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 #include <linux/elf.h>
  33 #include <linux/audit.h>
  34 #include <linux/seccomp.h>
  35 #include <linux/tracehook.h>
  36
  37 #include <linux/errno.h>
  38 #include <asm/processor.h>
  39 #include <linux/uaccess.h>
  40 #include <asm/asm-offsets.h>
  41
  42 /* Returns the address where the register at REG_OFFS in P is stashed away. */
  43 static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
  44                                         struct task_struct *t)
  45 {
  46         struct pt_regs *regs;
  47
  48         /*
  49          * Three basic cases:
  50          *
  51          * (1)  A register normally saved before calling the scheduler, is
  52          *      available in the kernel entry pt_regs structure at the top
  53          *      of the kernel stack. The kernel trap/irq exit path takes
  54          *      care to save/restore almost all registers for ptrace'd
  55          *      processes.
  56          *
  57          * (2)  A call-clobbered register, where the process P entered the
  58          *      kernel via [syscall] trap, is not stored anywhere; that's
  59          *      OK, because such registers are not expected to be preserved
  60          *      when the trap returns anyway (so we don't actually bother to
  61          *      test for this case).
  62          *
  63          * (3)  A few registers not used at all by the kernel, and so
  64          *      normally never saved except by context-switches, are in the
  65          *      context switch state.
  66          */
  67
  68         /* Register saved during kernel entry (or not available). */
  69         regs = task_pt_regs(t);
  70
  71         return (microblaze_reg_t *)((char *)regs + reg_offs);
  72 }
  73
  74 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
  75 {
  76         int rval;
  77         unsigned long val = 0;
  78         unsigned long copied;
  79
  80         switch (request) {
  81         case PTRACE_PEEKTEXT: /* read word at location addr. */
  82         case PTRACE_PEEKDATA:
  83                 pr_debug("PEEKTEXT/PEEKDATA at %08lX\n", addr);
  84                 copied = access_process_vm(child, addr, &val, sizeof(val), 0);
  85                 rval = -EIO;
  86                 if (copied != sizeof(val))
  87                         break;
  88                 rval = put_user(val, (unsigned long *)data);
  89                 break;
  90
  91         case PTRACE_POKETEXT: /* write the word at location addr. */
  92         case PTRACE_POKEDATA:
  93                 pr_debug("POKETEXT/POKEDATA to %08lX\n", addr);
  94                 rval = 0;
  95                 if (access_process_vm(child, addr, &data, sizeof(data), 1)
  96                     == sizeof(data))
  97                         break;
  98                 rval = -EIO;
  99                 break;
 100
 101         /* Read/write the word at location ADDR in the registers. */
 102         case PTRACE_PEEKUSR:
 103         case PTRACE_POKEUSR:
 104                 pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
 105                 rval = 0;
 106                 if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
 107                         /*
 108                          * Special requests that don't actually correspond
 109                          * to offsets in struct pt_regs.
 110                          */
 111                         if (addr == PT_TEXT_ADDR) {
 112                                 val = child->mm->start_code;
 113                         } else if (addr == PT_DATA_ADDR) {
 114                                 val = child->mm->start_data;
 115                         } else if (addr == PT_TEXT_LEN) {
 116                                 val = child->mm->end_code
 117                                         - child->mm->start_code;
 118                         } else {
 119                                 rval = -EIO;
 120                         }
 121                 } else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
 122                         microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
 123                         if (request == PTRACE_PEEKUSR)
 124                                 val = *reg_addr;
 125                         else
 126                                 *reg_addr = data;
 127                 } else
 128                         rval = -EIO;
 129
 130                 if (rval == 0 && request == PTRACE_PEEKUSR)
 131                         rval = put_user(val, (unsigned long *)data);
 132                 break;
 133         /* Continue and stop at next (return from) syscall */
 134         case PTRACE_SYSCALL:
 135                 pr_debug("PTRACE_SYSCALL\n");
 136         case PTRACE_SINGLESTEP:
 137                 pr_debug("PTRACE_SINGLESTEP\n");
 138         /* Restart after a signal.  */
 139         case PTRACE_CONT:
 140                 pr_debug("PTRACE_CONT\n");
 141                 rval = -EIO;
 142                 if (!valid_signal(data))
 143                         break;
 144
 145                 if (request == PTRACE_SYSCALL)
 146                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 147                 else
 148                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 149
 150                 child->exit_code = data;
 151                 pr_debug("wakeup_process\n");
 152                 wake_up_process(child);
 153                 rval = 0;
 154                 break;
 155
 156         /*
 157          * make the child exit.  Best I can do is send it a sigkill.
 158          * perhaps it should be put in the status that it wants to
 159          * exit.
 160          */
 161         case PTRACE_KILL:
 162                 pr_debug("PTRACE_KILL\n");
 163                 rval = 0;
 164                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 165                         break;
 166                 child->exit_code = SIGKILL;
 167                 wake_up_process(child);
 168                 break;
 169
 170         case PTRACE_DETACH: /* detach a process that was attached. */
 171                 pr_debug("PTRACE_DETACH\n");
 172                 rval = ptrace_detach(child, data);
 173                 break;
 174         default:
 175                 /* rval = ptrace_request(child, request, addr, data); noMMU */
 176                 rval = -EIO;
 177         }
 178         return rval;
 179 }
 180
 181 asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 182 {
 183         long ret = 0;
 184
 185         secure_computing(regs->r12);
 186
 187         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 188             tracehook_report_syscall_entry(regs))
 189                 /*
 190                  * Tracing decided this syscall should not happen.
 191                  * We'll return a bogus call number to get an ENOSYS
 192                  * error, but leave the original number in regs->regs[0].
 193                  */
 194                 ret = -1L;
 195
 196         if (unlikely(current->audit_context))
 197                 audit_syscall_entry(EM_XILINX_MICROBLAZE, regs->r12,
 198                                     regs->r5, regs->r6,
 199                                     regs->r7, regs->r8);
 200
 201         return ret ?: regs->r12;
 202 }
 203
 204 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 205 {
 206         int step;
 207
 208         if (unlikely(current->audit_context))
 209                 audit_syscall_exit(AUDITSC_RESULT(regs->r3), regs->r3);
 210
 211         step = test_thread_flag(TIF_SINGLESTEP);
 212         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
 213                 tracehook_report_syscall_exit(regs, step);
 214 }
 215
 216 #if 0
 217 static asmlinkage void syscall_trace(void)
 218 {
 219         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 220                 return;
 221         if (!(current->ptrace & PT_PTRACED))
 222                 return;
 223         /* The 0x80 provides a way for the tracing parent to distinguish
 224          between a syscall stop and SIGTRAP delivery */
 225         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 226                                 ? 0x80 : 0));
 227         /*
 228          * this isn't the same as continuing with a signal, but it will do
 229          * for normal use. strace only continues with a signal if the
 230          * stopping signal is not SIGTRAP. -brl
 231          */
 232         if (current->exit_code) {
 233                 send_sig(current->exit_code, current, 1);
 234                 current->exit_code = 0;
 235         }
 236 }
 237 #endif
 238
 239 void ptrace_disable(struct task_struct *child)
 240 {
 241         /* nothing to do */
 242 }