/*
 * Copyright (C) 2000-2003, Axis Communications AB.
 */

#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/security.h>

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

/* 
 * Determines which bits in DCCR the user has access to.
 * 1 = access, 0 = no access.
 */
#define DCCR_MASK 0x0000001f     /* XNZVC */

/*
 * Get contents of register REGNO in task TASK.
 */
inline long get_reg(struct task_struct *task, unsigned int regno)
{
        /* USP is a special case, it's not in the pt_regs struct but
         * in the tasks thread struct
         */

        if (regno == PT_USP)
                return task->thread.usp;
        else if (regno < PT_MAX)
                return ((unsigned long *)task_pt_regs(task))[regno];
        else
                return 0;
}

/*
 * Write contents of register REGNO in task TASK.
 */
inline int put_reg(struct task_struct *task, unsigned int regno,
                          unsigned long data)
{
        if (regno == PT_USP)
                task->thread.usp = data;
        else if (regno < PT_MAX)
                ((unsigned long *)task_pt_regs(task))[regno] = data;
        else
                return -1;
        return 0;
}

/*
 * Called by kernel/ptrace.c when detaching.
 *
 * Make sure the single step bit is not set.
 */
void 
ptrace_disable(struct task_struct *child)
{
       /* Todo - pending singlesteps? */
       clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}

/* 
 * Note that this implementation of ptrace behaves differently from vanilla
 * ptrace.  Contrary to what the man page says, in the PTRACE_PEEKTEXT,
 * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
 * ignored.  Instead, the data variable is expected to point at a location
 * (in user space) where the result of the ptrace call is written (instead of
 * being returned).
 */
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
        int ret;
        unsigned long __user *datap = (unsigned long __user *)data;

        switch (request) {
                /* Read word at location address. */ 
                case PTRACE_PEEKTEXT:
                case PTRACE_PEEKDATA:
                        ret = generic_ptrace_peekdata(child, addr, data);
                        break;

                /* Read the word at location address in the USER area. */
                case PTRACE_PEEKUSR: {
                        unsigned long tmp;

                        ret = -EIO;
                        if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                                break;

                        tmp = get_reg(child, addr >> 2);
                        ret = put_user(tmp, datap);
                        break;
                }
                
                /* Write the word at location address. */
                case PTRACE_POKETEXT:
                case PTRACE_POKEDATA:
                        ret = generic_ptrace_pokedata(child, addr, data);
                        break;
 
                /* Write the word at location address in the USER area. */
                case PTRACE_POKEUSR:
                        ret = -EIO;
                        if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                                break;

                        addr >>= 2;

                        if (addr == PT_DCCR) {
                                /* don't allow the tracing process to change stuff like
                                 * interrupt enable, kernel/user bit, dma enables etc.
                                 */
                                data &= DCCR_MASK;
                                data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
                        }
                        if (put_reg(child, addr, data))
                                break;
                        ret = 0;
                        break;

                case PTRACE_SYSCALL:
                case PTRACE_CONT:
                        ret = -EIO;
                        
                        if (!valid_signal(data))
                                break;
                        
                        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;
                        
                        /* TODO: make sure any pending breakpoint is killed */
                        wake_up_process(child);
                        ret = 0;
                        
                        break;
                
                /* Make the child exit by sending it a sigkill. */
                case PTRACE_KILL:
                        ret = 0;
                        
                        if (child->exit_state == EXIT_ZOMBIE)
                                break;
                        
                        child->exit_code = SIGKILL;
                        
                        /* TODO: make sure any pending breakpoint is killed */
                        wake_up_process(child);
                        break;

                /* Set the trap flag. */
                case PTRACE_SINGLESTEP:
                        ret = -EIO;
                        
                        if (!valid_signal(data))
                                break;
                        
                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                        /* TODO: set some clever breakpoint mechanism... */

                        child->exit_code = data;
                        wake_up_process(child);
                        ret = 0;
                        break;

                /* Get all GP registers from the child. */
                case PTRACE_GETREGS: {
                        int i;
                        unsigned long tmp;
                        
                        ret = 0;
                        for (i = 0; i <= PT_MAX; i++) {
                                tmp = get_reg(child, i);
                                
                                if (put_user(tmp, datap)) {
                                        ret = -EFAULT;
                                        break;
                                }
                                
                                data += sizeof(long);
                        }

                        break;
                }

                /* Set all GP registers in the child. */
                case PTRACE_SETREGS: {
                        int i;
                        unsigned long tmp;
                        
                        ret = 0;
                        for (i = 0; i <= PT_MAX; i++) {
                                if (get_user(tmp, datap)) {
                                        ret = -EFAULT;
                                        break;
                                }
                                
                                if (i == PT_DCCR) {
                                        tmp &= DCCR_MASK;
                                        tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
                                }
                                
                                put_reg(child, i, tmp);
                                data += sizeof(long);
                        }
                        
                        break;
                }

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

        return ret;
}

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