The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_devmap.c

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    1 /*-
    2  * Copyright (c) 2013 Ian Lepore <ian@freebsd.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 /* Routines for mapping device memory. */
   31 
   32 #include "opt_ddb.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/devmap.h>
   37 #include <vm/vm.h>
   38 #include <vm/vm_extern.h>
   39 #include <vm/pmap.h>
   40 #include <machine/vmparam.h>
   41 
   42 static const struct devmap_entry *devmap_table;
   43 static boolean_t devmap_bootstrap_done = false;
   44 
   45 /*
   46  * The allocated-kva (akva) devmap table and metadata.  Platforms can call
   47  * devmap_add_entry() to add static device mappings to this table using
   48  * automatically allocated virtual addresses carved out of the top of kva space.
   49  * Allocation begins immediately below the max kernel virtual address.
   50  */
   51 #define AKVA_DEVMAP_MAX_ENTRIES 32
   52 static struct devmap_entry      akva_devmap_entries[AKVA_DEVMAP_MAX_ENTRIES];
   53 static u_int                    akva_devmap_idx;
   54 static vm_offset_t              akva_devmap_vaddr = DEVMAP_MAX_VADDR;
   55 
   56 #if defined(__aarch64__) || defined(__riscv)
   57 extern int early_boot;
   58 #endif
   59 
   60 /*
   61  * Print the contents of the static mapping table using the provided printf-like
   62  * output function (which will be either printf or db_printf).
   63  */
   64 static void
   65 devmap_dump_table(int (*prfunc)(const char *, ...))
   66 {
   67         const struct devmap_entry *pd;
   68 
   69         if (devmap_table == NULL || devmap_table[0].pd_size == 0) {
   70                 prfunc("No static device mappings.\n");
   71                 return;
   72         }
   73 
   74         prfunc("Static device mappings:\n");
   75         for (pd = devmap_table; pd->pd_size != 0; ++pd) {
   76                 prfunc("  0x%08jx - 0x%08jx mapped at VA 0x%08jx\n",
   77                     (uintmax_t)pd->pd_pa,
   78                     (uintmax_t)(pd->pd_pa + pd->pd_size - 1),
   79                     (uintmax_t)pd->pd_va);
   80         }
   81 }
   82 
   83 /*
   84  * Print the contents of the static mapping table.  Used for bootverbose.
   85  */
   86 void
   87 devmap_print_table(void)
   88 {
   89         devmap_dump_table(printf);
   90 }
   91 
   92 /*
   93  * Return the "last" kva address used by the registered devmap table.  It's
   94  * actually the lowest address used by the static mappings, i.e., the address of
   95  * the first unusable byte of KVA.
   96  */
   97 vm_offset_t
   98 devmap_lastaddr(void)
   99 {
  100         const struct devmap_entry *pd;
  101         vm_offset_t lowaddr;
  102 
  103         if (akva_devmap_idx > 0)
  104                 return (akva_devmap_vaddr);
  105 
  106         lowaddr = DEVMAP_MAX_VADDR;
  107         for (pd = devmap_table; pd != NULL && pd->pd_size != 0; ++pd) {
  108                 if (lowaddr > pd->pd_va)
  109                         lowaddr = pd->pd_va;
  110         }
  111 
  112         return (lowaddr);
  113 }
  114 
  115 /*
  116  * Add an entry to the internal "akva" static devmap table using the given
  117  * physical address and size and a virtual address allocated from the top of
  118  * kva.  This automatically registers the akva table on the first call, so all a
  119  * platform has to do is call this routine to install as many mappings as it
  120  * needs and when the platform-specific init function calls devmap_bootstrap()
  121  * it will pick up all the entries in the akva table automatically.
  122  */
  123 void
  124 devmap_add_entry(vm_paddr_t pa, vm_size_t sz)
  125 {
  126         struct devmap_entry *m;
  127 
  128         if (devmap_bootstrap_done)
  129                 panic("devmap_add_entry() after devmap_bootstrap()");
  130 
  131         if (akva_devmap_idx == (AKVA_DEVMAP_MAX_ENTRIES - 1))
  132                 panic("AKVA_DEVMAP_MAX_ENTRIES is too small");
  133 
  134         if (akva_devmap_idx == 0)
  135                 devmap_register_table(akva_devmap_entries);
  136 
  137          /* Allocate virtual address space from the top of kva downwards. */
  138 #ifdef __arm__
  139         /*
  140          * If the range being mapped is aligned and sized to 1MB boundaries then
  141          * also align the virtual address to the next-lower 1MB boundary so that
  142          * we end with a nice efficient section mapping.
