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