ptrace.c

Go to the documentation of this file.

/*
 *  linux/arch/m68k/kernel/ptrace.c
 *
 *  Copyright (C) 1994 by Hamish Macdonald
 *  Taken from linux/kernel/ptrace.c and modified for M680x0.
 *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of
 * this archive for more details.
 */

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

#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>

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

/* determines which bits in the SR the user has access to. */
/* 1 = access 0 = no access */
#define SR_MASK 0x001f

/* sets the trace bits. */
#define TRACE_BITS 0xC000
#define T1_BIT 0x8000
#define T0_BIT 0x4000

/* Find the stack offset for a register, relative to thread.esp0. */
#define PT_REG(reg) ((long)&((struct pt_regs *)0)->reg)
#define SW_REG(reg) ((long)&((struct switch_stack *)0)->reg \
             - sizeof(struct switch_stack))
/* Mapping from PT_xxx to the stack offset at which the register is
   saved.  Notice that usp has no stack-slot and needs to be treated
   specially (see get_reg/put_reg below). */
static const int regoff[] = {
    [0] = PT_REG(d1),
    [1] = PT_REG(d2),
    [2] = PT_REG(d3),
    [3] = PT_REG(d4),
    [4] = PT_REG(d5),
    [5] = SW_REG(d6),
    [6] = SW_REG(d7),
    [7] = PT_REG(a0),
    [8] = PT_REG(a1),
    [9] = PT_REG(a2),
    [10]    = SW_REG(a3),
    [11]    = SW_REG(a4),
    [12]    = SW_REG(a5),
    [13]    = SW_REG(a6),
    [14]    = PT_REG(d0),
    [15]    = -1,
    [16]    = PT_REG(orig_d0),
    [17]    = PT_REG(sr),
    [18]    = PT_REG(pc),
};

/*
 * Get contents of register REGNO in task TASK.
 */
static inline long get_reg(struct task_struct *task, int regno)
{
    unsigned long *addr;

    if (regno == PT_USP)
        addr = &task->thread.usp;
    else if (regno < ARRAY_SIZE(regoff))
        addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
    else
        return 0;
    /* Need to take stkadj into account. */
    if (regno == PT_SR || regno == PT_PC) {
        long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
        addr = (unsigned long *) ((unsigned long)addr + stkadj);
        /* The sr is actually a 16 bit register.  */
        if (regno == PT_SR)
            return *(unsigned short *)addr;
    }
    return *addr;
}

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

    if (regno == PT_USP)
        addr = &task->thread.usp;
    else if (regno < ARRAY_SIZE(regoff))
        addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
    else
        return -1;
    /* Need to take stkadj into account. */
    if (regno == PT_SR || regno == PT_PC) {
        long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
        addr = (unsigned long *) ((unsigned long)addr + stkadj);
        /* The sr is actually a 16 bit register.  */
        if (regno == PT_SR) {
            *(unsigned short *)addr = data;
            return 0;
        }
    }
    *addr = data;
    return 0;
}

/*
 * Make sure the single step bit is not set.
 */
static inline void singlestep_disable(struct task_struct *child)
{
    unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
    put_reg(child, PT_SR, tmp);
    clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
    singlestep_disable(child);
}

void user_enable_single_step(struct task_struct *child)
{
    unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
    put_reg(child, PT_SR, tmp | T1_BIT);
    set_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

#ifdef CONFIG_MMU
void user_enable_block_step(struct task_struct *child)
{
    unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
    put_reg(child, PT_SR, tmp | T0_BIT);
}
#endif

void user_disable_single_step(struct task_struct *child)
{
    singlestep_disable(child);
}

long arch_ptrace(struct task_struct *child, long request,
         unsigned long addr, unsigned long data)
{
    unsigned long tmp;
    int i, ret = 0;
    int regno = addr >> 2; /* temporary hack. */
    unsigned long __user *datap = (unsigned long __user *) data;

    switch (request) {
    /* read the word at location addr in the USER area. */
    case PTRACE_PEEKUSR:
        if (addr & 3)
            goto out_eio;

        if (regno >= 0 && regno < 19) {
            tmp = get_reg(child, regno);
        } else if (regno >= 21 && regno < 49) {
            tmp = child->thread.fp[regno - 21];
            /* Convert internal fpu reg representation
             * into long double format
             */
            if (FPU_IS_EMU && (regno < 45) && !(regno % 3))
                tmp = ((tmp & 0xffff0000) << 15) |
                      ((tmp & 0x0000ffff) << 16);
#ifndef CONFIG_MMU
        } else if (regno == 49) {
            tmp = child->mm->start_code;
        } else if (regno == 50) {
            tmp = child->mm->start_data;
        } else if (regno == 51) {
            tmp = child->mm->end_code;
#endif
        } else
            goto out_eio;
        ret = put_user(tmp, datap);
        break;

    case PTRACE_POKEUSR:
    /* write the word at location addr in the USER area */
        if (addr & 3)
            goto out_eio;

        if (regno == PT_SR) {
            data &= SR_MASK;
            data |= get_reg(child, PT_SR) & ~SR_MASK;
        }
        if (regno >= 0 && regno < 19) {
            if (put_reg(child, regno, data))
                goto out_eio;
        } else if (regno >= 21 && regno < 48) {
            /* Convert long double format
             * into internal fpu reg representation
             */
            if (FPU_IS_EMU && (regno < 45) && !(regno % 3)) {
                data <<= 15;
                data = (data & 0xffff0000) |
                       ((data & 0x0000ffff) >> 1);
            }
            child->thread.fp[regno - 21] = data;
        } else
            goto out_eio;
        break;

    case PTRACE_GETREGS:    /* Get all gp regs from the child. */
        for (i = 0; i < 19; i++) {
            tmp = get_reg(child, i);
            ret = put_user(tmp, datap);
            if (ret)
                break;
            datap++;
        }
        break;

    case PTRACE_SETREGS:    /* Set all gp regs in the child. */
        for (i = 0; i < 19; i++) {
            ret = get_user(tmp, datap);
            if (ret)
                break;
            if (i == PT_SR) {
                tmp &= SR_MASK;
                tmp |= get_reg(child, PT_SR) & ~SR_MASK;
            }
            put_reg(child, i, tmp);
            datap++;
        }
        break;

    case PTRACE_GETFPREGS:  /* Get the child FPU state. */
        if (copy_to_user(datap, &child->thread.fp,
                 sizeof(struct user_m68kfp_struct)))
            ret = -EFAULT;
        break;

    case PTRACE_SETFPREGS:  /* Set the child FPU state. */
        if (copy_from_user(&child->thread.fp, datap,
                   sizeof(struct user_m68kfp_struct)))
            ret = -EFAULT;
        break;

    case PTRACE_GET_THREAD_AREA:
        ret = put_user(task_thread_info(child)->tp_value, datap);
        break;

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

    return ret;
out_eio:
    return -EIO;
}

asmlinkage void syscall_trace(void)
{
    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
     */
    if (current->exit_code) {
        send_sig(current->exit_code, current, 1);
        current->exit_code = 0;
    }
}

#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
asmlinkage int syscall_trace_enter(void)
{
    int ret = 0;

    if (test_thread_flag(TIF_SYSCALL_TRACE))
        ret = tracehook_report_syscall_entry(task_pt_regs(current));
    return ret;
}

asmlinkage void syscall_trace_leave(void)
{
    if (test_thread_flag(TIF_SYSCALL_TRACE))
        tracehook_report_syscall_exit(task_pt_regs(current), 0);
}
#endif /* CONFIG_COLDFIRE */