/*
 * Copyright (C) 2008 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );

#include <string.h>
#include <errno.h>
#include <assert.h>
#include <ipxe/uaccess.h>
#include <ipxe/umalloc.h>
#include <ipxe/efi/efi.h>

/** @file
 *
 * iPXE user memory allocation API for EFI
 *
 */

/**
 * Reallocate external memory
 *
 * @v old_ptr		Memory previously allocated by umalloc(), or NULL
 * @v new_size		Requested size
 * @ret new_ptr		Allocated memory, or NULL
 *
 * Calling realloc() with a new size of zero is a valid way to free a
 * memory block.
 */
static void * efi_urealloc ( void *old_ptr, size_t new_size ) {
	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
	EFI_PHYSICAL_ADDRESS phys_addr;
	unsigned int new_pages, old_pages;
	void *new_ptr = NOWHERE;
	size_t old_size;
	size_t *info;
	EFI_STATUS efirc;
	int rc;

	/* Allocate new memory if necessary.  If allocation fails,
	 * return without touching the old block.
	 */
	if ( new_size ) {
		new_pages = ( EFI_SIZE_TO_PAGES ( new_size ) + 1 );
		if ( ( efirc = bs->AllocatePages ( AllocateAnyPages,
						   EfiBootServicesData,
						   new_pages,
						   &phys_addr ) ) != 0 ) {
			rc = -EEFI ( efirc );
			DBG ( "EFI could not allocate %d pages: %s\n",
			      new_pages, strerror ( rc ) );
			return NULL;
		}
		assert ( phys_addr != 0 );
		new_ptr = phys_to_virt ( phys_addr + EFI_PAGE_SIZE );
		info = ( new_ptr - EFI_PAGE_SIZE );
		*info = new_size;
		DBG ( "EFI allocated %d pages at %llx\n",
		      new_pages, phys_addr );
	}

	/* Copy across relevant part of the old data region (if any),
	 * then free it.  Note that at this point either (a) new_ptr
	 * is valid, or (b) new_size is 0; either way, the memcpy() is
	 * valid.
	 */
	if ( old_ptr && ( old_ptr != NOWHERE ) ) {
		info = ( old_ptr - EFI_PAGE_SIZE );
		old_size = *info;
		memcpy ( new_ptr, old_ptr,
			 ( (old_size < new_size) ? old_size : new_size ) );
		old_pages = ( EFI_SIZE_TO_PAGES ( old_size ) + 1 );
		phys_addr = virt_to_phys ( old_ptr - EFI_PAGE_SIZE );
		if ( ( efirc = bs->FreePages ( phys_addr, old_pages ) ) != 0 ){
			rc = -EEFI ( efirc );
			DBG ( "EFI could not free %d pages at %llx: %s\n",
			      old_pages, phys_addr, strerror ( rc ) );
			/* Not fatal; we have leaked memory but successfully
			 * allocated (if asked to do so).
			 */
		}
		DBG ( "EFI freed %d pages at %llx\n", old_pages, phys_addr );
	}

	return new_ptr;
}

PROVIDE_UMALLOC ( efi, urealloc, efi_urealloc );