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978 jermar 1 
/*
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 * Copyright (C) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <as.h>
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#include <libc.h>
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#include <unistd.h>
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#include <align.h>
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/** Create address space area.
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 *
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 * @param address Virtual address where to place new address space area.
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 * @param size Size of the area.
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 * @param flags Flags describing type of the area.
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 *
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 * @return address on success, (void *) -1 otherwise.
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 */
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void *as_area_create(void *address, size_t size, int flags)
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{
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    return (void *) __SYSCALL3(SYS_AS_AREA_CREATE, (sysarg_t ) address, (sysarg_t) size, (sysarg_t) flags);
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}
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/** Resize address space area.
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 *
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 * @param address Virtual address pointing into already existing address space area.
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 * @param size New requested size of the area.
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 * @param flags Currently unused.
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 *
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 * @return Zero on success or a code from @ref errno.h on failure.
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 */
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int as_area_resize(void *address, size_t size, int flags)
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{
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    return __SYSCALL3(SYS_AS_AREA_RESIZE, (sysarg_t ) address, (sysarg_t) size, (sysarg_t) flags);
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}
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/** Destroy address space area.
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 *
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 * @param address Virtual address pointing into the address space area being destroyed.
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 *
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 * @return Zero on success or a code from @ref errno.h on failure.
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 */
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int as_area_destroy(void *address)
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{
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    return __SYSCALL1(SYS_AS_AREA_DESTROY, (sysarg_t ) address);
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}
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static size_t heapsize = 0;
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static size_t maxheapsize = (size_t)(-1);
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static void * last_allocated = 0;
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/* Start of heap linker symbol */
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extern char _heap;
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/** Sbrk emulation
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 *
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 * @param size New area that should be allocated or negative,
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               if it should be shrinked
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 * @return Pointer to newly allocated area
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 */
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void *sbrk(ssize_t incr)
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{
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    int rc;
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    void *res;
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    /* Check for invalid values */
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    if (incr < 0 && -incr > heapsize)
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        return NULL;
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    /* Check for too large value */
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    if (incr > 0 && incr+heapsize < heapsize)
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        return NULL;
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    /* Check for too small values */
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    if (incr < 0 && incr+heapsize > heapsize)
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        return NULL;
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    /* Check for user limit */
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    if ((maxheapsize!=(size_t)(-1)) && (heapsize + incr)>maxheapsize) return NULL;
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    rc = as_area_resize(&_heap, heapsize + incr,0);
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    if (rc != 0)
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        return NULL;
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    /* Compute start of new area */
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    res = (void *)&_heap + heapsize;
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    heapsize += incr;
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    return res;
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}
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/** Set maximum heap size and return pointer just after the heap */
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void *set_maxheapsize(size_t mhs)
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{
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    maxheapsize=mhs;
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    /* Return pointer to area not managed by sbrk */
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    return (void *)&_heap + maxheapsize;
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}
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/** Return pointer to some unmapped area, where fits new as_area
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 *
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 * TODO: make some first_fit/... algorithm, we are now just incrementing
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 *       the pointer to last area
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 */
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void * as_get_mappable_page(size_t sz)
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{
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    void *res;
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    /* Set heapsize to some meaningful value */
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    if (maxheapsize == -1)
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        set_maxheapsize(ALIGN_UP(USER_ADDRESS_SPACE_SIZE_ARCH>>1,PAGE_SIZE));
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    if (!last_allocated)
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        last_allocated = ALIGN_UP((void *)&_heap + maxheapsize, PAGE_SIZE);
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    sz = ALIGN_UP(sz, PAGE_SIZE);
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    res = last_allocated;
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    last_allocated += sz;
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    return res;
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}