gpxe/src/arch/i386/interface/syslinux/comboot_call.c - platform/external/syslinux - Git at Google

 /*
  * 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 COMBOOT API
  *
  */

 FILE_LICENCE ( GPL2_OR_LATER );

 #include <errno.h>
 #include <realmode.h>
 #include <biosint.h>
 #include <console.h>
 #include <stdlib.h>
 #include <comboot.h>
 #include <bzimage.h>
 #include <pxe_call.h>
 #include <setjmp.h>
 #include <string.h>
 #include <gpxe/posix_io.h>
 #include <gpxe/process.h>
 #include <gpxe/serial.h>
 #include <gpxe/init.h>
 #include <gpxe/image.h>
 #include <usr/imgmgmt.h>
 #include "config/console.h"
 #include "config/serial.h"

 /** The "SYSLINUX" version string */
 static char __data16_array ( syslinux_version, [] ) = "gPXE " VERSION;
 #define syslinux_version __use_data16 ( syslinux_version )

 /** The "SYSLINUX" copyright string */
 static char __data16_array ( syslinux_copyright, [] ) = "http://etherboot.org";
 #define syslinux_copyright __use_data16 ( syslinux_copyright )

 static char __data16_array ( syslinux_configuration_file, [] ) = "";
 #define syslinux_configuration_file __use_data16 ( syslinux_configuration_file )

 /** Feature flags */
 static uint8_t __data16 ( comboot_feature_flags ) = COMBOOT_FEATURE_IDLE_LOOP;
 #define comboot_feature_flags __use_data16 ( comboot_feature_flags )

 typedef union {
 	syslinux_pm_regs pm; syslinux_rm_regs rm;
 } syslinux_regs;

 /** Initial register values for INT 22h AX=1Ah and 1Bh */
 static syslinux_regs __text16 ( comboot_initial_regs );
 #define comboot_initial_regs __use_text16 ( comboot_initial_regs )

 static struct segoff __text16 ( int20_vector );
 #define int20_vector __use_text16 ( int20_vector )

 static struct segoff __text16 ( int21_vector );
 #define int21_vector __use_text16 ( int21_vector )

 static struct segoff __text16 ( int22_vector );
 #define int22_vector __use_text16 ( int22_vector )

 extern void int20_wrapper ( void );
 extern void int21_wrapper ( void );
 extern void int22_wrapper ( void );

 /* setjmp/longjmp context buffer used to return after loading an image */
 rmjmp_buf comboot_return;

 /* Replacement image when exiting with COMBOOT_EXIT_RUN_KERNEL */
 struct image *comboot_replacement_image;

 /* Mode flags set by INT 22h AX=0017h */
 static uint16_t comboot_graphics_mode = 0;


 /**
  * Print a string with a particular terminator
  */
 static void print_user_string ( unsigned int segment, unsigned int offset, char terminator ) {
 	int i = 0;
 	char c;
 	userptr_t str = real_to_user ( segment, offset );
 	for ( ; ; ) {
 		copy_from_user ( &c, str, i, 1 );
 		if ( c == terminator ) break;
 		putchar ( c );
 		i++;
 	}
 }


 /**
  * Perform a series of memory copies from a list in low memory
  */
 static void shuffle ( unsigned int list_segment, unsigned int list_offset, unsigned int count )
 {
 	comboot_shuffle_descriptor shuf[COMBOOT_MAX_SHUFFLE_DESCRIPTORS];
 	unsigned int i;

 	/* Copy shuffle descriptor list so it doesn't get overwritten */
 	copy_from_user ( shuf, real_to_user ( list_segment, list_offset ), 0,
 	                 count * sizeof( comboot_shuffle_descriptor ) );

 	/* Do the copies */
 	for ( i = 0; i < count; i++ ) {
 		userptr_t src_u = phys_to_user ( shuf[ i ].src );
 		userptr_t dest_u = phys_to_user ( shuf[ i ].dest );

 		if ( shuf[ i ].src == 0xFFFFFFFF ) {
 			/* Fill with 0 instead of copying */
 			memset_user ( dest_u, 0, 0, shuf[ i ].len );
 		} else if ( shuf[ i ].dest == 0xFFFFFFFF ) {
 			/* Copy new list of descriptors */
 			count = shuf[ i ].len / sizeof( comboot_shuffle_descriptor );
 			assert ( count <= COMBOOT_MAX_SHUFFLE_DESCRIPTORS );
 			copy_from_user ( shuf, src_u, 0, shuf[ i ].len );
 			i = -1;
 		} else {
 			/* Regular copy */
 			memmove_user ( dest_u, 0, src_u, 0, shuf[ i ].len );
 		}
 	}
 }


