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/smp.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/user.h>
  27 #include <linux/security.h>
  28
  29 #include <asm/cpu.h>
  30 #include <asm/fpu.h>
  31 #include <asm/mipsregs.h>
  32 #include <asm/pgtable.h>
  33 #include <asm/page.h>
  34 #include <asm/system.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/bootinfo.h>
  37
  38 /*
  39  * Called by kernel/ptrace.c when detaching..
  40  *
  41  * Make sure single step bits etc are not set.
  42  */
  43 void ptrace_disable(struct task_struct *child)
  44 {
  45         /* Nothing to do.. */
  46 }
  47
  48 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
  49 {
  50         struct task_struct *child;
  51         int ret;
  52
  53 #if 0
  54         printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
  55                (int) request, (int) pid, (unsigned long) addr,
  56                (unsigned long) data);
  57 #endif
  58         lock_kernel();
  59         ret = -EPERM;
  60         if (request == PTRACE_TRACEME) {
  61                 /* are we already being traced? */
  62                 if (current->ptrace & PT_PTRACED)
  63                         goto out;
  64                 if ((ret = security_ptrace(current->parent, current)))
  65                         goto out;
  66                 /* set the ptrace bit in the process flags. */
  67                 current->ptrace |= PT_PTRACED;
  68                 ret = 0;
  69                 goto out;
  70         }
  71         ret = -ESRCH;
  72         read_lock(&tasklist_lock);
  73         child = find_task_by_pid(pid);
  74         if (child)
  75                 get_task_struct(child);
  76         read_unlock(&tasklist_lock);
  77         if (!child)
  78                 goto out;
  79
  80         ret = -EPERM;
  81         if (pid == 1)           /* you may not mess with init */
  82                 goto out_tsk;
  83
  84         if (request == PTRACE_ATTACH) {
  85                 ret = ptrace_attach(child);
  86                 goto out_tsk;
  87         }
  88
  89         ret = ptrace_check_attach(child, request == PTRACE_KILL);
  90         if (ret < 0)
  91                 goto out_tsk;
  92
  93         switch (request) {
  94         /* when I and D space are separate, these will need to be fixed. */
  95         case PTRACE_PEEKTEXT: /* read word at location addr. */
  96         case PTRACE_PEEKDATA: {
  97                 unsigned long tmp;
  98                 int copied;
  99
 100                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 101                 ret = -EIO;
 102                 if (copied != sizeof(tmp))
 103                         break;
 104                 ret = put_user(tmp,(unsigned long *) data);
 105                 break;
 106         }
 107
 108         /* Read the word at location addr in the USER area. */
 109         case PTRACE_PEEKUSR: {
 110                 struct pt_regs *regs;
 111                 unsigned long tmp = 0;
 112
 113                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 114                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 115                 ret = 0;  /* Default return value. */
 116
 117                 switch (addr) {
 118                 case 0 ... 31:
 119                         tmp = regs->regs[addr];
 120                         break;
 121                 case FPR_BASE ... FPR_BASE + 31:
 122                         if (child->used_math) {
 123                                 fpureg_t *fregs = get_fpu_regs(child);
 124
 125 #ifdef CONFIG_MIPS32
 126                                 /*
 127                                  * The odd registers are actually the high
 128                                  * order bits of the values stored in the even
 129                                  * registers - unless we're using r2k_switch.S.
