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Overhaul the way LWP IDs are allocated.  Instead of each LWP having it's
own LWP ID space, LWP IDs came from the same number space as PIDs.  The
lead LWP of a process gets the PID as its LID.  If a multi-LWP process's
lead LWP exits, the PID persists for the process.

In addition to providing system-wide unique thread IDs, this also lets us
eliminate the per-process LWP radix tree, and some associated locks.

Remove the separate "global thread ID" map added previously; it is no longer
needed to provide this functionality.

Nudged in this direction by ad@ and chs@.

/*	$NetBSD: linux_exec.c,v 1.122 2020/04/24 03:22:06 thorpej Exp $	*/

/*-
 * Copyright (c) 1994, 1995, 1998, 2000, 2007, 2008, 2020
 *     The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas, Frank van der Linden, Eric Haszlakiewicz and
 * Thor Lancelot Simon.
 *
 * 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_exec.c,v 1.122 2020/04/24 03:22:06 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lwp.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/exec.h>
#include <sys/exec_elf.h>

#include <sys/mman.h>
#include <sys/syscallargs.h>

#include <sys/ptrace.h>	/* For proc_reparent() */

#include <uvm/uvm_extern.h>

#include <sys/cpu.h>
#include <machine/reg.h>

#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_signal.h>
#include <compat/linux/common/linux_util.h>
#include <compat/linux/common/linux_sched.h>
#include <compat/linux/common/linux_machdep.h>
#include <compat/linux/common/linux_exec.h>
#include <compat/linux/common/linux_futex.h>
#include <compat/linux/common/linux_ipc.h>
#include <compat/linux/common/linux_sem.h>

#include <compat/linux/linux_syscallargs.h>
#include <compat/linux/linux_syscall.h>
#include <compat/linux/common/linux_misc.h>
#include <compat/linux/common/linux_errno.h>
#include <compat/linux/common/linux_emuldata.h>

extern struct sysent linux_sysent[];
extern const uint32_t linux_sysent_nomodbits[];
extern const char * const linux_syscallnames[];
extern char linux_sigcode[], linux_esigcode[];

/*
 * Emulation switch.
 */

struct uvm_object *emul_linux_object;

struct emul emul_linux = {
	.e_name =		"linux",
	.e_path =		"/emul/linux",
#ifndef __HAVE_MINIMAL_EMUL
	.e_flags =		0,
	.e_errno =		native_to_linux_errno,
	.e_nosys =		LINUX_SYS_syscall,
	.e_nsysent =		LINUX_SYS_NSYSENT,
#endif
	.e_sysent =		linux_sysent,
	.e_nomodbits =		linux_sysent_nomodbits,
	.e_syscallnames =	linux_syscallnames,
	.e_sendsig =		linux_sendsig,
	.e_trapsignal =		linux_trapsignal,
	.e_sigcode =		linux_sigcode,
	.e_esigcode =		linux_esigcode,
	.e_sigobject =		&emul_linux_object,
	.e_setregs =		linux_setregs,
	.e_proc_exec =		linux_e_proc_exec,
	.e_proc_fork =		linux_e_proc_fork,
	.e_proc_exit =		linux_e_proc_exit,
	.e_lwp_fork =		linux_e_lwp_fork,
	.e_lwp_exit =		linux_e_lwp_exit,
#ifdef __HAVE_SYSCALL_INTERN
	.e_syscall_intern =	linux_syscall_intern,
#else
#error Implement __HAVE_SYSCALL_INTERN for this platform
#endif
	.e_sysctlovly =		NULL,
	.e_vm_default_addr =	uvm_default_mapaddr,
	.e_usertrap =		linux_usertrap,
	.e_ucsize =		0,
	.e_startlwp =		NULL
};

void
linux_e_proc_exec(struct proc *p, struct exec_package *epp)
{
	struct lwp *l;

	l = LIST_FIRST(&p->p_lwps);
	if (l->l_emuldata == NULL) {
		l->l_emuldata = kmem_zalloc(sizeof(struct linux_emuldata), KM_SLEEP);
	} else {
		memset(l->l_emuldata, 0, sizeof (struct linux_emuldata));
	}

	KASSERT(p->p_nlwps == 1);
}

void
linux_e_proc_exit(struct proc *p)
{
	struct lwp *l;

	KASSERT(p->p_nlwps == 1);
	l = LIST_FIRST(&p->p_lwps);
	linux_e_lwp_exit(l);
}

void
linux_e_proc_fork(struct proc *p2, struct lwp *l1, int flags)
{
	struct linux_emuldata *led1, *led2;
	struct lwp *l2;

	KASSERT(p2->p_nlwps == 1);
	l2 = LIST_FIRST(&p2->p_lwps);
	led1 = l1->l_emuldata;
	led2 = l2->l_emuldata;
	led2->led_child_tidptr = led1->led_child_tidptr;
}

void
linux_e_lwp_fork(struct lwp *l1, struct lwp *l2)
{
	struct linux_emuldata *led2;

	led2 = kmem_zalloc(sizeof(*led2), KM_SLEEP);
	l2->l_emuldata = led2;
}

void
linux_e_lwp_exit(struct lwp *l)
{
	struct linux_emuldata *led;
	struct linux_sys_futex_args cup;
	register_t retval;
	int error, zero = 0;

	led = l->l_emuldata;
	if (led->led_clear_tid == NULL) {
		return;
	}

	/* Emulate LINUX_CLONE_CHILD_CLEARTID */
	error = copyout(&zero, led->led_clear_tid, sizeof(zero));
#ifdef DEBUG_LINUX
	if (error != 0)
		printf("%s: cannot clear TID\n", __func__);
#endif

	SCARG(&cup, uaddr) = led->led_clear_tid;
	SCARG(&cup, op) = LINUX_FUTEX_WAKE;
	SCARG(&cup, val) = 0x7fffffff; /* Awake everyone */
	SCARG(&cup, timeout) = NULL;
	SCARG(&cup, uaddr2) = NULL;
	SCARG(&cup, val3) = 0;
	if ((error = linux_sys_futex(curlwp, &cup, &retval)) != 0)
		printf("%s: linux_sys_futex failed\n", __func__);

	release_futexes(l);

	led = l->l_emuldata;
	l->l_emuldata = NULL;
	kmem_free(led, sizeof(*led));
}