arch/avr32/kernel/ptrace.c

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #undef DEBUG
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/errno.h>
  14 #include <linux/user.h>
  15 #include <linux/security.h>
  16 #include <linux/unistd.h>
  17 #include <linux/notifier.h>
  18
  19 #include <asm/traps.h>
  20 #include <asm/uaccess.h>
  21 #include <asm/ocd.h>
  22 #include <asm/mmu_context.h>
  23 #include <linux/kdebug.h>
  24
  25 static struct pt_regs *get_user_regs(struct task_struct *tsk)
  26 {
  27         return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
  28                                   THREAD_SIZE - sizeof(struct pt_regs));
  29 }
  30
  31 static void ptrace_single_step(struct task_struct *tsk)
  32 {
  33         pr_debug("ptrace_single_step: pid=%u, SR=0x%08lx\n",
  34                  tsk->pid, tsk->thread.cpu_context.sr);
  35         if (!(tsk->thread.cpu_context.sr & SR_D)) {
  36                 /*
  37                  * Set a breakpoint at the current pc to force the
  38                  * process into debug mode.  The syscall/exception
  39                  * exit code will set a breakpoint at the return
  40                  * address when this flag is set.
  41                  */
  42                 pr_debug("ptrace_single_step: Setting TIF_BREAKPOINT\n");
  43                 set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
  44         }
  45
  46         /* The monitor code will do the actual step for us */
  47         set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
  48 }
  49
  50 /*
  51  * Called by kernel/ptrace.c when detaching
  52  *
  53  * Make sure any single step bits, etc. are not set
  54  */
  55 void ptrace_disable(struct task_struct *child)
  56 {
  57         clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
  58 }
  59
  60 /*
  61  * Handle hitting a breakpoint
  62  */
  63 static void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
  64 {
  65         siginfo_t info;
  66
  67         info.si_signo = SIGTRAP;
  68         info.si_errno = 0;
  69         info.si_code  = TRAP_BRKPT;
  70         info.si_addr  = (void __user *)instruction_pointer(regs);
  71
  72         pr_debug("ptrace_break: Sending SIGTRAP to PID %u (pc = 0x%p)\n",
  73                  tsk->pid, info.si_addr);
  74         force_sig_info(SIGTRAP, &info, tsk);
  75 }
  76
  77 /*
  78  * Read the word at offset "offset" into the task's "struct user". We
  79  * actually access the pt_regs struct stored on the kernel stack.
  80  */
  81 static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
  82                             unsigned long __user *data)
  83 {
  84         unsigned long *regs;
  85         unsigned long value;
  86
  87         pr_debug("ptrace_read_user(%p, %#lx, %p)\n",
  88                  tsk, offset, data);
  89
  90         if (offset & 3 || offset >= sizeof(struct user)) {
  91                 printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
  92                 return -EIO;
  93         }
  94
  95         regs = (unsigned long *)get_user_regs(tsk);
  96
  97         value = 0;
  98         if (offset < sizeof(struct pt_regs))
  99                 value = regs[offset / sizeof(regs[0])];
 100
 101         return put_user(value, data);
 102 }
 103
 104 /*
 105  * Write the word "value" to offset "offset" into the task's "struct
 106  * user". We actually access the pt_regs struct stored on the kernel
 107  * stack.
