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  */
  13 #include <linux/config.h>
  14 #include <linux/compiler.h>
  15 #include <linux/kernel.h>
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/errno.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/smp.h>
  21 #include <linux/smp_lock.h>
  22 #include <linux/user.h>
  23
  24 #include <asm/mipsregs.h>
  25 #include <asm/pgtable.h>
  26 #include <asm/page.h>
  27 #include <asm/system.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/bootinfo.h>
  30 #include <asm/cpu.h>
  31 #include <asm/fpu.h>
  32
  33 /*
  34  * Called by kernel/ptrace.c when detaching..
  35  *
  36  * Make sure single step bits etc are not set.
  37  */
  38 void ptrace_disable(struct task_struct *child)
  39 {
  40         /* Nothing to do.. */
  41 }
  42
  43 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
  44 {
  45         struct task_struct *child;
  46         int ret;
  47
  48         lock_kernel();
  49 #if 0
  50         printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
  51                (int) request, (int) pid, (unsigned long) addr,
  52                (unsigned long) data);
  53 #endif
  54         if (request == PTRACE_TRACEME) {
  55                 /* are we already being traced? */
  56                 if (current->ptrace & PT_PTRACED) {
  57                         ret = -EPERM;
  58                         goto out;
  59                 }
  60                 /* set the ptrace bit in the process flags. */
  61                 current->ptrace |= PT_PTRACED;
  62                 ret = 0;
  63                 goto out;
  64         }
  65         ret = -ESRCH;
  66         read_lock(&tasklist_lock);
  67         child = find_task_by_pid(pid);
  68         if (child)
  69                 get_task_struct(child);
  70         read_unlock(&tasklist_lock);
  71         if (!child)
  72                 goto out;
  73
  74         ret = -EPERM;
  75         if (pid == 1)           /* you may not mess with init */
  76                 goto out_tsk;
  77
  78         if (request == PTRACE_ATTACH) {
  79                 ret = ptrace_attach(child);
  80                 goto out_tsk;
  81         }
  82
  83         ret = ptrace_check_attach(child, request == PTRACE_KILL);
  84         if (ret < 0)
  85                 goto out_tsk;
  86
  87         switch (request) {
  88         case PTRACE_PEEKTEXT: /* read word at location addr. */
  89         case PTRACE_PEEKDATA: {
  90                 unsigned long tmp;
  91                 int copied;
  92
  93                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
  94                 ret = -EIO;
  95                 if (copied != sizeof(tmp))
  96                         break;
  97                 ret = put_user(tmp,(unsigned long *) data);
  98                 break;
  99                 }
 100
 101         /* Read the word at location addr in the USER area.  */
 102         case PTRACE_PEEKUSR: {
 103                 struct pt_regs *regs;
 104                 unsigned long tmp;
 105
 106                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 107                        KERNEL_STACK_SIZE - 32 - sizeof(struct pt_regs));
 108                 tmp = 0;  /* Default return value. */
 109
 110                 switch(addr) {
 111                 case 0 ... 31:
 112                         tmp = regs->regs[addr];
 113                         break;
 114                 case FPR_BASE ... FPR_BASE + 31:
 115                         if (child->used_math) {
 116                                 unsigned long long *fregs = get_fpu_regs(child);
 117                                 /*
 118                                  * The odd registers are actually the high
 119                                  * order bits of the values stored in the even
 120                                  * registers - unless we're using r2k_switch.S.
