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/user.h>
  17 #include <linux/personality.h>
  18 #include <linux/security.h>
  19 #include <linux/compat.h>
  20 #include <linux/signal.h>
  21
  22 #include <asm/uaccess.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/system.h>
  25 #include <asm/processor.h>
  26 #include <asm/asm-offsets.h>
  27
  28 /* PSW bits we allow the debugger to modify */
  29 #define USER_PSW_BITS   (PSW_N | PSW_V | PSW_CB)
  30
  31 /*
  32  * Called by kernel/ptrace.c when detaching..
  33  *
  34  * Make sure single step bits etc are not set.
  35  */
  36 void ptrace_disable(struct task_struct *task)
  37 {
  38         task->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
  39
  40         /* make sure the trap bits are not set */
  41         pa_psw(task)->r = 0;
  42         pa_psw(task)->t = 0;
  43         pa_psw(task)->h = 0;
  44         pa_psw(task)->l = 0;
  45 }
  46
  47 /*
  48  * The following functions are called by ptrace_resume() when
  49  * enabling or disabling single/block tracing.
  50  */
  51 void user_disable_single_step(struct task_struct *task)
  52 {
  53         ptrace_disable(task);
  54 }
  55
  56 void user_enable_single_step(struct task_struct *task)
  57 {
  58         task->ptrace &= ~PT_BLOCKSTEP;
  59         task->ptrace |= PT_SINGLESTEP;
  60
  61         if (pa_psw(task)->n) {
  62                 struct siginfo si;
  63
  64                 /* Nullified, just crank over the queue. */
  65                 task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
  66                 task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
  67                 task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
  68                 pa_psw(task)->n = 0;
  69                 pa_psw(task)->x = 0;
  70                 pa_psw(task)->y = 0;
  71                 pa_psw(task)->z = 0;
  72                 pa_psw(task)->b = 0;
  73                 ptrace_disable(task);
  74                 /* Don't wake up the task, but let the
  75                    parent know something happened. */
  76                 si.si_code = TRAP_TRACE;
  77                 si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
  78                 si.si_signo = SIGTRAP;
  79                 si.si_errno = 0;
  80                 force_sig_info(SIGTRAP, &si, task);
  81                 /* notify_parent(task, SIGCHLD); */
  82                 return;
  83         }
  84
  85         /* Enable recovery counter traps.  The recovery counter
  86          * itself will be set to zero on a task switch.  If the
  87          * task is suspended on a syscall then the syscall return
  88          * path will overwrite the recovery counter with a suitable
  89          * value such that it traps once back in user space.  We
  90          * disable interrupts in the tasks PSW here also, to avoid
  91          * interrupts while the recovery counter is decrementing.
  92          */
  93         pa_psw(task)->r = 1;
  94         pa_psw(task)->t = 0;
  95         pa_psw(task)->h = 0;
  96         pa_psw(task)->l = 0;
  97 }
  98
  99 void user_enable_block_step(struct task_struct *task)
 100 {
 101         task->ptrace &= ~PT_SINGLESTEP;
 102         task->ptrace |= PT_BLOCKSTEP;
 103
 104         /* Enable taken branch trap. */
 105         pa_psw(task)->r = 0;
 106         pa_psw(task)->t = 1;
 107         pa_psw(task)->h = 0;
 108         pa_psw(task)->l = 0;
 109 }
 110
 111 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 112 {
 113         unsigned long tmp;
 114         long ret = -EIO;
 115
 116         switch (request) {
 117
 118         /* Read the word at location addr in the USER area.  For ptraced
 119            processes, the kernel saves all regs on a syscall. */
 120         case PTRACE_PEEKUSR:
 121                 if ((addr & (sizeof(long)-1)) ||
 122                     (unsigned long) addr >= sizeof(struct pt_regs))
 123                         break;
 124                 tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 125                 ret = put_user(tmp, (unsigned long *) data);
 126                 break;
 127
 128         /* Write the word at location addr in the USER area.  This will need
 129            to change when the kernel no longer saves all regs on a syscall.
 130            FIXME.  There is a problem at the moment in that r3-r18 are only
 131            saved if the process is ptraced on syscall entry, and even then
 132            those values are overwritten by actual register values on syscall
 133            exit. */
 134         case PTRACE_POKEUSR:
 135                 /* Some register values written here may be ignored in
 136                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 137                  * r31/r31+4, and not with the values in pt_regs.
 138                  */
 139                 if (addr == PT_PSW) {
 140                         /* Allow writing to Nullify, Divide-step-correction,
 141                          * and carry/borrow bits.
