[apple/xnu.git] / osfmk / ipc / ipc_table.c

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/*
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/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   ipc/ipc_table.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Functions to manipulate tables of IPC capabilities.
 */

#include <mach/kern_return.h>
#include <mach/vm_param.h>
#include <ipc/ipc_table.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_entry.h>
#include <kern/kalloc.h>
#include <vm/vm_kern.h>

#define IPC_TABLE_ENTRIES_SIZE CONFIG_IPC_TABLE_ENTRIES_STEPS
SECURITY_READ_ONLY_LATE(struct ipc_table_size) ipc_table_entries[IPC_TABLE_ENTRIES_SIZE];

#define IPC_TABLE_REQUESTS_SIZE 64
SECURITY_READ_ONLY_LATE(struct ipc_table_size) ipc_table_requests[IPC_TABLE_REQUESTS_SIZE];

static void
ipc_table_fill(
        ipc_table_size_t        its,         /* array to fill */
        unsigned int            num,         /* size of array */
        unsigned int            min,         /* at least this many elements */
        vm_size_t               elemsize)    /* size of elements */
{
        unsigned int index;
        vm_size_t minsize = min * elemsize;
        vm_size_t size;
        vm_size_t incrsize;

        /* first use powers of two, up to the page size */

        for (index = 0, size = 1;
            (index < num) && (size < PAGE_MAX_SIZE);
            size <<= 1) {
                if (size >= minsize) {
                        its[index].its_size = (ipc_table_elems_t)(size / elemsize);
                        index++;
                }
        }

        /* then increments of a page, then two pages, etc. */

        for (incrsize = PAGE_MAX_SIZE; index < num;) {
                unsigned int period;

                for (period = 0;
                    (period < 15) && (index < num);
                    period++, size += incrsize) {
                        if (size >= minsize) {
                                its[index].its_size = (ipc_table_elems_t)(size / elemsize);
                                index++;
                        }
                }
                if (incrsize < (vm_size_t)(PAGE_MAX_SIZE << 3)) {
                        incrsize <<= 1;
                }
        }
}

__startup_func
static void
ipc_table_init(void)
{
        ipc_table_fill(ipc_table_entries, IPC_TABLE_ENTRIES_SIZE - 1,
            16, sizeof(struct ipc_entry));

        /* the last two elements should have the same size */

        ipc_table_entries[IPC_TABLE_ENTRIES_SIZE - 1].its_size =
            ipc_table_entries[IPC_TABLE_ENTRIES_SIZE - 2].its_size;

        /* make sure the robin hood hashing in ipc hash will work */
        assert(ipc_table_entries[IPC_TABLE_ENTRIES_SIZE - 1].its_size <=
            IPC_ENTRY_INDEX_MAX);

        ipc_table_fill(ipc_table_requests, IPC_TABLE_REQUESTS_SIZE - 1,
            2, sizeof(struct ipc_port_request));

        /* the last element should have zero size */

        ipc_table_requests[IPC_TABLE_REQUESTS_SIZE - 1].its_size = 0;
}
STARTUP(MACH_IPC, STARTUP_RANK_FIRST, ipc_table_init);


/*
 *      Routine: ipc_table_max_entries
 *      Purpose:
 *              returns the maximum number of entries an IPC space
 *              is allowed to contain (the maximum size to which it will grow)
 *      Conditions:
 *              none
 */
unsigned int
ipc_table_max_entries(void)
{
        static_assert(IPC_TABLE_ENTRIES_SIZE >= 1);
        return (unsigned int)ipc_table_entries[IPC_TABLE_ENTRIES_SIZE - 1].its_size;
}


/*
 *      Routine: ipc_table_max_requests
 *      Purpose:
 *              returns the maximum number of requests an IPC request table
 *              is allowed to contain (the maximum size to which it will grow)
 *      Conditions:
 *              none
 */
unsigned int
ipc_table_max_requests(void)
{
        static_assert(IPC_TABLE_REQUESTS_SIZE >= 2);
        return (unsigned int)ipc_table_requests[IPC_TABLE_REQUESTS_SIZE - 2].its_size;
}


/*
 *      Routine:        ipc_table_alloc
 *      Purpose:
 *              Allocate a table.
 *      Conditions:
 *              May block.
 */

void *
ipc_table_alloc(
        vm_size_t       size)
{
        return kalloc(size);
}


/*
 *      Routine:        ipc_table_free
 *      Purpose:
 *              Free a table allocated with ipc_table_alloc.
 *      Conditions:
 *              May block.
 */

void
ipc_table_free(
        vm_size_t       size,
        void *          table)
{
        kfree(table, size);
}