 /**
  * Set default text mode
  */
 void comboot_force_text_mode ( void ) {
 	if ( comboot_graphics_mode & COMBOOT_VIDEO_VESA ) {
 		/* Set VGA mode 3 via VESA VBE mode set */
 		__asm__ __volatile__ (
 			REAL_CODE (
 				"mov $0x4F02, %%ax\n\t"
 				"mov $0x03, %%bx\n\t"
 				"int $0x10\n\t"
 			)
 		: : );
 	} else if ( comboot_graphics_mode & COMBOOT_VIDEO_GRAPHICS ) {
 		/* Set VGA mode 3 via standard VGA mode set */
 		__asm__ __volatile__ (
 			REAL_CODE (
 				"mov $0x03, %%ax\n\t"
 				"int $0x10\n\t"
 			)
 		: : );
 	}

 	comboot_graphics_mode = 0;
 }


 /**
  * Fetch kernel and optional initrd
  */
 static int comboot_fetch_kernel ( char *kernel_file, char *cmdline ) {
 	struct image *kernel = NULL;
 	struct image *initrd = NULL;
 	char *initrd_file;
 	int rc;

 	/* Find initrd= parameter, if any */
 	if ( ( initrd_file = strstr ( cmdline, "initrd=" ) ) != NULL ) {
 		char *initrd_end;

 		/* skip "initrd=" */
 		initrd_file += 7;

 		/* Find terminating space, if any, and replace with NUL */
 		initrd_end = strchr ( initrd_file, ' ' );
 		if ( initrd_end )
 			*initrd_end = '\0';

 		DBG ( "COMBOOT: fetching initrd '%s'\n", initrd_file );

 		/* Allocate and fetch initrd */
 		initrd = alloc_image();
 		if ( ! initrd ) {
 			DBG ( "COMBOOT: could not allocate initrd\n" );
 			rc = -ENOMEM;
 			goto out;
 		}
 		if ( ( rc = imgfetch ( initrd, initrd_file,
 				       register_image ) ) != 0 ) {
 			DBG ( "COMBOOT: could not fetch initrd: %s\n",
 			      strerror ( rc ) );
 			goto out;
 		}

 		/* Restore space after initrd name, if applicable */
 		if ( initrd_end )
 			*initrd_end = ' ';
 	}

 	DBG ( "COMBOOT: fetching kernel '%s'\n", kernel_file );

 	/* Allocate and fetch kernel */
 	kernel = alloc_image();
 	if ( ! kernel ) {
 		DBG ( "COMBOOT: could not allocate kernel\n" );
 		rc = -ENOMEM;
 		goto out;
 	}
 	if ( ( rc = imgfetch ( kernel, kernel_file,
 			       register_image ) ) != 0 ) {
 		DBG ( "COMBOOT: could not fetch kernel: %s\n",
 		      strerror ( rc ) );
 		goto out;
 	}
 	if ( ( rc = image_set_cmdline ( kernel, cmdline ) ) != 0 ) {
 		DBG ( "COMBOOT: could not set kernel command line: %s\n",
 		      strerror ( rc ) );
 		goto out;
 	}

 	/* Store kernel as replacement image */
 	assert ( comboot_replacement_image == NULL );
 	comboot_replacement_image = image_get ( kernel );

  out:
 	/* Drop image references unconditionally; either we want to
 	 * discard them, or they have been registered and we should
 	 * drop out local reference.
 	 */
 	image_put ( kernel );
 	image_put ( initrd );
 	return rc;
 }


 /**
  * Terminate program interrupt handler
  */
 static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
 	rmlongjmp ( comboot_return, COMBOOT_EXIT );
 }


 /**
  * DOS-compatible API
  */
 static __asmcall void int21 ( struct i386_all_regs *ix86 ) {
 	ix86->flags |= CF;

 	switch ( ix86->regs.ah ) {
 	case 0x00:
 	case 0x4C: /* Terminate program */
 		rmlongjmp ( comboot_return, COMBOOT_EXIT );
 		break;

 	case 0x01: /* Get Key with Echo */
 	case 0x08: /* Get Key without Echo */
 		/* TODO: handle extended characters? */
 		ix86->regs.al = getchar( );

