arch/sh/kernel/ptrace_64.c

   1 /*
   2  * arch/sh/kernel/ptrace_64.c
   3  *
   4  * Copyright (C) 2000, 2001  Paolo Alberelli
   5  * Copyright (C) 2003 - 2008  Paul Mundt
   6  *
   7  * Started from SH3/4 version:
   8  *   SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
   9  *
  10  *   Original x86 implementation:
  11  *      By Ross Biro 1/23/92
  12  *      edited by Linus Torvalds
  13  *
  14  * This file is subject to the terms and conditions of the GNU General Public
  15  * License.  See the file "COPYING" in the main directory of this archive
  16  * for more details.
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/rwsem.h>
  20 #include <linux/sched.h>
  21 #include <linux/mm.h>
  22 #include <linux/smp.h>
  23 #include <linux/smp_lock.h>
  24 #include <linux/errno.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/user.h>
  27 #include <linux/signal.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/seccomp.h>
  31 #include <linux/tracehook.h>
  32 #include <linux/elf.h>
  33 #include <linux/regset.h>
  34 #include <asm/io.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/pgtable.h>
  37 #include <asm/system.h>
  38 #include <asm/processor.h>
  39 #include <asm/mmu_context.h>
  40 #include <asm/syscalls.h>
  41 #include <asm/fpu.h>
  42
  43 #define CREATE_TRACE_POINTS
  44 #include <trace/events/syscalls.h>
  45
  46 /* This mask defines the bits of the SR which the user is not allowed to
  47    change, which are everything except S, Q, M, PR, SZ, FR. */
  48 #define SR_MASK      (0xffff8cfd)
  49
  50 /*
  51  * does not yet catch signals sent when the child dies.
  52  * in exit.c or in signal.c.
  53  */
  54
  55 /*
  56  * This routine will get a word from the user area in the process kernel stack.
  57  */
  58 static inline int get_stack_long(struct task_struct *task, int offset)
  59 {
  60         unsigned char *stack;
  61
  62         stack = (unsigned char *)(task->thread.uregs);
  63         stack += offset;
  64         return (*((int *)stack));
  65 }
  66
  67 static inline unsigned long
  68 get_fpu_long(struct task_struct *task, unsigned long addr)
  69 {
  70         unsigned long tmp;
  71         struct pt_regs *regs;
  72         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
  73
  74         if (!tsk_used_math(task)) {
  75                 if (addr == offsetof(struct user_fpu_struct, fpscr)) {
  76                         tmp = FPSCR_INIT;
  77                 } else {
  78                         tmp = 0xffffffffUL; /* matches initial value in fpu.c */
  79                 }
  80                 return tmp;
  81         }
  82
  83         if (last_task_used_math == task) {
  84                 enable_fpu();
  85                 save_fpu(task);
  86                 disable_fpu();
  87                 last_task_used_math = 0;
  88                 regs->sr |= SR_FD;
  89         }
  90
  91         tmp = ((long *)task->thread.xstate)[addr / sizeof(unsigned long)];
  92         return tmp;
  93 }
  94
  95 /*
  96  * This routine will put a word into the user area in the process kernel stack.
