arch/sh/kernel/ptrace.c

   1 /*
   2  * linux/arch/sh/kernel/ptrace.c
   3  *
   4  * Original x86 implementation:
   5  *      By Ross Biro 1/23/92
   6  *      edited by Linus Torvalds
   7  *
   8  * SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
   9  *
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/smp.h>
  15 #include <linux/errno.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/user.h>
  18 #include <linux/slab.h>
  19 #include <linux/security.h>
  20 #include <linux/signal.h>
  21 #include <linux/io.h>
  22 #include <asm/uaccess.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/system.h>
  25 #include <asm/processor.h>
  26 #include <asm/mmu_context.h>
  27
  28 /*
  29  * does not yet catch signals sent when the child dies.
  30  * in exit.c or in signal.c.
  31  */
  32
  33 /*
  34  * This routine will get a word off of the process kernel stack.
  35  */
  36 static inline int get_stack_long(struct task_struct *task, int offset)
  37 {
  38         unsigned char *stack;
  39
  40         stack = (unsigned char *)task_pt_regs(task);
  41         stack += offset;
  42         return (*((int *)stack));
  43 }
  44
  45 /*
  46  * This routine will put a word on the process kernel stack.
  47  */
  48 static inline int put_stack_long(struct task_struct *task, int offset,
  49                                  unsigned long data)
  50 {
  51         unsigned char *stack;
  52
  53         stack = (unsigned char *)task_pt_regs(task);
  54         stack += offset;
  55         *(unsigned long *) stack = data;
  56         return 0;
  57 }
  58
  59 static void ptrace_disable_singlestep(struct task_struct *child)
  60 {
  61         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
  62
  63         /*
  64          * Ensure the UBC is not programmed at the next context switch.
  65          *
  66          * Normally this is not needed but there are sequences such as
  67          * singlestep, signal delivery, and continue that leave the
  68          * ubc_pc non-zero leading to spurious SIGTRAPs.
  69          */
  70         if (child->thread.ubc_pc != 0) {
  71                 ubc_usercnt -= 1;
  72                 child->thread.ubc_pc = 0;
  73         }
  74 }
  75
  76 /*
  77  * Called by kernel/ptrace.c when detaching..
  78  *
  79  * Make sure single step bits etc are not set.
  80  */
  81 void ptrace_disable(struct task_struct *child)
  82 {
  83         ptrace_disable_singlestep(child);
  84 }
  85
  86 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
  87 {
  88         struct user * dummy = NULL;
  89         int ret;
  90
  91         switch (request) {
  92         /* when I and D space are separate, these will need to be fixed. */
  93         case PTRACE_PEEKTEXT: /* read word at location addr. */
  94         case PTRACE_PEEKDATA:
  95                 ret = generic_ptrace_peekdata(child, addr, data);
  96                 break;
  97
  98         /* read the word at location addr in the USER area. */
  99         case PTRACE_PEEKUSR: {
 100                 unsigned long tmp;
 101
 102                 ret = -EIO;
 103                 if ((addr & 3) || addr < 0 ||
 104                     addr > sizeof(struct user) - 3)
 105                         break;
 106
 107                 if (addr < sizeof(struct pt_regs))
 108                         tmp = get_stack_long(child, addr);
 109                 else if (addr >= (long) &dummy->fpu &&
 110                          addr < (long) &dummy->u_fpvalid) {
 111                         if (!tsk_used_math(child)) {
 112                                 if (addr == (long)&dummy->fpu.fpscr)
 113                                         tmp = FPSCR_INIT;
 114                                 else
 115                                         tmp = 0;
 116                         } else
 117                                 tmp = ((long *)&child->thread.fpu)
 118                                         [(addr - (long)&dummy->fpu) >> 2];
 119                 } else if (addr == (long) &dummy->u_fpvalid)
 120                         tmp = !!tsk_used_math(child);
 121                 else
 122                         tmp = 0;
 123                 ret = put_user(tmp, (unsigned long __user *)data);
 124                 break;
 125         }
 126
 127         /* when I and D space are separate, this will have to be fixed. */
 128         case PTRACE_POKETEXT: /* write the word at location addr. */
 129         case PTRACE_POKEDATA:
 130                 ret = generic_ptrace_pokedata(child, addr, data);
 131                 break;
 132
 133         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 134                 ret = -EIO;
 135                 if ((addr & 3) || addr < 0 ||
 136                     addr > sizeof(struct user) - 3)
 137                         break;
 138
 139                 if (addr < sizeof(struct pt_regs))
 140                         ret = put_stack_long(child, addr, data);
 141                 else if (addr >= (long) &dummy->fpu &&
 142                          addr < (long) &dummy->u_fpvalid) {
 143                         set_stopped_child_used_math(child);
 144                         ((long *)&child->thread.fpu)
 145                                 [(addr - (long)&dummy->fpu) >> 2] = data;
 146                         ret = 0;
 147                 } else if (addr == (long) &dummy->u_fpvalid) {
 148                         conditional_stopped_child_used_math(data, child);
 149                         ret = 0;
 150                 }
 151                 break;
 152
 153         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 154         case PTRACE_CONT: { /* restart after signal. */
 155                 ret = -EIO;
 156                 if (!valid_signal(data))
 157                         break;
 158                 if (request == PTRACE_SYSCALL)
 159                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 160                 else
 161                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 162
 163                 ptrace_disable_singlestep(child);
 164
 165                 child->exit_code = data;
 166                 wake_up_process(child);
 167                 ret = 0;
 168                 break;
 169         }
 170
 171 /*
 172  * make the child exit.  Best I can do is send it a sigkill.