 		/* Enter */
 		if ( ix86->regs.al == 0x0A )
 			ix86->regs.al = 0x0D;

 		if ( ix86->regs.ah == 0x01 )
 			putchar ( ix86->regs.al );

 		ix86->flags &= ~CF;
 		break;

 	case 0x02: /* Write Character */
 		putchar ( ix86->regs.dl );
 		ix86->flags &= ~CF;
 		break;

 	case 0x04: /* Write Character to Serial Port */
 		serial_putc ( ix86->regs.dl );
 		ix86->flags &= ~CF;
 		break;

 	case 0x09: /* Write DOS String to Console */
 		print_user_string ( ix86->segs.ds, ix86->regs.dx, '$' );
 		ix86->flags &= ~CF;
 		break;

 	case 0x0B: /* Check Keyboard */
 		if ( iskey() )
 			ix86->regs.al = 0xFF;
 		else
 			ix86->regs.al = 0x00;

 		ix86->flags &= ~CF;
 		break;

 	case 0x30: /* Check DOS Version */
 		/* Bottom halves all 0; top halves spell "SYSLINUX" */
 		ix86->regs.eax = 0x59530000;
 		ix86->regs.ebx = 0x4C530000;
 		ix86->regs.ecx = 0x4E490000;
 		ix86->regs.edx = 0x58550000;
 		ix86->flags &= ~CF;
 		break;

 	default:
 		DBG ( "COMBOOT unknown int21 function %02x\n", ix86->regs.ah );
 		break;
 	}
 }


 /**
  * SYSLINUX API
  */
 static __asmcall void int22 ( struct i386_all_regs *ix86 ) {
 	ix86->flags |= CF;

 	switch ( ix86->regs.ax ) {
 	case 0x0001: /* Get Version */

 		/* Number of INT 22h API functions available */
 		ix86->regs.ax = 0x001D;

 		/* SYSLINUX version number */
 		ix86->regs.ch = 0; /* major */
 		ix86->regs.cl = 0; /* minor */

 		/* SYSLINUX derivative ID */
 		ix86->regs.dl = BZI_LOADER_TYPE_GPXE;

 		/* SYSLINUX version and copyright strings */
 		ix86->segs.es = rm_ds;
 		ix86->regs.si = ( ( unsigned ) __from_data16 ( syslinux_version ) );
 		ix86->regs.di = ( ( unsigned ) __from_data16 ( syslinux_copyright ) );

 		ix86->flags &= ~CF;
 		break;

 	case 0x0002: /* Write String */
 		print_user_string ( ix86->segs.es, ix86->regs.bx, '\0' );
 		ix86->flags &= ~CF;
 		break;

 	case 0x0003: /* Run command */
 		{
 			userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
 			int len = strlen_user ( cmd_u, 0 );
 			char cmd[len + 1];
 			copy_from_user ( cmd, cmd_u, 0, len + 1 );
 			DBG ( "COMBOOT: executing command '%s'\n", cmd );
 			system ( cmd );
 			DBG ( "COMBOOT: exiting after executing command...\n" );
 			rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
 		}
 		break;

 	case 0x0004: /* Run default command */
 		/* FIXME: just exit for now */
 		rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
 		break;

 	case 0x0005: /* Force text mode */
 		comboot_force_text_mode ( );
 		ix86->flags &= ~CF;
 		break;

 	case 0x0006: /* Open file */
 		{
 			int fd;
 			userptr_t file_u = real_to_user ( ix86->segs.es, ix86->regs.si );
 			int len = strlen_user ( file_u, 0 );
 			char file[len + 1];

 			copy_from_user ( file, file_u, 0, len + 1 );

 			if ( file[0] == '\0' ) {
 				DBG ( "COMBOOT: attempted open with empty file name\n" );
 				break;
 			}

 			DBG ( "COMBOOT: opening file '%s'\n", file );

 			fd = open ( file );

 			if ( fd < 0 ) {
 				DBG ( "COMBOOT: error opening file %s\n", file );
 				break;
 			}

 			/* This relies on the fact that a gPXE POSIX fd will
 			 * always fit in 16 bits.
 			 */
 #if (POSIX_FD_MAX > 65535)
 #error POSIX_FD_MAX too large
 #endif
 			ix86->regs.si = (uint16_t) fd;

 			ix86->regs.cx = COMBOOT_FILE_BLOCKSZ;
 			ix86->regs.eax = fsize ( fd );
 			ix86->flags &= ~CF;
 		}
 		break;

 	case 0x0007: /* Read file */
 		{
 			int fd = ix86->regs.si;
 			int len = ix86->regs.cx * COMBOOT_FILE_BLOCKSZ;
 			int rc;
 			fd_set fds;
 			userptr_t buf = real_to_user ( ix86->segs.es, ix86->regs.bx );