 142                          * BEWARE, if you set N, and then single step, it won't
 143                          * stop on the nullified instruction.
 144                          */
 145                         data &= USER_PSW_BITS;
 146                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 147                         task_regs(child)->gr[0] |= data;
 148                         ret = 0;
 149                         break;
 150                 }
 151
 152                 if ((addr & (sizeof(long)-1)) ||
 153                     (unsigned long) addr >= sizeof(struct pt_regs))
 154                         break;
 155                 if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 156                                 addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 157                                 (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 158                                 addr == PT_SAR) {
 159                         *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 160                         ret = 0;
 161                 }
 162                 break;
 163
 164         default:
 165                 ret = ptrace_request(child, request, addr, data);
 166                 break;
 167         }
 168
 169         return ret;
 170 }
 171
 172
 173 #ifdef CONFIG_COMPAT
 174
 175 /* This function is needed to translate 32 bit pt_regs offsets in to
 176  * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
 177  * will request offset 12 if it wants gr3, but the lower 32 bits of
 178  * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
 179  * This code relies on a 32 bit pt_regs being comprised of 32 bit values
 180  * except for the fp registers which (a) are 64 bits, and (b) follow
 181  * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
 182  * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
 183  * being 64 bit in both cases.
 184  */
 185
 186 static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
 187 {
 188         if (offset < 0)
 189                 return sizeof(struct pt_regs);
 190         else if (offset <= 32*4)        /* gr[0..31] */
 191                 return offset * 2 + 4;
 192         else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
 193                 return offset + 32*4;
 194         else if (offset < sizeof(struct pt_regs)/2 + 32*4)
 195                 return offset * 2 + 4 - 32*8;
 196         else
 197                 return sizeof(struct pt_regs);
 198 }
 199
 200 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 201                         compat_ulong_t addr, compat_ulong_t data)
 202 {
 203         compat_uint_t tmp;
 204         long ret = -EIO;
 205
 206         switch (request) {
 207
 208         case PTRACE_PEEKUSR:
 209                 if (addr & (sizeof(compat_uint_t)-1))
 210                         break;
 211                 addr = translate_usr_offset(addr);
 212                 if (addr >= sizeof(struct pt_regs))
 213                         break;
 214
 215                 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
 216                 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
 217                 break;
 218
 219         /* Write the word at location addr in the USER area.  This will need
 220            to change when the kernel no longer saves all regs on a syscall.
 221            FIXME.  There is a problem at the moment in that r3-r18 are only
 222            saved if the process is ptraced on syscall entry, and even then
 223            those values are overwritten by actual register values on syscall
 224            exit. */
 225         case PTRACE_POKEUSR:
 226                 /* Some register values written here may be ignored in
 227                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 228                  * r31/r31+4, and not with the values in pt_regs.
 229                  */
 230                 if (addr == PT_PSW) {
 231                         /* Since PT_PSW==0, it is valid for 32 bit processes
 232                          * under 64 bit kernels as well.
 233                          */
 234                         ret = arch_ptrace(child, request, addr, data);
 235                 } else {
 236                         if (addr & (sizeof(compat_uint_t)-1))
 237                                 break;
 238                         addr = translate_usr_offset(addr);
 239                         if (addr >= sizeof(struct pt_regs))
 240                                 break;
 241                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 242                                 /* Special case, fp regs are 64 bits anyway */
 243                                 *(__u64 *) ((char *) task_regs(child) + addr) = data;
 244                                 ret = 0;
 245                         }
 246                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 247                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 248                                         addr == PT_SAR+4) {
 249                                 /* Zero the top 32 bits */
 250                                 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
 251                                 *(__u32 *) ((char *) task_regs(child) + addr) = data;
 252                                 ret = 0;
 253                         }
 254                 }
 255                 break;
 256
 257         default:
 258                 ret = compat_ptrace_request(child, request, addr, data);
 259                 break;
 260         }
 261
 262         return ret;
 263 }
 264 #endif
 265
 266
 267 void syscall_trace(void)
 268 {
 269         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 270                 return;
 271         if (!(current->ptrace & PT_PTRACED))
 272                 return;
 273         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 274                                  ? 0x80 : 0));
 275         /*
 276          * this isn't the same as continuing with a signal, but it will do
 277          * for normal use.  strace only continues with a signal if the
 278          * stopping signal is not SIGTRAP.  -brl
 279          */
 280         if (current->exit_code) {
 281                 send_sig(current->exit_code, current, 1);
 282                 current->exit_code = 0;
 283         }
 284 }