  97  */
  98 static inline int put_stack_long(struct task_struct *task, int offset,
  99                                  unsigned long data)
 100 {
 101         unsigned char *stack;
 102
 103         stack = (unsigned char *)(task->thread.uregs);
 104         stack += offset;
 105         *(unsigned long *) stack = data;
 106         return 0;
 107 }
 108
 109 static inline int
 110 put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
 111 {
 112         struct pt_regs *regs;
 113
 114         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
 115
 116         if (!tsk_used_math(task)) {
 117                 init_fpu(task);
 118         } else if (last_task_used_math == task) {
 119                 enable_fpu();
 120                 save_fpu(task);
 121                 disable_fpu();
 122                 last_task_used_math = 0;
 123                 regs->sr |= SR_FD;
 124         }
 125
 126         ((long *)task->thread.xstate)[addr / sizeof(unsigned long)] = data;
 127         return 0;
 128 }
 129
 130 void user_enable_single_step(struct task_struct *child)
 131 {
 132         struct pt_regs *regs = child->thread.uregs;
 133
 134         regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 135
 136         set_tsk_thread_flag(child, TIF_SINGLESTEP);
 137 }
 138
 139 void user_disable_single_step(struct task_struct *child)
 140 {
 141         struct pt_regs *regs = child->thread.uregs;
 142
 143         regs->sr &= ~SR_SSTEP;
 144
 145         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 146 }
 147
 148 static int genregs_get(struct task_struct *target,
 149                        const struct user_regset *regset,
 150                        unsigned int pos, unsigned int count,
 151                        void *kbuf, void __user *ubuf)
 152 {
 153         const struct pt_regs *regs = task_pt_regs(target);
 154         int ret;
 155
 156         /* PC, SR, SYSCALL */
 157         ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 158                                   &regs->pc,
 159                                   0, 3 * sizeof(unsigned long long));
 160
 161         /* R1 -> R63 */
 162         if (!ret)
 163                 ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 164                                           regs->regs,
 165                                           offsetof(struct pt_regs, regs[0]),
 166                                           63 * sizeof(unsigned long long));
 167         /* TR0 -> TR7 */
 168         if (!ret)
 169                 ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 170                                           regs->tregs,
 171                                           offsetof(struct pt_regs, tregs[0]),
 172                                           8 * sizeof(unsigned long long));
 173
 174         if (!ret)
 175                 ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
 176                                                sizeof(struct pt_regs), -1);
 177
 178         return ret;
 179 }
 180
 181 static int genregs_set(struct task_struct *target,
 182                        const struct user_regset *regset,
 183                        unsigned int pos, unsigned int count,
 184                        const void *kbuf, const void __user *ubuf)
 185 {
 186         struct pt_regs *regs = task_pt_regs(target);
 187         int ret;
 188
 189         /* PC, SR, SYSCALL */
 190         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 191                                  &regs->pc,
 192                                  0, 3 * sizeof(unsigned long long));
 193
 194         /* R1 -> R63 */
 195         if (!ret && count > 0)
 196                 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 197                                          regs->regs,
 198                                          offsetof(struct pt_regs, regs[0]),
 199                                          63 * sizeof(unsigned long long));
 200
 201         /* TR0 -> TR7 */
 202         if (!ret && count > 0)
 203                 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 204                                          regs->tregs,
 205                                          offsetof(struct pt_regs, tregs[0]),
 206                                          8 * sizeof(unsigned long long));
 207
 208         if (!ret)
 209                 ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
 210                                                 sizeof(struct pt_regs), -1);
 211
 212         return ret;
 213 }
 214
 215 #ifdef CONFIG_SH_FPU
 216 int fpregs_get(struct task_struct *target,
 217                const struct user_regset *regset,
 218                unsigned int pos, unsigned int count,
 219                void *kbuf, void __user *ubuf)
 220 {
 221         int ret;
 222
 223         ret = init_fpu(target);
 224         if (ret)
 225                 return ret;
 226
 227         return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 228                                    &target->thread.xstate->hardfpu, 0, -1);
 229 }
 230
 231 static int fpregs_set(struct task_struct *target,
 232                        const struct user_regset *regset,
 233                        unsigned int pos, unsigned int count,
 234                        const void *kbuf, const void __user *ubuf)
 235 {
 236         int ret;
 237
 238         ret = init_fpu(target);
 239         if (ret)
 240                 return ret;
 241
 242         set_stopped_child_used_math(target);
 243
 244         return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 245                                   &target->thread.xstate->hardfpu, 0, -1);
 246 }
 247
 248 static int fpregs_active(struct task_struct *target,
 249                          const struct user_regset *regset)
 250 {
 251         return tsk_used_math(target) ? regset->n : 0;
 252 }
 253 #endif
 254
 255 /*
 256  * These are our native regset flavours.
