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 #include <asm/cacheflush.h>
  42 #include <asm/syscall.h>
  43 #include <asm/io.h>
  44
  45 /* Returns the address where the register at REG_OFFS in P is stashed away. */
  46 static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
  47                                         struct task_struct *t)
  48 {
  49         struct pt_regs *regs;
  50
  51         /*
  52          * Three basic cases:
  53          *
  54          * (1)  A register normally saved before calling the scheduler, is
  55          *      available in the kernel entry pt_regs structure at the top
  56          *      of the kernel stack. The kernel trap/irq exit path takes
  57          *      care to save/restore almost all registers for ptrace'd
  58          *      processes.
  59          *
  60          * (2)  A call-clobbered register, where the process P entered the
  61          *      kernel via [syscall] trap, is not stored anywhere; that's
  62          *      OK, because such registers are not expected to be preserved
  63          *      when the trap returns anyway (so we don't actually bother to
  64          *      test for this case).
  65          *
  66          * (3)  A few registers not used at all by the kernel, and so
  67          *      normally never saved except by context-switches, are in the
  68          *      context switch state.
  69          */
  70
  71         /* Register saved during kernel entry (or not available). */
  72         regs = task_pt_regs(t);
  73
  74         return (microblaze_reg_t *)((char *)regs + reg_offs);
  75 }
  76
  77 long arch_ptrace(struct task_struct *child, long request,
  78                  unsigned long addr, unsigned long data)
  79 {
  80         int rval;
  81         unsigned long val = 0;
  82
  83         switch (request) {
  84         /* Read/write the word at location ADDR in the registers. */
  85         case PTRACE_PEEKUSR:
  86         case PTRACE_POKEUSR:
  87                 pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
  88                 rval = 0;
  89                 if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
  90                         /*
  91                          * Special requests that don't actually correspond
  92                          * to offsets in struct pt_regs.
  93                          */
  94                         if (addr == PT_TEXT_ADDR) {
  95                                 val = child->mm->start_code;
  96                         } else if (addr == PT_DATA_ADDR) {
  97                                 val = child->mm->start_data;
  98                         } else if (addr == PT_TEXT_LEN) {
  99                                 val = child->mm->end_code
 100                                         - child->mm->start_code;
 101                         } else {
 102                                 rval = -EIO;
 103                         }
 104                 } else if (addr < PT_SIZE && (addr & 0x3) == 0) {
 105                         microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
 106                         if (request == PTRACE_PEEKUSR)
 107                                 val = *reg_addr;
 108                         else {
 109 #if 1
 110                                 *reg_addr = data;
 111 #else
 112                                 /* MS potential problem on WB system
 113                                  * Be aware that reg_addr is virtual address
 114                                  * virt_to_phys conversion is necessary.
 115                                  * This could be sensible solution.
 116                                  */
 117                                 u32 paddr = virt_to_phys((u32)reg_addr);
 118                                 invalidate_icache_range(paddr, paddr + 4);
 119                                 *reg_addr = data;
 120                                 flush_dcache_range(paddr, paddr + 4);
 121 #endif
 122                         }
 123                 } else
 124                         rval = -EIO;
 125
 126                 if (rval == 0 && request == PTRACE_PEEKUSR)
 127                         rval = put_user(val, (unsigned long __user *)data);
 128                 break;
 129         default:
 130                 rval = ptrace_request(child, request, addr, data);
 131         }
 132         return rval;
 133 }
 134
 135 asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 136 {
 137         long ret = 0;
 138
 139         secure_computing(regs->r12);
 140
 141         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 142             tracehook_report_syscall_entry(regs))
 143                 /*
 144                  * Tracing decided this syscall should not happen.
 145                  * We'll return a bogus call number to get an ENOSYS
 146                  * error, but leave the original number in regs->regs[0].
 147                  */
 148                 ret = -1L;
 149
 150         if (unlikely(current->audit_context))
 151                 audit_syscall_entry(EM_MICROBLAZE, regs->r12,
 152                                     regs->r5, regs->r6,
 153                                     regs->r7, regs->r8);
 154
 155         return ret ?: regs->r12;
 156 }
 157
 158 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 159 {
 160         int step;
 161
 162         if (unlikely(current->audit_context))
 163                 audit_syscall_exit(AUDITSC_RESULT(regs->r3), regs->r3);
 164
 165         step = test_thread_flag(TIF_SINGLESTEP);
 166         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
 167                 tracehook_report_syscall_exit(regs, step);
 168 }
 169
 170 #if 0
 171 static asmlinkage void syscall_trace(void)
 172 {
 173         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 174                 return;
 175         if (!(current->ptrace & PT_PTRACED))
 176                 return;
 177         /* The 0x80 provides a way for the tracing parent to distinguish
 178          between a syscall stop and SIGTRAP delivery */
 179         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 180                                 ? 0x80 : 0));
 181         /*
 182          * this isn't the same as continuing with a signal, but it will do
 183          * for normal use. strace only continues with a signal if the
 184          * stopping signal is not SIGTRAP. -brl
 185          */
 186         if (current->exit_code) {
 187                 send_sig(current->exit_code, current, 1);
 188                 current->exit_code = 0;
 189         }
 190 }
 191 #endif
 192
 193 void ptrace_disable(struct task_struct *child)
 194 {
 195         /* nothing to do */
 196 }