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_busdma_bufalloc.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2012 Ian Lepore
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_busdma_bufalloc.c 340401 2018-11-13 18:21:47Z markj $");
   31 
   32 /*
   33  * Buffer allocation support routines for bus_dmamem_alloc implementations.
   34  */
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/bus.h>
   39 #include <sys/busdma_bufalloc.h>
   40 #include <sys/domainset.h>
   41 #include <sys/malloc.h>
   42 
   43 #include <vm/vm.h>
   44 #include <vm/vm_extern.h>
   45 #include <vm/vm_kern.h>
   46 #include <vm/uma.h>
   47 
   48 /*
   49  * We manage buffer zones up to a page in size.  Buffers larger than a page can
   50  * be managed by one of the kernel's page-oriented memory allocation routines as
   51  * efficiently as what we can do here.  Also, a page is the largest size for
   52  * which we can g'tee contiguity when using uma, and contiguity is one of the
   53  * requirements we have to fulfill.
   54  */
   55 #define MIN_ZONE_BUFSIZE        32
   56 #define MAX_ZONE_BUFSIZE        PAGE_SIZE
   57 
   58 /*
   59  * The static array of 12 bufzones is big enough to handle all the zones for the
   60  * smallest supported allocation size of 32 through the largest supported page
   61  * size of 64K.  If you up the biggest page size number, up the array size too.
   62  * Basically the size of the array needs to be log2(maxsize)-log2(minsize)+1,
   63  * but I don't know of an easy way to express that as a compile-time constant.
   64  */
   65 #if PAGE_SIZE > 65536
   66 #error Unsupported page size
   67 #endif
   68 
   69 struct busdma_bufalloc {
   70         bus_size_t              min_size;
   71         size_t                  num_zones;
   72         struct busdma_bufzone   buf_zones[12];
   73 };
   74 
   75 busdma_bufalloc_t 
   76 busdma_bufalloc_create(const char *name, bus_size_t minimum_alignment,
   77     uma_alloc alloc_func, uma_free free_func, u_int32_t zcreate_flags)
   78 {
   79         struct busdma_bufalloc *ba;
   80         struct busdma_bufzone *bz;
   81         int i;
   82         bus_size_t cursize;
   83 
   84         ba = malloc(sizeof(struct busdma_bufalloc), M_DEVBUF, 
   85             M_ZERO | M_WAITOK);
   86 
   87         ba->min_size = MAX(MIN_ZONE_BUFSIZE, minimum_alignment);
   88 
   89         /*
   90          * Each uma zone is created with an alignment of size-1, meaning that
   91          * the alignment is equal to the size (I.E., 64 byte buffers are aligned
   92          * to 64 byte boundaries, etc).  This allows for a fast efficient test
   93          * when deciding whether a pool buffer meets the constraints of a given
   94          * tag used for allocation: the buffer is usable if tag->alignment <=
   95          * bufzone->size.
   96          */
   97         for (i = 0, bz = ba->buf_zones, cursize = ba->min_size;
   98             i < nitems(ba->buf_zones) && cursize <= MAX_ZONE_BUFSIZE;
   99             ++i, ++bz, cursize <<= 1) {
  100                 snprintf(bz->name, sizeof(bz->name), "dma %.10s %ju",
  101                     name, (uintmax_t)cursize);
  102                 bz->size = cursize;
  103                 bz->umazone = uma_zcreate(bz->name, bz->size,
  104                     NULL, NULL, NULL, NULL, bz->size - 1, zcreate_flags);
  105                 if (bz->umazone == NULL) {
  106                         busdma_bufalloc_destroy(ba);
  107                         return (NULL);
  108                 }
  109                 if (alloc_func != NULL)
  110                         uma_zone_set_allocf(bz->umazone, alloc_func);
  111                 if (free_func != NULL)
  112                         uma_zone_set_freef(bz->umazone, free_func);
  113                 ++ba->num_zones;
  114         }
  115 
  116         return (ba);
  117 }
  118 
  119 void 
  120 busdma_bufalloc_destroy(busdma_bufalloc_t ba)
  121 {
  122         struct busdma_bufzone *bz;
  123         int i;
  124 
  125         if (ba == NULL)
  126                 return;
  127 
  128         for (i = 0, bz = ba->buf_zones; i < ba->num_zones; ++i, ++bz) {
  129                 uma_zdestroy(bz->umazone);
  130         }
  131 
  132         free(ba, M_DEVBUF);
  133 }
  134 
  135 struct busdma_bufzone * 
  136 busdma_bufalloc_findzone(busdma_bufalloc_t ba, bus_size_t size)
  137 {
  138         struct busdma_bufzone *bz;
  139         int i;
  140 
  141         if (size > MAX_ZONE_BUFSIZE)
  142                 return (NULL);
  143 
  144         for (i = 0, bz = ba->buf_zones; i < ba->num_zones; ++i, ++bz) {
  145                 if (bz->size >= size)
  146                         return (bz);
  147         }
  148 
  149         panic("Didn't find a buffer zone of the right size");
  150 }
  151 
  152 void *
  153 busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, vm_size_t size, int domain,
  154     uint8_t *pflag, int wait)
  155 {
  156 
  157 #ifdef VM_MEMATTR_UNCACHEABLE
  158         /* Inform UMA that this allocator uses kernel_arena/object. */
  159         *pflag = UMA_SLAB_KERNEL;
  160 
  161         return ((void *)kmem_alloc_attr_domainset(DOMAINSET_FIXED(domain), size,
  162             wait, 0, BUS_SPACE_MAXADDR, VM_MEMATTR_UNCACHEABLE));
  163 #else
  164         panic("VM_MEMATTR_UNCACHEABLE unavailable");
  165 #endif  /* VM_MEMATTR_UNCACHEABLE */
  166 }
  167 
  168 void 
  169 busdma_bufalloc_free_uncacheable(void *item, vm_size_t size, uint8_t pflag)
  170 {
  171 
  172         kmem_free((vm_offset_t)item, size);
  173 }
  174 

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