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 #include <linux/signal.h>
  31
  32 #include <asm/io.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/system.h>
  36 #include <asm/processor.h>
  37 #include <asm/mmu_context.h>
  38
  39 /* This mask defines the bits of the SR which the user is not allowed to
  40    change, which are everything except S, Q, M, PR, SZ, FR. */
  41 #define SR_MASK      (0xffff8cfd)
  42
  43 /*
  44  * does not yet catch signals sent when the child dies.
  45  * in exit.c or in signal.c.
  46  */
  47
  48 /*
  49  * This routine will get a word from the user area in the process kernel stack.
  50  */
  51 static inline int get_stack_long(struct task_struct *task, int offset)
  52 {
  53         unsigned char *stack;
  54
  55         stack = (unsigned char *)(task->thread.uregs);
  56         stack += offset;
  57         return (*((int *)stack));
  58 }
  59
  60 static inline unsigned long
  61 get_fpu_long(struct task_struct *task, unsigned long addr)
  62 {
  63         unsigned long tmp;
  64         struct pt_regs *regs;
  65         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
  66
  67         if (!tsk_used_math(task)) {
  68                 if (addr == offsetof(struct user_fpu_struct, fpscr)) {
  69                         tmp = FPSCR_INIT;
  70                 } else {
  71                         tmp = 0xffffffffUL; /* matches initial value in fpu.c */
  72                 }
  73                 return tmp;
  74         }
  75
  76         if (last_task_used_math == task) {
  77                 grab_fpu();
  78                 fpsave(&task->thread.fpu.hard);
  79                 release_fpu();
  80                 last_task_used_math = 0;
  81                 regs->sr |= SR_FD;
  82         }
  83
  84         tmp = ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)];
  85         return tmp;
  86 }
  87
  88 /*
  89  * This routine will put a word into the user area in the process kernel stack.
  90  */
  91 static inline int put_stack_long(struct task_struct *task, int offset,
  92                                  unsigned long data)
  93 {
  94         unsigned char *stack;
  95
  96         stack = (unsigned char *)(task->thread.uregs);
  97         stack += offset;
  98         *(unsigned long *) stack = data;
  99         return 0;
 100 }
 101
 102 static inline int
 103 put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
 104 {
 105         struct pt_regs *regs;
 106
 107         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
 108
 109         if (!tsk_used_math(task)) {
 110                 fpinit(&task->thread.fpu.hard);
 111                 set_stopped_child_used_math(task);
 112         } else if (last_task_used_math == task) {
 113                 grab_fpu();
 114                 fpsave(&task->thread.fpu.hard);
 115                 release_fpu();
 116                 last_task_used_math = 0;
 117                 regs->sr |= SR_FD;
 118         }
 119
 120         ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)] = data;
 121         return 0;
 122 }
 123
 124 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
 125 {
 126         struct task_struct *child;
 127         extern void poke_real_address_q(unsigned long long addr, unsigned long long data);
 128 #define WPC_DBRMODE 0x0d104008
 129         static int first_call = 1;
 130         int ret;
 131
 132         lock_kernel();
 133
 134         if (first_call) {
 135                 /* Set WPC.DBRMODE to 0.  This makes all debug events get
 136                  * delivered through RESVEC, i.e. into the handlers in entry.S.
 137                  * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
 138                  * would normally be left set to 1, which makes debug events get
 139                  * delivered through DBRVEC, i.e. into the remote gdb's
 140                  * handlers.  This prevents ptrace getting them, and confuses
 141                  * the remote gdb.) */
 142                 printk("DBRMODE set to 0 to permit native debugging\n");
 143                 poke_real_address_q(WPC_DBRMODE, 0);
 144                 first_call = 0;
 145         }
 146
 147         ret = -EPERM;
 148         if (request == PTRACE_TRACEME) {
 149                 /* are we already being traced? */
 150                 if (current->ptrace & PT_PTRACED)
 151                         goto out;
 152                 /* set the ptrace bit in the process flags. */
 153                 current->ptrace |= PT_PTRACED;
 154                 ret = 0;
 155                 goto out;
 156         }
 157         ret = -ESRCH;
 158         read_lock(&tasklist_lock);
 159         child = find_task_by_pid(pid);
 160         if (child)
 161                 get_task_struct(child);
 162         read_unlock(&tasklist_lock);
 163         if (!child)
 164                 goto out;
 165
 166         ret = -EPERM;
 167         if (pid == 1)           /* you may not mess with init */
 168                 goto out_tsk;
 169
 170         if (request == PTRACE_ATTACH) {
 171                 ret = ptrace_attach(child);
 172                         goto out_tsk;
 173                 }
 174
 175         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 176         if (ret < 0)
 177                 goto out_tsk;
 178
 179         switch (request) {
 180         /* when I and D space are separate, these will need to be fixed. */
 181         case PTRACE_PEEKTEXT: /* read word at location addr. */
 182         case PTRACE_PEEKDATA: {
 183                 unsigned long tmp;
 184                 int copied;
 185
 186                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 187                 ret = -EIO;
 188                 if (copied != sizeof(tmp))
 189                         break;
 190                 ret = put_user(tmp,(unsigned long *) data);
 191                 break;
 192         }
 193
 194         /* read the word at location addr in the USER area. */
 195         case PTRACE_PEEKUSR: {
 196                 unsigned long tmp;
 197
 198                 ret = -EIO;
 199                 if ((addr & 3) || addr < 0)
 200                         break;
 201
 202                 if (addr < sizeof(struct pt_regs))
 203                         tmp = get_stack_long(child, addr);
 204                 else if ((addr >= offsetof(struct user, fpu)) &&
 205                          (addr <  offsetof(struct user, u_fpvalid))) {
 206                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 207                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 208                         tmp = !!tsk_used_math(child);
