LXR linux/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
  30enum {
  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 */
  71enum {
  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
  82static 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
 102static unsigned long zero;
 103
 104/*
 105 * Get address of register REGNO in task TASK.
 106 */
 107static unsigned long *
 108get_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 */
 128static unsigned long
 129get_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 */
 145static int
 146put_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
 158static inline int
 159read_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
 165static inline int
 166write_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 */
 175int
 176ptrace_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 */
 234int
 235ptrace_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 */
 258void ptrace_disable(struct task_struct *child)
 259{ 
 260        ptrace_cancel_bpt(child);
 261}
 262
 263long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 264{
 265        unsigned long tmp;
 266        size_t copied;
 267        long ret;
 268
 269        switch (request) {
 270        /* When I and D space are separate, these will need to be fixed.  */
 271        case PTRACE_PEEKTEXT: /* read word at location addr. */
 272        case PTRACE_PEEKDATA:
 273                copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 274                ret = -EIO;
 275                if (copied != sizeof(tmp))
 276                        break;
 277                
 278                force_successful_syscall_return();
 279                ret = tmp;
 280                break;
 281
 282        /* Read register number ADDR. */
 283        case PTRACE_PEEKUSR:
 284                force_successful_syscall_return();
 285                ret = get_reg(child, addr);
 286                DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
 287                break;
 288
 289        /* When I and D space are separate, this will have to be fixed.  */
 290        case PTRACE_POKETEXT: /* write the word at location addr. */
 291        case PTRACE_POKEDATA:
 292                ret = generic_ptrace_pokedata(child, addr, data);
 293                break;
 294
 295        case PTRACE_POKEUSR: /* write the specified register */
 296                DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
 297                ret = put_reg(child, addr, data);
 298                break;
 299
 300        case PTRACE_SYSCALL:
 301                /* continue and stop at next (return from) syscall */
 302        case PTRACE_CONT:    /* restart after signal. */
 303                ret = -EIO;
 304                if (!valid_signal(data))
 305                        break;
 306                if (request == PTRACE_SYSCALL)
 307                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 308                else
 309                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 310                child->exit_code = data;
 311                /* make sure single-step breakpoint is gone. */
 312                ptrace_cancel_bpt(child);
 313                wake_up_process(child);
 314                ret = 0;
 315                break;
 316
 317        /*
 318         * Make the child exit.  Best I can do is send it a sigkill.
 319         * perhaps it should be put in the status that it wants to
 320         * exit.
 321         */
 322        case PTRACE_KILL:
 323                ret = 0;
 324                if (child->exit_state == EXIT_ZOMBIE)
 325                        break;
 326                child->exit_code = SIGKILL;
 327                /* make sure single-step breakpoint is gone. */
 328                ptrace_cancel_bpt(child);
 329                wake_up_process(child);
 330                break;
 331
 332        case PTRACE_SINGLESTEP:  /* execute single instruction. */
 333                ret = -EIO;
 334                if (!valid_signal(data))
 335                        break;
 336                /* Mark single stepping.  */
 337                task_thread_info(child)->bpt_nsaved = -1;
 338                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 339                child->exit_code = data;
 340                wake_up_process(child);
 341                /* give it a chance to run. */
 342                ret = 0;
 343                break;
 344
 345        default:
 346                ret = ptrace_request(child, request, addr, data);
 347                break;
 348        }
 349        return ret;
 350}
 351
 352asmlinkage void
 353syscall_trace(void)
 354{
 355        if (!test_thread_flag(TIF_SYSCALL_TRACE))
 356                return;
 357        if (!(current->ptrace & PT_PTRACED))
 358                return;
 359        /* The 0x80 provides a way for the tracing parent to distinguish
 360           between a syscall stop and SIGTRAP delivery */
 361        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 362                                 ? 0x80 : 0));
 363
 364        /*
 365         * This isn't the same as continuing with a signal, but it will do
 366         * for normal use.  strace only continues with a signal if the
 367         * stopping signal is not SIGTRAP.  -brl
 368         */
 369        if (current->exit_code) {
 370                send_sig(current->exit_code, current, 1);
 371                current->exit_code = 0;
 372        }
 373}
 374