xref: /freebsd-12-stable/sys/kern/subr_physmem.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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>
__FBSDID("$FreeBSD: stable/12/sys/kern/subr_physmem.c 360703 2020-05-06 19:50:27Z mhorne $");

#include "opt_acpi.h"
#include "opt_ddb.h"

/*
 * Routines for describing and initializing anything related to physical memory.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/physmem.h>
#include <vm/vm.h>
#include <machine/md_var.h>

/*
 * These structures are used internally to keep track of regions of physical
 * ram, and regions within the physical ram that need to be excluded.  An
 * exclusion region can be excluded from crash dumps, from the vm pool of pages
 * that can be allocated, or both, depending on the exclusion flags associated
 * with the region.
 */
#ifdef DEV_ACPI
#define	MAX_HWCNT	32	/* ACPI needs more regions */
#define	MAX_EXCNT	32
#else
#define	MAX_HWCNT	16
#define	MAX_EXCNT	16
#endif

#if defined(__arm__)
#define	MAX_PHYS_ADDR	0xFFFFFFFFull
#elif defined(__aarch64__) || defined(__riscv)
#define	MAX_PHYS_ADDR	0xFFFFFFFFFFFFFFFFull
#endif

struct region {
	vm_paddr_t	addr;
	vm_size_t	size;
	uint32_t	flags;
};

static struct region hwregions[MAX_HWCNT];
static struct region exregions[MAX_EXCNT];

static size_t hwcnt;
static size_t excnt;

/*
 * These "avail lists" are globals used to communicate physical memory layout to
 * other parts of the kernel.  Within the arrays, each value is the starting
 * address of a contiguous area of physical address space.  The values at even
 * indexes are areas that contain usable memory and the values at odd indexes
 * are areas that aren't usable.  Each list is terminated by a pair of zero
 * entries.
 *
 * dump_avail tells the dump code what regions to include in a crash dump, and
 * phys_avail is the way we hand all the remaining physical ram we haven't used
 * in early kernel init over to the vm system for allocation management.
 *
 * We size these arrays to hold twice as many available regions as we allow for
 * hardware memory regions, to allow for the fact that exclusions can split a
 * hardware region into two or more available regions.  In the real world there
 * will typically be one or two hardware regions and two or three exclusions.
 *
 * Each available region in this list occupies two array slots (the start of the
 * available region and the start of the unavailable region that follows it).
 */
#define	MAX_AVAIL_REGIONS	(MAX_HWCNT * 2)
#define	MAX_AVAIL_ENTRIES	(MAX_AVAIL_REGIONS * 2)

vm_paddr_t phys_avail[MAX_AVAIL_ENTRIES + 2]; /* +2 to allow for a pair  */
vm_paddr_t dump_avail[MAX_AVAIL_ENTRIES + 2]; /* of zeroes to terminate. */

/*
 * realmem is the total number of hardware pages, excluded or not.
 * Maxmem is one greater than the last physical page number.
 */
long realmem;
long Maxmem;

/*
 * Print the contents of the physical and excluded region tables using the
 * provided printf-like output function (which will be either printf or
 * db_printf).
 */
static void
physmem_dump_tables(int (*prfunc)(const char *, ...))
{
	int flags, i;
	uintmax_t addr, size;
	const unsigned int mbyte = 1024 * 1024;

	prfunc("Physical memory chunk(s):\n");
	for (i = 0; i < hwcnt; ++i) {
		addr = hwregions[i].addr;
		size = hwregions[i].size;
		prfunc("  0x%08jx - 0x%08jx, %5ju MB (%7ju pages)\n", addr,
		    addr + size - 1, size / mbyte, size / PAGE_SIZE);
	}

	prfunc("Excluded memory regions:\n");
	for (i = 0; i < excnt; ++i) {
		addr  = exregions[i].addr;
		size  = exregions[i].size;
		flags = exregions[i].flags;
		prfunc("  0x%08jx - 0x%08jx, %5ju MB (%7ju pages) %s %s\n",
		    addr, addr + size - 1, size / mbyte, size / PAGE_SIZE,
		    (flags & EXFLAG_NOALLOC) ? "NoAlloc" : "",
		    (flags & EXFLAG_NODUMP)  ? "NoDump" : "");
	}

