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

     /*-
      * Copyright (c) 2013 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("$FreeBSD$");
    
    /* Routines for mapping device memory. */
    
    #include "opt_ddb.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/devmap.h>
    #include <vm/vm.h>
    #include <vm/vm_extern.h>
    #include <vm/pmap.h>
    #include <machine/vmparam.h>
    
    static const struct devmap_entry *devmap_table;
    static boolean_t devmap_bootstrap_done = false;
    
    /*
     * The allocated-kva (akva) devmap table and metadata.  Platforms can call
     * devmap_add_entry() to add static device mappings to this table using
     * automatically allocated virtual addresses carved out of the top of kva space.
     * Allocation begins immediately below the max kernel virtual address.
     */
    #define AKVA_DEVMAP_MAX_ENTRIES 32
    static struct devmap_entry      akva_devmap_entries[AKVA_DEVMAP_MAX_ENTRIES];
    static u_int                    akva_devmap_idx;
    static vm_offset_t              akva_devmap_vaddr = DEVMAP_MAX_VADDR;
    
    #if defined(__aarch64__) || defined(__riscv)
    extern int early_boot;
    #endif
    
    /*
     * Print the contents of the static mapping table using the provided printf-like
     * output function (which will be either printf or db_printf).
     */
    static void
    devmap_dump_table(int (*prfunc)(const char *, ...))
    {
            const struct devmap_entry *pd;
    
            if (devmap_table == NULL || devmap_table[0].pd_size == 0) {
                    prfunc("No static device mappings.\n");
                    return;
            }
    
            prfunc("Static device mappings:\n");
            for (pd = devmap_table; pd->pd_size != 0; ++pd) {
                    prfunc("  0x%08jx - 0x%08jx mapped at VA 0x%08jx\n",
                        (uintmax_t)pd->pd_pa,
                        (uintmax_t)(pd->pd_pa + pd->pd_size - 1),
                        (uintmax_t)pd->pd_va);
            }
    }
    
    /*
     * Print the contents of the static mapping table.  Used for bootverbose.
     */
    void
    devmap_print_table(void)
    {
            devmap_dump_table(printf);
    }
    
    /*
     * Return the "last" kva address used by the registered devmap table.  It's
     * actually the lowest address used by the static mappings, i.e., the address of
     * the first unusable byte of KVA.
     */
    vm_offset_t
    devmap_lastaddr(void)
    {
           const struct devmap_entry *pd;
           vm_offset_t lowaddr;
   
           if (akva_devmap_idx > 0)
                   return (akva_devmap_vaddr);
   
           lowaddr = DEVMAP_MAX_VADDR;
           for (pd = devmap_table; pd != NULL && pd->pd_size != 0; ++pd) {
                   if (lowaddr > pd->pd_va)
                           lowaddr = pd->pd_va;
           }
   
           return (lowaddr);
   }
   
   /*
    * Add an entry to the internal "akva" static devmap table using the given
    * physical address and size and a virtual address allocated from the top of
    * kva.  This automatically registers the akva table on the first call, so all a
    * platform has to do is call this routine to install as many mappings as it
    * needs and when the platform-specific init function calls devmap_bootstrap()
    * it will pick up all the entries in the akva table automatically.
    */
   void
   devmap_add_entry(vm_paddr_t pa, vm_size_t sz)
   {
           struct devmap_entry *m;
   
           if (devmap_bootstrap_done)
                   panic("devmap_add_entry() after devmap_bootstrap()");
   
           if (akva_devmap_idx == (AKVA_DEVMAP_MAX_ENTRIES - 1))
                   panic("AKVA_DEVMAP_MAX_ENTRIES is too small");
   
           if (akva_devmap_idx == 0)
                   devmap_register_table(akva_devmap_entries);
   
            /* Allocate virtual address space from the top of kva downwards. */
   #ifdef __arm__
           /*
            * If the range being mapped is aligned and sized to 1MB boundaries then
            * also align the virtual address to the next-lower 1MB boundary so that
            * we end with a nice efficient section mapping.
            */
           if ((pa & 0x000fffff) == 0 && (sz & 0x000fffff) == 0) {
                   akva_devmap_vaddr = trunc_1mpage(akva_devmap_vaddr - sz);
           } else
   #endif
           {
                   akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - sz);
           }
           m = &akva_devmap_entries[akva_devmap_idx++];
           m->pd_va    = akva_devmap_vaddr;
           m->pd_pa    = pa;
           m->pd_size  = sz;
   }
   
   /*
    * Register the given table as the one to use in devmap_bootstrap().
    */
   void
   devmap_register_table(const struct devmap_entry *table)
   {
   
           devmap_table = table;
   }
   
   /*
    * Map all of the static regions in the devmap table, and remember the devmap
    * table so the mapdev, ptov, and vtop functions can do lookups later.
    *
    * If a non-NULL table pointer is given it is used unconditionally, otherwise
    * the previously-registered table is used.  This smooths transition from legacy
    * code that fills in a local table then calls this function passing that table,
    * and newer code that uses devmap_register_table() in platform-specific
    * code, then lets the common platform-specific init function call this function
    * with a NULL pointer.
    */
   void
   devmap_bootstrap(vm_offset_t l1pt, const struct devmap_entry *table)
   {
           const struct devmap_entry *pd;
   
           devmap_bootstrap_done = true;
   
