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/*
* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/**
* @file
*
* External memory allocation
*
*/
#include <limits.h>
#include <errno.h>
#include <gpxe/uaccess.h>
#include <gpxe/hidemem.h>
#include <gpxe/memmap.h>
#include <gpxe/umalloc.h>
/** Alignment of external allocated memory */
#define EM_ALIGN ( 4 * 1024 )
/** Equivalent of NOWHERE for user pointers */
#define UNOWHERE ( ~UNULL )
/** An external memory block */
struct external_memory {
/** Size of this memory block (excluding this header) */
size_t size;
/** Block is currently in use */
int used;
};
/** Top of heap */
static userptr_t top = UNULL;
/** Bottom of heap (current lowest allocated block) */
static userptr_t bottom = UNULL;
/**
* Initialise external heap
*
* @ret rc Return status code
*/
static int init_eheap ( void ) {
struct memory_map memmap;
unsigned long heap_size = 0;
unsigned int i;
DBG ( "Allocating external heap\n" );
get_memmap ( &memmap );
for ( i = 0 ; i < memmap.count ; i++ ) {
struct memory_region *region = &memmap.regions[i];
unsigned long r_start, r_end;
unsigned long r_size;
DBG ( "Considering [%llx,%llx)\n", region->start, region->end);
/* Truncate block to 4GB */
if ( region->start > UINT_MAX ) {
DBG ( "...starts after 4GB\n" );
continue;
}
r_start = region->start;
if ( region->end > UINT_MAX ) {
DBG ( "...end truncated to 4GB\n" );
r_end = 0; /* =4GB, given the wraparound */
} else {
r_end = region->end;
}
/* Use largest block */
r_size = ( r_end - r_start );
if ( r_size > heap_size ) {
DBG ( "...new best block found\n" );
top = bottom = phys_to_user ( r_end );
heap_size = r_size;
}
}
if ( ! heap_size ) {
DBG ( "No external heap available\n" );
return -ENOMEM;
}
DBG ( "External heap grows downwards from %lx\n",
user_to_phys ( top, 0 ) );
return 0;
}
/**
* Collect free blocks
*
*/
static void ecollect_free ( void ) {
struct external_memory extmem;
/* Walk the free list and collect empty blocks */
while ( bottom != top ) {
copy_from_user ( &extmem, bottom, -sizeof ( extmem ),
sizeof ( extmem ) );
if ( extmem.used )
break;
DBG ( "EXTMEM freeing [%lx,%lx)\n", user_to_phys ( bottom, 0 ),
user_to_phys ( bottom, extmem.size ) );
bottom = userptr_add ( bottom,
( extmem.size + sizeof ( extmem ) ) );
}
}
/**
* Reallocate external memory
*
* @v old_ptr Memory previously allocated by umalloc(), or UNULL
* @v new_size Requested size
* @ret new_ptr Allocated memory, or UNULL
*
* Calling realloc() with a new size of zero is a valid way to free a
* memory block.
*/
static userptr_t memtop_urealloc ( userptr_t ptr, size_t new_size ) {
struct external_memory extmem;
userptr_t new = ptr;
size_t align;
int rc;
/* Initialise external memory allocator if necessary */
if ( bottom == top ) {
if ( ( rc = init_eheap() ) != 0 )
return UNULL;
}
/* Get block properties into extmem */
if ( ptr && ( ptr != UNOWHERE ) ) {
/* Determine old size */
copy_from_user ( &extmem, ptr, -sizeof ( extmem ),
sizeof ( extmem ) );
} else {
/* Create a zero-length block */
ptr = bottom = userptr_add ( bottom, -sizeof ( extmem ) );
DBG ( "EXTMEM allocating [%lx,%lx)\n",
user_to_phys ( ptr, 0 ), user_to_phys ( ptr, 0 ) );
extmem.size = 0;
}
extmem.used = ( new_size > 0 );
/* Expand/shrink block if possible */
if ( ptr == bottom ) {
/* Update block */
new = userptr_add ( ptr, - ( new_size - extmem.size ) );
align = ( user_to_phys ( new, 0 ) & ( EM_ALIGN - 1 ) );
new_size += align;
new = userptr_add ( new, -align );
DBG ( "EXTMEM expanding [%lx,%lx) to [%lx,%lx)\n",
user_to_phys ( ptr, 0 ),
user_to_phys ( ptr, extmem.size ),
user_to_phys ( new, 0 ),
user_to_phys ( new, new_size ));
memmove_user ( new, 0, ptr, 0, ( ( extmem.size < new_size ) ?
extmem.size : new_size ) );
extmem.size = new_size;
bottom = new;
} else {
/* Cannot expand; can only pretend to shrink */
if ( new_size > extmem.size ) {
/* Refuse to expand */
DBG ( "EXTMEM cannot expand [%lx,%lx)\n",
user_to_phys ( ptr, 0 ),
user_to_phys ( ptr, extmem.size ) );
return UNULL;
}
}
/* Write back block properties */
copy_to_user ( new, -sizeof ( extmem ), &extmem,
sizeof ( extmem ) );
/* Collect any free blocks and update hidden memory region */
ecollect_free();
hide_umalloc ( user_to_phys ( bottom, -sizeof ( extmem ) ),
user_to_phys ( top, 0 ) );
return ( new_size ? new : UNOWHERE );
}
PROVIDE_UMALLOC ( memtop, urealloc, memtop_urealloc );
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