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 #include <asm/fpu.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                 enable_fpu();
  77                 save_fpu(task, regs);
  78                 disable_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                 enable_fpu();
 113                 save_fpu(task, regs);
 114                 disable_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
 124 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 125 {
 126         int ret;
 127
 128         switch (request) {
 129         /* when I and D space are separate, these will need to be fixed. */
 130         case PTRACE_PEEKTEXT: /* read word at location addr. */
 131         case PTRACE_PEEKDATA:
 132                 ret = generic_ptrace_peekdata(child, addr, data);
 133                 break;
 134
 135         /* read the word at location addr in the USER area. */
 136         case PTRACE_PEEKUSR: {
 137                 unsigned long tmp;
 138
 139                 ret = -EIO;
 140                 if ((addr & 3) || addr < 0)
 141                         break;
 142
 143                 if (addr < sizeof(struct pt_regs))
 144                         tmp = get_stack_long(child, addr);
 145                 else if ((addr >= offsetof(struct user, fpu)) &&
 146                          (addr <  offsetof(struct user, u_fpvalid))) {
 147                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 148                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 149                         tmp = !!tsk_used_math(child);
 150                 } else {
 151                         break;
 152                 }
 153                 ret = put_user(tmp, (unsigned long *)data);
 154                 break;
 155         }
 156
 157         /* when I and D space are separate, this will have to be fixed. */
 158         case PTRACE_POKETEXT: /* write the word at location addr. */
 159         case PTRACE_POKEDATA:
 160                 ret = generic_ptrace_pokedata(child, addr, data);
 161                 break;
 162
 163         case PTRACE_POKEUSR:
 164                 /* write the word at location addr in the USER area. We must
 165                    disallow any changes to certain SR bits or u_fpvalid, since
 166                    this could crash the kernel or result in a security
 167                    loophole. */
 168                 ret = -EIO;
 169                 if ((addr & 3) || addr < 0)
 170                         break;
 171
 172                 if (addr < sizeof(struct pt_regs)) {
 173                         /* Ignore change of top 32 bits of SR */
 174                         if (addr == offsetof (struct pt_regs, sr)+4)
 175                         {
 176                                 ret = 0;
 177                                 break;
 178                         }
 179                         /* If lower 32 bits of SR, ignore non-user bits */
 180                         if (addr == offsetof (struct pt_regs, sr))
 181                         {
 182                                 long cursr = get_stack_long(child, addr);
 183                                 data &= ~(SR_MASK);
 184                                 data |= (cursr & SR_MASK);
 185                         }
 186                         ret = put_stack_long(child, addr, data);
 187                 }
 188                 else if ((addr >= offsetof(struct user, fpu)) &&
 189                          (addr <  offsetof(struct user, u_fpvalid))) {
 190                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 191                 }
 192                 break;
 193
 194         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 195         case PTRACE_CONT: { /* restart after signal. */
 196                 ret = -EIO;
 197                 if (!valid_signal(data))
 198                         break;
 199                 if (request == PTRACE_SYSCALL)
 200                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 201                 else
 202                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 203                 child->exit_code = data;
 204                 wake_up_process(child);
 205                 ret = 0;
 206                 break;
 207         }
 208
 209 /*
 210  * make the child exit.  Best I can do is send it a sigkill.
 211  * perhaps it should be put in the status that it wants to
 212  * exit.
 213  */
 214         case PTRACE_KILL: {
 215                 ret = 0;
 216                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 217                         break;
 218                 child->exit_code = SIGKILL;
 219                 wake_up_process(child);
 220                 break;
 221         }
 222
 223         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 224                 struct pt_regs *regs;
 225
 226                 ret = -EIO;
 227                 if (!valid_signal(data))
 228                         break;
 229                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 230                 if ((child->ptrace & PT_DTRACE) == 0) {
 231                         /* Spurious delayed TF traps may occur */
 232                         child->ptrace |= PT_DTRACE;
 233                 }
 234
 235                 regs = child->thread.uregs;
 236
 237                 regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 238
 239                 child->exit_code = data;
 240                 /* give it a chance to run. */
 241                 wake_up_process(child);
 242                 ret = 0;
 243                 break;
 244         }
 245
 246         default:
 247                 ret = ptrace_request(child, request, addr, data);
 248                 break;
 249         }
 250         return ret;
 251 }
 252
 253 asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
 254 {
 255 #define WPC_DBRMODE 0x0d104008
 256         static int first_call = 1;
 257
 258         lock_kernel();
 259         if (first_call) {
 260                 /* Set WPC.DBRMODE to 0.  This makes all debug events get
 261                  * delivered through RESVEC, i.e. into the handlers in entry.S.
 262                  * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
 263                  * would normally be left set to 1, which makes debug events get
 264                  * delivered through DBRVEC, i.e. into the remote gdb's
 265                  * handlers.  This prevents ptrace getting them, and confuses
 266                  * the remote gdb.) */
 267                 printk("DBRMODE set to 0 to permit native debugging\n");
 268                 poke_real_address_q(WPC_DBRMODE, 0);
 269                 first_call = 0;
 270         }
 271         unlock_kernel();
 272
 273         return sys_ptrace(request, pid, addr, data);
 274 }
 275
 276 asmlinkage void syscall_trace(struct pt_regs *regs, int entryexit)
 277 {
 278         struct task_struct *tsk = current;
 279
 280         if (unlikely(current->audit_context) && entryexit)
 281                 audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 282                                    regs->regs[9]);
 283
 284         if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
 285             !test_thread_flag(TIF_SINGLESTEP))
 286                 goto out;
 287         if (!(tsk->ptrace & PT_PTRACED))
 288                 goto out;
 289
 290         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
 291                                 !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
 292
 293         /*
 294          * this isn't the same as continuing with a signal, but it will do
 295          * for normal use.  strace only continues with a signal if the
 296          * stopping signal is not SIGTRAP.  -brl
 297          */
 298         if (tsk->exit_code) {
 299                 send_sig(tsk->exit_code, tsk, 1);
 300                 tsk->exit_code = 0;
 301         }
 302
 303 out:
 304         if (unlikely(current->audit_context) && !entryexit)
 305                 audit_syscall_entry(AUDIT_ARCH_SH, regs->regs[1],
 306                                     regs->regs[2], regs->regs[3],
 307                                     regs->regs[4], regs->regs[5]);
 308 }
 309
 310 /* Called with interrupts disabled */
 311 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 312 {
 313         /* This is called after a single step exception (DEBUGSS).
 314            There is no need to change the PC, as it is a post-execution
 315            exception, as entry.S does not do anything to the PC for DEBUGSS.
 316            We need to clear the Single Step setting in SR to avoid
 317            continually stepping. */
 318         local_irq_enable();
 319         regs->sr &= ~SR_SSTEP;
 320         force_sig(SIGTRAP, current);
 321 }
 322
 323 /* Called with interrupts disabled */
 324 asmlinkage void do_software_break_point(unsigned long long vec,
 325                                         struct pt_regs *regs)
 326 {
 327         /* We need to forward step the PC, to counteract the backstep done
 328            in signal.c. */
 329         local_irq_enable();
 330         force_sig(SIGTRAP, current);
 331         regs->pc += 4;
 332 }
 333
 334 /*
 335  * Called by kernel/ptrace.c when detaching..
 336  *
 337  * Make sure single step bits etc are not set.
 338  */
 339 void ptrace_disable(struct task_struct *child)
 340 {
 341         /* nothing to do.. */
 342 }