 			/* Wait for data ready to read */
 			FD_ZERO ( &fds );
 			FD_SET ( fd, &fds );

 			select ( &fds, 1 );

 			rc = read_user ( fd, buf, 0, len );
 			if ( rc < 0 ) {
 				DBG ( "COMBOOT: read failed\n" );
 				ix86->regs.si = 0;
 				break;
 			}

 			ix86->regs.ecx = rc;
 			ix86->flags &= ~CF;
 		}
 		break;

 	case 0x0008: /* Close file */
 		{
 			int fd = ix86->regs.si;
 			close ( fd );
 			ix86->flags &= ~CF;
 		}
 		break;

 	case 0x0009: /* Call PXE Stack */
 		if ( pxe_api_call_weak ( ix86 ) != 0 )
 			ix86->flags |= CF;
 		else
 			ix86->flags &= ~CF;
 		break;

 	case 0x000A: /* Get Derivative-Specific Information */

 		/* gPXE has its own derivative ID, so there is no defined
 		 * output here; just return AL for now */
 		ix86->regs.al = BZI_LOADER_TYPE_GPXE;
 		ix86->flags &= ~CF;
 		break;

 	case 0x000B: /* Get Serial Console Configuration */
 #if defined(CONSOLE_SERIAL) && !defined(COMPRESERVE)
 		ix86->regs.dx = COMCONSOLE;
 		ix86->regs.cx = 115200 / COMSPEED;
 		ix86->regs.bx = 0;
 #else
 		ix86->regs.dx = 0;
 #endif

 		ix86->flags &= ~CF;
 		break;

 	case 0x000E: /* Get configuration file name */
 		/* FIXME: stub */
 		ix86->segs.es = rm_ds;
 		ix86->regs.bx = ( ( unsigned ) __from_data16 ( syslinux_configuration_file ) );
 		ix86->flags &= ~CF;
 		break;

 	case 0x000F: /* Get IPAPPEND strings */
 		/* FIXME: stub */
 		ix86->regs.cx = 0;
 		ix86->segs.es = 0;
 		ix86->regs.bx = 0;
 		ix86->flags &= ~CF;
 		break;

 	case 0x0010: /* Resolve hostname */
 		{
 			userptr_t hostname_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
 			int len = strlen_user ( hostname_u, 0 );
 			char hostname[len];
 			struct in_addr addr;

 			copy_from_user ( hostname, hostname_u, 0, len + 1 );

 			/* TODO:
 			 * "If the hostname does not contain a dot (.), the
 			 * local domain name is automatically appended."
 			 */

 			comboot_resolv ( hostname, &addr );

 			ix86->regs.eax = addr.s_addr;
 			ix86->flags &= ~CF;
 		}
 		break;

 	case 0x0011: /* Maximum number of shuffle descriptors */
 		ix86->regs.cx = COMBOOT_MAX_SHUFFLE_DESCRIPTORS;
 		ix86->flags &= ~CF;
 		break;

 	case 0x0012: /* Cleanup, shuffle and boot */
 		if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
 			break;

 		/* Perform final cleanup */
 		shutdown ( SHUTDOWN_BOOT );

 		/* Perform sequence of copies */
 		shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );

 		/* Jump to real-mode entry point */
 		__asm__ __volatile__ (
 			REAL_CODE (
 				"pushw %0\n\t"
 				"popw %%ds\n\t"
 				"pushl %1\n\t"
 				"lret\n\t"
 			)
 			:
 			: "r" ( ix86->segs.ds ),
 			  "r" ( ix86->regs.ebp ),
 			  "d" ( ix86->regs.ebx ),
 			  "S" ( ix86->regs.esi ) );

 		assert ( 0 ); /* Execution should never reach this point */

 		break;

 	case 0x0013: /* Idle loop call */
 		step ( );
 		ix86->flags &= ~CF;
 		break;

 	case 0x0015: /* Get feature flags */
 		ix86->segs.es = rm_ds;
 		ix86->regs.bx = ( ( unsigned ) __from_data16 ( &comboot_feature_flags ) );
 		ix86->regs.cx = 1; /* Number of feature flag bytes */
 		ix86->flags &= ~CF;
 		break;

 	case 0x0016: /* Run kernel image */
 		{
 			userptr_t file_u = real_to_user ( ix86->segs.ds, ix86->regs.si );
 			userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
 			int file_len = strlen_user ( file_u, 0 );
 			int cmd_len = strlen_user ( cmd_u, 0 );
 			char file[file_len + 1];
 			char cmd[cmd_len + 1];

 			copy_from_user ( file, file_u, 0, file_len + 1 );
 			copy_from_user ( cmd, cmd_u, 0, cmd_len + 1 );

