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/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  */
  37 void 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  */
  53 void user_disable_single_step(struct task_struct *task)
  54 {
  55         ptrace_disable(task);
  56 }
  57
  58 void 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
 101 void 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
 113 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 114 {
 115         unsigned long tmp;
 116         long ret = -EIO;
 117
 118         switch (request) {
 119
 120         /* Read the word at location addr in the USER area.  For ptraced
 121            processes, the kernel saves all regs on a syscall. */
 122         case PTRACE_PEEKUSR:
 123                 if ((addr & (sizeof(long)-1)) ||
 124                     (unsigned long) addr >= sizeof(struct pt_regs))
 125                         break;
 126                 tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 127                 ret = put_user(tmp, (unsigned long *) data);
 128                 break;
 129
 130         /* Write the word at location addr in the USER area.  This will need
 131            to change when the kernel no longer saves all regs on a syscall.
 132            FIXME.  There is a problem at the moment in that r3-r18 are only
 133            saved if the process is ptraced on syscall entry, and even then
 134            those values are overwritten by actual register values on syscall
 135            exit. */
 136         case PTRACE_POKEUSR:
 137                 /* Some register values written here may be ignored in
 138                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 139                  * r31/r31+4, and not with the values in pt_regs.
 140                  */
 141                 if (addr == PT_PSW) {
 142                         /* Allow writing to Nullify, Divide-step-correction,
 143                          * and carry/borrow bits.
 144                          * BEWARE, if you set N, and then single step, it won't
 145                          * stop on the nullified instruction.
 146                          */
 147                         data &= USER_PSW_BITS;
 148                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 149                         task_regs(child)->gr[0] |= data;
 150                         ret = 0;
 151                         break;
 152                 }
 153
 154                 if ((addr & (sizeof(long)-1)) ||
 155                     (unsigned long) addr >= sizeof(struct pt_regs))
 156                         break;
 157                 if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 158                                 addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 159                                 (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 160                                 addr == PT_SAR) {
 161                         *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 162                         ret = 0;
 163                 }
 164                 break;
 165
 166         default:
 167                 ret = ptrace_request(child, request, addr, data);
 168                 break;
 169         }
 170
 171         return ret;
 172 }
 173
 174
 175 #ifdef CONFIG_COMPAT
 176
 177 /* This function is needed to translate 32 bit pt_regs offsets in to
 178  * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
 179  * will request offset 12 if it wants gr3, but the lower 32 bits of
 180  * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
 181  * This code relies on a 32 bit pt_regs being comprised of 32 bit values
 182  * except for the fp registers which (a) are 64 bits, and (b) follow
 183  * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
 184  * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
 185  * being 64 bit in both cases.
 186  */
 187
 188 static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
 189 {
 190         if (offset < 0)
 191                 return sizeof(struct pt_regs);
 192         else if (offset <= 32*4)        /* gr[0..31] */
 193                 return offset * 2 + 4;
 194         else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
 195                 return offset + 32*4;
 196         else if (offset < sizeof(struct pt_regs)/2 + 32*4)
 197                 return offset * 2 + 4 - 32*8;
 198         else
 199                 return sizeof(struct pt_regs);
 200 }
 201
 202 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 203                         compat_ulong_t addr, compat_ulong_t data)
 204 {
 205         compat_uint_t tmp;
 206         long ret = -EIO;
 207
 208         switch (request) {
 209
 210         case PTRACE_PEEKUSR:
 211                 if (addr & (sizeof(compat_uint_t)-1))
 212                         break;
 213                 addr = translate_usr_offset(addr);
 214                 if (addr >= sizeof(struct pt_regs))
 215                         break;
 216
 217                 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
 218                 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
 219                 break;
 220
 221         /* Write the word at location addr in the USER area.  This will need
 222            to change when the kernel no longer saves all regs on a syscall.
 223            FIXME.  There is a problem at the moment in that r3-r18 are only
 224            saved if the process is ptraced on syscall entry, and even then
 225            those values are overwritten by actual register values on syscall
 226            exit. */
 227         case PTRACE_POKEUSR:
 228                 /* Some register values written here may be ignored in
 229                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 230                  * r31/r31+4, and not with the values in pt_regs.
 231                  */
 232                 if (addr == PT_PSW) {
 233                         /* Since PT_PSW==0, it is valid for 32 bit processes
 234                          * under 64 bit kernels as well.
 235                          */
 236                         ret = arch_ptrace(child, request, addr, data);
 237                 } else {
 238                         if (addr & (sizeof(compat_uint_t)-1))
 239                                 break;
 240                         addr = translate_usr_offset(addr);
 241                         if (addr >= sizeof(struct pt_regs))
 242                                 break;
 243                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 244                                 /* Special case, fp regs are 64 bits anyway */
 245                                 *(__u64 *) ((char *) task_regs(child) + addr) = data;
 246                                 ret = 0;
 247                         }
 248                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 249                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 250                                         addr == PT_SAR+4) {
 251                                 /* Zero the top 32 bits */
 252                                 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
 253                                 *(__u32 *) ((char *) task_regs(child) + addr) = data;
 254                                 ret = 0;
 255                         }
 256                 }
 257                 break;
 258
 259         default:
 260                 ret = compat_ptrace_request(child, request, addr, data);
 261                 break;
 262         }
 263
 264         return ret;
 265 }
 266 #endif
 267
 268 long do_syscall_trace_enter(struct pt_regs *regs)
 269 {
 270         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 271             tracehook_report_syscall_entry(regs))
 272                 return -1L;
 273
 274         return regs->gr[20];
 275 }
 276
 277 void do_syscall_trace_exit(struct pt_regs *regs)
 278 {
 279         int stepping = test_thread_flag(TIF_SINGLESTEP) ||
 280                 test_thread_flag(TIF_BLOCKSTEP);
 281
 282         if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
 283                 tracehook_report_syscall_exit(regs, stepping);
 284 }