/*
 * 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 <linux/regset.h>
#include <linux/elf.h>
#include <linux/tracehook.h>
#include <asm/traps.h>
#include <arch/chip.h>

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.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);
}

/*
 * Get registers from task and ready the result for userspace.
 * Note that we localize the API issues to getregs() and putregs() at
 * some cost in performance, e.g. we need a full pt_regs copy for
 * PEEKUSR, and two copies for POKEUSR.  But in general we expect
 * GETREGS/PUTREGS to be the API of choice anyway.
 */
static char *getregs(struct task_struct *child, struct pt_regs *uregs)
{
        *uregs = *task_pt_regs(child);

        /* Set up flags ABI bits. */
        uregs->flags = 0;
#ifdef CONFIG_COMPAT
        if (task_thread_info(child)->status & TS_COMPAT)
                uregs->flags |= PT_FLAGS_COMPAT;
#endif

        return (char *)uregs;
}

/* Put registers back to task. */
static void putregs(struct task_struct *child, struct pt_regs *uregs)
{
        struct pt_regs *regs = task_pt_regs(child);

        /* Don't allow overwriting the kernel-internal flags word. */
        uregs->flags = regs->flags;

        /* Only allow setting the ICS bit in the ex1 word. */
        uregs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(uregs->ex1));

        *regs = *uregs;
}

enum tile_regset {
        REGSET_GPR,
};

static int tile_gpr_get(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          void *kbuf, void __user *ubuf)
{
        struct pt_regs regs;

        getregs(target, &regs);

        return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &regs, 0,
                                   sizeof(regs));
}

static int tile_gpr_set(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          const void *kbuf, const void __user *ubuf)
{
        int ret;
        struct pt_regs regs;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &regs, 0,
                                 sizeof(regs));
        if (ret)
                return ret;

        putregs(target, &regs);

        return 0;
}

static const struct user_regset tile_user_regset[] = {
        [REGSET_GPR] = {
                .core_note_type = NT_PRSTATUS,
                .n = ELF_NGREG,
                .size = sizeof(elf_greg_t),
                .align = sizeof(elf_greg_t),
                .get = tile_gpr_get,
                .set = tile_gpr_set,
        },
};

static const struct user_regset_view tile_user_regset_view = {
        .name = CHIP_ARCH_NAME,
        .e_machine = ELF_ARCH,
        .ei_osabi = ELF_OSABI,
        .regsets = tile_user_regset,
        .n = ARRAY_SIZE(tile_user_regset),
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
        return &tile_user_regset_view;
}

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;

        switch (request) {

        case PTRACE_PEEKUSR:  /* Read register from pt_regs. */
                if (addr >= PTREGS_SIZE)
                        break;
                childreg = getregs(child, &copyregs) + 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 = getregs(child, &copyregs) + addr;
#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;
                }
                putregs(child, &copyregs);
                ret = 0;
                break;

        case PTRACE_GETREGS:  /* Get all registers from the child. */
                ret = copy_regset_to_user(child, &tile_user_regset_view,
                                          REGSET_GPR, 0,
                                          sizeof(struct pt_regs), datap);
                break;

        case PTRACE_SETREGS:  /* Set all registers in the child. */
                ret = copy_regset_from_user(child, &tile_user_regset_view,
                                            REGSET_GPR, 0,
                                            sizeof(struct pt_regs), datap);
                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. */
                BUILD_BUG_ON(PTRACE_O_MASK_TILE & PTRACE_O_MASK);
                tmp = data & PTRACE_O_MASK_TILE;
                data &= ~PTRACE_O_MASK_TILE;
                ret = ptrace_request(child, request, addr, data);
                if (ret == 0) {
                        unsigned int flags = child->ptrace;
                        flags &= ~(PTRACE_O_MASK_TILE << PT_OPT_FLAG_SHIFT);
                        flags |= (tmp << PT_OPT_FLAG_SHIFT);
                        child->ptrace = flags;
                }
                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

int do_syscall_trace_enter(struct pt_regs *regs)
{
        if (test_thread_flag(TIF_SYSCALL_TRACE)) {
                if (tracehook_report_syscall_entry(regs))
                        regs->regs[TREG_SYSCALL_NR] = -1;
        }

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_enter(regs, regs->regs[TREG_SYSCALL_NR]);

        return regs->regs[TREG_SYSCALL_NR];
}

void do_syscall_trace_exit(struct pt_regs *regs)
{
        long errno;

        /*
         * The standard tile calling convention returns the value (or negative
         * errno) in r0, and zero (or positive errno) in r1.
         * It saves a couple of cycles on the hot path to do this work in
         * registers only as we return, rather than updating the in-memory
         * struct ptregs.
         */
        errno = (long) regs->regs[0];
        if (errno < 0 && errno > -4096)
                regs->regs[1] = -errno;
        else
                regs->regs[1] = 0;

        if (test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall_exit(regs, 0);

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_exit(regs, regs->regs[0]);
}

void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs)
{
        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);
}