/*
* Copyright (C) 2008 Daniel Verkamp <daniel@drv.nu>.
*
* 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
*
* SYSLINUX COM32 image format
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <assert.h>
#include <realmode.h>
#include <basemem.h>
#include <comboot.h>
#include <gpxe/uaccess.h>
#include <gpxe/image.h>
#include <gpxe/segment.h>
#include <gpxe/init.h>
#include <gpxe/memmap.h>
struct image_type com32_image_type __image_type ( PROBE_NORMAL );
/**
* Execute COMBOOT image
*
* @v image COM32 image
* @ret rc Return status code
*/
static int com32_exec ( struct image *image ) {
struct memory_map memmap;
unsigned int i;
int state;
uint32_t avail_mem_top;
state = rmsetjmp ( comboot_return );
switch ( state ) {
case 0: /* First time through; invoke COM32 program */
/* Get memory map */
get_memmap ( &memmap );
/* Find end of block covering COM32 image loading area */
for ( i = 0, avail_mem_top = 0 ; i < memmap.count ; i++ ) {
if ( (memmap.regions[i].start <= COM32_START_PHYS) &&
(memmap.regions[i].end > COM32_START_PHYS + image->len) ) {
avail_mem_top = memmap.regions[i].end;
break;
}
}
DBGC ( image, "COM32 %p: available memory top = 0x%x\n",
image, avail_mem_top );
assert ( avail_mem_top != 0 );
com32_external_esp = phys_to_virt ( avail_mem_top );
/* Hook COMBOOT API interrupts */
hook_comboot_interrupts();
/* Unregister image, so that a "boot" command doesn't
* throw us into an execution loop. We never
* reregister ourselves; COMBOOT images expect to be
* removed on exit.
*/
unregister_image ( image );
__asm__ __volatile__ (
"movl %%esp, (com32_internal_esp)\n\t" /* Save internal virtual address space ESP */
"movl (com32_external_esp), %%esp\n\t" /* Switch to COM32 ESP (top of available memory) */
"call _virt_to_phys\n\t" /* Switch to flat physical address space */
"pushl %0\n\t" /* Pointer to CDECL helper function */
"pushl %1\n\t" /* Pointer to FAR call helper function */
"pushl %2\n\t" /* Size of low memory bounce buffer */
"pushl %3\n\t" /* Pointer to low memory bounce buffer */
"pushl %4\n\t" /* Pointer to INT call helper function */
"pushl %5\n\t" /* Pointer to the command line arguments */
"pushl $6\n\t" /* Number of additional arguments */
"call *%6\n\t" /* Execute image */
"call _phys_to_virt\n\t" /* Switch back to internal virtual address space */
"movl (com32_internal_esp), %%esp\n\t" /* Switch back to internal stack */
:
:
/* %0 */ "r" ( virt_to_phys ( com32_cfarcall_wrapper ) ),
/* %1 */ "r" ( virt_to_phys ( com32_farcall_wrapper ) ),
/* %2 */ "r" ( get_fbms() * 1024 - (COM32_BOUNCE_SEG << 4) ),
/* %3 */ "i" ( COM32_BOUNCE_SEG << 4 ),
/* %4 */ "r" ( virt_to_phys ( com32_intcall_wrapper ) ),
/* %5 */ "r" ( virt_to_phys ( image->cmdline ) ),
/* %6 */ "r" ( COM32_START_PHYS )
:
"memory" );
DBGC ( image, "COM32 %p: returned\n", image );
break;
case COMBOOT_EXIT:
DBGC ( image, "COM32 %p: exited\n", image );
break;
case COMBOOT_EXIT_RUN_KERNEL:
DBGC ( image, "COM32 %p: exited to run kernel %p\n",
image, comboot_replacement_image );
image->replacement = comboot_replacement_image;
comboot_replacement_image = NULL;
image_autoload ( image->replacement );
break;
case COMBOOT_EXIT_COMMAND:
DBGC ( image, "COM32 %p: exited after executing command\n",
image );
break;
default:
assert ( 0 );
break;
}
unhook_comboot_interrupts();
comboot_force_text_mode();
return 0;
}
/**
* Check image name extension
*
* @v image COM32 image
* @ret rc Return status code
*/
static int com32_identify ( struct image *image ) {
const char *ext;
static const uint8_t magic[] = { 0xB8, 0xFF, 0x4C, 0xCD, 0x21 };
uint8_t buf[5];
if ( image->len >= 5 ) {
/* Check for magic number
* mov eax,21cd4cffh
* B8 FF 4C CD 21
*/
copy_from_user ( buf, image->data, 0, sizeof(buf) );
if ( ! memcmp ( buf, magic, sizeof(buf) ) ) {
DBGC ( image, "COM32 %p: found magic number\n",
image );
return 0;
}
}
/* Magic number not found; check filename extension */
ext = strrchr( image->name, '.' );
if ( ! ext ) {
DBGC ( image, "COM32 %p: no extension\n",
image );
return -ENOEXEC;
}
++ext;
if ( strcasecmp( ext, "c32" ) ) {
DBGC ( image, "COM32 %p: unrecognized extension %s\n",
image, ext );
return -ENOEXEC;
}
return 0;
}
/**
* Load COM32 image into memory
* @v image COM32 image
* @ret rc Return status code
*/
static int comboot_load_image ( struct image *image ) {
size_t filesz, memsz;
userptr_t buffer;
int rc;
filesz = image->len;
memsz = filesz;
buffer = phys_to_user ( COM32_START_PHYS );
if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
DBGC ( image, "COM32 %p: could not prepare segment: %s\n",
image, strerror ( rc ) );
return rc;
}
/* Copy image to segment */
memcpy_user ( buffer, 0, image->data, 0, filesz );
return 0;
}
/**
* Prepare COM32 low memory bounce buffer
* @v image COM32 image
* @ret rc Return status code
*/
static int comboot_prepare_bounce_buffer ( struct image * image ) {
unsigned int seg;
userptr_t seg_userptr;
size_t filesz, memsz;
int rc;
seg = COM32_BOUNCE_SEG;
seg_userptr = real_to_user ( seg, 0 );
/* Ensure the entire 64k segment is free */
memsz = 0xFFFF;
filesz = 0;
/* Prepare, verify, and load the real-mode segment */
if ( ( rc = prep_segment ( seg_userptr, filesz, memsz ) ) != 0 ) {
DBGC ( image, "COM32 %p: could not prepare bounce buffer segment: %s\n",
image, strerror ( rc ) );
return rc;
}
return 0;
}
/**
* Load COM32 image into memory
*
* @v image COM32 image
* @ret rc Return status code
*/
static int com32_load ( struct image *image ) {
int rc;
DBGC ( image, "COM32 %p: name '%s', cmdline '%s'\n",
image, image->name, image->cmdline );
/* Check if this is a COMBOOT image */
if ( ( rc = com32_identify ( image ) ) != 0 ) {
return rc;
}
/* This is a COM32 image, valid or otherwise */
if ( ! image->type )
image->type = &com32_image_type;
/* Load image */
if ( ( rc = comboot_load_image ( image ) ) != 0 ) {
return rc;
}
/* Prepare bounce buffer segment */
if ( ( rc = comboot_prepare_bounce_buffer ( image ) ) != 0 ) {
return rc;
}
return 0;
}
/** SYSLINUX COM32 image type */
struct image_type com32_image_type __image_type ( PROBE_NORMAL ) = {
.name = "COM32",
.load = com32_load,
.exec = com32_exec,
};