ipxe/src/arch/i386/image/pxe_image.c

/*
 * 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
 *
 * PXE image format
 *
 */

#include <pxe.h>
#include <pxe_call.h>
#include <gpxe/uaccess.h>
#include <gpxe/image.h>
#include <gpxe/segment.h>
#include <gpxe/netdevice.h>

/** PXE load address segment */
#define PXE_LOAD_SEGMENT 0

/** PXE load address offset */
#define PXE_LOAD_OFFSET 0x7c00

struct image_type pxe_image_type __image_type ( PROBE_PXE );

/**
 * Execute PXE image
 *
 * @v image		PXE image
 * @ret rc		Return status code
 */
static int pxe_exec ( struct image *image __unused ) {
	struct net_device *netdev;
	int discard_b, discard_c;
	uint16_t rc;

	/* Ensure that PXE stack is ready to use */
	pxe_init_structures();
	pxe_hook_int1a();

	/* Arbitrarily pick the first open network device to use for PXE */
	for_each_netdev ( netdev ) {
		pxe_netdev = netdev;
		break;
	}

	/* Far call to PXE NBP */
	__asm__ __volatile__ ( REAL_CODE ( "pushw %%cx\n\t"
					   "pushw %%ax\n\t"
					   "movw %%cx, %%es\n\t"
					   "lcall $0, $0x7c00\n\t"
					   "addw $4, %%sp\n\t" )
			       : "=a" ( rc ), "=b" ( discard_b ),
			         "=c" ( discard_c )
			       :  "a" ( & __from_text16 ( ppxe ) ),
			          "b" ( & __from_text16 ( pxenv ) ),
			          "c" ( rm_cs )
			       : "edx", "esi", "edi", "ebp", "memory" );

	return rc;
}

/**
 * Load PXE image into memory
 *
 * @v image		PXE file
 * @ret rc		Return status code
 */
int pxe_load ( struct image *image ) {
	userptr_t buffer = real_to_user ( 0, 0x7c00 );
	size_t filesz = image->len;
	size_t memsz = image->len;
	int rc;

	/* There are no signature checks for PXE; we will accept anything */
	if ( ! image->type )
		image->type = &pxe_image_type;

	/* Verify and prepare segment */
	if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
		DBG ( "PXE image could not prepare segment: %s\n",
		      strerror ( rc ) );
		return rc;
	}

	/* Copy image to segment */
	memcpy_user ( buffer, 0, image->data, 0, filesz );

	return 0;
}

/** PXE image type */
struct image_type pxe_image_type __image_type ( PROBE_PXE ) = {
	.name = "PXE",
	.load = pxe_load,
	.exec = pxe_exec,
};