arch/xtensa/kernel/ptrace.c

   1 // TODO some minor issues
   2 /*
   3  * This file is subject to the terms and conditions of the GNU General Public
   4  * License.  See the file "COPYING" in the main directory of this archive
   5  * for more details.
   6  *
   7  * Copyright (C) 2001 - 2007  Tensilica Inc.
   8  *
   9  * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
  10  * Chris Zankel <chris@zankel.net>
  11  * Scott Foehner<sfoehner@yahoo.com>,
  12  * Kevin Chea
  13  * Marc Gauthier<marc@tensilica.com> <marc@alumni.uwaterloo.ca>
  14  */
  15
  16 #include <linux/errno.h>
  17 #include <linux/hw_breakpoint.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/perf_event.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/sched.h>
  23 #include <linux/security.h>
  24 #include <linux/signal.h>
  25 #include <linux/smp.h>
  26
  27 #include <asm/coprocessor.h>
  28 #include <asm/elf.h>
  29 #include <asm/page.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/ptrace.h>
  32 #include <asm/uaccess.h>
  33
  34
  35 void user_enable_single_step(struct task_struct *child)
  36 {
  37         child->ptrace |= PT_SINGLESTEP;
  38 }
  39
  40 void user_disable_single_step(struct task_struct *child)
  41 {
  42         child->ptrace &= ~PT_SINGLESTEP;
  43 }
  44
  45 /*
  46  * Called by kernel/ptrace.c when detaching to disable single stepping.
  47  */
  48
  49 void ptrace_disable(struct task_struct *child)
  50 {
  51         /* Nothing to do.. */
  52 }
  53
  54 int ptrace_getregs(struct task_struct *child, void __user *uregs)
  55 {
  56         struct pt_regs *regs = task_pt_regs(child);
  57         xtensa_gregset_t __user *gregset = uregs;
  58         unsigned long wb = regs->windowbase;
  59         int i;
  60
  61         if (!access_ok(VERIFY_WRITE, uregs, sizeof(xtensa_gregset_t)))
  62                 return -EIO;
  63
  64         __put_user(regs->pc, &gregset->pc);
  65         __put_user(regs->ps & ~(1 << PS_EXCM_BIT), &gregset->ps);
  66         __put_user(regs->lbeg, &gregset->lbeg);
  67         __put_user(regs->lend, &gregset->lend);
  68         __put_user(regs->lcount, &gregset->lcount);
  69         __put_user(regs->windowstart, &gregset->windowstart);
  70         __put_user(regs->windowbase, &gregset->windowbase);
  71         __put_user(regs->threadptr, &gregset->threadptr);
  72
  73         for (i = 0; i < XCHAL_NUM_AREGS; i++)
  74                 __put_user(regs->areg[i],
  75                                 gregset->a + ((wb * 4 + i) % XCHAL_NUM_AREGS));
  76
  77         return 0;
  78 }
  79
  80 int ptrace_setregs(struct task_struct *child, void __user *uregs)
  81 {
  82         struct pt_regs *regs = task_pt_regs(child);
  83         xtensa_gregset_t *gregset = uregs;
  84         const unsigned long ps_mask = PS_CALLINC_MASK | PS_OWB_MASK;
  85         unsigned long ps;
  86         unsigned long wb, ws;
  87
  88         if (!access_ok(VERIFY_WRITE, uregs, sizeof(xtensa_gregset_t)))
  89                 return -EIO;
  90
  91         __get_user(regs->pc, &gregset->pc);
  92         __get_user(ps, &gregset->ps);
  93         __get_user(regs->lbeg, &gregset->lbeg);
  94         __get_user(regs->lend, &gregset->lend);
  95         __get_user(regs->lcount, &gregset->lcount);
  96         __get_user(ws, &gregset->windowstart);
  97         __get_user(wb, &gregset->windowbase);
  98         __get_user(regs->threadptr, &gregset->threadptr);
  99
 100         regs->ps = (regs->ps & ~ps_mask) | (ps & ps_mask) | (1 << PS_EXCM_BIT);
 101
 102         if (wb >= XCHAL_NUM_AREGS / 4)
 103                 return -EFAULT;
 104
 105         if (wb != regs->windowbase || ws != regs->windowstart) {
 106                 unsigned long rotws, wmask;
 107
 108                 rotws = (((ws | (ws << WSBITS)) >> wb) &
 109                                 ((1 << WSBITS) - 1)) & ~1;
 110                 wmask = ((rotws ? WSBITS + 1 - ffs(rotws) : 0) << 4) |
 111                         (rotws & 0xF) | 1;
 112                 regs->windowbase = wb;
 113                 regs->windowstart = ws;
 114                 regs->wmask = wmask;
 115         }
 116
 117         if (wb != 0 &&  __copy_from_user(regs->areg + XCHAL_NUM_AREGS - wb * 4,
 118                                 gregset->a, wb * 16))
 119                 return -EFAULT;
 120
 121         if (__copy_from_user(regs->areg, gregset->a + wb * 4,
 122                                 (WSBITS - wb) * 16))
 123                 return -EFAULT;
 124
 125         return 0;
 126 }
 127
 128
 129 int ptrace_getxregs(struct task_struct *child, void __user *uregs)
