arch/alpha/kernel/ptrace.c

   1 /* ptrace.c */
   2 /* By Ross Biro 1/23/92 */
   3 /* edited by Linus Torvalds */
   4 /* mangled further by Bob Manson (manson@santafe.edu) */
   5 /* more mutilation by David Mosberger (davidm@azstarnet.com) */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/sched.h>
   9 #include <linux/mm.h>
  10 #include <linux/smp.h>
  11 #include <linux/smp_lock.h>
  12 #include <linux/errno.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/user.h>
  15 #include <linux/slab.h>
  16 #include <linux/security.h>
  17 #include <linux/signal.h>
  18
  19 #include <asm/uaccess.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/system.h>
  22 #include <asm/fpu.h>
  23
  24 #include "proto.h"
  25
  26 #define DEBUG   DBG_MEM
  27 #undef DEBUG
  28
  29 #ifdef DEBUG
  30 enum {
  31         DBG_MEM         = (1<<0),
  32         DBG_BPT         = (1<<1),
  33         DBG_MEM_ALL     = (1<<2)
  34 };
  35 #define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
  36 #else
  37 #define DBG(fac,args)
  38 #endif
  39
  40 #define BREAKINST       0x00000080      /* call_pal bpt */
  41
  42 /*
  43  * does not yet catch signals sent when the child dies.
  44  * in exit.c or in signal.c.
  45  */
  46
  47 /*
  48  * Processes always block with the following stack-layout:
  49  *
  50  *  +================================+ <---- task + 2*PAGE_SIZE
  51  *  | PALcode saved frame (ps, pc,   | ^
  52  *  | gp, a0, a1, a2)                | |
  53  *  +================================+ | struct pt_regs
  54  *  |                                | |
  55  *  | frame generated by SAVE_ALL    | |
  56  *  |                                | v
  57  *  +================================+
  58  *  |                                | ^
  59  *  | frame saved by do_switch_stack | | struct switch_stack
  60  *  |                                | v
  61  *  +================================+
  62  */
  63
  64 /*
  65  * The following table maps a register index into the stack offset at
  66  * which the register is saved.  Register indices are 0-31 for integer
  67  * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
  68  * zero have no stack-slot and need to be treated specially (see
  69  * get_reg/put_reg below).
  70  */
  71 enum {
  72         REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
  73 };
  74
  75 #define PT_REG(reg) \
  76   (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
  77
  78 #define SW_REG(reg) \
  79  (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
  80   + offsetof(struct switch_stack, reg))
  81
  82 static int regoff[] = {
  83         PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
  84         PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
  85         PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
  86         SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
  87         PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
  88         PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
  89         PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
  90         PT_REG(   r28), PT_REG(    gp),            -1,             -1,
  91         SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
  92         SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
  93         SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
  94         SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
  95         SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
  96         SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
  97         SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
  98         SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
  99         PT_REG(    pc)
 100 };
 101
 102 static unsigned long zero;
 103
 104 /*
 105  * Get address of register REGNO in task TASK.
 106  */
 107 static unsigned long *
 108 get_reg_addr(struct task_struct * task, unsigned long regno)
 109 {
 110         unsigned long *addr;
 111
 112         if (regno == 30) {
 113                 addr = &task_thread_info(task)->pcb.usp;
 114         } else if (regno == 65) {
 115                 addr = &task_thread_info(task)->pcb.unique;
 116         } else if (regno == 31 || regno > 65) {
 117                 zero = 0;
 118                 addr = &zero;
 119         } else {
 120                 addr = task_stack_page(task) + regoff[regno];
 121         }
 122         return addr;
 123 }
 124
 125 /*
 126  * Get contents of register REGNO in task TASK.
 127  */
 128 static unsigned long
 129 get_reg(struct task_struct * task, unsigned long regno)
 130 {
 131         /* Special hack for fpcr -- combine hardware and software bits.  */
 132         if (regno == 63) {
 133                 unsigned long fpcr = *get_reg_addr(task, regno);
 134                 unsigned long swcr
 135                   = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
 136                 swcr = swcr_update_status(swcr, fpcr);
 137                 return fpcr | swcr;
 138         }
 139         return *get_reg_addr(task, regno);
 140 }
 141
 142 /*
 143  * Write contents of register REGNO in task TASK.
