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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
- *
- * 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 )
-
- /** Start of Etherboot text, as defined by the linker */
- extern char _text[];
-
- /** 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 ( ! top ) {
- 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.
- */
- userptr_t 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 ( ! top ) {
- if ( ( rc = init_eheap() ) != 0 )
- return rc;
- }
-
- /* 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_region ( EXTMEM, user_to_phys ( bottom, -sizeof ( extmem ) ),
- user_to_phys ( top, 0 ) );
-
- return ( new_size ? new : UNOWHERE );
- }
-
- /**
- * Allocate external memory
- *
- * @v size Requested size
- * @ret ptr Memory, or UNULL
- *
- * Memory is guaranteed to be aligned to a page boundary.
- */
- userptr_t umalloc ( size_t size ) {
- return urealloc ( UNULL, size );
- }
-
- /**
- * Free external memory
- *
- * @v ptr Memory allocated by umalloc(), or UNULL
- *
- * If @c ptr is UNULL, no action is taken.
- */
- void ufree ( userptr_t ptr ) {
- urealloc ( ptr, 0 );
- }
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