/*
 * Based on arch/arm/kernel/ptrace.c
 *
 * By Ross Biro 1/23/92
 * edited by Linus Torvalds
 * ARM modifications Copyright (C) 2000 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/audit.h>
#include <linux/compat.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/elf.h>

#include <asm/compat.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
#include <asm/syscall.h>
#include <asm/traps.h>
#include <asm/system_misc.h>

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

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

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

#ifdef CONFIG_HAVE_HW_BREAKPOINT
/*
 * Handle hitting a HW-breakpoint.
 */
static void ptrace_hbptriggered(struct perf_event *bp,
                                struct perf_sample_data *data,
                                struct pt_regs *regs)
{
        struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
        siginfo_t info = {
                .si_signo       = SIGTRAP,
                .si_errno       = 0,
                .si_code        = TRAP_HWBKPT,
                .si_addr        = (void __user *)(bkpt->trigger),
        };

#ifdef CONFIG_COMPAT
        int i;

        if (!is_compat_task())
                goto send_sig;

        for (i = 0; i < ARM_MAX_BRP; ++i) {
                if (current->thread.debug.hbp_break[i] == bp) {
                        info.si_errno = (i << 1) + 1;
                        break;
                }
        }

        for (i = 0; i < ARM_MAX_WRP; ++i) {
                if (current->thread.debug.hbp_watch[i] == bp) {
                        info.si_errno = -((i << 1) + 1);
                        break;
                }
        }

send_sig:
#endif
        force_sig_info(SIGTRAP, &info, current);
}

/*
 * Unregister breakpoints from this task and reset the pointers in
 * the thread_struct.
 */
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
        int i;
        struct thread_struct *t = &tsk->thread;

        for (i = 0; i < ARM_MAX_BRP; i++) {
                if (t->debug.hbp_break[i]) {
                        unregister_hw_breakpoint(t->debug.hbp_break[i]);
                        t->debug.hbp_break[i] = NULL;
                }
        }

        for (i = 0; i < ARM_MAX_WRP; i++) {
                if (t->debug.hbp_watch[i]) {
                        unregister_hw_breakpoint(t->debug.hbp_watch[i]);
                        t->debug.hbp_watch[i] = NULL;
                }
        }
}

void ptrace_hw_copy_thread(struct task_struct *tsk)
{
        memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
}

static struct perf_event *ptrace_hbp_get_event(unsigned int note_type,
                                               struct task_struct *tsk,
                                               unsigned long idx)
{
        struct perf_event *bp = ERR_PTR(-EINVAL);

        switch (note_type) {
        case NT_ARM_HW_BREAK:
                if (idx < ARM_MAX_BRP)
                        bp = tsk->thread.debug.hbp_break[idx];
                break;
        case NT_ARM_HW_WATCH:
                if (idx < ARM_MAX_WRP)
                        bp = tsk->thread.debug.hbp_watch[idx];
                break;
        }

        return bp;
}

static int ptrace_hbp_set_event(unsigned int note_type,
                                struct task_struct *tsk,
                                unsigned long idx,
                                struct perf_event *bp)
{
        int err = -EINVAL;

        switch (note_type) {
        case NT_ARM_HW_BREAK:
                if (idx < ARM_MAX_BRP) {
                        tsk->thread.debug.hbp_break[idx] = bp;
                        err = 0;
                }
                break;
        case NT_ARM_HW_WATCH:
                if (idx < ARM_MAX_WRP) {
                        tsk->thread.debug.hbp_watch[idx] = bp;
                        err = 0;
                }
                break;
        }

        return err;
}

static struct perf_event *ptrace_hbp_create(unsigned int note_type,
                                            struct task_struct *tsk,
                                            unsigned long idx)
{
        struct perf_event *bp;
        struct perf_event_attr attr;
        int err, type;

        switch (note_type) {
        case NT_ARM_HW_BREAK:
                type = HW_BREAKPOINT_X;
                break;
        case NT_ARM_HW_WATCH:
                type = HW_BREAKPOINT_RW;
                break;
        default:
                return ERR_PTR(-EINVAL);
        }

        ptrace_breakpoint_init(&attr);