 121                                  */
 122                                 if (addr & 1)
 123                                         tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
 124                                 else
 125                                         tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
 126                         } else {
 127                                 tmp = -1;       /* FP not yet used  */
 128                         }
 129                         break;
 130                 case PC:
 131                         tmp = regs->cp0_epc;
 132                         break;
 133                 case CAUSE:
 134                         tmp = regs->cp0_cause;
 135                         break;
 136                 case BADVADDR:
 137                         tmp = regs->cp0_badvaddr;
 138                         break;
 139                 case MMHI:
 140                         tmp = regs->hi;
 141                         break;
 142                 case MMLO:
 143                         tmp = regs->lo;
 144                         break;
 145                 case FPC_CSR:
 146                         if (!(current_cpu_data.options & MIPS_CPU_FPU))
 147                                 tmp = child->thread.fpu.soft.sr;
 148                         else
 149                                 tmp = child->thread.fpu.hard.control;
 150                         break;
 151                 case FPC_EIR: { /* implementation / version register */
 152                         unsigned int flags;
 153
 154                         if (!(current_cpu_data.options & MIPS_CPU_FPU)) {
 155                                 break;
 156                         }
 157
 158                         flags = read_c0_status();
 159                         __enable_fpu();
 160                         __asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
 161                         write_c0_status(flags);
 162                         break;
 163                 }
 164                 default:
 165                         tmp = 0;
 166                         ret = -EIO;
 167                         goto out_tsk;
 168                 }
 169                 ret = put_user(tmp, (unsigned long *) data);
 170                 break;
 171                 }
 172
 173         case PTRACE_POKETEXT: /* write the word at location addr. */
 174         case PTRACE_POKEDATA:
 175                 ret = 0;
 176                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 177                     == sizeof(data))
 178                         break;
 179                 ret = -EIO;
 180                 break;
 181
 182         case PTRACE_POKEUSR: {
 183                 struct pt_regs *regs;
 184                 ret = 0;
 185                 regs = (struct pt_regs *) ((unsigned long) child->thread_info +
 186                        KERNEL_STACK_SIZE - 32 - sizeof(struct pt_regs));
 187
 188                 switch (addr) {
 189                 case 0 ... 31:
 190                         regs->regs[addr] = data;
 191                         break;
 192                 case FPR_BASE ... FPR_BASE + 31: {
 193                         unsigned long long *fregs;
 194                         fregs = (unsigned long long *)get_fpu_regs(child);
 195                         if (!child->used_math) {
 196                                 /* FP not yet used  */
 197                                 memset(&child->thread.fpu.hard, ~0,
 198                                        sizeof(child->thread.fpu.hard));
 199                                 child->thread.fpu.hard.control = 0;
 200                         }
 201                         /*
 202                          * The odd registers are actually the high order bits
 203                          * of the values stored in the even registers - unless
 204                          * we're using r2k_switch.S.
 205                          */
 206                         if (addr & 1) {
 207                                 fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
 208                                 fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
 209                         } else {
 210                                 fregs[addr - FPR_BASE] &= ~0xffffffffLL;
 211                                 fregs[addr - FPR_BASE] |= data;
 212                         }
 213                         break;
 214                 }
 215                 case PC:
 216                         regs->cp0_epc = data;
 217                         break;
 218                 case MMHI:
 219                         regs->hi = data;
 220                         break;
 221                 case MMLO:
 222                         regs->lo = data;
 223                         break;
 224                 case FPC_CSR:
 225                         if (!(current_cpu_data.options & MIPS_CPU_FPU))
 226                                 child->thread.fpu.soft.sr = data;
 227                         else
 228                                 child->thread.fpu.hard.control = data;
 229                         break;
 230                 default:
 231                         /* The rest are not allowed. */
 232                         ret = -EIO;
 233                         break;
 234                 }
 235                 break;
 236                 }
 237
 238         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 239         case PTRACE_CONT: { /* restart after signal. */
 240                 ret = -EIO;
 241                 if ((unsigned long) data > _NSIG)
 242                         break;
 243                 if (request == PTRACE_SYSCALL) {
 244                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 245                 }
 246                 else {
 247                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 248                 }
 249                 child->exit_code = data;
 250                 wake_up_process(child);
 251                 ret = 0;
 252                 break;
 253                 }
 254
 255         /*
 256          * make the child exit.  Best I can do is send it a sigkill.
 257          * perhaps it should be put in the status that it wants to
 258          * exit.
 259          */
 260         case PTRACE_KILL:
 261                 ret = 0;
 262                 if (child->state == TASK_ZOMBIE)        /* already dead */
 263                         break;
 264                 child->exit_code = SIGKILL;
 265                 wake_up_process(child);
 266                 break;
 267
 268         case PTRACE_DETACH: /* detach a process that was attached. */
 269                 ret = ptrace_detach(child, data);
 270                 break;
 271
 272         default:
 273                 ret = ptrace_request(child, request, addr, data);
 274                 break;
 275         }
 276 out_tsk:
 277         put_task_struct(child);
 278 out:
 279         unlock_kernel();
 280         return ret;
 281 }
 282
 283 /*
 284  * Notification of system call entry/exit
 285  * - triggered by current->work.syscall_trace
 286  */
 287 asmlinkage void do_syscall_trace(void)
 288 {
 289         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 290                 return;
 291         if (!(current->ptrace & PT_PTRACED))
 292                 return;
 293
 294         /* The 0x80 provides a way for the tracing parent to distinguish
 295            between a syscall stop and SIGTRAP delivery */
 296         current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 297                                         ? 0x80 : 0);
 298         preempt_disable();
 299         current->state = TASK_STOPPED;
 300         notify_parent(current, SIGCHLD);
 301         schedule();
 302         preempt_enable();
 303         /*
 304          * this isn't the same as continuing with a signal, but it will do
 305          * for normal use.  strace only continues with a signal if the
 306          * stopping signal is not SIGTRAP.  -brl
 307          */
 308         if (current->exit_code) {
 309                 send_sig(current->exit_code, current, 1);
 310                 current->exit_code = 0;
 311         }
 312 }