 130 {
 131         struct pt_regs *regs = task_pt_regs(child);
 132         struct thread_info *ti = task_thread_info(child);
 133         elf_xtregs_t __user *xtregs = uregs;
 134         int ret = 0;
 135
 136         if (!access_ok(VERIFY_WRITE, uregs, sizeof(elf_xtregs_t)))
 137                 return -EIO;
 138
 139 #if XTENSA_HAVE_COPROCESSORS
 140         /* Flush all coprocessor registers to memory. */
 141         coprocessor_flush_all(ti);
 142         ret |= __copy_to_user(&xtregs->cp0, &ti->xtregs_cp,
 143                               sizeof(xtregs_coprocessor_t));
 144 #endif
 145         ret |= __copy_to_user(&xtregs->opt, &regs->xtregs_opt,
 146                               sizeof(xtregs->opt));
 147         ret |= __copy_to_user(&xtregs->user,&ti->xtregs_user,
 148                               sizeof(xtregs->user));
 149
 150         return ret ? -EFAULT : 0;
 151 }
 152
 153 int ptrace_setxregs(struct task_struct *child, void __user *uregs)
 154 {
 155         struct thread_info *ti = task_thread_info(child);
 156         struct pt_regs *regs = task_pt_regs(child);
 157         elf_xtregs_t *xtregs = uregs;
 158         int ret = 0;
 159
 160         if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t)))
 161                 return -EFAULT;
 162
 163 #if XTENSA_HAVE_COPROCESSORS
 164         /* Flush all coprocessors before we overwrite them. */
 165         coprocessor_flush_all(ti);
 166         coprocessor_release_all(ti);
 167
 168         ret |= __copy_from_user(&ti->xtregs_cp, &xtregs->cp0,
 169                                 sizeof(xtregs_coprocessor_t));
 170 #endif
 171         ret |= __copy_from_user(&regs->xtregs_opt, &xtregs->opt,
 172                                 sizeof(xtregs->opt));
 173         ret |= __copy_from_user(&ti->xtregs_user, &xtregs->user,
 174                                 sizeof(xtregs->user));
 175
 176         return ret ? -EFAULT : 0;
 177 }
 178
 179 int ptrace_peekusr(struct task_struct *child, long regno, long __user *ret)
 180 {
 181         struct pt_regs *regs;
 182         unsigned long tmp;
 183
 184         regs = task_pt_regs(child);
 185         tmp = 0;  /* Default return value. */
 186
 187         switch(regno) {
 188
 189                 case REG_AR_BASE ... REG_AR_BASE + XCHAL_NUM_AREGS - 1:
 190                         tmp = regs->areg[regno - REG_AR_BASE];
 191                         break;
 192
 193                 case REG_A_BASE ... REG_A_BASE + 15:
 194                         tmp = regs->areg[regno - REG_A_BASE];
 195                         break;
 196
 197                 case REG_PC:
 198                         tmp = regs->pc;
 199                         break;
 200
 201                 case REG_PS:
 202                         /* Note:  PS.EXCM is not set while user task is running;
 203                          * its being set in regs is for exception handling
 204                          * convenience.  */
 205                         tmp = (regs->ps & ~(1 << PS_EXCM_BIT));
 206                         break;
 207
 208                 case REG_WB:
 209                         break;          /* tmp = 0 */
 210
 211                 case REG_WS:
 212                 {
 213                         unsigned long wb = regs->windowbase;
 214                         unsigned long ws = regs->windowstart;
 215                         tmp = ((ws>>wb) | (ws<<(WSBITS-wb))) & ((1<<WSBITS)-1);
 216                         break;
 217                 }
 218                 case REG_LBEG:
 219                         tmp = regs->lbeg;
 220                         break;
 221
 222                 case REG_LEND:
 223                         tmp = regs->lend;
 224                         break;
 225
 226                 case REG_LCOUNT:
 227                         tmp = regs->lcount;
 228                         break;
 229
 230                 case REG_SAR:
 231                         tmp = regs->sar;
 232                         break;
 233
 234                 case SYSCALL_NR:
 235                         tmp = regs->syscall;
 236                         break;
 237
 238                 default:
 239                         return -EIO;
 240         }
 241         return put_user(tmp, ret);
 242 }
 243
 244 int ptrace_pokeusr(struct task_struct *child, long regno, long val)
 245 {
 246         struct pt_regs *regs;
 247         regs = task_pt_regs(child);
 248
 249         switch (regno) {
 250                 case REG_AR_BASE ... REG_AR_BASE + XCHAL_NUM_AREGS - 1:
 251                         regs->areg[regno - REG_AR_BASE] = val;
