80 : 0));
 343
 344         /*
 345          * this isn't the same as continuing with a signal, but it will do
 346          * for normal use.  strace only continues with a signal if the
 347          * stopping signal is not SIGTRAP.  -brl
 348          */
 349         if (current->exit_code) {
 350                 send_sig(current->exit_code, current, 1);
 351                 current->exit_code = 0;
 352         }
 353  out:
 354         if (unlikely(current->audit_context) && !entryexit)
 355                 audit_syscall_entry(current, audit_arch(), regs->regs[2],
 356                                     regs->regs[4], regs->regs[5],
 357                                     regs->regs[6], regs->regs[7]);
 358 }