ptrace.c

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/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * Copied from i386: Ross Biro 1/23/92
 */

#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/kprobes.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
#include <asm/traps.h>

void user_enable_single_step(struct task_struct *child)
{
    set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
    clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
    clear_tsk_thread_flag(child, TIF_SINGLESTEP);

    /*
     * These two are currently unused, but will be set by arch_ptrace()
     * and used in the syscall assembly when we do support them.
     */
    clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}

long arch_ptrace(struct task_struct *child, long request,
         unsigned long addr, unsigned long data)
{
    unsigned long __user *datap = (long __user __force *)data;
    unsigned long tmp;
    long ret = -EIO;
    char *childreg;
    struct pt_regs copyregs;
    int ex1_offset;

    switch (request) {

    case PTRACE_PEEKUSR:  /* Read register from pt_regs. */
        if (addr >= PTREGS_SIZE)
            break;
        childreg = (char *)task_pt_regs(child) + addr;
#ifdef CONFIG_COMPAT
        if (is_compat_task()) {
            if (addr & (sizeof(compat_long_t)-1))
                break;
            ret = put_user(*(compat_long_t *)childreg,
                       (compat_long_t __user *)datap);
        } else
#endif
        {
            if (addr & (sizeof(long)-1))
                break;
            ret = put_user(*(long *)childreg, datap);
        }
        break;

    case PTRACE_POKEUSR:  /* Write register in pt_regs. */
        if (addr >= PTREGS_SIZE)
            break;
        childreg = (char *)task_pt_regs(child) + addr;

        /* Guard against overwrites of the privilege level. */
        ex1_offset = PTREGS_OFFSET_EX1;
#if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN)
        if (is_compat_task())   /* point at low word */
            ex1_offset += sizeof(compat_long_t);
#endif
        if (addr == ex1_offset)
            data = PL_ICS_EX1(USER_PL, EX1_ICS(data));

#ifdef CONFIG_COMPAT
        if (is_compat_task()) {
            if (addr & (sizeof(compat_long_t)-1))
                break;
            *(compat_long_t *)childreg = data;
        } else
#endif
        {
            if (addr & (sizeof(long)-1))
                break;
            *(long *)childreg = data;
        }
        ret = 0;
        break;

    case PTRACE_GETREGS:  /* Get all registers from the child. */
        if (copy_to_user(datap, task_pt_regs(child),
                 sizeof(struct pt_regs)) == 0) {
            ret = 0;
        }
        break;

    case PTRACE_SETREGS:  /* Set all registers in the child. */
        if (copy_from_user(&copyregs, datap,
                   sizeof(struct pt_regs)) == 0) {
            copyregs.ex1 =
                PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1));
            *task_pt_regs(child) = copyregs;
            ret = 0;
        }
        break;

    case PTRACE_GETFPREGS:  /* Get the child FPU state. */
    case PTRACE_SETFPREGS:  /* Set the child FPU state. */
        break;

    case PTRACE_SETOPTIONS:
        /* Support TILE-specific ptrace options. */
        child->ptrace &= ~PT_TRACE_MASK_TILE;
        tmp = data & PTRACE_O_MASK_TILE;
        data &= ~PTRACE_O_MASK_TILE;
        ret = ptrace_request(child, request, addr, data);
        if (tmp & PTRACE_O_TRACEMIGRATE)
            child->ptrace |= PT_TRACE_MIGRATE;
        break;

    default:
#ifdef CONFIG_COMPAT
        if (task_thread_info(current)->status & TS_COMPAT) {
            ret = compat_ptrace_request(child, request,
                            addr, data);
            break;
        }
#endif
        ret = ptrace_request(child, request, addr, data);
        break;
    }

    return ret;
}

#ifdef CONFIG_COMPAT
/* Not used; we handle compat issues in arch_ptrace() directly. */
long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                   compat_ulong_t addr, compat_ulong_t data)
{
    BUG();
}
#endif

void do_syscall_trace(void)
{
    if (!test_thread_flag(TIF_SYSCALL_TRACE))
        return;

    if (!(current->ptrace & PT_PTRACED))
        return;

    /*
     * The 0x80 provides a way for the tracing parent to distinguish
     * between a syscall stop and SIGTRAP delivery
     */
    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;
    }
}

void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
{
    struct siginfo info;

    memset(&info, 0, sizeof(info));
    info.si_signo = SIGTRAP;
    info.si_code  = TRAP_BRKPT;
    info.si_addr  = (void __user *) regs->pc;

    /* Send us the fakey SIGTRAP */
    force_sig_info(SIGTRAP, &info, tsk);
}

/* Handle synthetic interrupt delivered only by the simulator. */
void __kprobes do_breakpoint(struct pt_regs* regs, int fault_num)
{
    send_sigtrap(current, regs, fault_num);
}