 209                 } else {
 210                         break;
 211                 }
 212                 ret = put_user(tmp, (unsigned long *)data);
 213                 break;
 214         }
 215
 216         /* when I and D space are separate, this will have to be fixed. */
 217         case PTRACE_POKETEXT: /* write the word at location addr. */
 218         case PTRACE_POKEDATA:
 219                 ret = 0;
 220                 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 221                         break;
 222                 ret = -EIO;
 223                 break;
 224
 225         case PTRACE_POKEUSR:
 226                 /* write the word at location addr in the USER area. We must
 227                    disallow any changes to certain SR bits or u_fpvalid, since
 228                    this could crash the kernel or result in a security
 229                    loophole. */
 230                 ret = -EIO;
 231                 if ((addr & 3) || addr < 0)
 232                         break;
 233
 234                 if (addr < sizeof(struct pt_regs)) {
 235                         /* Ignore change of top 32 bits of SR */
 236                         if (addr == offsetof (struct pt_regs, sr)+4)
 237                         {
 238                                 ret = 0;
 239                                 break;
 240                         }
 241                         /* If lower 32 bits of SR, ignore non-user bits */
 242                         if (addr == offsetof (struct pt_regs, sr))
 243                         {
 244                                 long cursr = get_stack_long(child, addr);
 245                                 data &= ~(SR_MASK);
 246                                 data |= (cursr & SR_MASK);
 247                         }
 248                         ret = put_stack_long(child, addr, data);
 249                 }
 250                 else if ((addr >= offsetof(struct user, fpu)) &&
 251                          (addr <  offsetof(struct user, u_fpvalid))) {
 252                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 253                 }
 254                 break;
 255
 256         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 257         case PTRACE_CONT: { /* restart after signal. */
 258                 ret = -EIO;
 259                 if (!valid_signal(data))
 260                         break;
 261                 if (request == PTRACE_SYSCALL)
 262                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 263                 else
 264                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 265                 child->exit_code = data;
 266                 wake_up_process(child);
 267                 ret = 0;
 268                 break;
 269         }
 270
 271 /*
 272  * make the child exit.  Best I can do is send it a sigkill.
 273  * perhaps it should be put in the status that it wants to
 274  * exit.
 275  */
 276         case PTRACE_KILL: {
 277                 ret = 0;
 278                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 279                         break;
 280                 child->exit_code = SIGKILL;
 281                 wake_up_process(child);
 282                 break;
 283         }
 284
 285         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 286                 struct pt_regs *regs;
 287
 288                 ret = -EIO;
 289                 if (!valid_signal(data))
 290                         break;
 291                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 292                 if ((child->ptrace & PT_DTRACE) == 0) {
 293                         /* Spurious delayed TF traps may occur */
 294                         child->ptrace |= PT_DTRACE;
 295                 }
 296
 297                 regs = child->thread.uregs;
 298
 299                 regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 300
 301                 child->exit_code = data;
 302                 /* give it a chance to run. */
 303                 wake_up_process(child);
 304                 ret = 0;
 305                 break;
 306         }
 307
 308         case PTRACE_DETACH: /* detach a process that was attached. */
 309                 ret = ptrace_detach(child, data);
 310                 break;
 311
 312         default:
 313                 ret = ptrace_request(child, request, addr, data);
 314                 break;
 315         }
 316 out_tsk:
 317         put_task_struct(child);
 318 out:
 319         unlock_kernel();
 320         return ret;
 321 }
 322
 323 asmlinkage void syscall_trace(void)
 324 {
 325         struct task_struct *tsk = current;
 326
 327         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 328                 return;
 329         if (!(tsk->ptrace & PT_PTRACED))
 330                 return;
 331
 332         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 333                                  ? 0x80 : 0));
 334         /*
 335          * this isn't the same as continuing with a signal, but it will do
 336          * for normal use.  strace only continues with a signal if the
 337          * stopping signal is not SIGTRAP.  -brl
 338          */
 339         if (tsk->exit_code) {
 340                 send_sig(tsk->exit_code, tsk, 1);
 341                 tsk->exit_code = 0;
 342         }
 343 }
 344
 345 /* Called with interrupts disabled */
 346 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 347 {
 348         /* This is called after a single step exception (DEBUGSS).
 349            There is no need to change the PC, as it is a post-execution
 350            exception, as entry.S does not do anything to the PC for DEBUGSS.
 351            We need to clear the Single Step setting in SR to avoid
 352            continually stepping. */
 353         local_irq_enable();
 354         regs->sr &= ~SR_SSTEP;
 355         force_sig(SIGTRAP, current);
 356 }
 357
 358 /* Called with interrupts disabled */
 359 asmlinkage void do_software_break_point(unsigned long long vec,
 360                                         struct pt_regs *regs)
 361 {
 362         /* We need to forward step the PC, to counteract the backstep done
 363            in signal.c. */
 364         local_irq_enable();
 365         force_sig(SIGTRAP, current);
 366         regs->pc += 4;
 367 }
 368
 369 /*
 370  * Called by kernel/ptrace.c when detaching..
 371  *
 372  * Make sure single step bits etc are not set.
 373  */
 374 void ptrace_disable(struct task_struct *child)
 375 {
 376         /* nothing to do.. */
 377 }