        /*
         * Initialise fields to sane defaults
         * (i.e. values that will pass validation).
         */
        attr.bp_addr    = 0;
        attr.bp_len     = HW_BREAKPOINT_LEN_4;
        attr.bp_type    = type;
        attr.disabled   = 1;

        bp = register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL, tsk);
        if (IS_ERR(bp))
                return bp;

        err = ptrace_hbp_set_event(note_type, tsk, idx, bp);
        if (err)
                return ERR_PTR(err);

        return bp;
}

static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
                                     struct arch_hw_breakpoint_ctrl ctrl,
                                     struct perf_event_attr *attr)
{
        int err, len, type, disabled = !ctrl.enabled;

        attr->disabled = disabled;
        if (disabled)
                return 0;

        err = arch_bp_generic_fields(ctrl, &len, &type);
        if (err)
                return err;

        switch (note_type) {
        case NT_ARM_HW_BREAK:
                if ((type & HW_BREAKPOINT_X) != type)
                        return -EINVAL;
                break;
        case NT_ARM_HW_WATCH:
                if ((type & HW_BREAKPOINT_RW) != type)
                        return -EINVAL;
                break;
        default:
                return -EINVAL;
        }

        attr->bp_len    = len;
        attr->bp_type   = type;

        return 0;
}

static int ptrace_hbp_get_resource_info(unsigned int note_type, u32 *info)
{
        u8 num;
        u32 reg = 0;

        switch (note_type) {
        case NT_ARM_HW_BREAK:
                num = hw_breakpoint_slots(TYPE_INST);
                break;
        case NT_ARM_HW_WATCH:
                num = hw_breakpoint_slots(TYPE_DATA);
                break;
        default:
                return -EINVAL;
        }

        reg |= debug_monitors_arch();
        reg <<= 8;
        reg |= num;

        *info = reg;
        return 0;
}

static int ptrace_hbp_get_ctrl(unsigned int note_type,
                               struct task_struct *tsk,
                               unsigned long idx,
                               u32 *ctrl)
{
        struct perf_event *bp = ptrace_hbp_get_event(note_type, tsk, idx);

        if (IS_ERR(bp))
                return PTR_ERR(bp);

        *ctrl = bp ? encode_ctrl_reg(counter_arch_bp(bp)->ctrl) : 0;
        return 0;
}

static int ptrace_hbp_get_addr(unsigned int note_type,
                               struct task_struct *tsk,
                               unsigned long idx,
                               u64 *addr)
{
        struct perf_event *bp = ptrace_hbp_get_event(note_type, tsk, idx);

        if (IS_ERR(bp))
                return PTR_ERR(bp);

        *addr = bp ? bp->attr.bp_addr : 0;
        return 0;
}

static struct perf_event *ptrace_hbp_get_initialised_bp(unsigned int note_type,
                                                        struct task_struct *tsk,
                                                        unsigned long idx)
{
        struct perf_event *bp = ptrace_hbp_get_event(note_type, tsk, idx);

        if (!bp)
                bp = ptrace_hbp_create(note_type, tsk, idx);

        return bp;
}

static int ptrace_hbp_set_ctrl(unsigned int note_type,
                               struct task_struct *tsk,
                               unsigned long idx,
                               u32 uctrl)
{
        int err;
        struct perf_event *bp;
        struct perf_event_attr attr;
        struct arch_hw_breakpoint_ctrl ctrl;

        bp = ptrace_hbp_get_initialised_bp(note_type, tsk, idx);
        if (IS_ERR(bp)) {
                err = PTR_ERR(bp);
                return err;
        }

        attr = bp->attr;
        decode_ctrl_reg(uctrl, &ctrl);
        err = ptrace_hbp_fill_attr_ctrl(note_type, ctrl, &attr);
        if (err)
                return err;

        return modify_user_hw_breakpoint(bp, &attr);
}

static int ptrace_hbp_set_addr(unsigned int note_type,
                               struct task_struct *tsk,
                               unsigned long idx,
                               u64 addr)
{
        int err;
        struct perf_event *bp;
        struct perf_event_attr attr;

        bp = ptrace_hbp_get_initialised_bp(note_type, tsk, idx);
        if (IS_ERR(bp)) {
                err = PTR_ERR(bp);
                return err;
        }

        attr = bp->attr;
        attr.bp_addr = addr;
        err = modify_user_hw_breakpoint(bp, &attr);
        return err;
}

