/*
 * arch/sh/kernel/ptrace_64.c
 *
 * Copyright (C) 2000, 2001  Paolo Alberelli
 * Copyright (C) 2003 - 2007  Paul Mundt
 *
 * Started from SH3/4 version:
 *   SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
 *
 *   Original x86 implementation:
 *      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/rwsem.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu_context.h>
#include <asm/fpu.h>

/* This mask defines the bits of the SR which the user is not allowed to
   change, which are everything except S, Q, M, PR, SZ, FR. */
#define SR_MASK      (0xffff8cfd)

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

/*
 * This routine will get a word from the user area in the process kernel stack.
 */
static inline int get_stack_long(struct task_struct *task, int offset)
{
        unsigned char *stack;

        stack = (unsigned char *)(task->thread.uregs);
        stack += offset;
        return (*((int *)stack));
}

static inline unsigned long
get_fpu_long(struct task_struct *task, unsigned long addr)
{
        unsigned long tmp;
        struct pt_regs *regs;
        regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;

        if (!tsk_used_math(task)) {
                if (addr == offsetof(struct user_fpu_struct, fpscr)) {
                        tmp = FPSCR_INIT;
                } else {
                        tmp = 0xffffffffUL; /* matches initial value in fpu.c */
                }
                return tmp;
        }

        if (last_task_used_math == task) {
                enable_fpu();
                save_fpu(task, regs);
                disable_fpu();
                last_task_used_math = 0;
                regs->sr |= SR_FD;
        }

        tmp = ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)];
        return tmp;
}

/*
 * This routine will put a word into the user area in the process kernel stack.
 */
static inline int put_stack_long(struct task_struct *task, int offset,
                                 unsigned long data)
{
        unsigned char *stack;

        stack = (unsigned char *)(task->thread.uregs);
        stack += offset;
        *(unsigned long *) stack = data;
        return 0;
}

static inline int
put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
{
        struct pt_regs *regs;

        regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;

        if (!tsk_used_math(task)) {
                fpinit(&task->thread.fpu.hard);
                set_stopped_child_used_math(task);
        } else if (last_task_used_math == task) {
                enable_fpu();
                save_fpu(task, regs);
                disable_fpu();
                last_task_used_math = 0;
                regs->sr |= SR_FD;
        }

        ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)] = data;
        return 0;
}


long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
        int ret;

        switch (request) {
        /* when I and D space are separate, these will need to be fixed. */
        case PTRACE_PEEKTEXT: /* read word at location addr. */
        case PTRACE_PEEKDATA:
                ret = generic_ptrace_peekdata(child, addr, data);
                break;

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

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

                if (addr < sizeof(struct pt_regs))
                        tmp = get_stack_long(child, addr);
                else if ((addr >= offsetof(struct user, fpu)) &&
                         (addr <  offsetof(struct user, u_fpvalid))) {
                        tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
                } else if (addr == offsetof(struct user, u_fpvalid)) {
                        tmp = !!tsk_used_math(child);
                } else {
                        break;
                }
                ret = put_user(tmp, (unsigned long *)data);
                break;
        }

        /* when I and D space are separate, this will have to be fixed. */
        case PTRACE_POKETEXT: /* write the word at location addr. */
        case PTRACE_POKEDATA:
                ret = generic_ptrace_pokedata(child, addr, data);
                break;

        case PTRACE_POKEUSR:
                /* write the word at location addr in the USER area. We must
                   disallow any changes to certain SR bits or u_fpvalid, since
                   this could crash the kernel or result in a security
                   loophole. */
                ret = -EIO;
                if ((addr & 3) || addr < 0)
                        break;

                if (addr < sizeof(struct pt_regs)) {
                        /* Ignore change of top 32 bits of SR */
                        if (addr == offsetof (struct pt_regs, sr)+4)
                        {
                                ret = 0;
                                break;
                        }
                        /* If lower 32 bits of SR, ignore non-user bits */
                        if (addr == offsetof (struct pt_regs, sr))
                        {
                                long cursr = get_stack_long(child, addr);
                                data &= ~(SR_MASK);
                                data |= (cursr & SR_MASK);
                        }
                        ret = put_stack_long(child, addr, data);
                }
                else if ((addr >= offsetof(struct user, fpu)) &&
                         (addr <  offsetof(struct user, u_fpvalid))) {
                        ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
                }
                break;

        case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
        case PTRACE_CONT: { /* restart after signal. */
                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;
                wake_up_process(child);
                ret = 0;
                break;
        }

/*
 * 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: {
                ret = 0;
                if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
                        break;
                child->exit_code = SIGKILL;
                wake_up_process(child);
                break;
        }

        case PTRACE_SINGLESTEP: {  /* set the trap flag. */
                struct pt_regs *regs;

                ret = -EIO;
                if (!valid_signal(data))
                        break;
                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                if ((child->ptrace & PT_DTRACE) == 0) {
                        /* Spurious delayed TF traps may occur */
                        child->ptrace |= PT_DTRACE;
                }

                regs = child->thread.uregs;

                regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */

                child->exit_code = data;
                /* give it a chance to run. */
                wake_up_process(child);
                ret = 0;
                break;
        }

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

asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
{
#define WPC_DBRMODE 0x0d104008
        static int first_call = 1;

        lock_kernel();
        if (first_call) {
                /* Set WPC.DBRMODE to 0.  This makes all debug events get
                 * delivered through RESVEC, i.e. into the handlers in entry.S.
                 * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
                 * would normally be left set to 1, which makes debug events get
                 * delivered through DBRVEC, i.e. into the remote gdb's
                 * handlers.  This prevents ptrace getting them, and confuses
                 * the remote gdb.) */
                printk("DBRMODE set to 0 to permit native debugging\n");
                poke_real_address_q(WPC_DBRMODE, 0);
                first_call = 0;
        }
        unlock_kernel();

        return sys_ptrace(request, pid, addr, data);
}

asmlinkage void syscall_trace(struct pt_regs *regs, int entryexit)
{
        struct task_struct *tsk = current;

        if (unlikely(current->audit_context) && entryexit)
                audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
                                   regs->regs[9]);

        if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
            !test_thread_flag(TIF_SINGLESTEP))
                goto out;
        if (!(tsk->ptrace & PT_PTRACED))
                goto out;

        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
                                !test_thread_flag(TIF_SINGLESTEP) ? 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 (tsk->exit_code) {
                send_sig(tsk->exit_code, tsk, 1);
                tsk->exit_code = 0;
        }

out:
        if (unlikely(current->audit_context) && !entryexit)
                audit_syscall_entry(AUDIT_ARCH_SH, regs->regs[1],
                                    regs->regs[2], regs->regs[3],
                                    regs->regs[4], regs->regs[5]);
}

/* Called with interrupts disabled */
asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
{
        /* This is called after a single step exception (DEBUGSS).
           There is no need to change the PC, as it is a post-execution
           exception, as entry.S does not do anything to the PC for DEBUGSS.
           We need to clear the Single Step setting in SR to avoid
           continually stepping. */
        local_irq_enable();
        regs->sr &= ~SR_SSTEP;
        force_sig(SIGTRAP, current);
}

/* Called with interrupts disabled */
asmlinkage void do_software_break_point(unsigned long long vec,
                                        struct pt_regs *regs)
{
        /* We need to forward step the PC, to counteract the backstep done
           in signal.c. */
        local_irq_enable();
        force_sig(SIGTRAP, current);
        regs->pc += 4;
}

/*
 * 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.. */
}