 173  * perhaps it should be put in the status that it wants to
 174  * exit.
 175  */
 176         case PTRACE_KILL: {
 177                 ret = 0;
 178                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 179                         break;
 180                 ptrace_disable_singlestep(child);
 181                 child->exit_code = SIGKILL;
 182                 wake_up_process(child);
 183                 break;
 184         }
 185
 186         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 187                 long pc;
 188                 struct pt_regs *regs = NULL;
 189
 190                 ret = -EIO;
 191                 if (!valid_signal(data))
 192                         break;
 193                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 194                 if ((child->ptrace & PT_DTRACE) == 0) {
 195                         /* Spurious delayed TF traps may occur */
 196                         child->ptrace |= PT_DTRACE;
 197                 }
 198
 199                 pc = get_stack_long(child, (long)&regs->pc);
 200
 201                 /* Next scheduling will set up UBC */
 202                 if (child->thread.ubc_pc == 0)
 203                         ubc_usercnt += 1;
 204                 child->thread.ubc_pc = pc;
 205
 206                 set_tsk_thread_flag(child, TIF_SINGLESTEP);
 207                 child->exit_code = data;
 208                 /* give it a chance to run. */
 209                 wake_up_process(child);
 210                 ret = 0;
 211                 break;
 212         }
 213
 214 #ifdef CONFIG_SH_DSP
 215         case PTRACE_GETDSPREGS: {
 216                 unsigned long dp;
 217
 218                 ret = -EIO;
 219                 dp = ((unsigned long) child) + THREAD_SIZE -
 220                          sizeof(struct pt_dspregs);
 221                 if (*((int *) (dp - 4)) == SR_FD) {
 222                         copy_to_user(addr, (void *) dp,
 223                                 sizeof(struct pt_dspregs));
 224                         ret = 0;
 225                 }
 226                 break;
 227         }
 228
 229         case PTRACE_SETDSPREGS: {
 230                 unsigned long dp;
 231
 232                 ret = -EIO;
 233                 dp = ((unsigned long) child) + THREAD_SIZE -
 234                          sizeof(struct pt_dspregs);
 235                 if (*((int *) (dp - 4)) == SR_FD) {
 236                         copy_from_user((void *) dp, addr,
 237                                 sizeof(struct pt_dspregs));
 238                         ret = 0;
 239                 }
 240                 break;
 241         }
 242 #endif
 243         default:
 244                 ret = ptrace_request(child, request, addr, data);
 245                 break;
 246         }
 247
 248         return ret;
 249 }
 250
 251 asmlinkage void do_syscall_trace(void)
 252 {
 253         struct task_struct *tsk = current;
 254
 255         if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
 256             !test_thread_flag(TIF_SINGLESTEP))
 257                 return;
 258         if (!(tsk->ptrace & PT_PTRACED))
 259                 return;
 260         /* the 0x80 provides a way for the tracing parent to distinguish
 261            between a syscall stop and SIGTRAP delivery */
 262         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
 263                                  !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
 264
 265         /*
 266          * this isn't the same as continuing with a signal, but it will do
 267          * for normal use.  strace only continues with a signal if the
 268          * stopping signal is not SIGTRAP.  -brl
 269          */
 270         if (tsk->exit_code) {
 271                 send_sig(tsk->exit_code, tsk, 1);
 272                 tsk->exit_code = 0;
 273         }
 274 }