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ptrace.c

/* ptrace.c: Sparc process tracing support.
 *
 * Copyright (C) 1996 David S. Miller (davem@caipfs.rutgers.edu)
 *
 * Based upon code written by Ross Biro, Linus Torvalds, Bob Manson,
 * and David Mosberger.
 *
 * Added Linux support -miguel (weird, eh?, the original code was meant
 * to emulate SunOS).
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/security.h>
#include <linux/signal.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#define MAGIC_CONSTANT 0x80000000


/* Returning from ptrace is a bit tricky because the syscall return
 * low level code assumes any value returned which is negative and
 * is a valid errno will mean setting the condition codes to indicate
 * an error return.  This doesn't work, so we have this hook.
 */
static inline void pt_error_return(struct pt_regs *regs, unsigned long error)
{
      regs->u_regs[UREG_I0] = error;
      regs->psr |= PSR_C;
      regs->pc = regs->npc;
      regs->npc += 4;
}

static inline void pt_succ_return(struct pt_regs *regs, unsigned long value)
{
      regs->u_regs[UREG_I0] = value;
      regs->psr &= ~PSR_C;
      regs->pc = regs->npc;
      regs->npc += 4;
}

static void
pt_succ_return_linux(struct pt_regs *regs, unsigned long value, long __user *addr)
{
      if (put_user(value, addr)) {
            pt_error_return(regs, EFAULT);
            return;
      }
      regs->u_regs[UREG_I0] = 0;
      regs->psr &= ~PSR_C;
      regs->pc = regs->npc;
      regs->npc += 4;
}

static void
pt_os_succ_return (struct pt_regs *regs, unsigned long val, long __user *addr)
{
      if (current->personality == PER_SUNOS)
            pt_succ_return (regs, val);
      else
            pt_succ_return_linux (regs, val, addr);
}

/* Fuck me gently with a chainsaw... */
static inline void read_sunos_user(struct pt_regs *regs, unsigned long offset,
                           struct task_struct *tsk, long __user *addr)
{
      struct pt_regs *cregs = tsk->thread.kregs;
      struct thread_info *t = task_thread_info(tsk);
      int v;
      
      if(offset >= 1024)
            offset -= 1024; /* whee... */
      if(offset & ((sizeof(unsigned long) - 1))) {
            pt_error_return(regs, EIO);
            return;
      }
      if(offset >= 16 && offset < 784) {
            offset -= 16; offset >>= 2;
            pt_os_succ_return(regs, *(((unsigned long *)(&t->reg_window[0]))+offset), addr);
            return;
      }
      if(offset >= 784 && offset < 832) {
            offset -= 784; offset >>= 2;
            pt_os_succ_return(regs, *(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset), addr);
            return;
      }
      switch(offset) {
      case 0:
            v = t->ksp;
            break;
      case 4:
            v = t->kpc;
            break;
      case 8:
            v = t->kpsr;
            break;
      case 12:
            v = t->uwinmask;
            break;
      case 832:
            v = t->w_saved;
            break;
      case 896:
            v = cregs->u_regs[UREG_I0];
            break;
      case 900:
            v = cregs->u_regs[UREG_I1];
            break;
      case 904:
            v = cregs->u_regs[UREG_I2];
            break;
      case 908:
            v = cregs->u_regs[UREG_I3];
            break;
      case 912:
            v = cregs->u_regs[UREG_I4];
            break;
      case 916:
            v = cregs->u_regs[UREG_I5];
            break;
      case 920:
            v = cregs->u_regs[UREG_I6];
            break;
      case 924:
            if(tsk->thread.flags & MAGIC_CONSTANT)
                  v = cregs->u_regs[UREG_G1];
            else
                  v = 0;
            break;
      case 940:
            v = cregs->u_regs[UREG_I0];
            break;
      case 944:
            v = cregs->u_regs[UREG_I1];
            break;

      case 948:
            /* Isn't binary compatibility _fun_??? */
            if(cregs->psr & PSR_C)
                  v = cregs->u_regs[UREG_I0] << 24;
            else
                  v = 0;
            break;

