diff options
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/arch/i386/interface/pcbios/memtop_umalloc.c')
| -rw-r--r-- | contrib/syslinux-4.02/gpxe/src/arch/i386/interface/pcbios/memtop_umalloc.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/interface/pcbios/memtop_umalloc.c b/contrib/syslinux-4.02/gpxe/src/arch/i386/interface/pcbios/memtop_umalloc.c new file mode 100644 index 0000000..0645fe6 --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/interface/pcbios/memtop_umalloc.c @@ -0,0 +1,202 @@ +/* + * 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 ); |