 130                                  */
 131                                 if (addr & 1)
 132                                         tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
 133                                 else
 134                                         tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
 135 #endif
 136 #ifdef CONFIG_MIPS64
 137                                 tmp = fregs[addr - FPR_BASE];
 138 #endif
 139                         } else {
 140                                 tmp = -1;       /* FP not yet used  */
 141                         }
 142                         break;
 143                 case PC:
 144                         tmp = regs->cp0_epc;
 145                         break;
 146                 case CAUSE:
 147                         tmp = regs->cp0_cause;
 148                         break;
 149                 case BADVADDR:
 150                         tmp = regs->cp0_badvaddr;
 151                         break;
 152                 case MMHI:
 153                         tmp = regs->hi;
 154                         break;
 155                 case MMLO:
 156                         tmp = regs->lo;
 157                         break;
 158                 case FPC_CSR:
 159                         if (cpu_has_fpu)
 160                                 tmp = child->thread.fpu.hard.fcr31;
 161                         else
 162                                 tmp = child->thread.fpu.soft.fcr31;
 163                         break;
 164                 case FPC_EIR: { /* implementation / version register */
 165                         unsigned int flags;
 166
 167                         if (!cpu_has_fpu)
 168                                 break;
 169
 170                         flags = read_c0_status();
 171                         __enable_fpu();
 172                         __asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
 173                         write_c0_status(flags);
 174                         break;
 175                 }
 176                 default:
 177                         tmp = 0;
 178                         ret = -EIO;
 179                         goto out_tsk;
 180                 }
 181                 ret = put_user(tmp, (unsigned long *) data);
 182                 break;
 183         }
 184
 185         /* when I and D space are separate, this will have to be fixed. */
 186         case PTRACE_POKETEXT: /* write the word at location addr. */
 187         case PTRACE_POKEDATA:
 188                 ret = 0;
 189                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 190                     == sizeof(data))
 191                         break;
 192                 ret = -EIO;
 193                 break;
 194
 195         case PTRACE_POKEUSR: {
 196                 struct pt_regs *regs;
 197                 ret = 0;
 198                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 199                        THREAD_SIZE - 32 - sizeof(struct pt_regs));
 200
 201                 switch (addr) {
 202                 case 0 ... 31:
 203                         regs->regs[addr] = data;
 204                         break;
 205                 case FPR_BASE ... FPR_BASE + 31: {
 206                         fpureg_t *fregs = get_fpu_regs(child);
 207
 208                         if (!child->used_math) {
 209                                 /* FP not yet used  */
 210                                 memset(&child->thread.fpu.hard, ~0,
 211                                        sizeof(child->thread.fpu.hard));
 212                                 child->thread.fpu.hard.fcr31 = 0;
 213                         }
 214 #ifdef CONFIG_MIPS32
 215                         /*
 216                          * The odd registers are actually the high order bits
 217                          * of the values stored in the even registers - unless
 218                          * we're using r2k_switch.S.
 219                          */
 220                         if (addr & 1) {
 221                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 222                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 223                         } else {
 224                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 225                                 fregs[addr - FPR_BASE] |= data;
 226                         }
 227 #endif
 228 #ifdef CONFIG_MIPS64
 229                         fregs[addr - FPR_BASE] = data;
 230 #endif
 231                         break;
 232                 }
 233                 case PC:
 234                         regs->cp0_epc = data;
 235                         break;
 236                 case MMHI:
 237                         regs->hi = data;
 238                         break;
 239                 case MMLO:
 240                         regs->lo = data;
 241                         break;
 242                 case FPC_CSR:
 243                         if (cpu_has_fpu)
 244                                 child->thread.fpu.hard.fcr31 = data;
 245                         else
 246                                 child->thread.fpu.soft.fcr31 = data;
 247                         break;
 248                 default:
 249                         /* The rest are not allowed. */
 250                         ret = -EIO;
 251                         break;
 252                 }
 253                 break;
 254                 }
 255
 256         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 257         case PTRACE_CONT: { /* restart after signal. */
 258                 ret = -EIO;
 259                 if ((unsigned long) data > _NSIG)
 260                         break;
 261                 if (request == PTRACE_SYSCALL) {
 262                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 263                 }
 264                 else {
 265                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 266                 }
 267                 child->exit_code = data;
 268                 wake_up_process(child);
 269                 ret = 0;
 270                 break;
 271         }
 272
 273         /*
 274          * make the child exit.  Best I can do is send it a sigkill.
 275          * perhaps it should be put in the status that it wants to
 276          * exit.
 277          */
 278         case PTRACE_KILL:
 279                 ret = 0;
 280                 if (child->state == TASK_ZOMBIE)        /* already dead */
 281                         break;
 282                 child->exit_code = SIGKILL;
 283                 wake_up_process(child);
 284                 break;
 285
 286         case PTRACE_DETACH: /* detach a process that was attached. */
 287                 ret = ptrace_detach(child, data);
 288                 break;
 289
 290         default:
 291                 ret = ptrace_request(child, request, addr, data);
 292                 break;
 293         }
 294
 295 out_tsk:
 296         put_task_struct(child);
 297 out:
 298         unlock_kernel();
 299         return ret;
 300 }
 301
 302 /*
 303  * Notification of system call entry/exit
 304  * - triggered by current->work.syscall_trace
 305  */
 306 asmlinkage void do_syscall_trace(void)
 307 {
 308         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 309                 return;
 310         if (!(current->ptrace & PT_PTRACED))
 311                 return;
 312
 313         /* The 0x80 provides a way for the tracing parent to distinguish
 314            between a syscall stop and SIGTRAP delivery */
 315         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
 316                                  0x80 : 0));
 317
 318         /*
 319          * this isn't the same as continuing with a signal, but it will do
 320          * for normal use.  strace only continues with a signal if the
 321          * stopping signal is not SIGTRAP.  -brl
 322          */
 323         if (current->exit_code) {
 324                 send_sig(current->exit_code, current, 1);
 325                 current->exit_code = 0;
 326         }
 327 }