FreeBSD/Linux Kernel Cross Reference
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("$FreeBSD$");
    
    #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 */

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