 108  */
 109 static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
 110                              unsigned long value)
 111 {
 112         unsigned long *regs;
 113
 114         if (offset & 3 || offset >= sizeof(struct user)) {
 115                 printk("ptrace_write_user: invalid offset 0x%08lx\n", offset);
 116                 return -EIO;
 117         }
 118
 119         if (offset >= sizeof(struct pt_regs))
 120                 return 0;
 121
 122         regs = (unsigned long *)get_user_regs(tsk);
 123         regs[offset / sizeof(regs[0])] = value;
 124
 125         return 0;
 126 }
 127
 128 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
 129 {
 130         struct pt_regs *regs = get_user_regs(tsk);
 131
 132         return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;
 133 }
 134
 135 static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)
 136 {
 137         struct pt_regs newregs;
 138         int ret;
 139
 140         ret = -EFAULT;
 141         if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
 142                 struct pt_regs *regs = get_user_regs(tsk);
 143
 144                 ret = -EINVAL;
 145                 if (valid_user_regs(&newregs)) {
 146                         *regs = newregs;
 147                         ret = 0;
 148                 }
 149         }
 150
 151         return ret;
 152 }
 153
 154 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 155 {
 156         unsigned long tmp;
 157         int ret;
 158
 159         pr_debug("arch_ptrace(%ld, %d, %#lx, %#lx)\n",
 160                  request, child->pid, addr, data);
 161
 162         pr_debug("ptrace: Enabling monitor mode...\n");
 163         __mtdr(DBGREG_DC, __mfdr(DBGREG_DC) | DC_MM | DC_DBE);
 164
 165         switch (request) {
 166         /* Read the word at location addr in the child process */
 167         case PTRACE_PEEKTEXT:
 168         case PTRACE_PEEKDATA:
 169                 ret = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 170                 if (ret == sizeof(tmp))
 171                         ret = put_user(tmp, (unsigned long __user *)data);
 172                 else
 173                         ret = -EIO;
 174                 break;
 175
 176         case PTRACE_PEEKUSR:
 177                 ret = ptrace_read_user(child, addr,
 178                                        (unsigned long __user *)data);
 179                 break;
 180
 181         /* Write the word in data at location addr */
 182         case PTRACE_POKETEXT:
 183         case PTRACE_POKEDATA:
 184                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 185                 if (ret == sizeof(data))
 186                         ret = 0;
 187                 else
 188                         ret = -EIO;
 189                 break;
 190
 191         case PTRACE_POKEUSR:
 192                 ret = ptrace_write_user(child, addr, data);
 193                 break;
 194
 195         /* continue and stop at next (return from) syscall */
 196         case PTRACE_SYSCALL:
 197         /* restart after signal */
 198         case PTRACE_CONT:
 199                 ret = -EIO;
 200                 if (!valid_signal(data))
 201                         break;
 202                 if (request == PTRACE_SYSCALL)
 203                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 204                 else
 205                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 206                 child->exit_code = data;
 207                 /* XXX: Are we sure no breakpoints are active here? */
 208                 wake_up_process(child);
 209                 ret = 0;
 210                 break;
 211
 212         /*
 213          * Make the child exit. Best I can do is send it a
 214          * SIGKILL. Perhaps it should be put in the status that it
 215          * wants to exit.
 216          */
 217         case PTRACE_KILL:
 218                 ret = 0;
 219                 if (child->exit_state == EXIT_ZOMBIE)
 220                         break;
 221                 child->exit_code = SIGKILL;
 222                 wake_up_process(child);
 223                 break;
 224
 225         /*
 226          * execute single instruction.
 227          */
 228         case PTRACE_SINGLESTEP:
 229                 ret = -EIO;
 230                 if (!valid_signal(data))
 231                         break;
 232                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 233                 ptrace_single_step(child);
 234                 child->exit_code = data;
 235                 wake_up_process(child);
 236                 ret = 0;
 237                 break;
 238
 239         /* Detach a process that was attached */
 240         case PTRACE_DETACH:
 241                 ret = ptrace_detach(child, data);
 242                 break;
 243