 144  */
 145 static int
 146 put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
 147 {
 148         if (regno == 63) {
 149                 task_thread_info(task)->ieee_state
 150                   = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
 151                      | (data & IEEE_SW_MASK));
 152                 data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
 153         }
 154         *get_reg_addr(task, regno) = data;
 155         return 0;
 156 }
 157
 158 static inline int
 159 read_int(struct task_struct *task, unsigned long addr, int * data)
 160 {
 161         int copied = access_process_vm(task, addr, data, sizeof(int), 0);
 162         return (copied == sizeof(int)) ? 0 : -EIO;
 163 }
 164
 165 static inline int
 166 write_int(struct task_struct *task, unsigned long addr, int data)
 167 {
 168         int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
 169         return (copied == sizeof(int)) ? 0 : -EIO;
 170 }
 171
 172 /*
 173  * Set breakpoint.
 174  */
 175 int
 176 ptrace_set_bpt(struct task_struct * child)
 177 {
 178         int displ, i, res, reg_b, nsaved = 0;
 179         unsigned int insn, op_code;
 180         unsigned long pc;
 181
 182         pc  = get_reg(child, REG_PC);
 183         res = read_int(child, pc, (int *) &insn);
 184         if (res < 0)
 185                 return res;
 186
 187         op_code = insn >> 26;
 188         if (op_code >= 0x30) {
 189                 /*
 190                  * It's a branch: instead of trying to figure out
 191                  * whether the branch will be taken or not, we'll put
 192                  * a breakpoint at either location.  This is simpler,
 193                  * more reliable, and probably not a whole lot slower
 194                  * than the alternative approach of emulating the
 195                  * branch (emulation can be tricky for fp branches).
 196                  */
 197                 displ = ((s32)(insn << 11)) >> 9;
 198                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 199                 if (displ)              /* guard against unoptimized code */
 200                         task_thread_info(child)->bpt_addr[nsaved++]
 201                           = pc + 4 + displ;
 202                 DBG(DBG_BPT, ("execing branch\n"));
 203         } else if (op_code == 0x1a) {
 204                 reg_b = (insn >> 16) & 0x1f;
 205                 task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
 206                 DBG(DBG_BPT, ("execing jump\n"));
 207         } else {
 208                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 209                 DBG(DBG_BPT, ("execing normal insn\n"));
 210         }
 211
 212         /* install breakpoints: */
 213         for (i = 0; i < nsaved; ++i) {
 214                 res = read_int(child, task_thread_info(child)->bpt_addr[i],
 215                                (int *) &insn);
 216                 if (res < 0)
 217                         return res;
 218                 task_thread_info(child)->bpt_insn[i] = insn;
 219                 DBG(DBG_BPT, ("    -> next_pc=%lx\n",
 220                               task_thread_info(child)->bpt_addr[i]));
 221                 res = write_int(child, task_thread_info(child)->bpt_addr[i],
 222                                 BREAKINST);
 223                 if (res < 0)
 224                         return res;
 225         }
 226         task_thread_info(child)->bpt_nsaved = nsaved;
 227         return 0;
 228 }
 229
 230 /*
 231  * Ensure no single-step breakpoint is pending.  Returns non-zero
 232  * value if child was being single-stepped.
 233  */
 234 int
 235 ptrace_cancel_bpt(struct task_struct * child)
 236 {
 237         int i, nsaved = task_thread_info(child)->bpt_nsaved;
 238
 239         task_thread_info(child)->bpt_nsaved = 0;
 240
 241         if (nsaved > 2) {
 242                 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
 243                 nsaved = 2;
 244         }
 245
 246         for (i = 0; i < nsaved; ++i) {
 247                 write_int(child, task_thread_info(child)->bpt_addr[i],
 248                           task_thread_info(child)->bpt_insn[i]);
 249         }
 250         return (nsaved != 0);
 251 }
 252
 253 /*
 254  * Called by kernel/ptrace.c when detaching..
 255  *
 256  * Make sure the single step bit is not set.
