LXR linux-old/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
  17#include <asm/uaccess.h>
  18#include <asm/pgtable.h>
  19#include <asm/system.h>
  20#include <asm/fpu.h>
  21
  22#include "proto.h"
  23
  24#define DEBUG   DBG_MEM
  25#undef DEBUG
  26
  27#ifdef DEBUG
  28enum {
  29        DBG_MEM         = (1<<0),
  30        DBG_BPT         = (1<<1),
  31        DBG_MEM_ALL     = (1<<2)
  32};
  33#define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
  34#else
  35#define DBG(fac,args)
  36#endif
  37
  38#define BREAKINST       0x00000080      /* call_pal bpt */
  39
  40/*
  41 * does not yet catch signals sent when the child dies.
  42 * in exit.c or in signal.c.
  43 */
  44
  45/*
  46 * Processes always block with the following stack-layout:
  47 *
  48 *  +================================+ <---- task + 2*PAGE_SIZE
  49 *  | PALcode saved frame (ps, pc,   | ^
  50 *  | gp, a0, a1, a2)                | |
  51 *  +================================+ | struct pt_regs
  52 *  |                                | |
  53 *  | frame generated by SAVE_ALL    | |
  54 *  |                                | v
  55 *  +================================+
  56 *  |                                | ^
  57 *  | frame saved by do_switch_stack | | struct switch_stack
  58 *  |                                | v
  59 *  +================================+
  60 */
  61
  62/* 
  63 * The following table maps a register index into the stack offset at
  64 * which the register is saved.  Register indices are 0-31 for integer
  65 * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
  66 * zero have no stack-slot and need to be treated specially (see
  67 * get_reg/put_reg below).
  68 */
  69enum {
  70        REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
  71};
  72
  73static int regoff[] = {
  74        PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
  75        PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
  76        PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
  77        SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
  78        PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
  79        PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
  80        PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
  81        PT_REG(   r28), PT_REG(    gp),            -1,             -1,
  82        SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
  83        SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
  84        SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
  85        SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
  86        SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
  87        SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
  88        SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
  89        SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
  90        PT_REG(    pc)
  91};
  92
  93static long zero;
  94
  95/*
  96 * Get address of register REGNO in task TASK.
  97 */
  98static long *
  99get_reg_addr(struct task_struct * task, unsigned long regno)
 100{
 101        long *addr;
 102
 103        if (regno == 30) {
 104                addr = &task->thread.usp;
 105        } else if (regno == 31 || regno > 64) {
 106                zero = 0;
 107                addr = &zero;
 108        } else {
 109                addr = (long *)((long)task + regoff[regno]);
 110        }
 111        return addr;
 112}
 113
 114/*
 115 * Get contents of register REGNO in task TASK.
 116 */
 117static long
 118get_reg(struct task_struct * task, unsigned long regno)
 119{
 120        /* Special hack for fpcr -- combine hardware and software bits.  */
 121        if (regno == 63) {
 122                unsigned long fpcr = *get_reg_addr(task, regno);
 123                unsigned long swcr = task->thread.flags & IEEE_SW_MASK;
 124                swcr = swcr_update_status(swcr, fpcr);
 125                return fpcr | swcr;
 126        }
 127        return *get_reg_addr(task, regno);
 128}
 129
 130/*
 131 * Write contents of register REGNO in task TASK.
 132 */
 133static int
 134put_reg(struct task_struct *task, unsigned long regno, long data)
 135{
 136        if (regno == 63) {
 137                task->thread.flags = ((task->thread.flags & ~IEEE_SW_MASK)
 138                                      | (data & IEEE_SW_MASK));
 139                data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
 140        }
 141        *get_reg_addr(task, regno) = data;
 142        return 0;
 143}
 144
 145static inline int
 146read_int(struct task_struct *task, unsigned long addr, int * data)
 147{
 148        int copied = access_process_vm(task, addr, data, sizeof(int), 0);
 149        return (copied == sizeof(int)) ? 0 : -EIO;
 150}
 151
 152static inline int
 153write_int(struct task_struct *task, unsigned long addr, int data)
 154{
 155        int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
 156        return (copied == sizeof(int)) ? 0 : -EIO;
 157}
 158
 159/*
 160 * Set breakpoint.
