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
  79         switch (request) {
  80         /* Read/write the word at location ADDR in the registers. */
  81         case PTRACE_PEEKUSR:
  82         case PTRACE_POKEUSR:
  83                 pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
  84                 rval = 0;
  85                 if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
  86                         /*
  87                          * Special requests that don't actually correspond
  88                          * to offsets in struct pt_regs.
  89                          */
  90                         if (addr == PT_TEXT_ADDR) {
  91                                 val = child->mm->start_code;
  92                         } else if (addr == PT_DATA_ADDR) {
  93                                 val = child->mm->start_data;
  94                         } else if (addr == PT_TEXT_LEN) {
  95                                 val = child->mm->end_code
  96                                         - child->mm->start_code;
  97                         } else {
  98                                 rval = -EIO;
  99                         }
 100                 } else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
 101                         microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
 102                         if (request == PTRACE_PEEKUSR)
 103                                 val = *reg_addr;
 104                         else
 105                                 *reg_addr = data;
 106                 } else
 107                         rval = -EIO;
 108
 109                 if (rval == 0 && request == PTRACE_PEEKUSR)
 110                         rval = put_user(val, (unsigned long *)data);
 111                 break;
 112         default:
 113                 rval = ptrace_request(child, request, addr, data);
 114         }
 115         return rval;
 116 }
 117
 118 asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 119 {
 120         long ret = 0;
 121
 122         secure_computing(regs->r12);
 123
 124         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 125             tracehook_report_syscall_entry(regs))
 126                 /*
 127                  * Tracing decided this syscall should not happen.
 128                  * We'll return a bogus call number to get an ENOSYS
 129                  * error, but leave the original number in regs->regs[0].
 130                  */
 131                 ret = -1L;
 132
 133         if (unlikely(current->audit_context))
 134                 audit_syscall_entry(EM_XILINX_MICROBLAZE, regs->r12,
 135                                     regs->r5, regs->r6,
 136                                     regs->r7, regs->r8);
 137
 138         return ret ?: regs->r12;
 139 }
 140
 141 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 142 {
 143         int step;
 144
 145         if (unlikely(current->audit_context))
 146                 audit_syscall_exit(AUDITSC_RESULT(regs->r3), regs->r3);
 147
 148         step = test_thread_flag(TIF_SINGLESTEP);
 149         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
 150                 tracehook_report_syscall_exit(regs, step);
 151 }
 152
 153 #if 0
 154 static asmlinkage void syscall_trace(void)
 155 {
 156         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 157                 return;
 158         if (!(current->ptrace & PT_PTRACED))
 159                 return;
 160         /* The 0x80 provides a way for the tracing parent to distinguish
 161          between a syscall stop and SIGTRAP delivery */
 162         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 163                                 ? 0x80 : 0));
 164         /*
 165          * this isn't the same as continuing with a signal, but it will do
 166          * for normal use. strace only continues with a signal if the
 167          * stopping signal is not SIGTRAP. -brl
 168          */
 169         if (current->exit_code) {
 170                 send_sig(current->exit_code, current, 1);
 171                 current->exit_code = 0;
 172         }
 173 }
 174 #endif
 175
 176 void ptrace_disable(struct task_struct *child)
 177 {
 178         /* nothing to do */
 179 }