#ifdef DEBUG
	prfunc("Avail lists:\n");
	for (i = 0; phys_avail[i] != 0; ++i) {
		prfunc("  phys_avail[%d] 0x%08x\n", i, phys_avail[i]);
	}
	for (i = 0; dump_avail[i] != 0; ++i) {
		prfunc("  dump_avail[%d] 0x%08x\n", i, dump_avail[i]);
	}
#endif
}

/*
 * Print the contents of the static mapping table.  Used for bootverbose.
 */
void
physmem_print_tables(void)
{

	physmem_dump_tables(printf);
}

/*
 * Walk the list of hardware regions, processing it against the list of
 * exclusions that contain the given exflags, and generating an "avail list".
 *
 * Updates the value at *pavail with the sum of all pages in all hw regions.
 *
 * Returns the number of pages of non-excluded memory added to the avail list.
 */
static size_t
regions_to_avail(vm_paddr_t *avail, uint32_t exflags, size_t maxavail,
    long *pavail, long *prealmem)
{
	size_t acnt, exi, hwi;
	uint64_t end, start, xend, xstart;
	long availmem, totalmem;
	const struct region *exp, *hwp;

	totalmem = 0;
	availmem = 0;
	acnt = 0;
	for (hwi = 0, hwp = hwregions; hwi < hwcnt; ++hwi, ++hwp) {
		start = hwp->addr;
		end   = hwp->size + start;
		totalmem += atop((vm_offset_t)(end - start));
		for (exi = 0, exp = exregions; exi < excnt; ++exi, ++exp) {
			/*
			 * If the excluded region does not match given flags,
			 * continue checking with the next excluded region.
			 */
			if ((exp->flags & exflags) == 0)
				continue;
			xstart = exp->addr;
			xend   = exp->size + xstart;
			/*
			 * If the excluded region ends before this hw region,
			 * continue checking with the next excluded region.
			 */
			if (xend <= start)
				continue;
			/*
			 * If the excluded region begins after this hw region
			 * we're done because both lists are sorted.
			 */
			if (xstart >= end)
				break;
			/*
			 * If the excluded region completely covers this hw
			 * region, shrink this hw region to zero size.
			 */
			if ((start >= xstart) && (end <= xend)) {
				start = xend;
				end = xend;
				break;
			}
			/*
			 * If the excluded region falls wholly within this hw
			 * region without abutting or overlapping the beginning
			 * or end, create an available entry from the leading
			 * fragment, then adjust the start of this hw region to
			 * the end of the excluded region, and continue checking
			 * the next excluded region because another exclusion
			 * could affect the remainder of this hw region.
			 */
			if ((xstart > start) && (xend < end)) {
				if (acnt > 0 &&
				    avail[acnt - 1] == (vm_paddr_t)start) {
					avail[acnt - 1] = (vm_paddr_t)xstart;
				} else {
					avail[acnt++] = (vm_paddr_t)start;
					avail[acnt++] = (vm_paddr_t)xstart;
				}
				availmem += atop((vm_offset_t)(xstart - start));
				start = xend;
				continue;
			}
			/*
			 * We know the excluded region overlaps either the start
			 * or end of this hardware region (but not both), trim
			 * the excluded portion off the appropriate end.
			 */
			if (xstart <= start)
				start = xend;
			else
				end = xstart;
		}
		/*
		 * If the trimming actions above left a non-zero size, create an
		 * available entry for it.
		 */
		if (end > start) {
			if (acnt > 0 && avail[acnt - 1] == (vm_paddr_t)start) {
				avail[acnt - 1] = (vm_paddr_t)end;
			} else {
				avail[acnt++] = (vm_paddr_t)start;
				avail[acnt++] = (vm_paddr_t)end;
			}
			availmem += atop((vm_offset_t)(end - start));
		}
		if (acnt >= maxavail)
			panic("Not enough space in the dump/phys_avail arrays");
	}

	if (pavail != NULL)
		*pavail = availmem;
	if (prealmem != NULL)
		*prealmem = totalmem;
	return (acnt);
}