 			DBG ( "COMBOOT: run kernel %s %s\n", file, cmd );
 			comboot_fetch_kernel ( file, cmd );
 			/* Technically, we should return if we
 			 * couldn't load the kernel, but it's not safe
 			 * to do that since we have just overwritten
 			 * part of the COMBOOT program's memory space.
 			 */
 			DBG ( "COMBOOT: exiting to run kernel...\n" );
 			rmlongjmp ( comboot_return, COMBOOT_EXIT_RUN_KERNEL );
 		}
 		break;

 	case 0x0017: /* Report video mode change */
 		comboot_graphics_mode = ix86->regs.bx;
 		ix86->flags &= ~CF;
 		break;

 	case 0x0018: /* Query custom font */
 		/* FIXME: stub */
 		ix86->regs.al = 0;
 		ix86->segs.es = 0;
 		ix86->regs.bx = 0;
 		ix86->flags &= ~CF;
 		break;

 	case 0x001B: /* Cleanup, shuffle and boot to real mode */
 		if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
 			break;

 		/* Perform final cleanup */
 		shutdown ( SHUTDOWN_BOOT );

 		/* Perform sequence of copies */
 		shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );

 		/* Copy initial register values to .text16 */
 		memcpy_user ( real_to_user ( rm_cs, (unsigned) __from_text16 ( &comboot_initial_regs ) ), 0,
 		              real_to_user ( ix86->segs.ds, ix86->regs.si ), 0,
 		              sizeof(syslinux_rm_regs) );

 		/* Load initial register values */
 		__asm__ __volatile__ (
 			REAL_CODE (
 				/* Point SS:SP at the register value structure */
 				"pushw %%cs\n\t"
 				"popw %%ss\n\t"
 				"movw $comboot_initial_regs, %%sp\n\t"

 				/* Segment registers */
 				"popw %%es\n\t"
 				"popw %%ax\n\t" /* Skip CS */
 				"popw %%ds\n\t"
 				"popw %%ax\n\t" /* Skip SS for now */
 				"popw %%fs\n\t"
 				"popw %%gs\n\t"

 				/* GP registers */
 				"popl %%eax\n\t"
 				"popl %%ecx\n\t"
 				"popl %%edx\n\t"
 				"popl %%ebx\n\t"
 				"popl %%ebp\n\t" /* Skip ESP for now */
 				"popl %%ebp\n\t"
 				"popl %%esi\n\t"
 				"popl %%edi\n\t"

 				/* Load correct SS:ESP */
 				"movw $(comboot_initial_regs + 6), %%sp\n\t"
 				"popw %%ss\n\t"
 				"movl %%cs:(comboot_initial_regs + 28), %%esp\n\t"

 				"ljmp *%%cs:(comboot_initial_regs + 44)\n\t"
 			)
 			: : );

 		break;

 	case 0x001C: /* Get pointer to auxilliary data vector */
 		/* FIXME: stub */
 		ix86->regs.cx = 0; /* Size of the ADV */
 		ix86->flags &= ~CF;
 		break;

 	case 0x001D: /* Write auxilliary data vector */
 		/* FIXME: stub */
 		ix86->flags &= ~CF;
 		break;

 	default:
 		DBG ( "COMBOOT unknown int22 function %04x\n", ix86->regs.ax );
 		break;
 	}
 }

 /**
  * Hook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
  */
 void hook_comboot_interrupts ( ) {

 	__asm__ __volatile__ (
 		TEXT16_CODE ( "\nint20_wrapper:\n\t"
 		              "pushl %0\n\t"
 		              "pushw %%cs\n\t"
 		              "call prot_call\n\t"
 		              "addw $4, %%sp\n\t"
 		              "iret\n\t" )
 		          : : "i" ( int20 ) );

 	hook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
 		                      &int20_vector );

 	__asm__ __volatile__ (
 		TEXT16_CODE ( "\nint21_wrapper:\n\t"
 		              "pushl %0\n\t"
 		              "pushw %%cs\n\t"
 		              "call prot_call\n\t"
 		              "addw $4, %%sp\n\t"
 		              "iret\n\t" )
 		          : : "i" ( int21 ) );

 	hook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
 	                      &int21_vector );

 	__asm__  __volatile__ (
 		TEXT16_CODE ( "\nint22_wrapper:\n\t"
 		              "pushl %0\n\t"
 		              "pushw %%cs\n\t"
 		              "call prot_call\n\t"
 		              "addw $4, %%sp\n\t"
 		              "iret\n\t" )
 		          : : "i" ( int22) );

 	hook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
 	                      &int22_vector );
 }

 /**
  * Unhook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
  */
 void unhook_comboot_interrupts ( ) {

 	unhook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
 				&int20_vector );

 	unhook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
 				&int21_vector );

 	unhook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
 				&int22_vector );
 }
	/*
	* 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 COMBOOT API
	*
	*/

	FILE_LICENCE ( GPL2_OR_LATER );