 257  */
 258 enum sh_regset {
 259         REGSET_GENERAL,
 260 #ifdef CONFIG_SH_FPU
 261         REGSET_FPU,
 262 #endif
 263 };
 264
 265 static const struct user_regset sh_regsets[] = {
 266         /*
 267          * Format is:
 268          *      PC, SR, SYSCALL,
 269          *      R1 --> R63,
 270          *      TR0 --> TR7,
 271          */
 272         [REGSET_GENERAL] = {
 273                 .core_note_type = NT_PRSTATUS,
 274                 .n              = ELF_NGREG,
 275                 .size           = sizeof(long long),
 276                 .align          = sizeof(long long),
 277                 .get            = genregs_get,
 278                 .set            = genregs_set,
 279         },
 280
 281 #ifdef CONFIG_SH_FPU
 282         [REGSET_FPU] = {
 283                 .core_note_type = NT_PRFPREG,
 284                 .n              = sizeof(struct user_fpu_struct) /
 285                                   sizeof(long long),
 286                 .size           = sizeof(long long),
 287                 .align          = sizeof(long long),
 288                 .get            = fpregs_get,
 289                 .set            = fpregs_set,
 290                 .active         = fpregs_active,
 291         },
 292 #endif
 293 };
 294
 295 static const struct user_regset_view user_sh64_native_view = {
 296         .name           = "sh64",
 297         .e_machine      = EM_SH,
 298         .regsets        = sh_regsets,
 299         .n              = ARRAY_SIZE(sh_regsets),
 300 };
 301
 302 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 303 {
 304         return &user_sh64_native_view;
 305 }
 306
 307 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 308 {
 309         int ret;
 310
 311         switch (request) {
 312         /* read the word at location addr in the USER area. */
 313         case PTRACE_PEEKUSR: {
 314                 unsigned long tmp;
 315
 316                 ret = -EIO;
 317                 if ((addr & 3) || addr < 0)
 318                         break;
 319
 320                 if (addr < sizeof(struct pt_regs))
 321                         tmp = get_stack_long(child, addr);
 322                 else if ((addr >= offsetof(struct user, fpu)) &&
 323                          (addr <  offsetof(struct user, u_fpvalid))) {
 324                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 325                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 326                         tmp = !!tsk_used_math(child);
 327                 } else {
 328                         break;
 329                 }
 330                 ret = put_user(tmp, (unsigned long *)data);
 331                 break;
 332         }
 333
 334         case PTRACE_POKEUSR:
 335                 /* write the word at location addr in the USER area. We must
 336                    disallow any changes to certain SR bits or u_fpvalid, since
 337                    this could crash the kernel or result in a security
 338                    loophole. */
 339                 ret = -EIO;
 340                 if ((addr & 3) || addr < 0)
 341                         break;
 342
 343                 if (addr < sizeof(struct pt_regs)) {
 344                         /* Ignore change of top 32 bits of SR */
 345                         if (addr == offsetof (struct pt_regs, sr)+4)
 346                         {
 347                                 ret = 0;
 348                                 break;
 349                         }
 350                         /* If lower 32 bits of SR, ignore non-user bits */
 351                         if (addr == offsetof (struct pt_regs, sr))
 352                         {
 353                                 long cursr = get_stack_long(child, addr);
 354                                 data &= ~(SR_MASK);
 355                                 data |= (cursr & SR_MASK);
 356                         }
 357                         ret = put_stack_long(child, addr, data);
 358                 }
 359                 else if ((addr >= offsetof(struct user, fpu)) &&
 360                          (addr <  offsetof(struct user, u_fpvalid))) {
 361                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 362                 }
 363                 break;
 364
 365         case PTRACE_GETREGS:
 366                 return copy_regset_to_user(child, &user_sh64_native_view,
 367                                            REGSET_GENERAL,
 368                                            0, sizeof(struct pt_regs),
 369                                            (void __user *)data);
 370         case PTRACE_SETREGS:
 371                 return copy_regset_from_user(child, &user_sh64_native_view,
 372                                              REGSET_GENERAL,
 373                                              0, sizeof(struct pt_regs),
 374                                              (const void __user *)data);
 375 #ifdef CONFIG_SH_FPU
 376         case PTRACE_GETFPREGS:
 377                 return copy_regset_to_user(child, &user_sh64_native_view,
 378                                            REGSET_FPU,
 379                                            0, sizeof(struct user_fpu_struct),
 380                                            (void __user *)data);
 381         case PTRACE_SETFPREGS:
 382                 return copy_regset_from_user(child, &user_sh64_native_view,
 383                                              REGSET_FPU,
 384                                              0, sizeof(struct user_fpu_struct),
 385                                              (const void __user *)data);
 386 #endif
 387         default:
 388                 ret = ptrace_request(child, request, addr, data);
 389                 break;
 390         }
 391
 392         return ret;
 393 }
 394
 395 asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
 396 {
 397 #define WPC_DBRMODE 0x0d104008
 398         static int first_call = 1;
 399
 400         lock_kernel();
 401         if (first_call) {
 402                 /* Set WPC.DBRMODE to 0.  This makes all debug events get
 403                  * delivered through RESVEC, i.e. into the handlers in entry.S.
