linux/arch/parisc/kernel/ptrace.c
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   1/*
   2 * Kernel support for the ptrace() and syscall tracing interfaces.
   3 *
   4 * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
   5 * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
   6 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
   7 * Copyright (C) 2008 Helge Deller <deller@gmx.de>
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/sched.h>
  12#include <linux/mm.h>
  13#include <linux/smp.h>
  14#include <linux/errno.h>
  15#include <linux/ptrace.h>
  16#include <linux/tracehook.h>
  17#include <linux/user.h>
  18#include <linux/personality.h>
  19#include <linux/security.h>
  20#include <linux/compat.h>
  21#include <linux/signal.h>
  22
  23#include <asm/uaccess.h>
  24#include <asm/pgtable.h>
  25#include <asm/system.h>
  26#include <asm/processor.h>
  27#include <asm/asm-offsets.h>
  28
  29/* PSW bits we allow the debugger to modify */
  30#define USER_PSW_BITS   (PSW_N | PSW_V | PSW_CB)
  31
  32/*
  33 * Called by kernel/ptrace.c when detaching..
  34 *
  35 * Make sure single step bits etc are not set.
  36 */
  37void ptrace_disable(struct task_struct *task)
  38{
  39        clear_tsk_thread_flag(task, TIF_SINGLESTEP);
  40        clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
  41
  42        /* make sure the trap bits are not set */
  43        pa_psw(task)->r = 0;
  44        pa_psw(task)->t = 0;
  45        pa_psw(task)->h = 0;
  46        pa_psw(task)->l = 0;
  47}
  48
  49/*
  50 * The following functions are called by ptrace_resume() when
  51 * enabling or disabling single/block tracing.
  52 */
  53void user_disable_single_step(struct task_struct *task)
  54{
  55        ptrace_disable(task);
  56}
  57
  58void user_enable_single_step(struct task_struct *task)
  59{
  60        clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
  61        set_tsk_thread_flag(task, TIF_SINGLESTEP);
  62
  63        if (pa_psw(task)->n) {
  64                struct siginfo si;
  65
  66                /* Nullified, just crank over the queue. */
  67                task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
  68                task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
  69                task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
  70                pa_psw(task)->n = 0;
  71                pa_psw(task)->x = 0;
  72                pa_psw(task)->y = 0;
  73                pa_psw(task)->z = 0;
  74                pa_psw(task)->b = 0;
  75                ptrace_disable(task);
  76                /* Don't wake up the task, but let the
  77                   parent know something happened. */
  78                si.si_code = TRAP_TRACE;
  79                si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
  80                si.si_signo = SIGTRAP;
  81                si.si_errno = 0;
  82                force_sig_info(SIGTRAP, &si, task);
  83                /* notify_parent(task, SIGCHLD); */
  84                return;
  85        }
  86
  87        /* Enable recovery counter traps.  The recovery counter
  88         * itself will be set to zero on a task switch.  If the
  89         * task is suspended on a syscall then the syscall return
  90         * path will overwrite the recovery counter with a suitable
  91         * value such that it traps once back in user space.  We
  92         * disable interrupts in the tasks PSW here also, to avoid
  93         * interrupts while the recovery counter is decrementing.
  94         */
  95        pa_psw(task)->r = 1;
  96        pa_psw(task)->t = 0;
  97        pa_psw(task)->h = 0;
  98        pa_psw(task)->l = 0;
  99}
 100
 101void user_enable_block_step(struct task_struct *task)
 102{
 103        clear_tsk_thread_flag(task, TIF_SINGLESTEP);
 104        set_tsk_thread_flag(task, TIF_BLOCKSTEP);
 105
 106        /* Enable taken branch trap. */
 107        pa_psw(task)->r = 0;
 108        pa_psw(task)->t = 1;
 109        pa_psw(task)->h = 0;
 110        pa_psw(task)->l = 0;
 111}
 112
 113long arch_ptrace(struct task_struct *child, long request,
 114                 unsigned long addr, unsigned long data)
 115{
 116        unsigned long tmp;
 117        long ret = -EIO;
 118
 119        switch (request) {
 120
 121        /* Read the word at location addr in the USER area.  For ptraced
 122           processes, the kernel saves all regs on a syscall. */
 123        case PTRACE_PEEKUSR:
 124                if ((addr & (sizeof(unsigned long)-1)) ||
 125                     addr >= sizeof(struct pt_regs))
 126                        break;
 127                tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 128                ret = put_user(tmp, (unsigned long __user *) data);
 129                break;
 130
 131        /* Write the word at location addr in the USER area.  This will need
 132           to change when the kernel no longer saves all regs on a syscall.
