/*      $NetBSD: linux_ptrace.c,v 1.34 2022/09/05 14:14:42 tsutsui Exp $ */

/*-
 * Copyright (c) 1999, 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matthias Scheler and Emmanuel Dreyfus.
 *
 * 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 1.34 2022/09/05 14:14:42 tsutsui 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 <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() */

/*
 * From Linux's include/asm-ppc/ptrace.h.
 * structure used for storing reg context:  defined in linux_machdep.h
 * structure used for storing floating point context:
 * Linux just uses a double fpr[32], no struct
 */

/*
 * user struct for linux process - this is used for Linux ptrace emulation
 * most of it is junk only used by gdb
 *
 * From Linux's include/asm-ppc/user.h
 *
 * XXX u_ar0 was a struct reg in Linux/powerpc
 * Can't find out what a struct regs is for Linux/powerpc,
 * so we use a struct pt_regs instead. don't know if this is right.
 */

struct linux_user {
        struct linux_pt_regs regs;
#define lusr_startgdb regs
        size_t u_tsize;
        size_t u_dsize;
        size_t u_ssize;
        unsigned long start_code;
        unsigned long start_data;
        unsigned long start_stack;
        long int signal;
        struct linux_pt_regs *u_ar0;            /* help gdb find registers */
        unsigned long magic;
        char u_comm[32];
#define lu_comm_end u_comm[31]
};

#define LUSR_OFF(member) offsetof(struct linux_user, member)
#define LUSR_REG_OFF(member) offsetof(struct linux_pt_regs, member)

int linux_ptrace_disabled = 1;  /* bitrotted */

/* XXX Check me! (From NetBSD/i386) */
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;
        struct reg *regs = NULL;
        struct fpreg *fpregs = NULL;
        struct linux_pt_regs *linux_regs = NULL;
        double *linux_fpreg = NULL;  /* it's an array, not a struct */
        int request, error, addr, i;

        if (linux_ptrace_disabled)
                return ENOSYS;

        error = 0;
        request = SCARG(uap, request);

        switch (request) {
        case LINUX_PTRACE_PEEKUSR:
        case LINUX_PTRACE_POKEUSR:
                regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
                break;
        case LINUX_PTRACE_GETREGS:
        case LINUX_PTRACE_SETREGS:
                regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
                linux_regs = kmem_alloc(sizeof(*linux_regs), KM_SLEEP);
                if (request == LINUX_PTRACE_SETREGS) {
                        error = copyin((void *)SCARG(uap, data), linux_regs,
                            sizeof(struct linux_pt_regs));
                        if (error) {
                                goto out;
                        }
                }
                break;
        case LINUX_PTRACE_GETFPREGS:
        case LINUX_PTRACE_SETFPREGS:
                fpregs = kmem_alloc(sizeof(struct fpreg), KM_SLEEP);
                linux_fpreg = kmem_alloc(32 * sizeof(double), KM_SLEEP);
                if (request == LINUX_PTRACE_SETFPREGS) {
                        error = copyin((void *)SCARG(uap, data), linux_fpreg,
                            32 * sizeof(double));
                        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 not being traced by _you_, or
         * 3. 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));
                for (i = 0; i <= 31; i++) {
                        linux_regs->lgpr[i] = regs->fixreg[i];
                }
                linux_regs->lnip = regs->pc;
                linux_regs->lmsr = 0;
                /* XXX Is that right? */
                linux_regs->lorig_gpr3 = regs->fixreg[3];
                linux_regs->lctr = regs->ctr;
                linux_regs->llink = regs->lr;
                linux_regs->lxer = regs->xer;
                linux_regs->lccr = regs->cr;
                linux_regs->lmq = 0;
                linux_regs->ltrap = 0;
                linux_regs->ldar = 0;
                linux_regs->ldsisr = 0;
                linux_regs->lresult = 0;

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

        case LINUX_PTRACE_SETREGS:
                for (i = 0; i <= 31; i++) {
                        regs->fixreg[i] = linux_regs->lgpr[i];
                }
                regs->lr = linux_regs->llink;
                regs->cr = linux_regs->lccr;
                regs->xer = linux_regs->lxer;
                regs->ctr = linux_regs->lctr;
                regs->pc = linux_regs->lnip; /* XXX */

                error = process_write_regs(lt, regs);
                mutex_exit(t->p_lock);
                break;

        case LINUX_PTRACE_GETFPREGS:
                error = process_read_fpregs(lt, fpregs, NULL);
                mutex_exit(t->p_lock);
                if (error) {
                        break;
                }
                /* Zero the contents if NetBSD fpreg structure is smaller */
                if (sizeof(struct fpreg) < (32 * sizeof(double))) {
                        memset(linux_fpreg, '\0', (32 * sizeof(double)));
                }
                memcpy(linux_fpreg, fpregs,
                    uimin(32 * sizeof(double), sizeof(struct fpreg)));
                error = copyout(linux_fpreg, (void *)SCARG(uap, data),
                    32 * sizeof(double));
                break;

