arch/blackfin/kernel/ptrace.c

   1 /*
   2  * File:         arch/blackfin/kernel/ptrace.c
   3  * Based on:     Taken from linux/kernel/ptrace.c
   4  * Author:       linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
   5  *
   6  * Created:      1/23/92
   7  * Description:
   8  *
   9  * Modified:
  10  *               Copyright 2004-2006 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  28  */
  29
  30 #include <linux/kernel.h>
  31 #include <linux/sched.h>
  32 #include <linux/mm.h>
  33 #include <linux/smp.h>
  34 #include <linux/smp_lock.h>
  35 #include <linux/errno.h>
  36 #include <linux/ptrace.h>
  37 #include <linux/user.h>
  38 #include <linux/signal.h>
  39 #include <linux/uaccess.h>
  40
  41 #include <asm/page.h>
  42 #include <asm/pgtable.h>
  43 #include <asm/system.h>
  44 #include <asm/processor.h>
  45 #include <asm/asm-offsets.h>
  46 #include <asm/dma.h>
  47 #include <asm/fixed_code.h>
  48
  49 #define MAX_SHARED_LIBS 3
  50 #define TEXT_OFFSET 0
  51 /*
  52  * does not yet catch signals sent when the child dies.
  53  * in exit.c or in signal.c.
  54  */
  55
  56 /* determines which bits in the SYSCFG reg the user has access to. */
  57 /* 1 = access 0 = no access */
  58 #define SYSCFG_MASK 0x0007      /* SYSCFG reg */
  59 /* sets the trace bits. */
  60 #define TRACE_BITS 0x0001
  61
  62 /* Find the stack offset for a register, relative to thread.esp0. */
  63 #define PT_REG(reg)     ((long)&((struct pt_regs *)0)->reg)
  64
  65 /*
  66  * Get the address of the live pt_regs for the specified task.
  67  * These are saved onto the top kernel stack when the process
  68  * is not running.
  69  *
  70  * Note: if a user thread is execve'd from kernel space, the
  71  * kernel stack will not be empty on entry to the kernel, so
  72  * ptracing these tasks will fail.
  73  */
  74 static inline struct pt_regs *get_user_regs(struct task_struct *task)
  75 {
  76         return (struct pt_regs *)
  77             ((unsigned long)task_stack_page(task) +
  78              (THREAD_SIZE - sizeof(struct pt_regs)));
  79 }
  80
  81 /*
  82  * Get all user integer registers.
  83  */
  84 static inline int ptrace_getregs(struct task_struct *tsk, void __user * uregs)
  85 {
  86         struct pt_regs *regs = get_user_regs(tsk);
  87         return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
  88 }
  89
  90 /* Mapping from PT_xxx to the stack offset at which the register is
  91  * saved.  Notice that usp has no stack-slot and needs to be treated
  92  * specially (see get_reg/put_reg below).
  93  */
  94
  95 /*
  96  * Get contents of register REGNO in task TASK.
  97  */
  98 static inline long get_reg(struct task_struct *task, int regno)
  99 {
 100         unsigned char *reg_ptr;
 101
 102         struct pt_regs *regs =
 103             (struct pt_regs *)((unsigned long)task_stack_page(task) +
 104                                (THREAD_SIZE - sizeof(struct pt_regs)));
 105         reg_ptr = (char *)regs;
 106
 107         switch (regno) {
 108         case PT_USP:
 109                 return task->thread.usp;
 110         default:
 111                 if (regno <= 216)
 112                         return *(long *)(reg_ptr + regno);
 113         }
 114         /* slight mystery ... never seems to come here but kernel misbehaves without this code! */
 115
 116         printk(KERN_WARNING "Request to get for unknown register %d\n", regno);
 117         return 0;
 118 }
 119
 120 /*
 121  * Write contents of register REGNO in task TASK.
