/*
 * `ptrace' system call
 *
 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2007-2009 PetaLogix
 * Copyright (C) 2004-2007 John Williams <john.williams@petalogix.com>
 *
 * derived from arch/v850/kernel/ptrace.c
 *
 * Copyright (C) 2002,03 NEC Electronics Corporation
 * Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
 *
 * Derived from arch/mips/kernel/ptrace.c:
 *
 * Copyright (C) 1992 Ross Biro
 * Copyright (C) Linus Torvalds
 * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
 * Copyright (C) 1996 David S. Miller
 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999 MIPS Technologies, Inc.
 *
 * 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/mm.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <linux/elf.h>
#include <linux/audit.h>
#include <linux/seccomp.h>

#include <linux/errno.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/syscall.h>
#include <linux/io.h>

/* Returns the address where the register at REG_OFFS in P is stashed away. */
static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
                                        struct task_struct *t)
{
        struct pt_regs *regs;

        /*
         * Three basic cases:
         *
         * (1)  A register normally saved before calling the scheduler, is
         *      available in the kernel entry pt_regs structure at the top
         *      of the kernel stack. The kernel trap/irq exit path takes
         *      care to save/restore almost all registers for ptrace'd
         *      processes.
         *
         * (2)  A call-clobbered register, where the process P entered the
         *      kernel via [syscall] trap, is not stored anywhere; that's
         *      OK, because such registers are not expected to be preserved
         *      when the trap returns anyway (so we don't actually bother to
         *      test for this case).
         *
         * (3)  A few registers not used at all by the kernel, and so
         *      normally never saved except by context-switches, are in the
         *      context switch state.
         */

        /* Register saved during kernel entry (or not available). */
        regs = task_pt_regs(t);

        return (microblaze_reg_t *)((char *)regs + reg_offs);
}

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        int rval;
        unsigned long val = 0;

        switch (request) {
        /* Read/write the word at location ADDR in the registers. */
        case PTRACE_PEEKUSR:
        case PTRACE_POKEUSR:
                pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
                rval = 0;
                if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
                        /*
                         * Special requests that don't actually correspond
                         * to offsets in struct pt_regs.
                         */
                        if (addr == PT_TEXT_ADDR) {
                                val = child->mm->start_code;
                        } else if (addr == PT_DATA_ADDR) {
                                val = child->mm->start_data;
                        } else if (addr == PT_TEXT_LEN) {
                                val = child->mm->end_code
                                        - child->mm->start_code;
                        } else {
                                rval = -EIO;
                        }
                } else if (addr < PT_SIZE && (addr & 0x3) == 0) {
                        microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
                        if (request == PTRACE_PEEKUSR)
                                val = *reg_addr;
                        else {
#if 1
                                *reg_addr = data;
#else
                                /* MS potential problem on WB system
                                 * Be aware that reg_addr is virtual address
                                 * virt_to_phys conversion is necessary.
                                 * This could be sensible solution.
                                 */
                                u32 paddr = virt_to_phys((u32)reg_addr);
                                invalidate_icache_range(paddr, paddr + 4);
                                *reg_addr = data;
                                flush_dcache_range(paddr, paddr + 4);
#endif
                        }
                } else
                        rval = -EIO;

                if (rval == 0 && request == PTRACE_PEEKUSR)
                        rval = put_user(val, (unsigned long __user *)data);
                break;
        default:
                rval = ptrace_request(child, request, addr, data);
        }
        return rval;
}

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

        secure_computing_strict(regs->r12);

        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
            ptrace_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->r12, regs->r5, regs->r6, regs->r7, regs->r8);

        return ret ?: regs->r12;
}

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))
                ptrace_report_syscall_exit(regs, step);
}

void ptrace_disable(struct task_struct *child)
{
        /* nothing to do */
}