 244         case PTRACE_GETREGS:
 245                 ret = ptrace_getregs(child, (void __user *)data);
 246                 break;
 247
 248         case PTRACE_SETREGS:
 249                 ret = ptrace_setregs(child, (const void __user *)data);
 250                 break;
 251
 252         default:
 253                 ret = ptrace_request(child, request, addr, data);
 254                 break;
 255         }
 256
 257         pr_debug("sys_ptrace returning %d (DC = 0x%08lx)\n", ret, __mfdr(DBGREG_DC));
 258         return ret;
 259 }
 260
 261 asmlinkage void syscall_trace(void)
 262 {
 263         pr_debug("syscall_trace called\n");
 264         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 265                 return;
 266         if (!(current->ptrace & PT_PTRACED))
 267                 return;
 268
 269         pr_debug("syscall_trace: notifying parent\n");
 270         /* The 0x80 provides a way for the tracing parent to
 271          * distinguish between a syscall stop and SIGTRAP delivery */
 272         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 273                                  ? 0x80 : 0));
 274
 275         /*
 276          * this isn't the same as continuing with a signal, but it
 277          * will do for normal use.  strace only continues with a
 278          * signal if the stopping signal is not SIGTRAP.  -brl
 279          */
 280         if (current->exit_code) {
 281                 pr_debug("syscall_trace: sending signal %d to PID %u\n",
 282                          current->exit_code, current->pid);
 283                 send_sig(current->exit_code, current, 1);
 284                 current->exit_code = 0;
 285         }
 286 }
 287
 288 asmlinkage void do_debug_priv(struct pt_regs *regs)
 289 {
 290         unsigned long dc, ds;
 291         unsigned long die_val;
 292
 293         ds = __mfdr(DBGREG_DS);
 294
 295         pr_debug("do_debug_priv: pc = %08lx, ds = %08lx\n", regs->pc, ds);
 296
 297         if (ds & DS_SSS)
 298                 die_val = DIE_SSTEP;
 299         else
 300                 die_val = DIE_BREAKPOINT;
 301
 302         if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
 303                 return;
 304
 305         if (likely(ds & DS_SSS)) {
 306                 extern void itlb_miss(void);
 307                 extern void tlb_miss_common(void);
 308                 struct thread_info *ti;
 309
 310                 dc = __mfdr(DBGREG_DC);
 311                 dc &= ~DC_SS;
 312                 __mtdr(DBGREG_DC, dc);
 313
 314                 ti = current_thread_info();
 315                 set_ti_thread_flag(ti, TIF_BREAKPOINT);
 316
 317                 /* The TLB miss handlers don't check thread flags */
 318                 if ((regs->pc >= (unsigned long)&itlb_miss)
 319                     && (regs->pc <= (unsigned long)&tlb_miss_common)) {
 320                         __mtdr(DBGREG_BWA2A, sysreg_read(RAR_EX));
 321                         __mtdr(DBGREG_BWC2A, 0x40000001 | (get_asid() << 1));
 322                 }
 323
 324                 /*
 325                  * If we're running in supervisor mode, the breakpoint
 326                  * will take us where we want directly, no need to
 327                  * single step.
 328                  */
 329                 if ((regs->sr & MODE_MASK) != MODE_SUPERVISOR)
 330                         set_ti_thread_flag(ti, TIF_SINGLE_STEP);
 331         } else {
 332                 panic("Unable to handle debug trap at pc = %08lx\n",
 333                       regs->pc);
 334         }
 335 }
 336
 337 /*
 338  * Handle breakpoints, single steps and other debuggy things. To keep
 339  * things simple initially, we run with interrupts and exceptions
 340  * disabled all the time.
 341  */
 342 asmlinkage void do_debug(struct pt_regs *regs)
 343 {
 344         unsigned long dc, ds;
 345
 346         ds = __mfdr(DBGREG_DS);
 347         pr_debug("do_debug: pc = %08lx, ds = %08lx\n", regs->pc, ds);
 348
 349         if (test_thread_flag(TIF_BREAKPOINT)) {
 350                 pr_debug("TIF_BREAKPOINT set\n");
 351                 /* We're taking care of it */
 352                 clear_thread_flag(TIF_BREAKPOINT);
 353                 __mtdr(DBGREG_BWC2A, 0);
 354         }
 355
 356         if (test_thread_flag(TIF_SINGLE_STEP)) {
 357                 pr_debug("TIF_SINGLE_STEP set, ds = 0x%08lx\n", ds);
 358                 if (ds & DS_SSS) {
 359                         dc = __mfdr(DBGREG_DC);
 360                         dc &= ~DC_SS;
 361                         __mtdr(DBGREG_DC, dc);
 362
 363                         clear_thread_flag(TIF_SINGLE_STEP);
 364                         ptrace_break(current, regs);
 365                 }
 366         } else {
 367                 /* regular breakpoint */
 368                 ptrace_break(current, regs);
 369         }
 370 }