 122  */
 123 static inline int
 124 put_reg(struct task_struct *task, int regno, unsigned long data)
 125 {
 126         char *reg_ptr;
 127
 128         struct pt_regs *regs =
 129             (struct pt_regs *)((unsigned long)task_stack_page(task) +
 130                                (THREAD_SIZE - sizeof(struct pt_regs)));
 131         reg_ptr = (char *)regs;
 132
 133         switch (regno) {
 134         case PT_PC:
 135                 /*********************************************************************/
 136                 /* At this point the kernel is most likely in exception.             */
 137                 /* The RETX register will be used to populate the pc of the process. */
 138                 /*********************************************************************/
 139                 regs->retx = data;
 140                 regs->pc = data;
 141                 break;
 142         case PT_RETX:
 143                 break;          /* regs->retx = data; break; */
 144         case PT_USP:
 145                 regs->usp = data;
 146                 task->thread.usp = data;
 147                 break;
 148         default:
 149                 if (regno <= 216)
 150                         *(long *)(reg_ptr + regno) = data;
 151         }
 152         return 0;
 153 }
 154
 155 /*
 156  * check that an address falls within the bounds of the target process's memory mappings
 157  */
 158 static inline int is_user_addr_valid(struct task_struct *child,
 159                                      unsigned long start, unsigned long len)
 160 {
 161         struct vm_list_struct *vml;
 162         struct sram_list_struct *sraml;
 163
 164         for (vml = child->mm->context.vmlist; vml; vml = vml->next)
 165                 if (start >= vml->vma->vm_start && start + len <= vml->vma->vm_end)
 166                         return 0;
 167
 168         for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next)
 169                 if (start >= (unsigned long)sraml->addr
 170                     && start + len <= (unsigned long)sraml->addr + sraml->length)
 171                         return 0;
 172
 173         if (start >= FIXED_CODE_START && start + len <= FIXED_CODE_END)
 174                 return 0;
 175
 176         return -EIO;
 177 }
 178
 179 /*
 180  * Called by kernel/ptrace.c when detaching..
 181  *
 182  * Make sure the single step bit is not set.
 183  */
 184 void ptrace_disable(struct task_struct *child)
 185 {
 186         unsigned long tmp;
 187         /* make sure the single step bit is not set. */
 188         tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
 189         put_reg(child, PT_SR, tmp);
 190 }
 191
 192 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 193 {
 194         int ret;
 195         int add = 0;
 196
 197         switch (request) {
 198                 /* when I and D space are separate, these will need to be fixed. */
 199         case PTRACE_PEEKDATA:
 200                 pr_debug("ptrace: PEEKDATA\n");
 201                 add = MAX_SHARED_LIBS * 4;      /* space between text and data */
 202                 /* fall through */
 203         case PTRACE_PEEKTEXT:   /* read word at location addr. */
 204                 {
 205                         unsigned long tmp = 0;
 206                         int copied;
 207
 208                         ret = -EIO;
 209                         pr_debug("ptrace: PEEKTEXT at addr 0x%08lx + add %d %ld\n", addr, add,
 210                                  sizeof(data));
 211                         if (is_user_addr_valid(child, addr + add, sizeof(tmp)) < 0)
 212                                 break;
 213                         pr_debug("ptrace: user address is valid\n");
 214
 215 #if L1_CODE_LENGTH != 0
 216                         if (addr + add >= L1_CODE_START
 217                             && addr + add + sizeof(tmp) <= L1_CODE_START + L1_CODE_LENGTH) {
 218                                 safe_dma_memcpy (&tmp, (const void *)(addr + add), sizeof(tmp));
 219                                 copied = sizeof(tmp);
 220                         } else
 221 #endif
 222                         if (addr + add >= FIXED_CODE_START
 223                             && addr + add + sizeof(tmp) <= FIXED_CODE_END) {
 224                                 memcpy(&tmp, (const void *)(addr + add), sizeof(tmp));
 225                                 copied = sizeof(tmp);
 226                         } else
 227                                 copied = access_process_vm(child, addr + add, &tmp,
 228                                                            sizeof(tmp), 0);
 229                         pr_debug("ptrace: copied size %d [0x%08lx]\n", copied, tmp);