 252                         break;
 253
 254                 case REG_A_BASE ... REG_A_BASE + 15:
 255                         regs->areg[regno - REG_A_BASE] = val;
 256                         break;
 257
 258                 case REG_PC:
 259                         regs->pc = val;
 260                         break;
 261
 262                 case SYSCALL_NR:
 263                         regs->syscall = val;
 264                         break;
 265
 266                 default:
 267                         return -EIO;
 268         }
 269         return 0;
 270 }
 271
 272 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 273 static void ptrace_hbptriggered(struct perf_event *bp,
 274                                 struct perf_sample_data *data,
 275                                 struct pt_regs *regs)
 276 {
 277         int i;
 278         siginfo_t info;
 279         struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
 280
 281         if (bp->attr.bp_type & HW_BREAKPOINT_X) {
 282                 for (i = 0; i < XCHAL_NUM_IBREAK; ++i)
 283                         if (current->thread.ptrace_bp[i] == bp)
 284                                 break;
 285                 i <<= 1;
 286         } else {
 287                 for (i = 0; i < XCHAL_NUM_DBREAK; ++i)
 288                         if (current->thread.ptrace_wp[i] == bp)
 289                                 break;
 290                 i = (i << 1) | 1;
 291         }
 292
 293         info.si_signo = SIGTRAP;
 294         info.si_errno = i;
 295         info.si_code = TRAP_HWBKPT;
 296         info.si_addr = (void __user *)bkpt->address;
 297
 298         force_sig_info(SIGTRAP, &info, current);
 299 }
 300
 301 static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
 302 {
 303         struct perf_event_attr attr;
 304
 305         ptrace_breakpoint_init(&attr);
 306
 307         /* Initialise fields to sane defaults. */
 308         attr.bp_addr    = 0;
 309         attr.bp_len     = 1;
 310         attr.bp_type    = type;
 311         attr.disabled   = 1;
 312
 313         return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
 314                                            tsk);
 315 }
 316
 317 /*
 318  * Address bit 0 choose instruction (0) or data (1) break register, bits
 319  * 31..1 are the register number.
 320  * Both PTRACE_GETHBPREGS and PTRACE_SETHBPREGS transfer two 32-bit words:
 321  * address (0) and control (1).
 322  * Instruction breakpoint contorl word is 0 to clear breakpoint, 1 to set.
 323  * Data breakpoint control word bit 31 is 'trigger on store', bit 30 is
 324  * 'trigger on load, bits 29..0 are length. Length 0 is used to clear a
 325  * breakpoint. To set a breakpoint length must be a power of 2 in the range
 326  * 1..64 and the address must be length-aligned.
 327  */
 328
 329 static long ptrace_gethbpregs(struct task_struct *child, long addr,
 330                               long __user *datap)
 331 {
 332         struct perf_event *bp;
 333         u32 user_data[2] = {0};
 334         bool dbreak = addr & 1;
 335         unsigned idx = addr >> 1;
 336
 337         if ((!dbreak && idx >= XCHAL_NUM_IBREAK) ||
 338             (dbreak && idx >= XCHAL_NUM_DBREAK))
 339                 return -EINVAL;
 340
 341         if (dbreak)
 342                 bp = child->thread.ptrace_wp[idx];
 343         else
 344                 bp = child->thread.ptrace_bp[idx];
 345
 346         if (bp) {
 347                 user_data[0] = bp->attr.bp_addr;
 348                 user_data[1] = bp->attr.disabled ? 0 : bp->attr.bp_len;
 349                 if (dbreak) {
 350                         if (bp->attr.bp_type & HW_BREAKPOINT_R)
 351                                 user_data[1] |= DBREAKC_LOAD_MASK;
 352                         if (bp->attr.bp_type & HW_BREAKPOINT_W)
 353                                 user_data[1] |= DBREAKC_STOR_MASK;
 354                 }
 355         }
 356
 357         if (copy_to_user(datap, user_data, sizeof(user_data)))
 358                 return -EFAULT;
 359
 360         return 0;
 361 }
 362
 363 static long ptrace_sethbpregs(struct task_struct *child, long addr,
 364                               long __user *datap)
 365 {
 366         struct perf_event *bp;
 367         struct perf_event_attr attr;
 368         u32 user_data[2];
 369         bool dbreak = addr & 1;
 370         unsigned idx = addr >> 1;
 371         int bp_type = 0;
 372
 373         if ((!dbreak && idx >= XCHAL_NUM_IBREAK) ||
 374             (dbreak && idx >= XCHAL_NUM_DBREAK))
 375                 return -EINVAL;
 376
