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 - 2007  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 <asm/io.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/pgtable.h>
  33 #include <asm/system.h>
  34 #include <asm/processor.h>
  35 #include <asm/mmu_context.h>
  36
  37 /* This mask defines the bits of the SR which the user is not allowed to
  38    change, which are everything except S, Q, M, PR, SZ, FR. */
  39 #define SR_MASK      (0xffff8cfd)
  40
  41 /*
  42  * does not yet catch signals sent when the child dies.
  43  * in exit.c or in signal.c.
  44  */
  45
  46 /*
  47  * This routine will get a word from the user area in the process kernel stack.
  48  */
  49 static inline int get_stack_long(struct task_struct *task, int offset)
  50 {
  51         unsigned char *stack;
  52
  53         stack = (unsigned char *)(task->thread.uregs);
  54         stack += offset;
  55         return (*((int *)stack));
  56 }
  57
  58 static inline unsigned long
  59 get_fpu_long(struct task_struct *task, unsigned long addr)
  60 {
  61         unsigned long tmp;
  62         struct pt_regs *regs;
  63         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
  64
  65         if (!tsk_used_math(task)) {
  66                 if (addr == offsetof(struct user_fpu_struct, fpscr)) {
  67                         tmp = FPSCR_INIT;
  68                 } else {
  69                         tmp = 0xffffffffUL; /* matches initial value in fpu.c */
  70                 }
  71                 return tmp;
  72         }
  73
  74         if (last_task_used_math == task) {
  75                 enable_fpu();
  76                 save_fpu(task, regs);
  77                 disable_fpu();
  78                 last_task_used_math = 0;
  79                 regs->sr |= SR_FD;
  80         }
  81
  82         tmp = ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)];
  83         return tmp;
  84 }
  85
  86 /*
  87  * This routine will put a word into the user area in the process kernel stack.
  88  */
  89 static inline int put_stack_long(struct task_struct *task, int offset,
  90                                  unsigned long data)
  91 {
  92         unsigned char *stack;
  93
  94         stack = (unsigned char *)(task->thread.uregs);
  95         stack += offset;
  96         *(unsigned long *) stack = data;
  97         return 0;
  98 }
  99
 100 static inline int
 101 put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
 102 {
 103         struct pt_regs *regs;
 104
 105         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
 106
 107         if (!tsk_used_math(task)) {
 108                 fpinit(&task->thread.fpu.hard);
 109                 set_stopped_child_used_math(task);
 110         } else if (last_task_used_math == task) {
 111                 enable_fpu();
 112                 save_fpu(task, regs);
 113                 disable_fpu();
 114                 last_task_used_math = 0;
 115                 regs->sr |= SR_FD;
 116         }
 117
 118         ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)] = data;
 119         return 0;
 120 }
 121
 122
 123 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 124 {
 125         int ret;
 126
 127         switch (request) {
 128         /* when I and D space are separate, these will need to be fixed. */
 129         case PTRACE_PEEKTEXT: /* read word at location addr. */
 130         case PTRACE_PEEKDATA:
 131                 ret = generic_ptrace_peekdata(child, addr, data);
 132                 break;
 133
 134         /* read the word at location addr in the USER area. */
 135         case PTRACE_PEEKUSR: {
 136                 unsigned long tmp;
 137
 138                 ret = -EIO;
 139                 if ((addr & 3) || addr < 0)
 140                         break;
 141
 142                 if (addr < sizeof(struct pt_regs))
 143                         tmp = get_stack_long(child, addr);
 144                 else if ((addr >= offsetof(struct user, fpu)) &&
 145                          (addr <  offsetof(struct user, u_fpvalid))) {
 146                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 147                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 148                         tmp = !!tsk_used_math(child);
 149                 } else {
 150                         break;
 151                 }
 152                 ret = put_user(tmp, (unsigned long *)data);
 153                 break;
 154         }
 155
 156         /* when I and D space are separate, this will have to be fixed. */
 157         case PTRACE_POKETEXT: /* write the word at location addr. */
 158         case PTRACE_POKEDATA:
 159                 ret = generic_ptrace_pokedata(child, addr, data);
 160                 break;
 161
 162         case PTRACE_POKEUSR:
 163                 /* write the word at location addr in the USER area. We must
 164                    disallow any changes to certain SR bits or u_fpvalid, since
 165                    this could crash the kernel or result in a security
 166                    loophole. */
 167                 ret = -EIO;
 168                 if ((addr & 3) || addr < 0)
 169                         break;
 170
 171                 if (addr < sizeof(struct pt_regs)) {
 172                         /* Ignore change of top 32 bits of SR */
 173                         if (addr == offsetof (struct pt_regs, sr)+4)
 174                         {
 175                                 ret = 0;
 176                                 break;
 177                         }
 178                         /* If lower 32 bits of SR, ignore non-user bits */
 179                         if (addr == offsetof (struct pt_regs, sr))
 180                         {
 181                                 long cursr = get_stack_long(child, addr);
 182                                 data &= ~(SR_MASK);
 183                                 data |= (cursr & SR_MASK);
 184                         }
 185                         ret = put_stack_long(child, addr, data);
 186                 }
 187                 else if ((addr >= offsetof(struct user, fpu)) &&
 188                          (addr <  offsetof(struct user, u_fpvalid))) {
 189                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 190                 }
 191                 break;
 192
 193         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 194         case PTRACE_CONT: { /* restart after signal. */
 195                 ret = -EIO;
 196                 if (!valid_signal(data))
 197                         break;
 198                 if (request == PTRACE_SYSCALL)
 199                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 200                 else
 201                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 202                 child->exit_code = data;
 203                 wake_up_process(child);
 204                 ret = 0;
 205                 break;
 206         }
 207
 208 /*
 209  * make the child exit.  Best I can do is send it a sigkill.