 230                         if (copied != sizeof(tmp))
 231                                 break;
 232                         ret = put_user(tmp, (unsigned long *)data);
 233                         break;
 234                 }
 235
 236                 /* read the word at location addr in the USER area. */
 237         case PTRACE_PEEKUSR:
 238                 {
 239                         unsigned long tmp;
 240                         ret = -EIO;
 241                         tmp = 0;
 242                         if ((addr & 3) || (addr > (sizeof(struct pt_regs) + 16))) {
 243                                 printk(KERN_WARNING "ptrace error : PEEKUSR : temporarily returning "
 244                                                     "0 - %x sizeof(pt_regs) is %lx\n",
 245                                      (int)addr, sizeof(struct pt_regs));
 246                                 break;
 247                         }
 248                         if (addr == sizeof(struct pt_regs)) {
 249                                 /* PT_TEXT_ADDR */
 250                                 tmp = child->mm->start_code + TEXT_OFFSET;
 251                         } else if (addr == (sizeof(struct pt_regs) + 4)) {
 252                                 /* PT_TEXT_END_ADDR */
 253                                 tmp = child->mm->end_code;
 254                         } else if (addr == (sizeof(struct pt_regs) + 8)) {
 255                                 /* PT_DATA_ADDR */
 256                                 tmp = child->mm->start_data;
 257 #ifdef CONFIG_BINFMT_ELF_FDPIC
 258                         } else if (addr == (sizeof(struct pt_regs) + 12)) {
 259                                 tmp = child->mm->context.exec_fdpic_loadmap;
 260                         } else if (addr == (sizeof(struct pt_regs) + 16)) {
 261                                 tmp = child->mm->context.interp_fdpic_loadmap;
 262 #endif
 263                         } else {
 264                                 tmp = get_reg(child, addr);
 265                         }
 266                         ret = put_user(tmp, (unsigned long *)data);
 267                         break;
 268                 }
 269
 270                 /* when I and D space are separate, this will have to be fixed. */
 271         case PTRACE_POKEDATA:
 272                 printk(KERN_NOTICE "ptrace: PTRACE_PEEKDATA\n");
 273                 /* fall through */
 274         case PTRACE_POKETEXT:   /* write the word at location addr. */
 275                 {
 276                         int copied;
 277
 278                         ret = -EIO;
 279                         pr_debug("ptrace: POKETEXT at addr 0x%08lx + add %d %ld bytes %lx\n",
 280                                  addr, add, sizeof(data), data);
 281                         if (is_user_addr_valid(child, addr + add, sizeof(data)) < 0)
 282                                 break;
 283                         pr_debug("ptrace: user address is valid\n");
 284
 285 #if L1_CODE_LENGTH != 0
 286                         if (addr + add >= L1_CODE_START
 287                             && addr + add + sizeof(data) <= L1_CODE_START + L1_CODE_LENGTH) {
 288                                 safe_dma_memcpy ((void *)(addr + add), &data, sizeof(data));
 289                                 copied = sizeof(data);
 290                         } else
 291 #endif
 292                         if (addr + add >= FIXED_CODE_START
 293                             && addr + add + sizeof(data) <= FIXED_CODE_END) {
 294                                 memcpy((void *)(addr + add), &data, sizeof(data));
 295                                 copied = sizeof(data);
 296                         } else
 297                                 copied = access_process_vm(child, addr + add, &data,
 298                                                            sizeof(data), 1);
 299                         pr_debug("ptrace: copied size %d\n", copied);
 300                         if (copied != sizeof(data))
 301                                 break;
 302                         ret = 0;
 303                         break;
 304                 }
 305
 306         case PTRACE_POKEUSR:    /* write the word at location addr in the USER area */
 307                 ret = -EIO;
 308                 if ((addr & 3) || (addr > (sizeof(struct pt_regs) + 16))) {
 309                         printk(KERN_WARNING "ptrace error : POKEUSR: temporarily returning 0\n");
 310                         break;
 311                 }
 312
 313                 if (addr >= (sizeof(struct pt_regs))) {
 314                         ret = 0;
 315                         break;
 316                 }
 317                 if (addr == PT_SYSCFG) {
 318                         data &= SYSCFG_MASK;
