arch/parisc/kernel/ptrace.c

   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/seccomp.h>
  21 #include <linux/compat.h>
  22 #include <linux/signal.h>
  23 #include <linux/audit.h>
  24
  25 #include <asm/uaccess.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/processor.h>
  28 #include <asm/asm-offsets.h>
  29
  30 /* PSW bits we allow the debugger to modify */
  31 #define USER_PSW_BITS   (PSW_N | PSW_B | PSW_V | PSW_CB)
  32
  33 /*
  34  * Called by kernel/ptrace.c when detaching..
  35  *
  36  * Make sure single step bits etc are not set.
  37  */
  38 void ptrace_disable(struct task_struct *task)
  39 {
  40         clear_tsk_thread_flag(task, TIF_SINGLESTEP);
  41         clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
  42
  43         /* make sure the trap bits are not set */
  44         pa_psw(task)->r = 0;
  45         pa_psw(task)->t = 0;
  46         pa_psw(task)->h = 0;
  47         pa_psw(task)->l = 0;
  48 }
  49
  50 /*
  51  * The following functions are called by ptrace_resume() when
  52  * enabling or disabling single/block tracing.
  53  */
  54 void user_disable_single_step(struct task_struct *task)
  55 {
  56         ptrace_disable(task);
  57 }
  58
  59 void user_enable_single_step(struct task_struct *task)
  60 {
  61         clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
  62         set_tsk_thread_flag(task, TIF_SINGLESTEP);
  63
  64         if (pa_psw(task)->n) {
  65                 struct siginfo si;
  66
  67                 /* Nullified, just crank over the queue. */
  68                 task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
  69                 task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
  70                 task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
  71                 pa_psw(task)->n = 0;
  72                 pa_psw(task)->x = 0;
  73                 pa_psw(task)->y = 0;
  74                 pa_psw(task)->z = 0;
  75                 pa_psw(task)->b = 0;
  76                 ptrace_disable(task);
  77                 /* Don't wake up the task, but let the
  78                    parent know something happened. */
  79                 si.si_code = TRAP_TRACE;
  80                 si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
  81                 si.si_signo = SIGTRAP;
  82                 si.si_errno = 0;
  83                 force_sig_info(SIGTRAP, &si, task);
  84                 /* notify_parent(task, SIGCHLD); */
  85                 return;
  86         }
  87
  88         /* Enable recovery counter traps.  The recovery counter
  89          * itself will be set to zero on a task switch.  If the
  90          * task is suspended on a syscall then the syscall return
  91          * path will overwrite the recovery counter with a suitable
  92          * value such that it traps once back in user space.  We
  93          * disable interrupts in the tasks PSW here also, to avoid
  94          * interrupts while the recovery counter is decrementing.
  95          */
  96         pa_psw(task)->r = 1;
  97         pa_psw(task)->t = 0;
  98         pa_psw(task)->h = 0;
  99         pa_psw(task)->l = 0;
 100 }
 101
 102 void user_enable_block_step(struct task_struct *task)
 103 {
 104         clear_tsk_thread_flag(task, TIF_SINGLESTEP);
 105         set_tsk_thread_flag(task, TIF_BLOCKSTEP);
 106
 107         /* Enable taken branch trap. */
 108         pa_psw(task)->r = 0;
 109         pa_psw(task)->t = 1;
 110         pa_psw(task)->h = 0;
 111         pa_psw(task)->l = 0;
 112 }
 113
 114 long arch_ptrace(struct task_struct *child, long request,
 115                  unsigned long addr, unsigned long data)
 116 {
 117         unsigned long tmp;
 118         long ret = -EIO;
 119
 120         switch (request) {
 121
 122         /* Read the word at location addr in the USER area.  For ptraced
 123            processes, the kernel saves all regs on a syscall. */
 124         case PTRACE_PEEKUSR:
 125                 if ((addr & (sizeof(unsigned long)-1)) ||
 126                      addr >= sizeof(struct pt_regs))
 127                         break;
 128                 tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 129                 ret = put_user(tmp, (unsigned long __user *) data);
 130                 break;
 131
 132         /* Write the word at location addr in the USER area.  This will need
 133            to change when the kernel no longer saves all regs on a syscall.
 134            FIXME.  There is a problem at the moment in that r3-r18 are only
 135            saved if the process is ptraced on syscall entry, and even then
 136            those values are overwritten by actual register values on syscall
 137            exit. */
 138         case PTRACE_POKEUSR:
 139                 /* Some register values written here may be ignored in
 140                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 141                  * r31/r31+4, and not with the values in pt_regs.
 142                  */
 143                 if (addr == PT_PSW) {
 144                         /* Allow writing to Nullify, Divide-step-correction,
 145                          * and carry/borrow bits.
 146                          * BEWARE, if you set N, and then single step, it won't
 147                          * stop on the nullified instruction.
