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ptrace.c

/*
 * linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 * these modifications are Copyright 2004-2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/regset.h>
#include <linux/signal.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/asm-offsets.h>
#include <asm/dma.h>
#include <asm/fixed_code.h>
#include <asm/cacheflush.h>
#include <asm/mem_map.h>
#include <asm/mmu_context.h>

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Get contents of register REGNO in task TASK.
 */
static inline long
get_reg(struct task_struct *task, unsigned long regno,
      unsigned long __user *datap)
{
      long tmp;
      struct pt_regs *regs = task_pt_regs(task);

      if (regno & 3 || regno > PT_LAST_PSEUDO)
            return -EIO;

      switch (regno) {
      case PT_TEXT_ADDR:
            tmp = task->mm->start_code;
            break;
      case PT_TEXT_END_ADDR:
            tmp = task->mm->end_code;
            break;
      case PT_DATA_ADDR:
            tmp = task->mm->start_data;
            break;
      case PT_USP:
            tmp = task->thread.usp;
            break;
      default:
            if (regno < sizeof(*regs)) {
                  void *reg_ptr = regs;
                  tmp = *(long *)(reg_ptr + regno);
            } else
                  return -EIO;
      }

      return put_user(tmp, datap);
}

/*
 * Write contents of register REGNO in task TASK.
 */
static inline int
put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
{
      struct pt_regs *regs = task_pt_regs(task);

      if (regno & 3 || regno > PT_LAST_PSEUDO)
            return -EIO;

      switch (regno) {
      case PT_PC:
            /*********************************************************************/
            /* At this point the kernel is most likely in exception.             */
            /* The RETX register will be used to populate the pc of the process. */
            /*********************************************************************/
            regs->retx = data;
            regs->pc = data;
            break;
      case PT_RETX:
            break;            /* regs->retx = data; break; */
      case PT_USP:
            regs->usp = data;
            task->thread.usp = data;
            break;
      case PT_SYSCFG:   /* don't let userspace screw with this */
            if ((data & ~1) != 0x6)
                  pr_warning("ptrace: ignore syscfg write of %#lx\n", data);
            break;            /* regs->syscfg = data; break; */
      default:
            if (regno < sizeof(*regs)) {
                  void *reg_offset = regs;
                  *(long *)(reg_offset + regno) = data;
            }
            /* Ignore writes to pseudo registers */
      }

      return 0;
}

/*
 * check that an address falls within the bounds of the target process's memory mappings
 */
int
is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long len)
{
      struct vm_area_struct *vma;
      struct sram_list_struct *sraml;

      /* overflow */
      if (start + len < start)
            return -EIO;

      vma = find_vma(child->mm, start);
      if (vma && start >= vma->vm_start && start + len <= vma->vm_end)
                  return 0;

      for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next)
            if (start >= (unsigned long)sraml->addr
                && start + len < (unsigned long)sraml->addr + sraml->length)
                  return 0;

      if (start >= FIXED_CODE_START && start + len < FIXED_CODE_END)
            return 0;

#ifdef CONFIG_APP_STACK_L1
      if (child->mm->context.l1_stack_save)
            if (start >= (unsigned long)l1_stack_base &&
                  start + len < (unsigned long)l1_stack_base + l1_stack_len)
                  return 0;
#endif

      return -EIO;
}

/*
 * retrieve the contents of Blackfin userspace general registers
 */
static int genregs_get(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
      struct pt_regs *regs = task_pt_regs(target);
      int ret;

      /* This sucks ... */
      regs->usp = target->thread.usp;

      ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                          regs, 0, sizeof(*regs));
      if (ret < 0)
            return ret;

      return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                              sizeof(*regs), -1);
}

/*
 * update the contents of the Blackfin userspace general registers
 */
static int genregs_set(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
{
      struct pt_regs *regs = task_pt_regs(target);
      int ret;

      /* Don't let people set SYSCFG (it's at the end of pt_regs) */
      ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                         regs, 0, PT_SYSCFG);
      if (ret < 0)
            return ret;

      /* This sucks ... */
      target->thread.usp = regs->usp;
      /* regs->retx = regs->pc; */

      return user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                              PT_SYSCFG, -1);
}

/*
 * Define the register sets available on the Blackfin under Linux
 */
enum bfin_regset {
      REGSET_GENERAL,
};

static const struct user_regset bfin_regsets[] = {
      [REGSET_GENERAL] = {
            .core_note_type = NT_PRSTATUS,
            .n              = sizeof(struct pt_regs) / sizeof(long),
            .size           = sizeof(long),
            .align          = sizeof(long),
            .get            = genregs_get,
            .set            = genregs_set,
      },
};

static const struct user_regset_view user_bfin_native_view = {
      .name      = "Blackfin",
      .e_machine = EM_BLACKFIN,
      .regsets   = bfin_regsets,
      .n         = ARRAY_SIZE(bfin_regsets),
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
      return &user_bfin_native_view;
}

void user_enable_single_step(struct task_struct *child)
{
      struct pt_regs *regs = task_pt_regs(child);
      regs->syscfg |= SYSCFG_SSSTEP;

      set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
      struct pt_regs *regs = task_pt_regs(child);
      regs->syscfg &= ~SYSCFG_SSSTEP;

      clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

long arch_ptrace(struct task_struct *child, long request,
             unsigned long addr, unsigned long data)
{
      int ret;
      unsigned long __user *datap = (unsigned long __user *)data;
      void *paddr = (void *)addr;