            /* Rest of them are completely unsupported. */
      default:
            printk("%s [%d]: Wants to read user offset %ld\n",
                   current->comm, task_pid_nr(current), offset);
            pt_error_return(regs, EIO);
            return;
      }
      if (current->personality == PER_SUNOS)
            pt_succ_return (regs, v);
      else
            pt_succ_return_linux (regs, v, addr);
      return;
}

static inline void write_sunos_user(struct pt_regs *regs, unsigned long offset,
                            struct task_struct *tsk)
{
      struct pt_regs *cregs = tsk->thread.kregs;
      struct thread_info *t = task_thread_info(tsk);
      unsigned long value = regs->u_regs[UREG_I3];

      if(offset >= 1024)
            offset -= 1024; /* whee... */
      if(offset & ((sizeof(unsigned long) - 1)))
            goto failure;
      if(offset >= 16 && offset < 784) {
            offset -= 16; offset >>= 2;
            *(((unsigned long *)(&t->reg_window[0]))+offset) = value;
            goto success;
      }
      if(offset >= 784 && offset < 832) {
            offset -= 784; offset >>= 2;
            *(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset) = value;
            goto success;
      }
      switch(offset) {
      case 896:
            cregs->u_regs[UREG_I0] = value;
            break;
      case 900:
            cregs->u_regs[UREG_I1] = value;
            break;
      case 904:
            cregs->u_regs[UREG_I2] = value;
            break;
      case 908:
            cregs->u_regs[UREG_I3] = value;
            break;
      case 912:
            cregs->u_regs[UREG_I4] = value;
            break;
      case 916:
            cregs->u_regs[UREG_I5] = value;
            break;
      case 920:
            cregs->u_regs[UREG_I6] = value;
            break;
      case 924:
            cregs->u_regs[UREG_I7] = value;
            break;
      case 940:
            cregs->u_regs[UREG_I0] = value;
            break;
      case 944:
            cregs->u_regs[UREG_I1] = value;
            break;

            /* Rest of them are completely unsupported or "no-touch". */
      default:
            printk("%s [%d]: Wants to write user offset %ld\n",
                   current->comm, task_pid_nr(current), offset);
            goto failure;
      }
success:
      pt_succ_return(regs, 0);
      return;
failure:
      pt_error_return(regs, EIO);
      return;
}

/* #define ALLOW_INIT_TRACING */
/* #define DEBUG_PTRACE */

#ifdef DEBUG_PTRACE
char *pt_rq [] = {
      /* 0  */ "TRACEME", "PEEKTEXT", "PEEKDATA", "PEEKUSR",
      /* 4  */ "POKETEXT", "POKEDATA", "POKEUSR", "CONT",
      /* 8  */ "KILL", "SINGLESTEP", "SUNATTACH", "SUNDETACH",
      /* 12 */ "GETREGS", "SETREGS", "GETFPREGS", "SETFPREGS",
      /* 16 */ "READDATA", "WRITEDATA", "READTEXT", "WRITETEXT",
      /* 20 */ "GETFPAREGS", "SETFPAREGS", "unknown", "unknown",
      /* 24 */ "SYSCALL", ""
};
#endif

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
      /* nothing to do */
}

asmlinkage void do_ptrace(struct pt_regs *regs)
{
      unsigned long request = regs->u_regs[UREG_I0];
      unsigned long pid = regs->u_regs[UREG_I1];
      unsigned long addr = regs->u_regs[UREG_I2];
      unsigned long data = regs->u_regs[UREG_I3];
      unsigned long addr2 = regs->u_regs[UREG_I4];
      struct task_struct *child;
      int ret;

      lock_kernel();
#ifdef DEBUG_PTRACE
      {
            char *s;

            if ((request >= 0) && (request <= 24))
                  s = pt_rq [request];
            else
                  s = "unknown";

            if (request == PTRACE_POKEDATA && data == 0x91d02001){
                  printk ("do_ptrace: breakpoint pid=%d, addr=%08lx addr2=%08lx\n",
                        pid, addr, addr2);
            } else 
                  printk("do_ptrace: rq=%s(%d) pid=%d addr=%08lx data=%08lx addr2=%08lx\n",
                         s, (int) request, (int) pid, addr, data, addr2);
      }
#endif

      if (request == PTRACE_TRACEME) {
            ret = ptrace_traceme();
            if (ret < 0)
                  pt_error_return(regs, -ret);
            else
                  pt_succ_return(regs, 0);
            goto out;
      }

      child = ptrace_get_task_struct(pid);
      if (IS_ERR(child)) {
            ret = PTR_ERR(child);
            pt_error_return(regs, -ret);
            goto out;
      }

      if ((current->personality == PER_SUNOS && request == PTRACE_SUNATTACH)
          || (current->personality != PER_SUNOS && request == PTRACE_ATTACH)) {
            if (ptrace_attach(child)) {
                  pt_error_return(regs, EPERM);
                  goto out_tsk;
            }
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      ret = ptrace_check_attach(child, request == PTRACE_KILL);
      if (ret < 0) {
            pt_error_return(regs, -ret);
            goto out_tsk;
      }

