arch/v850/kernel/ptrace.c

   1 /*
   2  * arch/v850/kernel/ptrace.c -- `ptrace' system call
   3  *
   4  *  Copyright (C) 2002,03,04  NEC Electronics Corporation
   5  *  Copyright (C) 2002,03,04  Miles Bader <miles@gnu.org>
   6  *
   7  * Derived from arch/mips/kernel/ptrace.c:
   8  *
   9  *  Copyright (C) 1992 Ross Biro
  10  *  Copyright (C) Linus Torvalds
  11  *  Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
  12  *  Copyright (C) 1996 David S. Miller
  13  *  Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
  14  *  Copyright (C) 1999 MIPS Technologies, Inc.
  15  *
  16  * This file is subject to the terms and conditions of the GNU General
  17  * Public License.  See the file COPYING in the main directory of this
  18  * archive for more details.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/mm.h>
  23 #include <linux/sched.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/signal.h>
  27
  28 #include <asm/errno.h>
  29 #include <asm/ptrace.h>
  30 #include <asm/processor.h>
  31 #include <asm/uaccess.h>
  32
  33 /* Returns the address where the register at REG_OFFS in P is stashed away.  */
  34 static v850_reg_t *reg_save_addr (unsigned reg_offs, struct task_struct *t)
  35 {
  36         struct pt_regs *regs;
  37
  38         /* Three basic cases:
  39
  40            (1) A register normally saved before calling the scheduler, is
  41                available in the kernel entry pt_regs structure at the top
  42                of the kernel stack.  The kernel trap/irq exit path takes
  43                care to save/restore almost all registers for ptrace'd
  44                processes.
  45
  46            (2) A call-clobbered register, where the process P entered the
  47                kernel via [syscall] trap, is not stored anywhere; that's
  48                OK, because such registers are not expected to be preserved
  49                when the trap returns anyway (so we don't actually bother to
  50                test for this case).
  51
  52            (3) A few registers not used at all by the kernel, and so
  53                normally never saved except by context-switches, are in the
  54                context switch state.  */
  55
  56         if (reg_offs == PT_CTPC || reg_offs == PT_CTPSW || reg_offs == PT_CTBP)
  57                 /* Register saved during context switch.  */
  58                 regs = thread_saved_regs (t);
  59         else
  60                 /* Register saved during kernel entry (or not available).  */
  61                 regs = task_pt_regs (t);
  62
  63         return (v850_reg_t *)((char *)regs + reg_offs);
  64 }
  65
  66 /* Set the bits SET and clear the bits CLEAR in the v850e DIR
  67    (`debug information register').  Returns the new value of DIR.  */
  68 static inline v850_reg_t set_dir (v850_reg_t set, v850_reg_t clear)
  69 {
  70         register v850_reg_t rval asm ("r10");
  71         register v850_reg_t arg0 asm ("r6") = set;
  72         register v850_reg_t arg1 asm ("r7") = clear;
  73
  74         /* The dbtrap handler has exactly this functionality when called
  75            from kernel mode.  0xf840 is a `dbtrap' insn.  */
  76         asm (".short 0xf840" : "=r" (rval) : "r" (arg0), "r" (arg1));
  77
  78         return rval;
  79 }
  80
  81 /* Makes sure hardware single-stepping is (globally) enabled.