#define PTRACE_HBP_ADDR_SZ      sizeof(u64)
#define PTRACE_HBP_CTRL_SZ      sizeof(u32)
#define PTRACE_HBP_PAD_SZ       sizeof(u32)

static int hw_break_get(struct task_struct *target,
                        const struct user_regset *regset,
                        unsigned int pos, unsigned int count,
                        void *kbuf, void __user *ubuf)
{
        unsigned int note_type = regset->core_note_type;
        int ret, idx = 0, offset, limit;
        u32 info, ctrl;
        u64 addr;

        /* Resource info */
        ret = ptrace_hbp_get_resource_info(note_type, &info);
        if (ret)
                return ret;

        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &info, 0,
                                  sizeof(info));
        if (ret)
                return ret;

        /* Pad */
        offset = offsetof(struct user_hwdebug_state, pad);
        ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, offset,
                                       offset + PTRACE_HBP_PAD_SZ);
        if (ret)
                return ret;

        /* (address, ctrl) registers */
        offset = offsetof(struct user_hwdebug_state, dbg_regs);
        limit = regset->n * regset->size;
        while (count && offset < limit) {
                ret = ptrace_hbp_get_addr(note_type, target, idx, &addr);
                if (ret)
                        return ret;
                ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &addr,
                                          offset, offset + PTRACE_HBP_ADDR_SZ);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_ADDR_SZ;

                ret = ptrace_hbp_get_ctrl(note_type, target, idx, &ctrl);
                if (ret)
                        return ret;
                ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &ctrl,
                                          offset, offset + PTRACE_HBP_CTRL_SZ);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_CTRL_SZ;

                ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                                               offset,
                                               offset + PTRACE_HBP_PAD_SZ);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_PAD_SZ;
                idx++;
        }

        return 0;
}

static int hw_break_set(struct task_struct *target,
                        const struct user_regset *regset,
                        unsigned int pos, unsigned int count,
                        const void *kbuf, const void __user *ubuf)
{
        unsigned int note_type = regset->core_note_type;
        int ret, idx = 0, offset, limit;
        u32 ctrl;
        u64 addr;

        /* Resource info and pad */
        offset = offsetof(struct user_hwdebug_state, dbg_regs);
        ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, offset);
        if (ret)
                return ret;

        /* (address, ctrl) registers */
        limit = regset->n * regset->size;
        while (count && offset < limit) {
                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &addr,
                                         offset, offset + PTRACE_HBP_ADDR_SZ);
                if (ret)
                        return ret;
                ret = ptrace_hbp_set_addr(note_type, target, idx, addr);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_ADDR_SZ;

                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ctrl,
                                         offset, offset + PTRACE_HBP_CTRL_SZ);
                if (ret)
                        return ret;
                ret = ptrace_hbp_set_ctrl(note_type, target, idx, ctrl);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_CTRL_SZ;

                ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                                                offset,
                                                offset + PTRACE_HBP_PAD_SZ);
                if (ret)
                        return ret;
                offset += PTRACE_HBP_PAD_SZ;
                idx++;
        }

        return 0;
}
#endif  /* CONFIG_HAVE_HW_BREAKPOINT */

static int gpr_get(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
        struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs;
        return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
}

static int 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 user_pt_regs newregs;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newregs, 0, -1);
        if (ret)
                return ret;

        if (!valid_user_regs(&newregs))
                return -EINVAL;

        task_pt_regs(target)->user_regs = newregs;
        return 0;
}

/*
 * TODO: update fp accessors for lazy context switching (sync/flush hwstate)
 */
static int fpr_get(struct task_struct *target, const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
        struct user_fpsimd_state *uregs;
        uregs = &target->thread.fpsimd_state.user_fpsimd;
        return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
}

static int fpr_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 user_fpsimd_state newstate;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate, 0, -1);
        if (ret)
                return ret;

        target->thread.fpsimd_state.user_fpsimd = newstate;
        fpsimd_flush_task_state(target);
        return ret;
}

static int tls_get(struct task_struct *target, const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
        unsigned long *tls = &target->thread.tp_value;
        return user_regset_copyout(&pos, &count, &kbuf, &ubuf, tls, 0, -1);
}