      switch(request) {
      case PTRACE_PEEKTEXT: /* read word at location addr. */ 
      case PTRACE_PEEKDATA: {
            unsigned long tmp;

            if (access_process_vm(child, addr,
                              &tmp, sizeof(tmp), 0) == sizeof(tmp))
                  pt_os_succ_return(regs, tmp, (long __user *)data);
            else
                  pt_error_return(regs, EIO);
            goto out_tsk;
      }

      case PTRACE_PEEKUSR:
            read_sunos_user(regs, addr, child, (long __user *) data);
            goto out_tsk;

      case PTRACE_POKEUSR:
            write_sunos_user(regs, addr, child);
            goto out_tsk;

      case PTRACE_POKETEXT: /* write the word at location addr. */
      case PTRACE_POKEDATA: {
            if (access_process_vm(child, addr,
                              &data, sizeof(data), 1) == sizeof(data))
                  pt_succ_return(regs, 0);
            else
                  pt_error_return(regs, EIO);
            goto out_tsk;
      }

      case PTRACE_GETREGS: {
            struct pt_regs __user *pregs = (struct pt_regs __user *) addr;
            struct pt_regs *cregs = child->thread.kregs;
            int rval;

            if (!access_ok(VERIFY_WRITE, pregs, sizeof(struct pt_regs))) {
                  rval = -EFAULT;
                  pt_error_return(regs, -rval);
                  goto out_tsk;
            }
            __put_user(cregs->psr, (&pregs->psr));
            __put_user(cregs->pc, (&pregs->pc));
            __put_user(cregs->npc, (&pregs->npc));
            __put_user(cregs->y, (&pregs->y));
            for(rval = 1; rval < 16; rval++)
                  __put_user(cregs->u_regs[rval], (&pregs->u_regs[rval - 1]));
            pt_succ_return(regs, 0);
#ifdef DEBUG_PTRACE
            printk ("PC=%x nPC=%x o7=%x\n", cregs->pc, cregs->npc, cregs->u_regs [15]);
#endif
            goto out_tsk;
      }

      case PTRACE_SETREGS: {
            struct pt_regs __user *pregs = (struct pt_regs __user *) addr;
            struct pt_regs *cregs = child->thread.kregs;
            unsigned long psr, pc, npc, y;
            int i;

            /* Must be careful, tracing process can only set certain
             * bits in the psr.
             */
            if (!access_ok(VERIFY_READ, pregs, sizeof(struct pt_regs))) {
                  pt_error_return(regs, EFAULT);
                  goto out_tsk;
            }
            __get_user(psr, (&pregs->psr));
            __get_user(pc, (&pregs->pc));
            __get_user(npc, (&pregs->npc));
            __get_user(y, (&pregs->y));
            psr &= PSR_ICC;
            cregs->psr &= ~PSR_ICC;
            cregs->psr |= psr;
            if (!((pc | npc) & 3)) {
                  cregs->pc = pc;
                  cregs->npc =npc;
            }
            cregs->y = y;
            for(i = 1; i < 16; i++)
                  __get_user(cregs->u_regs[i], (&pregs->u_regs[i-1]));
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      case PTRACE_GETFPREGS: {
            struct fps {
                  unsigned long regs[32];
                  unsigned long fsr;
                  unsigned long flags;
                  unsigned long extra;
                  unsigned long fpqd;
                  struct fq {
                        unsigned long *insnaddr;
                        unsigned long insn;
                  } fpq[16];
            };
            struct fps __user *fps = (struct fps __user *) addr;
            int i;

            if (!access_ok(VERIFY_WRITE, fps, sizeof(struct fps))) {
                  i = -EFAULT;
                  pt_error_return(regs, -i);
                  goto out_tsk;
            }
            for(i = 0; i < 32; i++)
                  __put_user(child->thread.float_regs[i], (&fps->regs[i]));
            __put_user(child->thread.fsr, (&fps->fsr));
            __put_user(child->thread.fpqdepth, (&fps->fpqd));
            __put_user(0, (&fps->flags));
            __put_user(0, (&fps->extra));
            for(i = 0; i < 16; i++) {
                  __put_user(child->thread.fpqueue[i].insn_addr,
                           (&fps->fpq[i].insnaddr));
                  __put_user(child->thread.fpqueue[i].insn, (&fps->fpq[i].insn));
            }
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      case PTRACE_SETFPREGS: {
            struct fps {
                  unsigned long regs[32];
                  unsigned long fsr;
                  unsigned long flags;
                  unsigned long extra;
                  unsigned long fpqd;
                  struct fq {
                        unsigned long *insnaddr;
                        unsigned long insn;
                  } fpq[16];
            };
            struct fps __user *fps = (struct fps __user *) addr;
            int i;