  143          */
  144         if ((pa & 0x000fffff) == 0 && (sz & 0x000fffff) == 0) {
  145                 akva_devmap_vaddr = trunc_1mpage(akva_devmap_vaddr - sz);
  146         } else
  147 #endif
  148         {
  149                 akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - sz);
  150         }
  151         m = &akva_devmap_entries[akva_devmap_idx++];
  152         m->pd_va    = akva_devmap_vaddr;
  153         m->pd_pa    = pa;
  154         m->pd_size  = sz;
  155 }
  156 
  157 /*
  158  * Register the given table as the one to use in devmap_bootstrap().
  159  */
  160 void
  161 devmap_register_table(const struct devmap_entry *table)
  162 {
  163 
  164         devmap_table = table;
  165 }
  166 
  167 /*
  168  * Map all of the static regions in the devmap table, and remember the devmap
  169  * table so the mapdev, ptov, and vtop functions can do lookups later.
  170  *
  171  * If a non-NULL table pointer is given it is used unconditionally, otherwise
  172  * the previously-registered table is used.  This smooths transition from legacy
  173  * code that fills in a local table then calls this function passing that table,
  174  * and newer code that uses devmap_register_table() in platform-specific
  175  * code, then lets the common platform-specific init function call this function
  176  * with a NULL pointer.
  177  */
  178 void
  179 devmap_bootstrap(vm_offset_t l1pt, const struct devmap_entry *table)
  180 {
  181         const struct devmap_entry *pd;
  182 
  183         devmap_bootstrap_done = true;
  184 
  185         /*
  186          * If given a table pointer, use it.  Otherwise, if a table was
  187          * previously registered, use it.  Otherwise, no work to do.
  188          */
  189         if (table != NULL)
  190                 devmap_table = table;
  191         else if (devmap_table == NULL)
  192                 return;
  193 
  194         for (pd = devmap_table; pd->pd_size != 0; ++pd) {
  195 #if defined(__arm__)
  196 #if __ARM_ARCH >= 6
  197                 pmap_preboot_map_attr(pd->pd_pa, pd->pd_va, pd->pd_size,
  198                     VM_PROT_READ | VM_PROT_WRITE, VM_MEMATTR_DEVICE);
  199 #else
  200                 pmap_map_chunk(l1pt, pd->pd_va, pd->pd_pa, pd->pd_size,
  201                     VM_PROT_READ | VM_PROT_WRITE, PTE_DEVICE);
  202 #endif
  203 #elif defined(__aarch64__) || defined(__riscv)
  204                 pmap_kenter_device(pd->pd_va, pd->pd_size, pd->pd_pa);
  205 #endif
  206         }
  207 }
  208 
  209 /*
  210  * Look up the given physical address in the static mapping data and return the
  211  * corresponding virtual address, or NULL if not found.
  212  */
  213 void *
  214 devmap_ptov(vm_paddr_t pa, vm_size_t size)
  215 {
  216         const struct devmap_entry *pd;
  217 
  218         if (devmap_table == NULL)
  219                 return (NULL);
  220 
  221         for (pd = devmap_table; pd->pd_size != 0; ++pd) {
  222                 if (pa >= pd->pd_pa && pa + size <= pd->pd_pa + pd->pd_size)
  223                         return ((void *)(pd->pd_va + (pa - pd->pd_pa)));
  224         }
  225 
  226         return (NULL);
  227 }
  228 
  229 /*
  230  * Look up the given virtual address in the static mapping data and return the
  231  * corresponding physical address, or DEVMAP_PADDR_NOTFOUND if not found.