 377         if (copy_from_user(user_data, datap, sizeof(user_data)))
 378                 return -EFAULT;
 379
 380         if (dbreak) {
 381                 bp = child->thread.ptrace_wp[idx];
 382                 if (user_data[1] & DBREAKC_LOAD_MASK)
 383                         bp_type |= HW_BREAKPOINT_R;
 384                 if (user_data[1] & DBREAKC_STOR_MASK)
 385                         bp_type |= HW_BREAKPOINT_W;
 386         } else {
 387                 bp = child->thread.ptrace_bp[idx];
 388                 bp_type = HW_BREAKPOINT_X;
 389         }
 390
 391         if (!bp) {
 392                 bp = ptrace_hbp_create(child,
 393                                        bp_type ? bp_type : HW_BREAKPOINT_RW);
 394                 if (IS_ERR(bp))
 395                         return PTR_ERR(bp);
 396                 if (dbreak)
 397                         child->thread.ptrace_wp[idx] = bp;
 398                 else
 399                         child->thread.ptrace_bp[idx] = bp;
 400         }
 401
 402         attr = bp->attr;
 403         attr.bp_addr = user_data[0];
 404         attr.bp_len = user_data[1] & ~(DBREAKC_LOAD_MASK | DBREAKC_STOR_MASK);
 405         attr.bp_type = bp_type;
 406         attr.disabled = !attr.bp_len;
 407
 408         return modify_user_hw_breakpoint(bp, &attr);
 409 }
 410 #endif
 411
 412 long arch_ptrace(struct task_struct *child, long request,
 413                  unsigned long addr, unsigned long data)
 414 {
 415         int ret = -EPERM;
 416         void __user *datap = (void __user *) data;
 417
 418         switch (request) {
 419         case PTRACE_PEEKTEXT:   /* read word at location addr. */
 420         case PTRACE_PEEKDATA:
 421                 ret = generic_ptrace_peekdata(child, addr, data);
 422                 break;
 423
 424         case PTRACE_PEEKUSR:    /* read register specified by addr. */
 425                 ret = ptrace_peekusr(child, addr, datap);
 426                 break;
 427
 428         case PTRACE_POKETEXT:   /* write the word at location addr. */
 429         case PTRACE_POKEDATA:
 430                 ret = generic_ptrace_pokedata(child, addr, data);
 431                 break;
 432
 433         case PTRACE_POKEUSR:    /* write register specified by addr. */
 434                 ret = ptrace_pokeusr(child, addr, data);
 435                 break;
 436
 437         case PTRACE_GETREGS:
 438                 ret = ptrace_getregs(child, datap);
 439                 break;
 440
 441         case PTRACE_SETREGS:
 442                 ret = ptrace_setregs(child, datap);
 443                 break;
 444
 445         case PTRACE_GETXTREGS:
 446                 ret = ptrace_getxregs(child, datap);
 447                 break;
 448
 449         case PTRACE_SETXTREGS:
 450                 ret = ptrace_setxregs(child, datap);
 451                 break;
 452 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 453         case PTRACE_GETHBPREGS:
 454                 ret = ptrace_gethbpregs(child, addr, datap);
 455                 break;
 456
 457         case PTRACE_SETHBPREGS:
 458                 ret = ptrace_sethbpregs(child, addr, datap);
 459                 break;
 460 #endif
 461         default:
 462                 ret = ptrace_request(child, request, addr, data);
 463                 break;
 464         }
 465
 466         return ret;
 467 }
 468
 469 void do_syscall_trace(void)
 470 {
 471         /*
 472          * The 0x80 provides a way for the tracing parent to distinguish
 473          * between a syscall stop and SIGTRAP delivery
 474          */
 475         ptrace_notify(SIGTRAP|((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
 476
 477         /*
 478          * this isn't the same as continuing with a signal, but it will do
 479          * for normal use.  strace only continues with a signal if the
 480          * stopping signal is not SIGTRAP.  -brl
 481          */
 482         if (current->exit_code) {
 483                 send_sig(current->exit_code, current, 1);
 484                 current->exit_code = 0;
 485         }
 486 }
 487
 488 void do_syscall_trace_enter(struct pt_regs *regs)
 489 {
 490         if (test_thread_flag(TIF_SYSCALL_TRACE)
 491                         && (current->ptrace & PT_PTRACED))
 492                 do_syscall_trace();
 493
 494 #if 0
 495         audit_syscall_entry(...);
 496 #endif
 497 }
 498
 499 void do_syscall_trace_leave(struct pt_regs *regs)
 500 {
 501         if ((test_thread_flag(TIF_SYSCALL_TRACE))
 502                         && (current->ptrace & PT_PTRACED))
 503                 do_syscall_trace();
 504 }