            if (!access_ok(VERIFY_READ, fps, sizeof(struct fps))) {
                  i = -EFAULT;
                  pt_error_return(regs, -i);
                  goto out_tsk;
            }
            copy_from_user(&child->thread.float_regs[0], &fps->regs[0], (32 * sizeof(unsigned long)));
            __get_user(child->thread.fsr, (&fps->fsr));
            __get_user(child->thread.fpqdepth, (&fps->fpqd));
            for(i = 0; i < 16; i++) {
                  __get_user(child->thread.fpqueue[i].insn_addr,
                           (&fps->fpq[i].insnaddr));
                  __get_user(child->thread.fpqueue[i].insn, (&fps->fpq[i].insn));
            }
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      case PTRACE_READTEXT:
      case PTRACE_READDATA: {
            int res = ptrace_readdata(child, addr,
                                (void __user *) addr2, data);

            if (res == data) {
                  pt_succ_return(regs, 0);
                  goto out_tsk;
            }
            /* Partial read is an IO failure */
            if (res >= 0)
                  res = -EIO;
            pt_error_return(regs, -res);
            goto out_tsk;
      }

      case PTRACE_WRITETEXT:
      case PTRACE_WRITEDATA: {
            int res = ptrace_writedata(child, (void __user *) addr2,
                                 addr, data);

            if (res == data) {
                  pt_succ_return(regs, 0);
                  goto out_tsk;
            }
            /* Partial write is an IO failure */
            if (res >= 0)
                  res = -EIO;
            pt_error_return(regs, -res);
            goto out_tsk;
      }

      case PTRACE_SYSCALL: /* continue and stop at (return from) syscall */
            addr = 1;

      case PTRACE_CONT: { /* restart after signal. */
            if (!valid_signal(data)) {
                  pt_error_return(regs, EIO);
                  goto out_tsk;
            }

            if (request == PTRACE_SYSCALL)
                  set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
            else
                  clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

            child->exit_code = data;
#ifdef DEBUG_PTRACE
            printk("CONT: %s [%d]: set exit_code = %x %lx %lx\n",
                  child->comm, child->pid, child->exit_code,
                  child->thread.kregs->pc,
                  child->thread.kregs->npc);
#endif
            wake_up_process(child);
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

/*
 * make the child exit.  Best I can do is send it a sigkill. 
 * perhaps it should be put in the status that it wants to 
 * exit.
 */
      case PTRACE_KILL: {
            if (child->exit_state == EXIT_ZOMBIE) {   /* already dead */
                  pt_succ_return(regs, 0);
                  goto out_tsk;
            }
            wake_up_process(child);
            child->exit_code = SIGKILL;
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      case PTRACE_SUNDETACH: { /* detach a process that was attached. */
            int err = ptrace_detach(child, data);
            if (err) {
                  pt_error_return(regs, EIO);
                  goto out_tsk;
            }
            pt_succ_return(regs, 0);
            goto out_tsk;
      }

      /* PTRACE_DUMPCORE unsupported... */

      default: {
            int err = ptrace_request(child, request, addr, data);
            if (err)
                  pt_error_return(regs, -err);
            else
                  pt_succ_return(regs, 0);
            goto out_tsk;
      }
      }
out_tsk:
      if (child)
            put_task_struct(child);
out:
      unlock_kernel();
}

asmlinkage void syscall_trace(void)
{
#ifdef DEBUG_PTRACE
      printk("%s [%d]: syscall_trace\n", current->comm, current->pid);
#endif
      if (!test_thread_flag(TIF_SYSCALL_TRACE))
            return;
      if (!(current->ptrace & PT_PTRACED))
            return;
      current->thread.flags ^= MAGIC_CONSTANT;
      ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
                         ? 0x80 : 0));
      /*
       * this isn't the same as continuing with a signal, but it will do
       * for normal use.  strace only continues with a signal if the
       * stopping signal is not SIGTRAP.  -brl
       */
#ifdef DEBUG_PTRACE
      printk("%s [%d]: syscall_trace exit= %x\n", current->comm,
            current->pid, current->exit_code);
#endif
      if (current->exit_code) {
            send_sig (current->exit_code, current, 1);
            current->exit_code = 0;
      }
}

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