/*
 *  linux/arch/h8300/kernel/ptrace.c
 *
 *  Copyright 2015 Yoshinori Sato <ysato@users.sourceforge.jp>
 *
 * 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/errno.h>
#include <linux/ptrace.h>
#include <linux/audit.h>
#include <linux/tracehook.h>
#include <linux/regset.h>
#include <linux/elf.h>

#define CCR_MASK 0x6f    /* mode/imask not set */
#define EXR_MASK 0x80    /* modify only T */

#define PT_REG(r) offsetof(struct pt_regs, r)

extern void user_disable_single_step(struct task_struct *child);

/* Mapping from PT_xxx to the stack offset at which the register is
   saved.  Notice that usp has no stack-slot and needs to be treated
   specially (see get_reg/put_reg below). */
static const int register_offset[] = {
        PT_REG(er1), PT_REG(er2), PT_REG(er3), PT_REG(er4),
        PT_REG(er5), PT_REG(er6), PT_REG(er0), -1,
        PT_REG(orig_er0), PT_REG(ccr), PT_REG(pc),
#if defined(CONFIG_CPU_H8S)
        PT_REG(exr),
#endif
};

/* read register */
long h8300_get_reg(struct task_struct *task, int regno)
{
        switch (regno) {
        case PT_USP:
                return task->thread.usp + sizeof(long)*2;
        case PT_CCR:
        case PT_EXR:
            return *(unsigned short *)(task->thread.esp0 +
                                       register_offset[regno]);
        default:
            return *(unsigned long *)(task->thread.esp0 +
                                      register_offset[regno]);
        }
}

int h8300_put_reg(struct task_struct *task, int regno, unsigned long data)
{
        unsigned short oldccr;
        unsigned short oldexr;

        switch (regno) {
        case PT_USP:
                task->thread.usp = data - sizeof(long)*2;
        case PT_CCR:
                oldccr = *(unsigned short *)(task->thread.esp0 +
                                             register_offset[regno]);
                oldccr &= ~CCR_MASK;
                data &= CCR_MASK;
                data |= oldccr;
                *(unsigned short *)(task->thread.esp0 +
                                    register_offset[regno]) = data;
                break;
        case PT_EXR:
                oldexr = *(unsigned short *)(task->thread.esp0 +
                                             register_offset[regno]);
                oldccr &= ~EXR_MASK;
                data &= EXR_MASK;
                data |= oldexr;
                *(unsigned short *)(task->thread.esp0 +
                                    register_offset[regno]) = data;
                break;
        default:
                *(unsigned long *)(task->thread.esp0 +
                                   register_offset[regno]) = data;
                break;
        }
        return 0;
}

static int regs_get(struct task_struct *target,
                    const struct user_regset *regset,
                    struct membuf to)
{
        int r;

        BUILD_BUG_ON(sizeof(struct user_regs_struct) % sizeof(long) != 0);
        for (r = 0; r < ELF_NGREG; r++)
                membuf_store(&to, h8300_get_reg(target, r));

        return 0;
}

static int regs_set(struct task_struct *target,
                    const struct user_regset *regset,
                    unsigned int pos, unsigned int count,
                    const void *kbuf, const void __user *ubuf)
{
        int r;
        int ret;
        struct user_regs_struct regs;
        long *reg;

        /* build user regs in buffer */
        BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
        for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
                *reg++ = h8300_get_reg(target, r);

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

        /* write back to pt_regs */
        for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
                h8300_put_reg(target, r, *reg++);
        return 0;
}

enum h8300_regset {
        REGSET_GENERAL,
};

static const struct user_regset h8300_regsets[] = {
        [REGSET_GENERAL] = {
                .core_note_type = NT_PRSTATUS,
                .n              = ELF_NGREG,
                .size           = sizeof(long),
                .align          = sizeof(long),
                .regset_get             = regs_get,
                .set            = regs_set,
        },
};

static const struct user_regset_view user_h8300_native_view = {
        .name = "h8300",
        .e_machine = EM_H8_300,
        .regsets = h8300_regsets,
        .n = ARRAY_SIZE(h8300_regsets),
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
        return &user_h8300_native_view;
}

void ptrace_disable(struct task_struct *child)
{
        user_disable_single_step(child);
}

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

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

asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
        long ret = 0;

        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
            tracehook_report_syscall_entry(regs))
                /*
                 * Tracing decided this syscall should not happen.
                 * We'll return a bogus call number to get an ENOSYS
                 * error, but leave the original number in regs->regs[0].
                 */
                ret = -1L;

        audit_syscall_entry(regs->er1, regs->er2, regs->er3,
                            regs->er4, regs->er5);

        return ret ?: regs->er0;
}

asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
{
        int step;

        audit_syscall_exit(regs);

        step = test_thread_flag(TIF_SINGLESTEP);
        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall_exit(regs, step);
}