 319                         data |= get_reg(child, PT_SYSCFG);
 320                 }
 321                 ret = put_reg(child, addr, data);
 322                 break;
 323
 324         case PTRACE_SYSCALL:    /* continue and stop at next (return from) syscall */
 325         case PTRACE_CONT:
 326                 {               /* restart after signal. */
 327                         long tmp;
 328
 329                         pr_debug("ptrace_cont\n");
 330
 331                         ret = -EIO;
 332                         if (!valid_signal(data))
 333                                 break;
 334                         if (request == PTRACE_SYSCALL)
 335                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 336                         else
 337                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 338
 339                         child->exit_code = data;
 340                         /* make sure the single step bit is not set. */
 341                         tmp = get_reg(child, PT_SYSCFG) & ~(TRACE_BITS);
 342                         put_reg(child, PT_SYSCFG, tmp);
 343                         pr_debug("before wake_up_process\n");
 344                         wake_up_process(child);
 345                         ret = 0;
 346                         break;
 347                 }
 348
 349         /*
 350          * make the child exit.  Best I can do is send it a sigkill.
 351          * perhaps it should be put in the status that it wants to
 352          * exit.
 353          */
 354         case PTRACE_KILL:
 355                 {
 356                         long tmp;
 357                         ret = 0;
 358                         if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 359                                 break;
 360                         child->exit_code = SIGKILL;
 361                         /* make sure the single step bit is not set. */
 362                         tmp = get_reg(child, PT_SYSCFG) & ~(TRACE_BITS);
 363                         put_reg(child, PT_SYSCFG, tmp);
 364                         wake_up_process(child);
 365                         break;
 366                 }
 367
 368         case PTRACE_SINGLESTEP:
 369                 {               /* set the trap flag. */
 370                         long tmp;
 371
 372                         pr_debug("single step\n");
 373                         ret = -EIO;
 374                         if (!valid_signal(data))
 375                                 break;
 376                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 377
 378                         tmp = get_reg(child, PT_SYSCFG) | (TRACE_BITS);
 379                         put_reg(child, PT_SYSCFG, tmp);
 380
 381                         child->exit_code = data;
 382                         /* give it a chance to run. */
 383                         wake_up_process(child);
 384                         ret = 0;
 385                         break;
 386                 }
 387
 388         case PTRACE_GETREGS:
 389                 {
 390
 391                         /* Get all gp regs from the child. */
 392                         ret = ptrace_getregs(child, (void __user *)data);
 393                         break;
 394                 }
 395
 396         case PTRACE_SETREGS:
 397                 {
 398                         printk(KERN_NOTICE
 399                                "ptrace: SETREGS: **** NOT IMPLEMENTED ***\n");
 400                         /* Set all gp regs in the child. */
 401                         ret = 0;
 402                         break;
 403                 }
 404         default:
 405                 ret = ptrace_request(child, request, addr, data);
 406                 break;
 407         }
 408
 409         return ret;
 410 }
 411
 412 asmlinkage void syscall_trace(void)
 413 {
 414
 415         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 416                 return;
 417
 418         if (!(current->ptrace & PT_PTRACED))
 419                 return;
 420
 421         /* the 0x80 provides a way for the tracing parent to distinguish
 422          * between a syscall stop and SIGTRAP delivery
 423          */
 424         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 425                                  ? 0x80 : 0));
 426
 427         /*
 428          * this isn't the same as continuing with a signal, but it will do
 429          * for normal use.  strace only continues with a signal if the
 430          * stopping signal is not SIGTRAP.  -brl
 431          */
 432         if (current->exit_code) {
 433                 send_sig(current->exit_code, current, 1);
 434                 current->exit_code = 0;
 435         }
 436 }