static int tls_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;
        unsigned long tls;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);
        if (ret)
                return ret;

        target->thread.tp_value = tls;
        return ret;
}

enum aarch64_regset {
        REGSET_GPR,
        REGSET_FPR,
        REGSET_TLS,
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        REGSET_HW_BREAK,
        REGSET_HW_WATCH,
#endif
};

static const struct user_regset aarch64_regsets[] = {
        [REGSET_GPR] = {
                .core_note_type = NT_PRSTATUS,
                .n = sizeof(struct user_pt_regs) / sizeof(u64),
                .size = sizeof(u64),
                .align = sizeof(u64),
                .get = gpr_get,
                .set = gpr_set
        },
        [REGSET_FPR] = {
                .core_note_type = NT_PRFPREG,
                .n = sizeof(struct user_fpsimd_state) / sizeof(u32),
                /*
                 * We pretend we have 32-bit registers because the fpsr and
                 * fpcr are 32-bits wide.
                 */
                .size = sizeof(u32),
                .align = sizeof(u32),
                .get = fpr_get,
                .set = fpr_set
        },
        [REGSET_TLS] = {
                .core_note_type = NT_ARM_TLS,
                .n = 1,
                .size = sizeof(void *),
                .align = sizeof(void *),
                .get = tls_get,
                .set = tls_set,
        },
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        [REGSET_HW_BREAK] = {
                .core_note_type = NT_ARM_HW_BREAK,
                .n = sizeof(struct user_hwdebug_state) / sizeof(u32),
                .size = sizeof(u32),
                .align = sizeof(u32),
                .get = hw_break_get,
                .set = hw_break_set,
        },
        [REGSET_HW_WATCH] = {
                .core_note_type = NT_ARM_HW_WATCH,
                .n = sizeof(struct user_hwdebug_state) / sizeof(u32),
                .size = sizeof(u32),
                .align = sizeof(u32),
                .get = hw_break_get,
                .set = hw_break_set,
        },
#endif
};

static const struct user_regset_view user_aarch64_view = {
        .name = "aarch64", .e_machine = EM_AARCH64,
        .regsets = aarch64_regsets, .n = ARRAY_SIZE(aarch64_regsets)
};

#ifdef CONFIG_COMPAT
#include <linux/compat.h>

enum compat_regset {
        REGSET_COMPAT_GPR,
        REGSET_COMPAT_VFP,
};

static int compat_gpr_get(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          void *kbuf, void __user *ubuf)
{
        int ret = 0;
        unsigned int i, start, num_regs;

        /* Calculate the number of AArch32 registers contained in count */
        num_regs = count / regset->size;

        /* Convert pos into an register number */
        start = pos / regset->size;

        if (start + num_regs > regset->n)
                return -EIO;

        for (i = 0; i < num_regs; ++i) {
                unsigned int idx = start + i;
                compat_ulong_t reg;

                switch (idx) {
                case 15:
                        reg = task_pt_regs(target)->pc;
                        break;
                case 16:
                        reg = task_pt_regs(target)->pstate;
                        break;
                case 17:
                        reg = task_pt_regs(target)->orig_x0;
                        break;
                default:
                        reg = task_pt_regs(target)->regs[idx];
                }

                if (kbuf) {
                        memcpy(kbuf, &reg, sizeof(reg));
                        kbuf += sizeof(reg);
                } else {
                        ret = copy_to_user(ubuf, &reg, sizeof(reg));
                        if (ret) {
                                ret = -EFAULT;
                                break;
                        }

                        ubuf += sizeof(reg);
                }
        }

        return ret;
}

static int compat_gpr_set(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          const void *kbuf, const void __user *ubuf)
{
        struct pt_regs newregs;
        int ret = 0;
        unsigned int i, start, num_regs;

        /* Calculate the number of AArch32 registers contained in count */
        num_regs = count / regset->size;

        /* Convert pos into an register number */
        start = pos / regset->size;

        if (start + num_regs > regset->n)
                return -EIO;

        newregs = *task_pt_regs(target);

        for (i = 0; i < num_regs; ++i) {
                unsigned int idx = start + i;
                compat_ulong_t reg;

                if (kbuf) {
                        memcpy(&reg, kbuf, sizeof(reg));
                        kbuf += sizeof(reg);
                } else {
                        ret = copy_from_user(&reg, ubuf, sizeof(reg));
                        if (ret) {
                                ret = -EFAULT;
                                break;
                        }

