arch/microblaze/kernel/ptrace.c

   1 /*
   2  * `ptrace' system call
   3  *
   4  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   5  * Copyright (C) 2007-2009 PetaLogix
   6  * Copyright (C) 2004-2007 John Williams <john.williams@petalogix.com>
   7  *
   8  * derived from arch/v850/kernel/ptrace.c
   9  *
  10  * Copyright (C) 2002,03 NEC Electronics Corporation
  11  * Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
  12  *
  13  * Derived from arch/mips/kernel/ptrace.c:
  14  *
  15  * Copyright (C) 1992 Ross Biro
  16  * Copyright (C) Linus Torvalds
  17  * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
  18  * Copyright (C) 1996 David S. Miller
  19  * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
  20  * Copyright (C) 1999 MIPS Technologies, Inc.
  21  *
  22  * This file is subject to the terms and conditions of the GNU General
  23  * Public License. See the file COPYING in the main directory of this
  24  * archive for more details.
  25  */
  26
  27 #include <linux/kernel.h>
  28 #include <linux/mm.h>
  29 #include <linux/sched.h>
  30 #include <linux/ptrace.h>
  31 #include <linux/signal.h>
  32
  33 #include <linux/errno.h>
  34 #include <asm/processor.h>
  35 #include <linux/uaccess.h>
  36 #include <asm/asm-offsets.h>
  37
  38 /* Returns the address where the register at REG_OFFS in P is stashed away. */
  39 static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
  40                                         struct task_struct *t)
  41 {
  42         struct pt_regs *regs;
  43
  44         /*
  45          * Three basic cases:
  46          *
  47          * (1)  A register normally saved before calling the scheduler, is
  48          *      available in the kernel entry pt_regs structure at the top
  49          *      of the kernel stack. The kernel trap/irq exit path takes
  50          *      care to save/restore almost all registers for ptrace'd
  51          *      processes.
  52          *
  53          * (2)  A call-clobbered register, where the process P entered the
  54          *      kernel via [syscall] trap, is not stored anywhere; that's
  55          *      OK, because such registers are not expected to be preserved
  56          *      when the trap returns anyway (so we don't actually bother to
  57          *      test for this case).
  58          *
  59          * (3)  A few registers not used at all by the kernel, and so
  60          *      normally never saved except by context-switches, are in the
  61          *      context switch state.
  62          */
  63
  64         /* Register saved during kernel entry (or not available). */
  65         regs = task_pt_regs(t);
  66
  67         return (microblaze_reg_t *)((char *)regs + reg_offs);
  68 }
  69
  70 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
  71 {
  72         int rval;
  73         unsigned long val = 0;
  74         unsigned long copied;
  75
  76         switch (request) {
  77         case PTRACE_PEEKTEXT: /* read word at location addr. */
  78         case PTRACE_PEEKDATA:
  79                 pr_debug("PEEKTEXT/PEEKDATA at %08lX\n", addr);
  80                 copied = access_process_vm(child, addr, &val, sizeof(val), 0);
  81                 rval = -EIO;
  82                 if (copied != sizeof(val))
  83                         break;
  84                 rval = put_user(val, (unsigned long *)data);
  85                 break;
  86
  87         case PTRACE_POKETEXT: /* write the word at location addr. */
  88         case PTRACE_POKEDATA:
  89                 pr_debug("POKETEXT/POKEDATA to %08lX\n", addr);
  90                 rval = 0;
  91                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
  92                     == sizeof(data))
  93                         break;
  94                 rval = -EIO;
  95                 break;
  96
  97         /* Read/write the word at location ADDR in the registers. */
  98         case PTRACE_PEEKUSR:
  99         case PTRACE_POKEUSR:
 100                 pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
 101                 rval = 0;
 102                 if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
 103                         /*
 104                          * Special requests that don't actually correspond
 105                          * to offsets in struct pt_regs.
 106                          */
 107                         if (addr == PT_TEXT_ADDR) {
 108                                 val = child->mm->start_code;
 109                         } else if (addr == PT_DATA_ADDR) {
 110                                 val = child->mm->start_data;
 111                         } else if (addr == PT_TEXT_LEN) {
 112                                 val = child->mm->end_code
 113                                         - child->mm->start_code;
 114                         } else {
 115                                 rval = -EIO;
 116                         }
 117                 } else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
 118                         microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
 119                         if (request == PTRACE_PEEKUSR)
 120                                 val = *reg_addr;
 121                         else
 122                                 *reg_addr = data;
 123                 } else
 124                         rval = -EIO;
 125
 126                 if (rval == 0 && request == PTRACE_PEEKUSR)
 127                         rval = put_user(val, (unsigned long *)data);
 128                 break;
 129         /* Continue and stop at next (return from) syscall */
 130         case PTRACE_SYSCALL:
 131                 pr_debug("PTRACE_SYSCALL\n");
 132         case PTRACE_SINGLESTEP:
 133                 pr_debug("PTRACE_SINGLESTEP\n");
 134         /* Restart after a signal.  */
 135         case PTRACE_CONT:
 136                 pr_debug("PTRACE_CONT\n");
 137                 rval = -EIO;
 138                 if (!valid_signal(data))
 139                         break;
 140
 141                 if (request == PTRACE_SYSCALL)
 142                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 143                 else
 144                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 145
 146                 child->exit_code = data;
 147                 pr_debug("wakeup_process\n");
 148                 wake_up_process(child);
 149                 rval = 0;
 150                 break;
 151
 152         /*
 153          * make the child exit.  Best I can do is send it a sigkill.
 154          * perhaps it should be put in the status that it wants to
 155          * exit.
 156          */
 157         case PTRACE_KILL:
 158                 pr_debug("PTRACE_KILL\n");
 159                 rval = 0;
 160                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 161                         break;
 162                 child->exit_code = SIGKILL;
 163                 wake_up_process(child);
 164                 break;
 165
 166         case PTRACE_DETACH: /* detach a process that was attached. */
 167                 pr_debug("PTRACE_DETACH\n");
 168                 rval = ptrace_detach(child, data);
 169                 break;
 170         default:
 171                 /* rval = ptrace_request(child, request, addr, data); noMMU */
 172                 rval = -EIO;
 173         }
 174         return rval;
 175 }
 176
 177 void ptrace_disable(struct task_struct *child)
 178 {
 179         /* nothing to do */
 180 }