           /*
            * If given a table pointer, use it.  Otherwise, if a table was
            * previously registered, use it.  Otherwise, no work to do.
            */
           if (table != NULL)
                   devmap_table = table;
           else if (devmap_table == NULL)
                   return;
   
           for (pd = devmap_table; pd->pd_size != 0; ++pd) {
   #if defined(__arm__)
                   pmap_preboot_map_attr(pd->pd_pa, pd->pd_va, pd->pd_size,
                       VM_PROT_READ | VM_PROT_WRITE, VM_MEMATTR_DEVICE);
   #elif defined(__aarch64__) || defined(__riscv)
                   pmap_kenter_device(pd->pd_va, pd->pd_size, pd->pd_pa);
   #endif
           }
   }
   
   /*
    * Look up the given physical address in the static mapping data and return the
    * corresponding virtual address, or NULL if not found.
    */
   void *
   devmap_ptov(vm_paddr_t pa, vm_size_t size)
   {
           const struct devmap_entry *pd;
   
           if (devmap_table == NULL)
                   return (NULL);
   
           for (pd = devmap_table; pd->pd_size != 0; ++pd) {
                   if (pa >= pd->pd_pa && pa + size <= pd->pd_pa + pd->pd_size)
                           return ((void *)(pd->pd_va + (pa - pd->pd_pa)));
           }
   
           return (NULL);
   }
   
   /*
    * Look up the given virtual address in the static mapping data and return the
    * corresponding physical address, or DEVMAP_PADDR_NOTFOUND if not found.
    */
   vm_paddr_t
   devmap_vtop(void * vpva, vm_size_t size)
   {
           const struct devmap_entry *pd;
           vm_offset_t va;
   
           if (devmap_table == NULL)
                   return (DEVMAP_PADDR_NOTFOUND);
   
           va = (vm_offset_t)vpva;
           for (pd = devmap_table; pd->pd_size != 0; ++pd) {
                   if (va >= pd->pd_va && va + size <= pd->pd_va + pd->pd_size)
                           return ((vm_paddr_t)(pd->pd_pa + (va - pd->pd_va)));
           }
   
           return (DEVMAP_PADDR_NOTFOUND);
   }
   
   /*
    * Map a set of physical memory pages into the kernel virtual address space.
    * Return a pointer to where it is mapped.
    *
    * This uses a pre-established static mapping if one exists for the requested
    * range, otherwise it allocates kva space and maps the physical pages into it.
    *
    * This routine is intended to be used for mapping device memory, NOT real
    * memory; the mapping type is inherently VM_MEMATTR_DEVICE in
    * pmap_kenter_device().
    */
   void *
   pmap_mapdev(vm_paddr_t pa, vm_size_t size)
   {
           vm_offset_t va, offset;
           void * rva;
   
           /* First look in the static mapping table. */
           if ((rva = devmap_ptov(pa, size)) != NULL)
                   return (rva);
   
           offset = pa & PAGE_MASK;
           pa = trunc_page(pa);
           size = round_page(size + offset);
   
   #if defined(__aarch64__) || defined(__riscv)
           if (early_boot) {
                   akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - size);
                   va = akva_devmap_vaddr;
                   KASSERT(va >= VM_MAX_KERNEL_ADDRESS - PMAP_MAPDEV_EARLY_SIZE,
                       ("Too many early devmap mappings"));
           } else
   #endif
                   va = kva_alloc(size);
           if (!va)
                   panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
   
           pmap_kenter_device(va, size, pa);
   
           return ((void *)(va + offset));
   }
   
   #if defined(__aarch64__) || defined(__riscv)
   void *
   pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, vm_memattr_t ma)
   {
           vm_offset_t va, offset;
           void * rva;
   
           /* First look in the static mapping table. */
           if ((rva = devmap_ptov(pa, size)) != NULL)
                   return (rva);
   
           offset = pa & PAGE_MASK;
           pa = trunc_page(pa);
           size = round_page(size + offset);
   
           if (early_boot) {
                   akva_devmap_vaddr = trunc_page(akva_devmap_vaddr - size);
                   va = akva_devmap_vaddr;
                   KASSERT(va >= (VM_MAX_KERNEL_ADDRESS - (PMAP_MAPDEV_EARLY_SIZE)),
                       ("Too many early devmap mappings 2"));
           } else
                   va = kva_alloc(size);
           if (!va)
                   panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
   
           pmap_kenter(va, size, pa, ma);
   
           return ((void *)(va + offset));
   }
   #endif
   
   /*
    * Unmap device memory and free the kva space.
    */
   void
   pmap_unmapdev(void *p, vm_size_t size)
   {
           vm_offset_t offset, va;
   
           /* Nothing to do if we find the mapping in the static table. */
           if (devmap_vtop(p, size) != DEVMAP_PADDR_NOTFOUND)
                   return;
   
           va = (vm_offset_t)p;
           offset = va & PAGE_MASK;
           va = trunc_page(va);
           size = round_page(size + offset);
   
           pmap_kremove_device(va, size);
           kva_free(va, size);
   }
   
   #ifdef DDB
   #include <ddb/ddb.h>
   
   DB_SHOW_COMMAND_FLAGS(devmap, db_show_devmap, DB_CMD_MEMSAFE)
   {
           devmap_dump_table(db_printf);
   }
   
   #endif /* DDB */

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