/*      $NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh Exp $      */

/*-
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matthias Scheler.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */


#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh Exp $");

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/systm.h>
#include <sys/syscallargs.h>
#include <uvm/uvm_extern.h>

#include <machine/reg.h>
#include <machine/pcb.h>

#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_ptrace.h>
#include <compat/linux/common/linux_signal.h>

#include <compat/linux/common/linux_util.h>
#include <compat/linux/common/linux_machdep.h>
#include <compat/linux/common/linux_emuldata.h>
#include <compat/linux/common/linux_exec.h>     /* for emul_linux */

#include <compat/linux/linux_syscallargs.h>

#include <lib/libkern/libkern.h>        /* for offsetof() */

/*
 * On ARMv2, uregs contains R0--R15, orig_R0.
 * On ARMv3 and later, it's R0--R15, CPSR, orig_R0.
 * As far as I can see, Linux doesn't initialise orig_R0 on ARMv2, so we
 * just produce the ARMv3 version.
 */

struct linux_reg {
        long uregs[18];
};

#define LINUX_REG_R0    0
#define LINUX_REG_R1    1
#define LINUX_REG_R2    2
#define LINUX_REG_R3    3
#define LINUX_REG_R4    4
#define LINUX_REG_R5    5
#define LINUX_REG_R6    6
#define LINUX_REG_R7    7
#define LINUX_REG_R8    8
#define LINUX_REG_R9    9
#define LINUX_REG_R10   10
#define LINUX_REG_FP    11
#define LINUX_REG_IP    12
#define LINUX_REG_SP    13
#define LINUX_REG_LR    14
#define LINUX_REG_PC    15
#define LINUX_REG_CPSR  16
#define LINUX_REG_ORIG_R0 17

int linux_ptrace_disabled = 1;  /* bitrotted */

int
linux_sys_ptrace_arch(struct lwp *l, const struct linux_sys_ptrace_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) request;
                syscallarg(int) pid;
                syscallarg(int) addr;
                syscallarg(int) data;
        } */
        struct proc *p = l->l_proc, *t;
        struct lwp *lt;
#ifdef _ARM_ARCH_6
        struct pcb *pcb;
        void *val;
#endif
        struct reg *regs = NULL;
        struct linux_reg *linux_regs = NULL;
        int request, error;

        if (linux_ptrace_disabled)
                return ENOSYS;

        error = 0;
        request = SCARG(uap, request);
        regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
        linux_regs = kmem_alloc(sizeof(struct linux_reg), KM_SLEEP);

        switch (request) {
        case LINUX_PTRACE_GETREGS:
                break;
        case LINUX_PTRACE_SETREGS:
                error = copyin((void *)SCARG(uap, data), linux_regs,
                    sizeof(struct linux_reg));
                if (error) {
                        goto out;
                }
                break;
        default:
                error = EIO;
                goto out;
        }

        /* Find the process we are supposed to be operating on. */
        mutex_enter(&proc_lock);
        if ((t = proc_find(SCARG(uap, pid))) == NULL) {
                mutex_exit(&proc_lock);
                error = ESRCH;
                goto out;
        }
        mutex_enter(t->p_lock);

        /*
         * You cannot do what you want to the process if:
         * 1. It is not being traced at all,
         */
        if (!ISSET(t->p_slflag, PSL_TRACED)) {
                mutex_exit(t->p_lock);
                mutex_exit(&proc_lock);
                error = EPERM;
                goto out;
        }
        /*
         * 2. It is being traced by procfs (which has different signal
         *    delivery semantics),
         * 3. It is not being traced by _you_, or
         * 4. It is not currently stopped.
         */
        if (t->p_pptr != p || t->p_stat != SSTOP || !t->p_waited) {
                mutex_exit(t->p_lock);
                mutex_exit(&proc_lock);
                error = EBUSY;
                goto out;
        }
        mutex_exit(&proc_lock);
        /* XXX: ptrace needs revamp for multi-threading support. */
        if (t->p_nlwps > 1) {
                mutex_exit(t->p_lock);
                error = ENOSYS;
                goto out;
        }
        lt = LIST_FIRST(&t->p_lwps);
        *retval = 0;

        switch (request) {
        case LINUX_PTRACE_GETREGS:
                error = process_read_regs(lt, regs);
                mutex_exit(t->p_lock);
                if (error) {
                        break;
                }
                memset(linux_regs, 0, sizeof(*linux_regs));
                memcpy(linux_regs->uregs, regs->r, 13 * sizeof(register_t));
                linux_regs->uregs[LINUX_REG_SP] = regs->r_sp;
                linux_regs->uregs[LINUX_REG_LR] = regs->r_lr;
                linux_regs->uregs[LINUX_REG_PC] = regs->r_pc;
                linux_regs->uregs[LINUX_REG_CPSR] = regs->r_cpsr;
                linux_regs->uregs[LINUX_REG_ORIG_R0] = regs->r[0];

                error = copyout(linux_regs, (void *)SCARG(uap, data),
                    sizeof(struct linux_reg));
                break;

        case LINUX_PTRACE_SETREGS:
                memcpy(regs->r, linux_regs->uregs, 13 * sizeof(register_t));
                regs->r_sp = linux_regs->uregs[LINUX_REG_SP];
                regs->r_lr = linux_regs->uregs[LINUX_REG_LR];
                regs->r_pc = linux_regs->uregs[LINUX_REG_PC];
                regs->r_cpsr = linux_regs->uregs[LINUX_REG_CPSR];
                error = process_write_regs(lt, regs);
                mutex_exit(t->p_lock);
                break;

#ifdef _ARM_ARCH_6
#define LINUX_PTRACE_GET_THREAD_AREA    22
        case LINUX_PTRACE_GET_THREAD_AREA:
                mutex_exit(t->p_lock);
                pcb = lwp_getpcb(l);
                val = (void *)pcb->pcb_user_pid_ro;
                error = copyout(&val, (void *)SCARG(uap, data), sizeof(val));
                break;
#endif

        default:
                mutex_exit(t->p_lock);
        }
out:
        if (regs)
                kmem_free(regs, sizeof(*regs));
        if (linux_regs)
                kmem_free(linux_regs, sizeof(*linux_regs));
        return error;

}