                        ubuf += sizeof(reg);
                }

                switch (idx) {
                case 15:
                        newregs.pc = reg;
                        break;
                case 16:
                        newregs.pstate = reg;
                        break;
                case 17:
                        newregs.orig_x0 = reg;
                        break;
                default:
                        newregs.regs[idx] = reg;
                }

        }

        if (valid_user_regs(&newregs.user_regs))
                *task_pt_regs(target) = newregs;
        else
                ret = -EINVAL;

        return ret;
}

static int compat_vfp_get(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          void *kbuf, void __user *ubuf)
{
        struct user_fpsimd_state *uregs;
        compat_ulong_t fpscr;
        int ret;

        uregs = &target->thread.fpsimd_state.user_fpsimd;

        /*
         * The VFP registers are packed into the fpsimd_state, so they all sit
         * nicely together for us. We just need to create the fpscr separately.
         */
        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
                                  VFP_STATE_SIZE - sizeof(compat_ulong_t));

        if (count && !ret) {
                fpscr = (uregs->fpsr & VFP_FPSCR_STAT_MASK) |
                        (uregs->fpcr & VFP_FPSCR_CTRL_MASK);
                ret = put_user(fpscr, (compat_ulong_t *)ubuf);
        }

        return ret;
}

static int compat_vfp_set(struct task_struct *target,
                          const struct user_regset *regset,
                          unsigned int pos, unsigned int count,
                          const void *kbuf, const void __user *ubuf)
{
        struct user_fpsimd_state *uregs;
        compat_ulong_t fpscr;
        int ret;

        if (pos + count > VFP_STATE_SIZE)
                return -EIO;

        uregs = &target->thread.fpsimd_state.user_fpsimd;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,
                                 VFP_STATE_SIZE - sizeof(compat_ulong_t));

        if (count && !ret) {
                ret = get_user(fpscr, (compat_ulong_t *)ubuf);
                uregs->fpsr = fpscr & VFP_FPSCR_STAT_MASK;
                uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
        }

        fpsimd_flush_task_state(target);
        return ret;
}

static const struct user_regset aarch32_regsets[] = {
        [REGSET_COMPAT_GPR] = {
                .core_note_type = NT_PRSTATUS,
                .n = COMPAT_ELF_NGREG,
                .size = sizeof(compat_elf_greg_t),
                .align = sizeof(compat_elf_greg_t),
                .get = compat_gpr_get,
                .set = compat_gpr_set
        },
        [REGSET_COMPAT_VFP] = {
                .core_note_type = NT_ARM_VFP,
                .n = VFP_STATE_SIZE / sizeof(compat_ulong_t),
                .size = sizeof(compat_ulong_t),
                .align = sizeof(compat_ulong_t),
                .get = compat_vfp_get,
                .set = compat_vfp_set
        },
};

static const struct user_regset_view user_aarch32_view = {
        .name = "aarch32", .e_machine = EM_ARM,
        .regsets = aarch32_regsets, .n = ARRAY_SIZE(aarch32_regsets)
};

static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
                                   compat_ulong_t __user *ret)
{
        compat_ulong_t tmp;

        if (off & 3)
                return -EIO;

        if (off == COMPAT_PT_TEXT_ADDR)
                tmp = tsk->mm->start_code;
        else if (off == COMPAT_PT_DATA_ADDR)
                tmp = tsk->mm->start_data;
        else if (off == COMPAT_PT_TEXT_END_ADDR)
                tmp = tsk->mm->end_code;
        else if (off < sizeof(compat_elf_gregset_t))
                return copy_regset_to_user(tsk, &user_aarch32_view,
                                           REGSET_COMPAT_GPR, off,
                                           sizeof(compat_ulong_t), ret);
        else if (off >= COMPAT_USER_SZ)
                return -EIO;
        else
                tmp = 0;

        return put_user(tmp, ret);
}

static int compat_ptrace_write_user(struct task_struct *tsk, compat_ulong_t off,
                                    compat_ulong_t val)
{
        int ret;
        mm_segment_t old_fs = get_fs();

