src/interface/efi/efi_umalloc.c

   1 /*
   2  * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  *
  19  * You can also choose to distribute this program under the terms of
  20  * the Unmodified Binary Distribution Licence (as given in the file
  21  * COPYING.UBDL), provided that you have satisfied its requirements.
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  25
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <assert.h>
  29 #include <ipxe/umalloc.h>
  30 #include <ipxe/efi/efi.h>
  31
  32 /** @file
  33  *
  34  * iPXE user memory allocation API for EFI
  35  *
  36  */
  37
  38 /** Equivalent of NOWHERE for user pointers */
  39 #define UNOWHERE ( ~UNULL )
  40
  41 /**
  42  * Reallocate external memory
  43  *
  44  * @v old_ptr           Memory previously allocated by umalloc(), or UNULL
  45  * @v new_size          Requested size
  46  * @ret new_ptr         Allocated memory, or UNULL
  47  *
  48  * Calling realloc() with a new size of zero is a valid way to free a
  49  * memory block.
  50  */
  51 static userptr_t efi_urealloc ( userptr_t old_ptr, size_t new_size ) {
  52         EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
  53         EFI_PHYSICAL_ADDRESS phys_addr;
  54         unsigned int new_pages, old_pages;
  55         userptr_t new_ptr = UNOWHERE;
  56         size_t old_size;
  57         EFI_STATUS efirc;
  58         int rc;
  59
  60         /* Allocate new memory if necessary.  If allocation fails,
  61          * return without touching the old block.
  62          */
  63         if ( new_size ) {
  64                 new_pages = ( EFI_SIZE_TO_PAGES ( new_size ) + 1 );
  65                 if ( ( efirc = bs->AllocatePages ( AllocateAnyPages,
  66                                                    EfiBootServicesData,
  67                                                    new_pages,
  68                                                    &phys_addr ) ) != 0 ) {
  69                         rc = -EEFI ( efirc );
  70                         DBG ( "EFI could not allocate %d pages: %s\n",
  71                               new_pages, strerror ( rc ) );
  72                         return UNULL;
  73                 }
  74                 assert ( phys_addr != 0 );
  75                 new_ptr = phys_to_user ( phys_addr + EFI_PAGE_SIZE );
  76                 copy_to_user ( new_ptr, -EFI_PAGE_SIZE,
  77                                &new_size, sizeof ( new_size ) );
  78                 DBG ( "EFI allocated %d pages at %llx\n",
  79                       new_pages, phys_addr );
  80         }
  81
  82         /* Copy across relevant part of the old data region (if any),
  83          * then free it.  Note that at this point either (a) new_ptr
  84          * is valid, or (b) new_size is 0; either way, the memcpy() is
  85          * valid.
  86          */
  87         if ( old_ptr && ( old_ptr != UNOWHERE ) ) {
  88                 copy_from_user ( &old_size, old_ptr, -EFI_PAGE_SIZE,
  89                                  sizeof ( old_size ) );
  90                 memcpy_user ( new_ptr, 0, old_ptr, 0,
  91                               ( (old_size < new_size) ? old_size : new_size ));
  92                 old_pages = ( EFI_SIZE_TO_PAGES ( old_size ) + 1 );
  93                 phys_addr = user_to_phys ( old_ptr, -EFI_PAGE_SIZE );
  94                 if ( ( efirc = bs->FreePages ( phys_addr, old_pages ) ) != 0 ){
  95                         rc = -EEFI ( efirc );
  96                         DBG ( "EFI could not free %d pages at %llx: %s\n",
  97                               old_pages, phys_addr, strerror ( rc ) );
  98                         /* Not fatal; we have leaked memory but successfully
  99                          * allocated (if asked to do so).
 100                          */
 101                 }
 102                 DBG ( "EFI freed %d pages at %llx\n", old_pages, phys_addr );
 103         }
 104
 105         return new_ptr;
 106 }
 107
 108 PROVIDE_UMALLOC ( efi, urealloc, efi_urealloc );