	#include <errno.h>
	#include <realmode.h>
	#include <biosint.h>
	#include <console.h>
	#include <stdlib.h>
	#include <comboot.h>
	#include <bzimage.h>
	#include <pxe_call.h>
	#include <setjmp.h>
	#include <string.h>
	#include <gpxe/posix_io.h>
	#include <gpxe/process.h>
	#include <gpxe/serial.h>
	#include <gpxe/init.h>
	#include <gpxe/image.h>
	#include <usr/imgmgmt.h>
	#include "config/console.h"
	#include "config/serial.h"

	/** The "SYSLINUX" version string */
	static char __data16_array ( syslinux_version, [] ) = "gPXE " VERSION;
	#define syslinux_version __use_data16 ( syslinux_version )

	/** The "SYSLINUX" copyright string */
	static char __data16_array ( syslinux_copyright, [] ) = "http://etherboot.org";
	#define syslinux_copyright __use_data16 ( syslinux_copyright )

	static char __data16_array ( syslinux_configuration_file, [] ) = "";
	#define syslinux_configuration_file __use_data16 ( syslinux_configuration_file )

	/** Feature flags */
	static uint8_t __data16 ( comboot_feature_flags ) = COMBOOT_FEATURE_IDLE_LOOP;
	#define comboot_feature_flags __use_data16 ( comboot_feature_flags )

	typedef union {
	syslinux_pm_regs pm; syslinux_rm_regs rm;
	} syslinux_regs;

	/** Initial register values for INT 22h AX=1Ah and 1Bh */
	static syslinux_regs __text16 ( comboot_initial_regs );
	#define comboot_initial_regs __use_text16 ( comboot_initial_regs )

	static struct segoff __text16 ( int20_vector );
	#define int20_vector __use_text16 ( int20_vector )

	static struct segoff __text16 ( int21_vector );
	#define int21_vector __use_text16 ( int21_vector )

	static struct segoff __text16 ( int22_vector );
	#define int22_vector __use_text16 ( int22_vector )

	extern void int20_wrapper ( void );
	extern void int21_wrapper ( void );
	extern void int22_wrapper ( void );

	/* setjmp/longjmp context buffer used to return after loading an image */
	rmjmp_buf comboot_return;

	/* Replacement image when exiting with COMBOOT_EXIT_RUN_KERNEL */
	struct image *comboot_replacement_image;

	/* Mode flags set by INT 22h AX=0017h */
	static uint16_t comboot_graphics_mode = 0;


	/**
	* Print a string with a particular terminator
	*/
	static void print_user_string ( unsigned int segment, unsigned int offset, char terminator ) {
	int i = 0;
	char c;
	userptr_t str = real_to_user ( segment, offset );
	for ( ; ; ) {
	copy_from_user ( &c, str, i, 1 );
	if ( c == terminator ) break;
	putchar ( c );
	i++;
	}
	}


	/**
	* Perform a series of memory copies from a list in low memory
	*/
	static void shuffle ( unsigned int list_segment, unsigned int list_offset, unsigned int count )
	{
	comboot_shuffle_descriptor shuf[COMBOOT_MAX_SHUFFLE_DESCRIPTORS];
	unsigned int i;

	/* Copy shuffle descriptor list so it doesn't get overwritten */
	copy_from_user ( shuf, real_to_user ( list_segment, list_offset ), 0,
	count * sizeof( comboot_shuffle_descriptor ) );

	/* Do the copies */
	for ( i = 0; i < count; i++ ) {
	userptr_t src_u = phys_to_user ( shuf[ i ].src );
	userptr_t dest_u = phys_to_user ( shuf[ i ].dest );

	if ( shuf[ i ].src == 0xFFFFFFFF ) {
	/* Fill with 0 instead of copying */
	memset_user ( dest_u, 0, 0, shuf[ i ].len );
	} else if ( shuf[ i ].dest == 0xFFFFFFFF ) {
	/* Copy new list of descriptors */
	count = shuf[ i ].len / sizeof( comboot_shuffle_descriptor );
	assert ( count <= COMBOOT_MAX_SHUFFLE_DESCRIPTORS );
	copy_from_user ( shuf, src_u, 0, shuf[ i ].len );
	i = -1;
	} else {
	/* Regular copy */
	memmove_user ( dest_u, 0, src_u, 0, shuf[ i ].len );
	}
	}
	}


	/**
	* Set default text mode
	*/
	void comboot_force_text_mode ( void ) {
	if ( comboot_graphics_mode & COMBOOT_VIDEO_VESA ) {
	/* Set VGA mode 3 via VESA VBE mode set */
	__asm__ __volatile__ (
	REAL_CODE (
	"mov $0x4F02, %%ax\n\t"
	"mov $0x03, %%bx\n\t"
	"int $0x10\n\t"
	)
	: : );
	} else if ( comboot_graphics_mode & COMBOOT_VIDEO_GRAPHICS ) {
	/* Set VGA mode 3 via standard VGA mode set */
	__asm__ __volatile__ (
	REAL_CODE (
	"mov $0x03, %%ax\n\t"
	"int $0x10\n\t"
	)
	: : );
	}

	comboot_graphics_mode = 0;
	}


	/**
	* Fetch kernel and optional initrd
	*/
	static int comboot_fetch_kernel ( char kernel_file, char cmdline ) {
	struct image *kernel = NULL;
	struct image *initrd = NULL;
	char *initrd_file;
	int rc;