        if (off & 3 || off >= COMPAT_USER_SZ)
                return -EIO;

        if (off >= sizeof(compat_elf_gregset_t))
                return 0;

        set_fs(KERNEL_DS);
        ret = copy_regset_from_user(tsk, &user_aarch32_view,
                                    REGSET_COMPAT_GPR, off,
                                    sizeof(compat_ulong_t),
                                    &val);
        set_fs(old_fs);

        return ret;
}

#ifdef CONFIG_HAVE_HW_BREAKPOINT

/*
 * Convert a virtual register number into an index for a thread_info
 * breakpoint array. Breakpoints are identified using positive numbers
 * whilst watchpoints are negative. The registers are laid out as pairs
 * of (address, control), each pair mapping to a unique hw_breakpoint struct.
 * Register 0 is reserved for describing resource information.
 */
static int compat_ptrace_hbp_num_to_idx(compat_long_t num)
{
        return (abs(num) - 1) >> 1;
}

static int compat_ptrace_hbp_get_resource_info(u32 *kdata)
{
        u8 num_brps, num_wrps, debug_arch, wp_len;
        u32 reg = 0;

        num_brps        = hw_breakpoint_slots(TYPE_INST);
        num_wrps        = hw_breakpoint_slots(TYPE_DATA);

        debug_arch      = debug_monitors_arch();
        wp_len          = 8;
        reg             |= debug_arch;
        reg             <<= 8;
        reg             |= wp_len;
        reg             <<= 8;
        reg             |= num_wrps;
        reg             <<= 8;
        reg             |= num_brps;

        *kdata = reg;
        return 0;
}

static int compat_ptrace_hbp_get(unsigned int note_type,
                                 struct task_struct *tsk,
                                 compat_long_t num,
                                 u32 *kdata)
{
        u64 addr = 0;
        u32 ctrl = 0;

        int err, idx = compat_ptrace_hbp_num_to_idx(num);;

        if (num & 1) {
                err = ptrace_hbp_get_addr(note_type, tsk, idx, &addr);
                *kdata = (u32)addr;
        } else {
                err = ptrace_hbp_get_ctrl(note_type, tsk, idx, &ctrl);
                *kdata = ctrl;
        }

        return err;
}

static int compat_ptrace_hbp_set(unsigned int note_type,
                                 struct task_struct *tsk,
                                 compat_long_t num,
                                 u32 *kdata)
{
        u64 addr;
        u32 ctrl;

        int err, idx = compat_ptrace_hbp_num_to_idx(num);

        if (num & 1) {
                addr = *kdata;
                err = ptrace_hbp_set_addr(note_type, tsk, idx, addr);
        } else {
                ctrl = *kdata;
                err = ptrace_hbp_set_ctrl(note_type, tsk, idx, ctrl);
        }

        return err;
}

static int compat_ptrace_gethbpregs(struct task_struct *tsk, compat_long_t num,
                                    compat_ulong_t __user *data)
{
        int ret;
        u32 kdata;
        mm_segment_t old_fs = get_fs();

        set_fs(KERNEL_DS);
        /* Watchpoint */
        if (num < 0) {
                ret = compat_ptrace_hbp_get(NT_ARM_HW_WATCH, tsk, num, &kdata);
        /* Resource info */
        } else if (num == 0) {
                ret = compat_ptrace_hbp_get_resource_info(&kdata);
        /* Breakpoint */
        } else {
                ret = compat_ptrace_hbp_get(NT_ARM_HW_BREAK, tsk, num, &kdata);
        }
        set_fs(old_fs);

        if (!ret)
                ret = put_user(kdata, data);

        return ret;
}

static int compat_ptrace_sethbpregs(struct task_struct *tsk, compat_long_t num,
                                    compat_ulong_t __user *data)
{
        int ret;
        u32 kdata = 0;
        mm_segment_t old_fs = get_fs();

        if (num == 0)
                return 0;

        ret = get_user(kdata, data);
        if (ret)
                return ret;