        case LINUX_PTRACE_SETFPREGS:
                memset(fpregs, '\0', sizeof(struct fpreg));
                memcpy(fpregs, linux_fpreg,
                    uimin(32 * sizeof(double), sizeof(struct fpreg)));
                error = process_write_fpregs(lt, fpregs, sizeof fpregs);
                mutex_exit(t->p_lock);
                break;

        case LINUX_PTRACE_PEEKUSR:
                addr = SCARG(uap, addr);
                error = process_read_regs(lt, regs);
                mutex_exit(t->p_lock);
                if (error) {
                        break;
                }
                error = 0;
                if ((addr < LUSR_OFF(lusr_startgdb)) ||
                    (addr > LUSR_OFF(lu_comm_end)))
                        error = 1;
                else if (addr == LUSR_OFF(u_tsize))
                        *retval = p->p_vmspace->vm_tsize;
                else if (addr == LUSR_OFF(u_dsize))
                        *retval = p->p_vmspace->vm_dsize;
                else if (addr == LUSR_OFF(u_ssize))
                        *retval = p->p_vmspace->vm_ssize;
                else if (addr == LUSR_OFF(start_code))
                        *retval = (register_t) p->p_vmspace->vm_taddr;
                else if (addr == LUSR_OFF(start_stack))
                        *retval = (register_t) p->p_vmspace->vm_minsaddr;
                else if ((addr >= LUSR_REG_OFF(lpt_regs_fixreg_begin)) &&
                    (addr <= LUSR_REG_OFF(lpt_regs_fixreg_end)))
                        *retval = regs->fixreg[addr / sizeof (register_t)];
                else if (addr == LUSR_REG_OFF(lnip))
                        *retval = regs->pc;
                else if (addr == LUSR_REG_OFF(lctr))
                        *retval = regs->ctr;
                else if (addr == LUSR_REG_OFF(llink))
                        *retval = regs->lr;
                else if (addr == LUSR_REG_OFF(lxer))
                        *retval = regs->xer;
                else if (addr == LUSR_REG_OFF(lccr))
                        *retval = regs->cr;
                else if (addr == LUSR_OFF(signal))
                        error = 1;
                else if (addr == LUSR_OFF(magic))
                        error = 1;
                else if (addr == LUSR_OFF(u_comm))
                        error = 1;
                else {
#ifdef DEBUG_LINUX
                        printf("linux_ptrace: unsupported address: %d\n", addr);
#endif
                        error = 1;
                }
                if (error) {
                        break;
                }
                error = copyout (retval, (void *)SCARG(uap, data),
                    sizeof(*retval));
                *retval = SCARG(uap, data);
                break;

        case  LINUX_PTRACE_POKEUSR: /* XXX Not tested */
                addr = SCARG(uap, addr);
                error = process_read_regs(lt, regs);
                if (error) {
                        mutex_exit(t->p_lock);
                        break;
                }
                error = 0;
                if ((addr < LUSR_OFF(lusr_startgdb)) ||
                    (addr > LUSR_OFF(lu_comm_end)))
                        error = 1;
                else if (addr == LUSR_OFF(u_tsize))
                        error = 1;
                else if (addr == LUSR_OFF(u_dsize))
                        error = 1;
                else if (addr == LUSR_OFF(u_ssize))
                        error = 1;
                else if (addr == LUSR_OFF(start_code))
                        error = 1;
                else if (addr == LUSR_OFF(start_stack))
                        error = 1;
                else if ((addr >= LUSR_REG_OFF(lpt_regs_fixreg_begin)) &&
                    (addr <= LUSR_REG_OFF(lpt_regs_fixreg_end)))
                        regs->fixreg[addr / sizeof (register_t)] =
                            (register_t)SCARG(uap, data);
                else if (addr == LUSR_REG_OFF(lnip))
                        regs->pc = (register_t)SCARG(uap, data);
                else if (addr == LUSR_REG_OFF(lctr))
                        regs->ctr = (register_t)SCARG(uap, data);
                else if (addr == LUSR_REG_OFF(llink))
                        regs->lr = (register_t)SCARG(uap, data);
                else if (addr == LUSR_REG_OFF(lxer))
                        regs->xer = (register_t)SCARG(uap, data);
                else if (addr == LUSR_REG_OFF(lccr))
                        regs->cr = (register_t)SCARG(uap, data);
                else if (addr == LUSR_OFF(signal))
                        error = 1;
                else if (addr == LUSR_OFF(magic))
                        error = 1;
                else if (addr == LUSR_OFF(u_comm))
                        error = 1;
                else {
#ifdef DEBUG_LINUX
                        printf("linux_ptrace: unsupported address: %d\n", addr);
#endif
                        error = 1;
                }
                error = process_write_regs(lt,regs);
                mutex_exit(t->p_lock);
                break;
        default:
                mutex_exit(t->p_lock);
                break;
        }
out:
        if (regs)
                kmem_free(regs, sizeof(*regs));
        if (fpregs)
                kmem_free(fpregs, sizeof(*fpregs));
        if (linux_regs)
                kmem_free(linux_regs, sizeof(*linux_regs));
        if (linux_fpreg)
                kmem_free(linux_fpreg, sizeof(*linux_fpreg));
        return error;
}