Implement Linux alloc_page/__free_page and kmap_atomic/kunmap_atomic.


(riastradh)

/*	$NetBSD: linux_gfp.c,v 1.1.2.1 2013/07/24 03:31:12 riastradh Exp $	*/

/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R. Campbell.
 *
 * 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_gfp.c,v 1.1.2.1 2013/07/24 03:31:12 riastradh Exp $");

#include <sys/types.h>
#include <sys/queue.h>

#include <uvm/uvm_extern.h>

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm_types.h>

struct page *
alloc_page(gfp_t gfp)
{
	paddr_t low = 0;
	paddr_t high = ~(paddr_t)0;
	struct pglist pglist;
	struct vm_page *vm_page;
	int error;

	if (ISSET(gfp, __GFP_DMA32))
		high = 0xffffffff;

	error = uvm_pglistalloc(PAGE_SIZE, low, high, PAGE_SIZE, PAGE_SIZE,
	    &pglist, 1, ISSET(gfp, __GFP_WAIT));
	if (error)
		return NULL;

	vm_page = TAILQ_FIRST(&pglist);
	TAILQ_REMOVE(&pglist, vm_page, pageq.queue);	/* paranoia */
	KASSERT(TAILQ_EMPTY(&pglist));

	return container_of(vm_page, struct page, p_vmp);
}

void
__free_page(struct page *page)
{
	struct pglist pglist = TAILQ_HEAD_INITIALIZER(pglist);

	TAILQ_INSERT_TAIL(&pglist, &page->p_vmp, pageq.queue);

	uvm_pglistfree(&pglist);
}

/*	$NetBSD: linux_kmap.c,v 1.1.2.1 2013/07/24 03:31:12 riastradh Exp $	*/

/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R. Campbell.
 *
 * 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_kmap.c,v 1.1.2.1 2013/07/24 03:31:12 riastradh Exp $");

#include <sys/types.h>
#include <sys/mutex.h>

#include <uvm/uvm_extern.h>

#include <linux/highmem.h>

/*
 * XXX Kludgerific implementation of Linux kmap_atomic, which is
 * required not to fail.  To accomodate this, we reserve one page of
 * kva at boot (or load) and limit the system to at most kmap_atomic in
 * use at a time.
 */

static kmutex_t linux_kmap_atomic_lock;
static vaddr_t linux_kmap_atomic_vaddr;

int
linux_kmap_init(void)
{

	/* IPL_VM is needed to block pmap_kenter_pa.  */
	mutex_init(&linux_kmap_atomic_lock, MUTEX_DEFAULT, IPL_VM);

	linux_kmap_atomic_vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
	    (UVM_KMF_VAONLY | UVM_KMF_WAITVA));

	KASSERT(linux_kmap_atomic_vaddr != 0);
	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));

	return 0;
}

void
linux_kmap_fini(void)
{

	KASSERT(linux_kmap_atomic_vaddr != 0);
	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));

	uvm_km_free(kernel_map, linux_kmap_atomic_vaddr, PAGE_SIZE,
	    (UVM_KMF_VAONLY | UVM_KMF_WAITVA));

	mutex_destroy(&linux_kmap_atomic_lock);
}

void *
kmap_atomic(struct page *page)
{

	mutex_spin_enter(&linux_kmap_atomic_lock);

	KASSERT(linux_kmap_atomic_vaddr != 0);
	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));

	const vaddr_t vaddr = linux_kmap_atomic_vaddr;
	const paddr_t paddr = uvm_vm_page_to_phys(&page->p_vmp);
	const int prot = (VM_PROT_READ | VM_PROT_WRITE);
	const int flags = 0;
	pmap_kenter_pa(vaddr, paddr, prot, flags);
	pmap_update(pmap_kernel());

	return (void *)vaddr;
}

void
kunmap_atomic(void *addr)
{
	const vaddr_t vaddr = (vaddr_t)addr;

	KASSERT(linux_kmap_atomic_vaddr == vaddr);
	KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL));

	pmap_kremove(vaddr, PAGE_SIZE);
	pmap_update(pmap_kernel());

	mutex_spin_exit(&linux_kmap_atomic_lock);
}