/*
 * Insertion-sort a new entry into a regions list; sorted by start address.
 */
static size_t
insert_region(struct region *regions, size_t rcnt, vm_paddr_t addr,
    vm_size_t size, uint32_t flags)
{
	size_t i;
	struct region *ep, *rp;

	ep = regions + rcnt;
	for (i = 0, rp = regions; i < rcnt; ++i, ++rp) {
		if (rp->addr == addr && rp->size == size) /* Pure dup. */
			return (rcnt);
		if (flags == rp->flags) {
			if (addr + size == rp->addr) {
				rp->addr = addr;
				rp->size += size;
				return (rcnt);
			} else if (rp->addr + rp->size == addr) {
				rp->size += size;
				return (rcnt);
			}
		}
		if (addr < rp->addr) {
			bcopy(rp, rp + 1, (ep - rp) * sizeof(*rp));
			break;
		}
	}
	rp->addr  = addr;
	rp->size  = size;
	rp->flags = flags;
	rcnt++;

	return (rcnt);
}

/*
 * Add a hardware memory region.
 */
void
physmem_hardware_region(uint64_t pa, uint64_t sz)
{
	vm_offset_t adj;

	/*
	 * Filter out the page at PA 0x00000000.  The VM can't handle it, as
	 * pmap_extract() == 0 means failure.
	 */
	if (pa == 0) {
		if (sz <= PAGE_SIZE)
			return;
		pa  = PAGE_SIZE;
		sz -= PAGE_SIZE;
	} else if (pa > MAX_PHYS_ADDR) {
		/* This range is past usable memory, ignore it */
		return;
	}

	/*
	 * Also filter out the page at the end of the physical address space --
	 * if addr is non-zero and addr+size is zero we wrapped to the next byte
	 * beyond what vm_paddr_t can express.  That leads to a NULL pointer
	 * deref early in startup; work around it by leaving the last page out.
	 *
	 * XXX This just in:  subtract out a whole megabyte, not just 1 page.
	 * Reducing the size by anything less than 1MB results in the NULL
	 * pointer deref in _vm_map_lock_read().  Better to give up a megabyte
	 * than leave some folks with an unusable system while we investigate.
	 */
	if ((pa + sz) > (MAX_PHYS_ADDR - 1024 * 1024)) {
		sz = MAX_PHYS_ADDR - pa + 1;
		if (sz <= 1024 * 1024)
			return;
		sz -= 1024 * 1024;
	}

	/*
	 * Round the starting address up to a page boundary, and truncate the
	 * ending page down to a page boundary.
	 */
	adj = round_page(pa) - pa;
	pa  = round_page(pa);
	sz  = trunc_page(sz - adj);

	if (sz > 0 && hwcnt < nitems(hwregions))
		hwcnt = insert_region(hwregions, hwcnt, pa, sz, 0);
}

/*
 * Add an exclusion region.
 */
void
physmem_exclude_region(vm_paddr_t pa, vm_size_t sz, uint32_t exflags)
{
	vm_offset_t adj;

	/*
	 * Truncate the starting address down to a page boundary, and round the
	 * ending page up to a page boundary.
	 */
	adj = pa - trunc_page(pa);
	pa  = trunc_page(pa);
	sz  = round_page(sz + adj);

	if (excnt >= nitems(exregions))
		panic("failed to exclude region %#jx-%#jx", (uintmax_t)pa,
		    (uintmax_t)(pa + sz));
	excnt = insert_region(exregions, excnt, pa, sz, exflags);
}

size_t
physmem_avail(vm_paddr_t *avail, size_t maxavail)
{

	return (regions_to_avail(avail, EXFLAG_NOALLOC, maxavail, NULL, NULL));
}

/*
 * Process all the regions added earlier into the global avail lists.
 *
 * Updates the kernel global 'physmem' with the number of physical pages
 * available for use (all pages not in any exclusion region).
 *
 * Updates the kernel global 'Maxmem' with the page number one greater then the
 * last page of physical memory in the system.
 */
void
physmem_init_kernel_globals(void)
{
	size_t nextidx;

	regions_to_avail(dump_avail, EXFLAG_NODUMP, MAX_AVAIL_ENTRIES, NULL,
	    NULL);
	nextidx = regions_to_avail(phys_avail, EXFLAG_NOALLOC,
	    MAX_AVAIL_ENTRIES, &physmem, &realmem);
	if (nextidx == 0)
		panic("No memory entries in phys_avail");
	Maxmem = atop(phys_avail[nextidx - 1]);
}

#ifdef DDB
#include <ddb/ddb.h>

DB_SHOW_COMMAND(physmem, db_show_physmem)
{

	physmem_dump_tables(db_printf);
}

#endif /* DDB */