 161 */
 162int
 163ptrace_set_bpt(struct task_struct * child)
 164{
 165        int displ, i, res, reg_b, nsaved = 0;
 166        u32 insn, op_code;
 167        unsigned long pc;
 168
 169        pc  = get_reg(child, REG_PC);
 170        res = read_int(child, pc, &insn);
 171        if (res < 0)
 172                return res;
 173
 174        op_code = insn >> 26;
 175        if (op_code >= 0x30) {
 176                /*
 177                 * It's a branch: instead of trying to figure out
 178                 * whether the branch will be taken or not, we'll put
 179                 * a breakpoint at either location.  This is simpler,
 180                 * more reliable, and probably not a whole lot slower
 181                 * than the alternative approach of emulating the
 182                 * branch (emulation can be tricky for fp branches).
 183                 */
 184                displ = ((s32)(insn << 11)) >> 9;
 185                child->thread.bpt_addr[nsaved++] = pc + 4;
 186                if (displ)              /* guard against unoptimized code */
 187                        child->thread.bpt_addr[nsaved++] = pc + 4 + displ;
 188                DBG(DBG_BPT, ("execing branch\n"));
 189        } else if (op_code == 0x1a) {
 190                reg_b = (insn >> 16) & 0x1f;
 191                child->thread.bpt_addr[nsaved++] = get_reg(child, reg_b);
 192                DBG(DBG_BPT, ("execing jump\n"));
 193        } else {
 194                child->thread.bpt_addr[nsaved++] = pc + 4;
 195                DBG(DBG_BPT, ("execing normal insn\n"));
 196        }
 197
 198        /* install breakpoints: */
 199        for (i = 0; i < nsaved; ++i) {
 200                res = read_int(child, child->thread.bpt_addr[i], &insn);
 201                if (res < 0)
 202                        return res;
 203                child->thread.bpt_insn[i] = insn;
 204                DBG(DBG_BPT, ("    -> next_pc=%lx\n", child->thread.bpt_addr[i]));
 205                res = write_int(child, child->thread.bpt_addr[i], BREAKINST);
 206                if (res < 0)
 207                        return res;
 208        }
 209        child->thread.bpt_nsaved = nsaved;
 210        return 0;
 211}
 212
 213/*
 214 * Ensure no single-step breakpoint is pending.  Returns non-zero
 215 * value if child was being single-stepped.
 216 */
 217int
 218ptrace_cancel_bpt(struct task_struct * child)
 219{
 220        int i, nsaved = child->thread.bpt_nsaved;
 221
 222        child->thread.bpt_nsaved = 0;
 223
 224        if (nsaved > 2) {
 225                printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
 226                nsaved = 2;
 227        }
 228
 229        for (i = 0; i < nsaved; ++i) {
 230                write_int(child, child->thread.bpt_addr[i],
 231                          child->thread.bpt_insn[i]);
 232        }
 233        return (nsaved != 0);
 234}
 235
 236/*
 237 * Called by kernel/ptrace.c when detaching..
 238 *
 239 * Make sure the single step bit is not set.