      switch (request) {
            /* when I and D space are separate, these will need to be fixed. */
      case PTRACE_PEEKDATA:
            pr_debug("ptrace: PEEKDATA\n");
            /* fall through */
      case PTRACE_PEEKTEXT:   /* read word at location addr. */
            {
                  unsigned long tmp = 0;
                  int copied = 0, to_copy = sizeof(tmp);

                  ret = -EIO;
                  pr_debug("ptrace: PEEKTEXT at addr 0x%08lx + %i\n", addr, to_copy);
                  if (is_user_addr_valid(child, addr, to_copy) < 0)
                        break;
                  pr_debug("ptrace: user address is valid\n");

                  switch (bfin_mem_access_type(addr, to_copy)) {
                  case BFIN_MEM_ACCESS_CORE:
                  case BFIN_MEM_ACCESS_CORE_ONLY:
                        copied = access_process_vm(child, addr, &tmp,
                                                   to_copy, 0);
                        if (copied)
                              break;

                        /* hrm, why didn't that work ... maybe no mapping */
                        if (addr >= FIXED_CODE_START &&
                            addr + to_copy <= FIXED_CODE_END) {
                              copy_from_user_page(0, 0, 0, &tmp, paddr, to_copy);
                              copied = to_copy;
                        } else if (addr >= BOOT_ROM_START) {
                              memcpy(&tmp, paddr, to_copy);
                              copied = to_copy;
                        }

                        break;
                  case BFIN_MEM_ACCESS_DMA:
                        if (safe_dma_memcpy(&tmp, paddr, to_copy))
                              copied = to_copy;
                        break;
                  case BFIN_MEM_ACCESS_ITEST:
                        if (isram_memcpy(&tmp, paddr, to_copy))
                              copied = to_copy;
                        break;
                  default:
                        copied = 0;
                        break;
                  }

                  pr_debug("ptrace: copied size %d [0x%08lx]\n", copied, tmp);
                  if (copied == to_copy)
                        ret = put_user(tmp, datap);
                  break;
            }

            /* when I and D space are separate, this will have to be fixed. */
      case PTRACE_POKEDATA:
            pr_debug("ptrace: PTRACE_PEEKDATA\n");
            /* fall through */
      case PTRACE_POKETEXT:   /* write the word at location addr. */
            {
                  int copied = 0, to_copy = sizeof(data);

                  ret = -EIO;
                  pr_debug("ptrace: POKETEXT at addr 0x%08lx + %i bytes %lx\n",
                           addr, to_copy, data);
                  if (is_user_addr_valid(child, addr, to_copy) < 0)
                        break;
                  pr_debug("ptrace: user address is valid\n");

                  switch (bfin_mem_access_type(addr, to_copy)) {
                  case BFIN_MEM_ACCESS_CORE:
                  case BFIN_MEM_ACCESS_CORE_ONLY:
                        copied = access_process_vm(child, addr, &data,
                                                   to_copy, 1);
                        break;
                  case BFIN_MEM_ACCESS_DMA:
                        if (safe_dma_memcpy(paddr, &data, to_copy))
                              copied = to_copy;
                        break;
                  case BFIN_MEM_ACCESS_ITEST:
                        if (isram_memcpy(paddr, &data, to_copy))
                              copied = to_copy;
                        break;
                  default:
                        copied = 0;
                        break;
                  }

                  pr_debug("ptrace: copied size %d\n", copied);
                  if (copied == to_copy)
                        ret = 0;
                  break;
            }

      case PTRACE_PEEKUSR:
            switch (addr) {
#ifdef CONFIG_BINFMT_ELF_FDPIC      /* backwards compat */
            case PT_FDPIC_EXEC:
                  request = PTRACE_GETFDPIC;
                  addr = PTRACE_GETFDPIC_EXEC;
                  goto case_default;
            case PT_FDPIC_INTERP:
                  request = PTRACE_GETFDPIC;
                  addr = PTRACE_GETFDPIC_INTERP;
                  goto case_default;
#endif
            default:
                  ret = get_reg(child, addr, datap);
            }
            pr_debug("ptrace: PEEKUSR reg %li with %#lx = %i\n", addr, data, ret);
            break;

      case PTRACE_POKEUSR:
            ret = put_reg(child, addr, data);
            pr_debug("ptrace: POKEUSR reg %li with %li = %i\n", addr, data, ret);
            break;

      case PTRACE_GETREGS:
            pr_debug("ptrace: PTRACE_GETREGS\n");
            return copy_regset_to_user(child, &user_bfin_native_view,
                                 REGSET_GENERAL,
                                 0, sizeof(struct pt_regs),
                                 datap);

      case PTRACE_SETREGS:
            pr_debug("ptrace: PTRACE_SETREGS\n");
            return copy_regset_from_user(child, &user_bfin_native_view,
                                   REGSET_GENERAL,
                                   0, sizeof(struct pt_regs),
                                   datap);

      case_default:
      default:
            ret = ptrace_request(child, request, addr, data);
            break;
      }

      return ret;
}

asmlinkage int syscall_trace_enter(struct pt_regs *regs)
{
      int ret = 0;

      if (test_thread_flag(TIF_SYSCALL_TRACE))
            ret = tracehook_report_syscall_entry(regs);

      return ret;
}

asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
      int step;

      step = test_thread_flag(TIF_SINGLESTEP);
      if (step || test_thread_flag(TIF_SYSCALL_TRACE))
            tracehook_report_syscall_exit(regs, step);
}

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