  82    Returns true if successful.  */
  83 static inline int enable_single_stepping (void)
  84 {
  85         static int enabled = 0; /* Remember whether we already did it.  */
  86         if (! enabled) {
  87                 /* Turn on the SE (`single-step enable') bit, 0x100, in the
  88                    DIR (`debug information register').  This may fail if a
  89                    processor doesn't support it or something.  We also try
  90                    to clear bit 0x40 (`INI'), which is necessary to use the
  91                    debug stuff on the v850e2; on the v850e, clearing 0x40
  92                    shouldn't cause any problem.  */
  93                 v850_reg_t dir = set_dir (0x100, 0x40);
  94                 /* Make sure it really got set.  */
  95                 if (dir & 0x100)
  96                         enabled = 1;
  97         }
  98         return enabled;
  99 }
 100
 101 /* Try to set CHILD's single-step flag to VAL.  Returns true if successful.  */
 102 static int set_single_step (struct task_struct *t, int val)
 103 {
 104         v850_reg_t *psw_addr = reg_save_addr(PT_PSW, t);
 105         if (val) {
 106                 /* Make sure single-stepping is enabled.  */
 107                 if (! enable_single_stepping ())
 108                         return 0;
 109                 /* Set T's single-step flag.  */
 110                 *psw_addr |= 0x800;
 111         } else
 112                 *psw_addr &= ~0x800;
 113         return 1;
 114 }
 115
 116 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 117 {
 118         int rval;
 119
 120         switch (request) {
 121                 unsigned long val, copied;
 122
 123         case PTRACE_PEEKTEXT: /* read word at location addr. */
 124         case PTRACE_PEEKDATA:
 125                 copied = access_process_vm(child, addr, &val, sizeof(val), 0);
 126                 rval = -EIO;
 127                 if (copied != sizeof(val))
 128                         break;
 129                 rval = put_user(val, (unsigned long *)data);
 130                 goto out;
 131
 132         case PTRACE_POKETEXT: /* write the word at location addr. */
 133         case PTRACE_POKEDATA:
 134                 rval = 0;
 135                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
 136                     == sizeof(data))
 137                         break;
 138                 rval = -EIO;
 139                 goto out;
 140
 141         /* Read/write the word at location ADDR in the registers.  */
 142         case PTRACE_PEEKUSR:
 143         case PTRACE_POKEUSR:
 144                 rval = 0;
 145                 if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
 146                         /* Special requests that don't actually correspond
 147                            to offsets in struct pt_regs.  */
 148                         if (addr == PT_TEXT_ADDR)
 149                                 val = child->mm->start_code;
 150                         else if (addr == PT_DATA_ADDR)
 151                                 val = child->mm->start_data;
 152                         else if (addr == PT_TEXT_LEN)
 153                                 val = child->mm->end_code
 154                                         - child->mm->start_code;
 155                         else
 156                                 rval = -EIO;
 157                 } else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
 158                         v850_reg_t *reg_addr = reg_save_addr(addr, child);
 159                         if (request == PTRACE_PEEKUSR)
 160                                 val = *reg_addr;
 161                         else
 162                                 *reg_addr = data;
 163                 } else
 164                         rval = -EIO;
 165
 166                 if (rval == 0 && request == PTRACE_PEEKUSR)
 167                         rval = put_user (val, (unsigned long *)data);
 168                 goto out;
 169
 170         /* Continue and stop at next (return from) syscall */
 171         case PTRACE_SYSCALL:
 172         /* Restart after a signal.  */
 173         case PTRACE_CONT:
 174         /* Execute a single instruction. */
 175         case PTRACE_SINGLESTEP:
 176                 rval = -EIO;
 177                 if (!valid_signal(data))
 178                         break;
 179
 180                 /* Turn CHILD's single-step flag on or off.  */
 181                 if (! set_single_step (child, request == PTRACE_SINGLESTEP))
 182                         break;
 183
 184                 if (request == PTRACE_SYSCALL)
 185                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 186                 else
 187                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 188
 189                 child->exit_code = data;
 190                 wake_up_process(child);
 191                 rval = 0;
 192                 break;
 193
 194         /*
 195          * make the child exit.  Best I can do is send it a sigkill.
 196          * perhaps it should be put in the status that it wants to
 197          * exit.
 198          */
 199         case PTRACE_KILL:
 200                 rval = 0;
 201                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 202                         break;
 203                 child->exit_code = SIGKILL;
 204                 wake_up_process(child);
 205                 break;
 206
 207         case PTRACE_DETACH: /* detach a process that was attached. */
 208                 set_single_step (child, 0);  /* Clear single-step flag */
 209                 rval = ptrace_detach(child, data);
 210                 break;
 211
 212         default:
 213                 rval = -EIO;
 214                 goto out;
 215         }
 216  out:
 217         return rval;
 218 }
 219
 220 asmlinkage void syscall_trace(void)
 221 {
 222         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 223                 return;
 224         if (!(current->ptrace & PT_PTRACED))
 225                 return;
 226         /* The 0x80 provides a way for the tracing parent to distinguish
 227            between a syscall stop and SIGTRAP delivery */
 228         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 229                                  ? 0x80 : 0));
 230         /*
 231          * this isn't the same as continuing with a signal, but it will do
 232          * for normal use.  strace only continues with a signal if the
 233          * stopping signal is not SIGTRAP.  -brl
 234          */
 235         if (current->exit_code) {
 236                 send_sig(current->exit_code, current, 1);
 237                 current->exit_code = 0;
 238         }
 239 }
 240
 241 void ptrace_disable (struct task_struct *child)
 242 {
 243         /* nothing to do */
 244 }