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