 210  * perhaps it should be put in the status that it wants to
 211  * exit.
 212  */
 213         case PTRACE_KILL: {
 214                 ret = 0;
 215                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 216                         break;
 217                 child->exit_code = SIGKILL;
 218                 wake_up_process(child);
 219                 break;
 220         }
 221
 222         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 223                 struct pt_regs *regs;
 224
 225                 ret = -EIO;
 226                 if (!valid_signal(data))
 227                         break;
 228                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 229                 if ((child->ptrace & PT_DTRACE) == 0) {
 230                         /* Spurious delayed TF traps may occur */
 231                         child->ptrace |= PT_DTRACE;
 232                 }
 233
 234                 regs = child->thread.uregs;
 235
 236                 regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 237
 238                 child->exit_code = data;
 239                 /* give it a chance to run. */
 240                 wake_up_process(child);
 241                 ret = 0;
 242                 break;
 243         }
 244
 245         default:
 246                 ret = ptrace_request(child, request, addr, data);
 247                 break;
 248         }
 249         return ret;
 250 }
 251
 252 asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
 253 {
 254 #define WPC_DBRMODE 0x0d104008
 255         static int first_call = 1;
 256
 257         lock_kernel();
 258         if (first_call) {
 259                 /* Set WPC.DBRMODE to 0.  This makes all debug events get
 260                  * delivered through RESVEC, i.e. into the handlers in entry.S.
 261                  * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
 262                  * would normally be left set to 1, which makes debug events get
 263                  * delivered through DBRVEC, i.e. into the remote gdb's
 264                  * handlers.  This prevents ptrace getting them, and confuses
 265                  * the remote gdb.) */
 266                 printk("DBRMODE set to 0 to permit native debugging\n");
 267                 poke_real_address_q(WPC_DBRMODE, 0);
 268                 first_call = 0;
 269         }
 270         unlock_kernel();
 271
 272         return sys_ptrace(request, pid, addr, data);
 273 }
 274
 275 asmlinkage void syscall_trace(struct pt_regs *regs, int entryexit)
 276 {
 277         struct task_struct *tsk = current;
 278
 279         if (unlikely(current->audit_context) && entryexit)
 280                 audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 281                                    regs->regs[9]);
 282
 283         if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
 284             !test_thread_flag(TIF_SINGLESTEP))
 285                 goto out;
 286         if (!(tsk->ptrace & PT_PTRACED))
 287                 goto out;
 288
 289         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
 290                                 !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
 291
 292         /*
 293          * this isn't the same as continuing with a signal, but it will do
 294          * for normal use.  strace only continues with a signal if the
 295          * stopping signal is not SIGTRAP.  -brl
 296          */
 297         if (tsk->exit_code) {
 298                 send_sig(tsk->exit_code, tsk, 1);
 299                 tsk->exit_code = 0;
 300         }
 301
 302 out:
 303         if (unlikely(current->audit_context) && !entryexit)
 304                 audit_syscall_entry(AUDIT_ARCH_SH, regs->regs[1],
 305                                     regs->regs[2], regs->regs[3],
 306                                     regs->regs[4], regs->regs[5]);
 307 }
 308
 309 /* Called with interrupts disabled */
 310 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 311 {
 312         /* This is called after a single step exception (DEBUGSS).
 313            There is no need to change the PC, as it is a post-execution
 314            exception, as entry.S does not do anything to the PC for DEBUGSS.
 315            We need to clear the Single Step setting in SR to avoid
 316            continually stepping. */
 317         local_irq_enable();
 318         regs->sr &= ~SR_SSTEP;
 319         force_sig(SIGTRAP, current);
 320 }
 321
 322 /* Called with interrupts disabled */
 323 asmlinkage void do_software_break_point(unsigned long long vec,
 324                                         struct pt_regs *regs)
 325 {
 326         /* We need to forward step the PC, to counteract the backstep done
 327            in signal.c. */
 328         local_irq_enable();
 329         force_sig(SIGTRAP, current);
 330         regs->pc += 4;
 331 }
 332
 333 /*
 334  * Called by kernel/ptrace.c when detaching..
 335  *
 336  * Make sure single step bits etc are not set.
 337  */
 338 void ptrace_disable(struct task_struct *child)
 339 {
 340         /* nothing to do.. */
 341 }