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., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <assert.h>
  22 #include <gpxe/umalloc.h>
  23 #include <gpxe/efi/efi.h>
  24
  25 /** @file
  26  *
  27  * gPXE user memory allocation API for EFI
  28  *
  29  */
  30
  31 /** Equivalent of NOWHERE for user pointers */
  32 #define UNOWHERE ( ~UNULL )
  33
  34 /**
  35  * Reallocate external memory
  36  *
  37  * @v old_ptr           Memory previously allocated by umalloc(), or UNULL
  38  * @v new_size          Requested size
  39  * @ret new_ptr         Allocated memory, or UNULL
  40  *
  41  * Calling realloc() with a new size of zero is a valid way to free a
  42  * memory block.
  43  */
  44 static userptr_t efi_urealloc ( userptr_t old_ptr, size_t new_size ) {
  45         EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
  46         EFI_PHYSICAL_ADDRESS phys_addr;
  47         unsigned int new_pages, old_pages;
  48         userptr_t new_ptr = UNOWHERE;
  49         size_t old_size;
  50         EFI_STATUS efirc;
  51
  52         /* Allocate new memory if necessary.  If allocation fails,
  53          * return without touching the old block.
  54          */
  55         if ( new_size ) {
  56                 new_pages = ( EFI_SIZE_TO_PAGES ( new_size ) + 1 );
  57                 if ( ( efirc = bs->AllocatePages ( AllocateAnyPages,
  58                                                    EfiBootServicesData,
  59                                                    new_pages,
  60                                                    &phys_addr ) ) != 0 ) {
  61                         DBG ( "EFI could not allocate %d pages: %s\n",
  62                               new_pages, efi_strerror ( efirc ) );
  63                         return UNULL;
  64                 }
  65                 assert ( phys_addr != 0 );
  66                 new_ptr = phys_to_user ( phys_addr + EFI_PAGE_SIZE );
  67                 copy_to_user ( new_ptr, -EFI_PAGE_SIZE,
  68                                &new_size, sizeof ( new_size ) );
  69                 DBG ( "EFI allocated %d pages at %llx\n",
  70                       new_pages, phys_addr );
  71         }
  72
  73         /* Copy across relevant part of the old data region (if any),
  74          * then free it.  Note that at this point either (a) new_ptr
  75          * is valid, or (b) new_size is 0; either way, the memcpy() is
  76          * valid.
  77          */
  78         if ( old_ptr && ( old_ptr != UNOWHERE ) ) {
  79                 copy_from_user ( &old_size, old_ptr, -EFI_PAGE_SIZE,
  80                                  sizeof ( old_size ) );
  81                 memcpy_user ( new_ptr, 0, old_ptr, 0,
  82                               ( (old_size < new_size) ? old_size : new_size ));
  83                 old_pages = ( EFI_SIZE_TO_PAGES ( old_size ) + 1 );
  84                 phys_addr = user_to_phys ( old_ptr, -EFI_PAGE_SIZE );
  85                 if ( ( efirc = bs->FreePages ( phys_addr, old_pages ) ) != 0 ){
  86                         DBG ( "EFI could not free %d pages at %llx: %s\n",
  87                               old_pages, phys_addr, efi_strerror ( efirc ) );
  88                         /* Not fatal; we have leaked memory but successfully
  89                          * allocated (if asked to do so).
  90                          */
  91                 }
  92                 DBG ( "EFI freed %d pages at %llx\n", old_pages, phys_addr );
  93         }
  94
  95         return new_ptr;
  96 }
  97
  98 PROVIDE_UMALLOC ( efi, urealloc, efi_urealloc );