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