	/* Find initrd= parameter, if any */
	if ( ( initrd_file = strstr ( cmdline, "initrd=" ) ) != NULL ) {
	char *initrd_end;

	/* skip "initrd=" */
	initrd_file += 7;

	/* Find terminating space, if any, and replace with NUL */
	initrd_end = strchr ( initrd_file, ' ' );
	if ( initrd_end )
	*initrd_end = '\0';

	DBG ( "COMBOOT: fetching initrd '%s'\n", initrd_file );

	/* Allocate and fetch initrd */
	initrd = alloc_image();
	if ( ! initrd ) {
	DBG ( "COMBOOT: could not allocate initrd\n" );
	rc = -ENOMEM;
	goto out;
	}
	if ( ( rc = imgfetch ( initrd, initrd_file,
	register_image ) ) != 0 ) {
	DBG ( "COMBOOT: could not fetch initrd: %s\n",
	strerror ( rc ) );
	goto out;
	}

	/* Restore space after initrd name, if applicable */
	if ( initrd_end )
	*initrd_end = ' ';
	}

	DBG ( "COMBOOT: fetching kernel '%s'\n", kernel_file );

	/* Allocate and fetch kernel */
	kernel = alloc_image();
	if ( ! kernel ) {
	DBG ( "COMBOOT: could not allocate kernel\n" );
	rc = -ENOMEM;
	goto out;
	}
	if ( ( rc = imgfetch ( kernel, kernel_file,
	register_image ) ) != 0 ) {
	DBG ( "COMBOOT: could not fetch kernel: %s\n",
	strerror ( rc ) );
	goto out;
	}
	if ( ( rc = image_set_cmdline ( kernel, cmdline ) ) != 0 ) {
	DBG ( "COMBOOT: could not set kernel command line: %s\n",
	strerror ( rc ) );
	goto out;
	}

	/* Store kernel as replacement image */
	assert ( comboot_replacement_image == NULL );
	comboot_replacement_image = image_get ( kernel );

	out:
	/* Drop image references unconditionally; either we want to
	* discard them, or they have been registered and we should
	* drop out local reference.
	*/
	image_put ( kernel );
	image_put ( initrd );
	return rc;
	}


	/**
	* Terminate program interrupt handler
	*/
	static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
	rmlongjmp ( comboot_return, COMBOOT_EXIT );
	}


	/**
	* DOS-compatible API
	*/
	static __asmcall void int21 ( struct i386_all_regs *ix86 ) {
	ix86->flags \|= CF;

	switch ( ix86->regs.ah ) {
	case 0x00:
	case 0x4C: /* Terminate program */
	rmlongjmp ( comboot_return, COMBOOT_EXIT );
	break;

	case 0x01: /* Get Key with Echo */
	case 0x08: /* Get Key without Echo */
	/* TODO: handle extended characters? */
	ix86->regs.al = getchar( );

	/* Enter */
	if ( ix86->regs.al == 0x0A )
	ix86->regs.al = 0x0D;

	if ( ix86->regs.ah == 0x01 )
	putchar ( ix86->regs.al );

	ix86->flags &= ~CF;
	break;

	case 0x02: /* Write Character */
	putchar ( ix86->regs.dl );
	ix86->flags &= ~CF;
	break;

	case 0x04: /* Write Character to Serial Port */
	serial_putc ( ix86->regs.dl );
	ix86->flags &= ~CF;
	break;

	case 0x09: /* Write DOS String to Console */
	print_user_string ( ix86->segs.ds, ix86->regs.dx, '$' );
	ix86->flags &= ~CF;
	break;

	case 0x0B: /* Check Keyboard */
	if ( iskey() )
	ix86->regs.al = 0xFF;
	else
	ix86->regs.al = 0x00;

	ix86->flags &= ~CF;
	break;

	case 0x30: /* Check DOS Version */
	/* Bottom halves all 0; top halves spell "SYSLINUX" */
	ix86->regs.eax = 0x59530000;
	ix86->regs.ebx = 0x4C530000;
	ix86->regs.ecx = 0x4E490000;
	ix86->regs.edx = 0x58550000;
	ix86->flags &= ~CF;
	break;

	default:
	DBG ( "COMBOOT unknown int21 function %02x\n", ix86->regs.ah );
	break;
	}
	}