 240 */
 241void ptrace_disable(struct task_struct *child)
 242{ 
 243        ptrace_cancel_bpt(child);
 244}
 245
 246asmlinkage long
 247sys_ptrace(long request, long pid, long addr, long data,
 248           int a4, int a5, struct pt_regs regs)
 249{
 250        struct task_struct *child;
 251        long ret;
 252
 253        lock_kernel();
 254        DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
 255                      request, pid, addr, data));
 256        ret = -EPERM;
 257        if (request == PTRACE_TRACEME) {
 258                /* are we already being traced? */
 259                if (current->ptrace & PT_PTRACED)
 260                        goto out_notsk;
 261                /* set the ptrace bit in the process ptrace flags. */
 262                current->ptrace |= PT_PTRACED;
 263                ret = 0;
 264                goto out_notsk;
 265        }
 266        if (pid == 1)           /* you may not mess with init */
 267                goto out_notsk;
 268        ret = -ESRCH;
 269        read_lock(&tasklist_lock);
 270        child = find_task_by_pid(pid);
 271        if (child)
 272                get_task_struct(child);
 273        read_unlock(&tasklist_lock);
 274        if (!child)
 275                goto out_notsk;
 276        if (request == PTRACE_ATTACH) {
 277                ret = ptrace_attach(child);
 278                goto out;
 279        }
 280        ret = -ESRCH;
 281        if (!(child->ptrace & PT_PTRACED)) {
 282                DBG(DBG_MEM, ("child not traced\n"));
 283                goto out;
 284        }
 285        if (child->state != TASK_STOPPED) {
 286                DBG(DBG_MEM, ("child process not stopped\n"));
 287                if (request != PTRACE_KILL)
 288                        goto out;
 289        }
 290        if (child->p_pptr != current) {
 291                DBG(DBG_MEM, ("child not parent of this process\n"));
 292                goto out;
 293        }
 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                unsigned long tmp;
 300                int copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 301                ret = -EIO;
 302                if (copied != sizeof(tmp))
 303                        goto out;
 304                
 305                regs.r0 = 0;    /* special return: no errors */
 306                ret = tmp;
 307                goto out;
 308        }
 309
 310        /* Read register number ADDR. */
 311        case PTRACE_PEEKUSR:
 312                regs.r0 = 0;    /* special return: no errors */
 313                ret = get_reg(child, addr);
 314                DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
 315                goto out;
 316
 317        /* When I and D space are separate, this will have to be fixed.  */
 318        case PTRACE_POKETEXT: /* write the word at location addr. */
 319        case PTRACE_POKEDATA: {
 320                unsigned long tmp = data;
 321                int copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1);
 322                ret = (copied == sizeof(tmp)) ? 0 : -EIO;
 323                goto out;
 324        }
 325
 326        case PTRACE_POKEUSR: /* write the specified register */
 327                DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
 328                ret = put_reg(child, addr, data);
 329                goto out;
 330
 331        case PTRACE_SYSCALL: /* continue and stop at next
 332                                (return from) syscall */
 333        case PTRACE_CONT:    /* restart after signal. */
 334                ret = -EIO;
 335                if ((unsigned long) data > _NSIG)
 336                        goto out;
 337                if (request == PTRACE_SYSCALL)
 338                        child->ptrace |= PT_TRACESYS;
 339                else
 340                        child->ptrace &= ~PT_TRACESYS;
 341                child->exit_code = data;
 342                wake_up_process(child);
 343                /* make sure single-step breakpoint is gone. */
 344                ptrace_cancel_bpt(child);
 345                ret = data;
 346                goto out;
 347
 348        /*
 349         * Make the child exit.  Best I can do is send it a sigkill.
 350         * perhaps it should be put in the status that it wants to
 351         * exit.
 352         */
 353        case PTRACE_KILL:
 354                if (child->state != TASK_ZOMBIE) {
 355                        wake_up_process(child);
 356                        child->exit_code = SIGKILL;
 357                }
 358                /* make sure single-step breakpoint is gone. */
 359                ptrace_cancel_bpt(child);
 360                ret = 0;
 361                goto out;
 362
 363        case PTRACE_SINGLESTEP:  /* execute single instruction. */
 364                ret = -EIO;
 365                if ((unsigned long) data > _NSIG)
 366                        goto out;
 367                child->thread.bpt_nsaved = -1;  /* mark single-stepping */
 368                child->ptrace &= ~PT_TRACESYS;
 369                wake_up_process(child);
 370                child->exit_code = data;
 371                /* give it a chance to run. */
 372                ret = 0;
 373                goto out;
 374
 375        case PTRACE_DETACH:      /* detach a process that was attached. */
 376                ret = ptrace_detach(child, data);
 377                goto out;
 378
 379        default:
 380                ret = -EIO;
 381                goto out;
 382        }
 383 out:
 384        free_task_struct(child);
 385 out_notsk:
 386        unlock_kernel();
 387        return ret;
 388}
 389
 390asmlinkage void
 391syscall_trace(void)
 392{
 393        if ((current->ptrace & (PT_PTRACED|PT_TRACESYS))
 394            != (PT_PTRACED|PT_TRACESYS))
 395                return;
 396        current->exit_code = SIGTRAP;
 397        current->state = TASK_STOPPED;
 398        notify_parent(current, SIGCHLD);
 399        schedule();
 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}
 410