  232  */
  233 vm_paddr_t
  234 devmap_vtop(void * vpva, vm_size_t size)
  235 {
  236         const struct devmap_entry *pd;
  237         vm_offset_t va;
  238 
  239         if (devmap_table == NULL)
  240                 return (DEVMAP_PADDR_NOTFOUND);
  241 
  242         va = (vm_offset_t)vpva;
  243         for (pd = devmap_table; pd->pd_size != 0; ++pd) {
  244                 if (va >= pd->pd_va && va + size <= pd->pd_va + pd->pd_size)
  245                         return ((vm_paddr_t)(pd->pd_pa + (va - pd->pd_va)));
  246         }
  247 
  248         return (DEVMAP_PADDR_NOTFOUND);
  249 }
  250 
  251 /*
  252  * Map a set of physical memory pages into the kernel virtual address space.
  253  * Return a pointer to where it is mapped.
  254  *
  255  * This uses a pre-established static mapping if one exists for the requested
  256  * range, otherwise it allocates kva space and maps the physical pages into it.
  257  *
  258  * This routine is intended to be used for mapping device memory, NOT real
  259  * memory; the mapping type is inherently VM_MEMATTR_DEVICE in
  260  * pmap_kenter_device().
  261  */
  262 void *
  263 pmap_mapdev(vm_offset_t pa, vm_size_t size)
  264 {
  265         vm_offset_t va, offset;
  266         void * rva;
  267 
  268         /* First look in the static mapping table. */
  269         if ((rva = devmap_ptov(pa, size)) != NULL)
  270                 return (rva);
  271 
  272         offset = pa & PAGE_MASK;
  273         pa = trunc_page(pa);
  274         size = round_page(size + offset);
  275 
  276 #if defined(__aarch64__) || defined(__riscv)
  277         if (early_boot) {
  278                 akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - size);
  279                 va = akva_devmap_vaddr;
  280                 KASSERT(va >= VM_MAX_KERNEL_ADDRESS - PMAP_MAPDEV_EARLY_SIZE,
  281                     ("Too many early devmap mappings"));
  282         } else
  283 #endif
  284                 va = kva_alloc(size);
  285         if (!va)
  286                 panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
  287 
  288         pmap_kenter_device(va, size, pa);
  289 
  290         return ((void *)(va + offset));
  291 }
  292 
  293 #if defined(__aarch64__) || defined(__riscv)
  294 void *
  295 pmap_mapdev_attr(vm_offset_t pa, vm_size_t size, vm_memattr_t ma)
  296 {
  297         vm_offset_t va, offset;
  298         void * rva;
  299 
  300         /* First look in the static mapping table. */
  301         if ((rva = devmap_ptov(pa, size)) != NULL)
  302                 return (rva);
  303 
  304         offset = pa & PAGE_MASK;
  305         pa = trunc_page(pa);
  306         size = round_page(size + offset);
  307 
  308         if (early_boot) {
  309                 akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - size);
  310                 va = akva_devmap_vaddr;
  311                 KASSERT(va >= (VM_MAX_KERNEL_ADDRESS - (PMAP_MAPDEV_EARLY_SIZE)),
  312                     ("Too many early devmap mappings 2"));
  313         } else
  314                 va = kva_alloc(size);
  315         if (!va)
  316                 panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
  317 
  318         pmap_kenter(va, size, pa, ma);
  319 
  320         return ((void *)(va + offset));
  321 }
  322 #endif
  323 
  324 /*
  325  * Unmap device memory and free the kva space.
  326  */
  327 void
  328 pmap_unmapdev(vm_offset_t va, vm_size_t size)
  329 {
  330         vm_offset_t offset;
  331 
  332         /* Nothing to do if we find the mapping in the static table. */
  333         if (devmap_vtop((void*)va, size) != DEVMAP_PADDR_NOTFOUND)
  334                 return;
  335 
  336         offset = va & PAGE_MASK;
  337         va = trunc_page(va);
  338         size = round_page(size + offset);
  339 
  340         pmap_kremove_device(va, size);
  341         kva_free(va, size);
  342 }
  343 
  344 #ifdef DDB
  345 #include <ddb/ddb.h>
  346 
  347 DB_SHOW_COMMAND(devmap, db_show_devmap)
  348 {
  349         devmap_dump_table(db_printf);
  350 }
  351 
  352 #endif /* DDB */

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