 404                  * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
 405                  * would normally be left set to 1, which makes debug events get
 406                  * delivered through DBRVEC, i.e. into the remote gdb's
 407                  * handlers.  This prevents ptrace getting them, and confuses
 408                  * the remote gdb.) */
 409                 printk("DBRMODE set to 0 to permit native debugging\n");
 410                 poke_real_address_q(WPC_DBRMODE, 0);
 411                 first_call = 0;
 412         }
 413         unlock_kernel();
 414
 415         return sys_ptrace(request, pid, addr, data);
 416 }
 417
 418 static inline int audit_arch(void)
 419 {
 420         int arch = EM_SH;
 421
 422 #ifdef CONFIG_64BIT
 423         arch |= __AUDIT_ARCH_64BIT;
 424 #endif
 425 #ifdef CONFIG_CPU_LITTLE_ENDIAN
 426         arch |= __AUDIT_ARCH_LE;
 427 #endif
 428
 429         return arch;
 430 }
 431
 432 asmlinkage long long do_syscall_trace_enter(struct pt_regs *regs)
 433 {
 434         long long ret = 0;
 435
 436         secure_computing(regs->regs[9]);
 437
 438         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 439             tracehook_report_syscall_entry(regs))
 440                 /*
 441                  * Tracing decided this syscall should not happen.
 442                  * We'll return a bogus call number to get an ENOSYS
 443                  * error, but leave the original number in regs->regs[0].
 444                  */
 445                 ret = -1LL;
 446
 447         if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 448                 trace_sys_enter(regs, regs->regs[9]);
 449
 450         if (unlikely(current->audit_context))
 451                 audit_syscall_entry(audit_arch(), regs->regs[1],
 452                                     regs->regs[2], regs->regs[3],
 453                                     regs->regs[4], regs->regs[5]);
 454
 455         return ret ?: regs->regs[9];
 456 }
 457
 458 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 459 {
 460         int step;
 461
 462         if (unlikely(current->audit_context))
 463                 audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 464                                    regs->regs[9]);
 465
 466         if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 467                 trace_sys_exit(regs, regs->regs[9]);
 468
 469         step = test_thread_flag(TIF_SINGLESTEP);
 470         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
 471                 tracehook_report_syscall_exit(regs, step);
 472 }
 473
 474 /* Called with interrupts disabled */
 475 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 476 {
 477         /* This is called after a single step exception (DEBUGSS).
 478            There is no need to change the PC, as it is a post-execution
 479            exception, as entry.S does not do anything to the PC for DEBUGSS.
 480            We need to clear the Single Step setting in SR to avoid
 481            continually stepping. */
 482         local_irq_enable();
 483         regs->sr &= ~SR_SSTEP;
 484         force_sig(SIGTRAP, current);
 485 }
 486
 487 /* Called with interrupts disabled */
 488 BUILD_TRAP_HANDLER(breakpoint)
 489 {
 490         TRAP_HANDLER_DECL;
 491
 492         /* We need to forward step the PC, to counteract the backstep done
 493            in signal.c. */
 494         local_irq_enable();
 495         force_sig(SIGTRAP, current);
 496         regs->pc += 4;
 497 }
 498
 499 /*
 500  * Called by kernel/ptrace.c when detaching..
 501  *
 502  * Make sure single step bits etc are not set.
 503  */
 504 void ptrace_disable(struct task_struct *child)
 505 {
 506         user_disable_single_step(child);
 507 }