arch/sh64/kernel/ptrace.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * arch/sh64/kernel/ptrace.c
   7  *
   8  * Copyright (C) 2000, 2001  Paolo Alberelli
   9  * Copyright (C) 2003  Paul Mundt
  10  *
  11  * Started from SH3/4 version:
  12  *   SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
  13  *
  14  *   Original x86 implementation:
  15  *      By Ross Biro 1/23/92
  16  *      edited by Linus Torvalds
  17  *
  18  */
  19
  20 #include <linux/config.h>
  21 #include <linux/kernel.h>
  22 #include <linux/rwsem.h>
  23 #include <linux/sched.h>
  24 #include <linux/mm.h>
  25 #include <linux/smp.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/errno.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/user.h>
  30
  31 #include <asm/io.h>
  32 #include <asm/uaccess.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/system.h>
  35 #include <asm/processor.h>
  36 #include <asm/mmu_context.h>
  37
  38 /* This mask defines the bits of the SR which the user is not allowed to
  39    change, which are everything except S, Q, M, PR, SZ, FR. */
  40 #define SR_MASK      (0xffff8cfd)
  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  * This routine will get a word from the user area in the process kernel stack.
  49  */
  50 static inline int get_stack_long(struct task_struct *task, int offset)
  51 {
  52         unsigned char *stack;
  53
  54         stack = (unsigned char *)(task->thread.uregs);
  55         stack += offset;
  56         return (*((int *)stack));
  57 }
  58
  59 static inline unsigned long
  60 get_fpu_long(struct task_struct *task, unsigned long addr)
  61 {
  62         unsigned long tmp;
  63         struct pt_regs *regs;
  64         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
  65
  66         if (!task->used_math) {
  67                 if (addr == offsetof(struct user_fpu_struct, fpscr)) {
  68                         tmp = FPSCR_INIT;
  69                 } else {
  70                         tmp = 0xffffffffUL; /* matches initial value in fpu.c */
  71                 }
  72                 return tmp;
  73         }
  74
  75         if (last_task_used_math == task) {
  76                 grab_fpu();
  77                 fpsave(&task->thread.fpu.hard);
  78                 release_fpu();
  79                 last_task_used_math = 0;
  80                 regs->sr |= SR_FD;
  81         }
  82
  83         tmp = ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)];
  84         return tmp;
  85 }
  86
  87 /*
  88  * This routine will put a word into the user area in the process kernel stack.
  89  */
  90 static inline int put_stack_long(struct task_struct *task, int offset,
  91                                  unsigned long data)
  92 {
  93         unsigned char *stack;
  94
  95         stack = (unsigned char *)(task->thread.uregs);
  96         stack += offset;
  97         *(unsigned long *) stack = data;
  98         return 0;
  99 }
 100
 101 static inline int
 102 put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
 103 {
 104         struct pt_regs *regs;
 105
 106         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
 107
 108         if (!task->used_math) {
 109                 fpinit(&task->thread.fpu.hard);
 110                 task->used_math = 1;
 111         } else if (last_task_used_math == task) {
 112                 grab_fpu();
 113                 fpsave(&task->thread.fpu.hard);
 114                 release_fpu();
 115                 last_task_used_math = 0;
 116                 regs->sr |= SR_FD;
 117         }
 118
 119         ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)] = data;
 120         return 0;
 121 }
 122
 123 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
 124 {
 125         struct task_struct *child;
 126         int ret;
 127
 128         lock_kernel();
 129         ret = -EPERM;
 130         if (request == PTRACE_TRACEME) {
 131                 /* are we already being traced? */
 132                 if (current->ptrace & PT_PTRACED)
 133                         goto out;
 134                 /* set the ptrace bit in the process flags. */
 135                 current->ptrace |= PT_PTRACED;
 136                 ret = 0;
 137                 goto out;
 138         }
 139         ret = -ESRCH;
 140         read_lock(&tasklist_lock);
 141         child = find_task_by_pid(pid);
 142         if (child)
 143                 get_task_struct(child);
 144         read_unlock(&tasklist_lock);
 145         if (!child)
 146                 goto out;
 147
 148         ret = -EPERM;
 149         if (pid == 1)           /* you may not mess with init */
 150                 goto out_tsk;
 151
 152         if (request == PTRACE_ATTACH) {
 153                 ret = ptrace_attach(child);
 154                         goto out_tsk;
 155                 }
 156
 157         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 158         if (ret < 0)
 159                 goto out_tsk;
 160
 161         switch (request) {
 162         /* when I and D space are separate, these will need to be fixed. */
 163         case PTRACE_PEEKTEXT: /* read word at location addr. */
 164         case PTRACE_PEEKDATA: {
 165                 unsigned long tmp;
 166                 int copied;
 167
 168                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 169                 ret = -EIO;
 170                 if (copied != sizeof(tmp))
 171                         break;
 172                 ret = put_user(tmp,(unsigned long *) data);
 173                 break;
 174         }
 175
 176         /* read the word at location addr in the USER area. */
 177         case PTRACE_PEEKUSR: {
 178                 unsigned long tmp;
 179
 180                 ret = -EIO;
 181                 if ((addr & 3) || addr < 0)
 182                         break;
 183
 184                 if (addr < sizeof(struct pt_regs))
 185                         tmp = get_stack_long(child, addr);
 186                 else if ((addr >= offsetof(struct user, fpu)) &&
 187                          (addr <  offsetof(struct user, u_fpvalid))) {
 188                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 189                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 190                         tmp = child->used_math;
 191                 } else {
 192                         break;
 193                 }
 194                 ret = put_user(tmp, (unsigned long *)data);