 133           FIXME.  There is a problem at the moment in that r3-r18 are only
 134           saved if the process is ptraced on syscall entry, and even then
 135           those values are overwritten by actual register values on syscall
 136           exit. */
 137        case PTRACE_POKEUSR:
 138                /* Some register values written here may be ignored in
 139                 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 140                 * r31/r31+4, and not with the values in pt_regs.
 141                 */
 142                if (addr == PT_PSW) {
 143                        /* Allow writing to Nullify, Divide-step-correction,
 144                         * and carry/borrow bits.
 145                         * BEWARE, if you set N, and then single step, it won't
 146                         * stop on the nullified instruction.
 147                         */
 148                        data &= USER_PSW_BITS;
 149                        task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 150                        task_regs(child)->gr[0] |= data;
 151                        ret = 0;
 152                        break;
 153                }
 154
 155                if ((addr & (sizeof(unsigned long)-1)) ||
 156                     addr >= sizeof(struct pt_regs))
 157                        break;
 158                if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 159                                addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 160                                (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 161                                addr == PT_SAR) {
 162                        *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 163                        ret = 0;
 164                }
 165                break;
 166
 167        default:
 168                ret = ptrace_request(child, request, addr, data);
 169                break;
 170        }
 171
 172        return ret;
 173}
 174
 175
 176#ifdef CONFIG_COMPAT
 177
 178/* This function is needed to translate 32 bit pt_regs offsets in to
 179 * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
 180 * will request offset 12 if it wants gr3, but the lower 32 bits of
 181 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
 182 * This code relies on a 32 bit pt_regs being comprised of 32 bit values
 183 * except for the fp registers which (a) are 64 bits, and (b) follow
 184 * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
 185 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
 186 * being 64 bit in both cases.
 187 */
 188
 189static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
 190{
 191        if (offset < 0)
 192                return sizeof(struct pt_regs);
 193        else if (offset <= 32*4)        /* gr[0..31] */
 194                return offset * 2 + 4;
 195        else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
 196                return offset + 32*4;
 197        else if (offset < sizeof(struct pt_regs)/2 + 32*4)
 198                return offset * 2 + 4 - 32*8;
 199        else
 200                return sizeof(struct pt_regs);
 201}
 202
 203long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 204                        compat_ulong_t addr, compat_ulong_t data)
 205{
 206        compat_uint_t tmp;
 207        long ret = -EIO;
 208
 209        switch (request) {
 210
 211        case PTRACE_PEEKUSR:
 212                if (addr & (sizeof(compat_uint_t)-1))
 213                        break;
 214                addr = translate_usr_offset(addr);
 215                if (addr >= sizeof(struct pt_regs))
 216                        break;
 217
 218                tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
 219                ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
 220                break;
 221
 222        /* Write the word at location addr in the USER area.  This will need
 223           to change when the kernel no longer saves all regs on a syscall.
 224           FIXME.  There is a problem at the moment in that r3-r18 are only
 225           saved if the process is ptraced on syscall entry, and even then
 226           those values are overwritten by actual register values on syscall
 227           exit. */
 228        case PTRACE_POKEUSR:
 229                /* Some register values written here may be ignored in
 230                 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 231                 * r31/r31+4, and not with the values in pt_regs.
 232                 */
 233                if (addr == PT_PSW) {
 234                        /* Since PT_PSW==0, it is valid for 32 bit processes
 235                         * under 64 bit kernels as well.
 236                         */
 237                        ret = arch_ptrace(child, request, addr, data);
 238                } else {
 239                        if (addr & (sizeof(compat_uint_t)-1))
 240                                break;
 241                        addr = translate_usr_offset(addr);
 242                        if (addr >= sizeof(struct pt_regs))
 243                                break;
 244                        if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 245                                /* Special case, fp regs are 64 bits anyway */
 246                                *(__u64 *) ((char *) task_regs(child) + addr) = data;
 247                                ret = 0;
 248                        }
 249                        else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 250                                        addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 251                                        addr == PT_SAR+4) {
 252                                /* Zero the top 32 bits */
 253                                *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
 254                                *(__u32 *) ((char *) task_regs(child) + addr) = data;
 255                                ret = 0;
 256                        }
 257                }
 258                break;
 259
 260        default:
 261                ret = compat_ptrace_request(child, request, addr, data);
 262                break;
 263        }
 264
 265        return ret;
 266}
 267#endif
 268
 269long do_syscall_trace_enter(struct pt_regs *regs)
 270{
 271        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 272            tracehook_report_syscall_entry(regs))
 273                return -1L;
 274
 275        return regs->gr[20];
 276}
 277
 278void do_syscall_trace_exit(struct pt_regs *regs)
 279{
 280        int stepping = test_thread_flag(TIF_SINGLESTEP) ||
 281                test_thread_flag(TIF_BLOCKSTEP);
 282
 283        if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
 284                tracehook_report_syscall_exit(regs, stepping);
 285}
 286