 148                          */
 149                         data &= USER_PSW_BITS;
 150                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 151                         task_regs(child)->gr[0] |= data;
 152                         ret = 0;
 153                         break;
 154                 }
 155
 156                 if ((addr & (sizeof(unsigned long)-1)) ||
 157                      addr >= sizeof(struct pt_regs))
 158                         break;
 159                 if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 160                                 addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 161                                 (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 162                                 addr == PT_SAR) {
 163                         *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 164                         ret = 0;
 165                 }
 166                 break;
 167
 168         default:
 169                 ret = ptrace_request(child, request, addr, data);
 170                 break;
 171         }
 172
 173         return ret;
 174 }
 175
 176
 177 #ifdef CONFIG_COMPAT
 178
 179 /* This function is needed to translate 32 bit pt_regs offsets in to
 180  * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
 181  * will request offset 12 if it wants gr3, but the lower 32 bits of
 182  * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
 183  * This code relies on a 32 bit pt_regs being comprised of 32 bit values
 184  * except for the fp registers which (a) are 64 bits, and (b) follow
 185  * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
 186  * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
 187  * being 64 bit in both cases.
 188  */
 189
 190 static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
 191 {
 192         if (offset < 0)
 193                 return sizeof(struct pt_regs);
 194         else if (offset <= 32*4)        /* gr[0..31] */
 195                 return offset * 2 + 4;
 196         else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
 197                 return offset + 32*4;
 198         else if (offset < sizeof(struct pt_regs)/2 + 32*4)
 199                 return offset * 2 + 4 - 32*8;
 200         else
 201                 return sizeof(struct pt_regs);
 202 }
 203
 204 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 205                         compat_ulong_t addr, compat_ulong_t data)
 206 {
 207         compat_uint_t tmp;
 208         long ret = -EIO;
 209
 210         switch (request) {
 211
 212         case PTRACE_PEEKUSR:
 213                 if (addr & (sizeof(compat_uint_t)-1))
 214                         break;
 215                 addr = translate_usr_offset(addr);
 216                 if (addr >= sizeof(struct pt_regs))
 217                         break;
 218
 219                 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
 220                 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
 221                 break;
 222
 223         /* Write the word at location addr in the USER area.  This will need
 224            to change when the kernel no longer saves all regs on a syscall.
 225            FIXME.  There is a problem at the moment in that r3-r18 are only
 226            saved if the process is ptraced on syscall entry, and even then
 227            those values are overwritten by actual register values on syscall
 228            exit. */
 229         case PTRACE_POKEUSR:
 230                 /* Some register values written here may be ignored in
 231                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 232                  * r31/r31+4, and not with the values in pt_regs.
 233                  */
 234                 if (addr == PT_PSW) {
 235                         /* Since PT_PSW==0, it is valid for 32 bit processes
 236                          * under 64 bit kernels as well.
 237                          */
 238                         ret = arch_ptrace(child, request, addr, data);
 239                 } else {
 240                         if (addr & (sizeof(compat_uint_t)-1))
 241                                 break;
 242                         addr = translate_usr_offset(addr);
 243                         if (addr >= sizeof(struct pt_regs))
 244                                 break;
 245                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 246                                 /* Special case, fp regs are 64 bits anyway */
 247                                 *(__u64 *) ((char *) task_regs(child) + addr) = data;
 248                                 ret = 0;
 249                         }
 250                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 251                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 252                                         addr == PT_SAR+4) {
 253                                 /* Zero the top 32 bits */
 254                                 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
 255                                 *(__u32 *) ((char *) task_regs(child) + addr) = data;
 256                                 ret = 0;
 257                         }
 258                 }
 259                 break;
 260
 261         default:
 262                 ret = compat_ptrace_request(child, request, addr, data);
 263                 break;
 264         }
 265
 266         return ret;
 267 }
 268 #endif
 269
 270 long do_syscall_trace_enter(struct pt_regs *regs)
 271 {
 272         /* Do the secure computing check first. */
 273         secure_computing_strict(regs->gr[20]);
 274
 275         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 276             tracehook_report_syscall_entry(regs)) {
 277                 /*
 278                  * Tracing decided this syscall should not happen or the
 279                  * debugger stored an invalid system call number. Skip
 280                  * the system call and the system call restart handling.
 281                  */
 282                 regs->gr[20] = -1UL;
 283                 goto out;
 284         }
 285
 286 #ifdef CONFIG_64BIT
 287         if (!is_compat_task())
 288                 audit_syscall_entry(regs->gr[20], regs->gr[26], regs->gr[25],
 289                                     regs->gr[24], regs->gr[23]);
 290         else
 291 #endif
 292                 audit_syscall_entry(regs->gr[20] & 0xffffffff,
 293                         regs->gr[26] & 0xffffffff,
 294                         regs->gr[25] & 0xffffffff,
 295                         regs->gr[24] & 0xffffffff,
 296                         regs->gr[23] & 0xffffffff);
 297
 298 out:
 299         return regs->gr[20];
 300 }
 301
 302 void do_syscall_trace_exit(struct pt_regs *regs)
 303 {
 304         int stepping = test_thread_flag(TIF_SINGLESTEP) ||
 305                 test_thread_flag(TIF_BLOCKSTEP);
 306
 307         audit_syscall_exit(regs);
 308
 309         if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
 310                 tracehook_report_syscall_exit(regs, stepping);
 311 }