 195                 break;
 196         }
 197
 198         /* when I and D space are separate, this will have to be fixed. */
 199         case PTRACE_POKETEXT: /* write the word at location addr. */
 200         case PTRACE_POKEDATA:
 201                 ret = 0;
 202                 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 203                         break;
 204                 ret = -EIO;
 205                 break;
 206
 207         case PTRACE_POKEUSR:
 208                 /* write the word at location addr in the USER area. We must
 209                    disallow any changes to certain SR bits or u_fpvalid, since
 210                    this could crash the kernel or result in a security
 211                    loophole. */
 212                 ret = -EIO;
 213                 if ((addr & 3) || addr < 0)
 214                         break;
 215
 216                 if (addr < sizeof(struct pt_regs)) {
 217                         /* Ignore change of top 32 bits of SR */
 218                         if (addr == offsetof (struct pt_regs, sr)+4)
 219                         {
 220                                 ret = 0;
 221                                 break;
 222                         }
 223                         /* If lower 32 bits of SR, ignore non-user bits */
 224                         if (addr == offsetof (struct pt_regs, sr))
 225                         {
 226                                 long cursr = get_stack_long(child, addr);
 227                                 data &= ~(SR_MASK);
 228                                 data |= (cursr & SR_MASK);
 229                         }
 230                         ret = put_stack_long(child, addr, data);
 231                 }
 232                 else if ((addr >= offsetof(struct user, fpu)) &&
 233                          (addr <  offsetof(struct user, u_fpvalid))) {
 234                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 235                 }
 236                 break;
 237
 238         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 239         case PTRACE_CONT: { /* restart after signal. */
 240                 ret = -EIO;
 241                 if ((unsigned long) data > _NSIG)
 242                         break;
 243                 if (request == PTRACE_SYSCALL)
 244                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 245                 else
 246                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 247                 child->exit_code = data;
 248                 wake_up_process(child);
 249                 ret = 0;
 250                 break;
 251         }
 252
 253 /*
 254  * make the child exit.  Best I can do is send it a sigkill.
 255  * perhaps it should be put in the status that it wants to
 256  * exit.
 257  */
 258         case PTRACE_KILL: {
 259                 ret = 0;
 260                 if (child->state == TASK_ZOMBIE)        /* already dead */
 261                         break;
 262                 child->exit_code = SIGKILL;
 263                 wake_up_process(child);
 264                 break;
 265         }
 266
 267         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 268                 struct pt_regs *regs;
 269
 270                 ret = -EIO;
 271                 if ((unsigned long) data > _NSIG)
 272                         break;
 273                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 274                 if ((child->ptrace & PT_DTRACE) == 0) {
 275                         /* Spurious delayed TF traps may occur */
 276                         child->ptrace |= PT_DTRACE;
 277                 }
 278
 279                 regs = child->thread.uregs;
 280
 281                 regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 282
 283                 child->exit_code = data;
 284                 /* give it a chance to run. */
 285                 wake_up_process(child);
 286                 ret = 0;
 287                 break;
 288         }
 289
 290         case PTRACE_DETACH: /* detach a process that was attached. */
 291                 ret = ptrace_detach(child, data);
 292                 break;
 293
 294         default:
 295                 ret = ptrace_request(child, request, addr, data);
 296                 break;
 297         }
 298 out_tsk:
 299         put_task_struct(child);
 300 out:
 301         unlock_kernel();
 302         return ret;
 303 }
 304
 305 asmlinkage void syscall_trace(void)
 306 {
 307         struct task_struct *tsk = current;
 308
 309         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 310                 return;
 311         if (!(tsk->ptrace & PT_PTRACED))
 312                 return;
 313
 314         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 315                                  ? 0x80 : 0));
 316         /*
 317          * this isn't the same as continuing with a signal, but it will do
 318          * for normal use.  strace only continues with a signal if the
 319          * stopping signal is not SIGTRAP.  -brl
 320          */
 321         if (tsk->exit_code) {
 322                 send_sig(tsk->exit_code, tsk, 1);
 323                 tsk->exit_code = 0;
 324         }
 325 }
 326
 327 /* Called with interrupts disabled */
 328 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 329 {
 330         /* This is called after a single step exception (DEBUGSS).
 331            There is no need to change the PC, as it is a post-execution
 332            exception, as entry.S does not do anything to the PC for DEBUGSS.
 333            We need to clear the Single Step setting in SR to avoid
 334            continually stepping. */
 335         local_irq_enable();
 336         regs->sr &= ~SR_SSTEP;
 337         force_sig(SIGTRAP, current);
 338 }
 339
 340 /* Called with interrupts disabled */
 341 asmlinkage void do_software_break_point(unsigned long long vec,
 342                                         struct pt_regs *regs)
 343 {
 344         /* We need to forward step the PC, to counteract the backstep done
 345            in signal.c. */
 346         local_irq_enable();
 347         force_sig(SIGTRAP, current);
 348         regs->pc += 4;
 349 }
 350
 351 /*
 352  * Called by kernel/ptrace.c when detaching..
 353  *
 354  * Make sure single step bits etc are not set.
 355  */
 356 void ptrace_disable(struct task_struct *child)
 357 {
 358         /* nothing to do.. */
 359 }