        set_fs(KERNEL_DS);
        if (num < 0)
                ret = compat_ptrace_hbp_set(NT_ARM_HW_WATCH, tsk, num, &kdata);
        else
                ret = compat_ptrace_hbp_set(NT_ARM_HW_BREAK, tsk, num, &kdata);
        set_fs(old_fs);

        return ret;
}
#endif  /* CONFIG_HAVE_HW_BREAKPOINT */

long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                        compat_ulong_t caddr, compat_ulong_t cdata)
{
        unsigned long addr = caddr;
        unsigned long data = cdata;
        void __user *datap = compat_ptr(data);
        int ret;

        switch (request) {
                case PTRACE_PEEKUSR:
                        ret = compat_ptrace_read_user(child, addr, datap);
                        break;

                case PTRACE_POKEUSR:
                        ret = compat_ptrace_write_user(child, addr, data);
                        break;

                case COMPAT_PTRACE_GETREGS:
                        ret = copy_regset_to_user(child,
                                                  &user_aarch32_view,
                                                  REGSET_COMPAT_GPR,
                                                  0, sizeof(compat_elf_gregset_t),
                                                  datap);
                        break;

                case COMPAT_PTRACE_SETREGS:
                        ret = copy_regset_from_user(child,
                                                    &user_aarch32_view,
                                                    REGSET_COMPAT_GPR,
                                                    0, sizeof(compat_elf_gregset_t),
                                                    datap);
                        break;

                case COMPAT_PTRACE_GET_THREAD_AREA:
                        ret = put_user((compat_ulong_t)child->thread.tp_value,
                                       (compat_ulong_t __user *)datap);
                        break;

                case COMPAT_PTRACE_SET_SYSCALL:
                        task_pt_regs(child)->syscallno = data;
                        ret = 0;
                        break;

                case COMPAT_PTRACE_GETVFPREGS:
                        ret = copy_regset_to_user(child,
                                                  &user_aarch32_view,
                                                  REGSET_COMPAT_VFP,
                                                  0, VFP_STATE_SIZE,
                                                  datap);
                        break;

                case COMPAT_PTRACE_SETVFPREGS:
                        ret = copy_regset_from_user(child,
                                                    &user_aarch32_view,
                                                    REGSET_COMPAT_VFP,
                                                    0, VFP_STATE_SIZE,
                                                    datap);
                        break;

#ifdef CONFIG_HAVE_HW_BREAKPOINT
                case COMPAT_PTRACE_GETHBPREGS:
                        ret = compat_ptrace_gethbpregs(child, addr, datap);
                        break;

                case COMPAT_PTRACE_SETHBPREGS:
                        ret = compat_ptrace_sethbpregs(child, addr, datap);
                        break;
#endif

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

        return ret;
}
#endif /* CONFIG_COMPAT */

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_COMPAT
        if (is_compat_thread(task_thread_info(task)))
                return &user_aarch32_view;
#endif
        return &user_aarch64_view;
}

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        return ptrace_request(child, request, addr, data);
}

enum ptrace_syscall_dir {
        PTRACE_SYSCALL_ENTER = 0,
        PTRACE_SYSCALL_EXIT,
};

static void tracehook_report_syscall(struct pt_regs *regs,
                                     enum ptrace_syscall_dir dir)
{
        int regno;
        unsigned long saved_reg;

        /*
         * A scratch register (ip(r12) on AArch32, x7 on AArch64) is
         * used to denote syscall entry/exit:
         */
        regno = (is_compat_task() ? 12 : 7);
        saved_reg = regs->regs[regno];
        regs->regs[regno] = dir;

        if (dir == PTRACE_SYSCALL_EXIT)
                tracehook_report_syscall_exit(regs, 0);
        else if (tracehook_report_syscall_entry(regs))
                regs->syscallno = ~0UL;

        regs->regs[regno] = saved_reg;
}

asmlinkage int syscall_trace_enter(struct pt_regs *regs)
{
        if (test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_enter(regs, regs->syscallno);

        audit_syscall_entry(syscall_get_arch(), regs->syscallno,
                regs->orig_x0, regs->regs[1], regs->regs[2], regs->regs[3]);

        return regs->syscallno;
}

asmlinkage void syscall_trace_exit(struct pt_regs *regs)
{
        audit_syscall_exit(regs);

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_exit(regs, regs_return_value(regs));

        if (test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);
}