 257  */
 258 void ptrace_disable(struct task_struct *child)
 259 {
 260         ptrace_cancel_bpt(child);
 261 }
 262
 263 asmlinkage long
 264 do_sys_ptrace(long request, long pid, long addr, long data,
 265               struct pt_regs *regs)
 266 {
 267         struct task_struct *child;
 268         unsigned long tmp;
 269         size_t copied;
 270         long ret;
 271
 272         lock_kernel();
 273         DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
 274                       request, pid, addr, data));
 275         if (request == PTRACE_TRACEME) {
 276                 ret = ptrace_traceme();
 277                 goto out_notsk;
 278         }
 279
 280         child = ptrace_get_task_struct(pid);
 281         if (IS_ERR(child)) {
 282                 ret = PTR_ERR(child);
 283                 goto out_notsk;
 284         }
 285
 286         if (request == PTRACE_ATTACH) {
 287                 ret = ptrace_attach(child);
 288                 goto out;
 289         }
 290
 291         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 292         if (ret < 0)
 293                 goto out;
 294
 295         switch (request) {
 296         /* When I and D space are separate, these will need to be fixed.  */
 297         case PTRACE_PEEKTEXT: /* read word at location addr. */
 298         case PTRACE_PEEKDATA:
 299                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 300                 ret = -EIO;
 301                 if (copied != sizeof(tmp))
 302                         break;
 303
 304                 regs->r0 = 0;   /* special return: no errors */
 305                 ret = tmp;
 306                 break;
 307
 308         /* Read register number ADDR. */
 309         case PTRACE_PEEKUSR:
 310                 regs->r0 = 0;   /* special return: no errors */
 311                 ret = get_reg(child, addr);
 312                 DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
 313                 break;
 314
 315         /* When I and D space are separate, this will have to be fixed.  */
 316         case PTRACE_POKETEXT: /* write the word at location addr. */
 317         case PTRACE_POKEDATA:
 318                 tmp = data;
 319                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1);
 320                 ret = (copied == sizeof(tmp)) ? 0 : -EIO;
 321                 break;
 322
 323         case PTRACE_POKEUSR: /* write the specified register */
 324                 DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
 325                 ret = put_reg(child, addr, data);
 326                 break;
 327
 328         case PTRACE_SYSCALL:
 329                 /* continue and stop at next (return from) syscall */
 330         case PTRACE_CONT:    /* restart after signal. */
 331                 ret = -EIO;
 332                 if (!valid_signal(data))
 333                         break;
 334                 if (request == PTRACE_SYSCALL)
 335                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 336                 else
 337                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 338                 child->exit_code = data;
 339                 /* make sure single-step breakpoint is gone. */
 340                 ptrace_cancel_bpt(child);
 341                 wake_up_process(child);
 342                 ret = 0;
 343                 break;
 344
 345         /*
 346          * Make the child exit.  Best I can do is send it a sigkill.
 347          * perhaps it should be put in the status that it wants to
 348          * exit.
 349          */
 350         case PTRACE_KILL:
 351                 ret = 0;
 352                 if (child->exit_state == EXIT_ZOMBIE)
 353                         break;
 354                 child->exit_code = SIGKILL;
 355                 /* make sure single-step breakpoint is gone. */
 356                 ptrace_cancel_bpt(child);
 357                 wake_up_process(child);
 358                 goto out;
 359
 360         case PTRACE_SINGLESTEP:  /* execute single instruction. */
 361                 ret = -EIO;
 362                 if (!valid_signal(data))
 363                         break;
 364                 /* Mark single stepping.  */
 365                 task_thread_info(child)->bpt_nsaved = -1;
 366                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 367                 child->exit_code = data;
 368                 wake_up_process(child);
 369                 /* give it a chance to run. */
 370                 ret = 0;
 371                 goto out;
 372
 373         case PTRACE_DETACH:      /* detach a process that was attached. */
 374                 ret = ptrace_detach(child, data);
 375                 goto out;
 376
 377         default:
 378                 ret = ptrace_request(child, request, addr, data);
 379                 goto out;
 380         }
 381  out:
 382         put_task_struct(child);
 383  out_notsk:
 384         unlock_kernel();
 385         return ret;
 386 }
 387
 388 asmlinkage void
 389 syscall_trace(void)
 390 {
 391         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 392                 return;
 393         if (!(current->ptrace & PT_PTRACED))
 394                 return;
 395         /* The 0x80 provides a way for the tracing parent to distinguish
 396            between a syscall stop and SIGTRAP delivery */
 397         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 398                                  ? 0x80 : 0));
 399
 400         /*
 401          * This isn't the same as continuing with a signal, but it will do
 402          * for normal use.  strace only continues with a signal if the
 403          * stopping signal is not SIGTRAP.  -brl
 404          */
 405         if (current->exit_code) {
 406                 send_sig(current->exit_code, current, 1);
 407                 current->exit_code = 0;
 408         }
 409 }