	/**
	* SYSLINUX API
	*/
	static __asmcall void int22 ( struct i386_all_regs *ix86 ) {
	ix86->flags \|= CF;

	switch ( ix86->regs.ax ) {
	case 0x0001: /* Get Version */

	/* Number of INT 22h API functions available */
	ix86->regs.ax = 0x001D;

	/* SYSLINUX version number */
	ix86->regs.ch = 0; /* major */
	ix86->regs.cl = 0; /* minor */

	/* SYSLINUX derivative ID */
	ix86->regs.dl = BZI_LOADER_TYPE_GPXE;

	/* SYSLINUX version and copyright strings */
	ix86->segs.es = rm_ds;
	ix86->regs.si = ( ( unsigned ) __from_data16 ( syslinux_version ) );
	ix86->regs.di = ( ( unsigned ) __from_data16 ( syslinux_copyright ) );

	ix86->flags &= ~CF;
	break;

	case 0x0002: /* Write String */
	print_user_string ( ix86->segs.es, ix86->regs.bx, '\0' );
	ix86->flags &= ~CF;
	break;

	case 0x0003: /* Run command */
	{
	userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
	int len = strlen_user ( cmd_u, 0 );
	char cmd[len + 1];
	copy_from_user ( cmd, cmd_u, 0, len + 1 );
	DBG ( "COMBOOT: executing command '%s'\n", cmd );
	system ( cmd );
	DBG ( "COMBOOT: exiting after executing command...\n" );
	rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
	}
	break;

	case 0x0004: /* Run default command */
	/* FIXME: just exit for now */
	rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
	break;

	case 0x0005: /* Force text mode */
	comboot_force_text_mode ( );
	ix86->flags &= ~CF;
	break;

	case 0x0006: /* Open file */
	{
	int fd;
	userptr_t file_u = real_to_user ( ix86->segs.es, ix86->regs.si );
	int len = strlen_user ( file_u, 0 );
	char file[len + 1];

	copy_from_user ( file, file_u, 0, len + 1 );

	if ( file[0] == '\0' ) {
	DBG ( "COMBOOT: attempted open with empty file name\n" );
	break;
	}

	DBG ( "COMBOOT: opening file '%s'\n", file );

	fd = open ( file );

	if ( fd < 0 ) {
	DBG ( "COMBOOT: error opening file %s\n", file );
	break;
	}

	/* This relies on the fact that a gPXE POSIX fd will
	* always fit in 16 bits.
	*/
	#if (POSIX_FD_MAX > 65535)
	#error POSIX_FD_MAX too large
	#endif
	ix86->regs.si = (uint16_t) fd;

	ix86->regs.cx = COMBOOT_FILE_BLOCKSZ;
	ix86->regs.eax = fsize ( fd );
	ix86->flags &= ~CF;
	}
	break;

	case 0x0007: /* Read file */
	{
	int fd = ix86->regs.si;
	int len = ix86->regs.cx * COMBOOT_FILE_BLOCKSZ;
	int rc;
	fd_set fds;
	userptr_t buf = real_to_user ( ix86->segs.es, ix86->regs.bx );

	/* Wait for data ready to read */
	FD_ZERO ( &fds );
	FD_SET ( fd, &fds );

	select ( &fds, 1 );

	rc = read_user ( fd, buf, 0, len );
	if ( rc < 0 ) {
	DBG ( "COMBOOT: read failed\n" );
	ix86->regs.si = 0;
	break;
	}

	ix86->regs.ecx = rc;
	ix86->flags &= ~CF;
	}
	break;

	case 0x0008: /* Close file */
	{
	int fd = ix86->regs.si;
	close ( fd );
	ix86->flags &= ~CF;
	}
	break;

	case 0x0009: /* Call PXE Stack */
	if ( pxe_api_call_weak ( ix86 ) != 0 )
	ix86->flags \|= CF;
	else
	ix86->flags &= ~CF;
	break;

	case 0x000A: /* Get Derivative-Specific Information */

	/* gPXE has its own derivative ID, so there is no defined
	* output here; just return AL for now */
	ix86->regs.al = BZI_LOADER_TYPE_GPXE;
	ix86->flags &= ~CF;
	break;

	case 0x000B: /* Get Serial Console Configuration */
	#if defined(CONSOLE_SERIAL) && !defined(COMPRESERVE)
	ix86->regs.dx = COMCONSOLE;
	ix86->regs.cx = 115200 / COMSPEED;
	ix86->regs.bx = 0;
	#else
	ix86->regs.dx = 0;
	#endif

	ix86->flags &= ~CF;
	break;

	case 0x000E: /* Get configuration file name */
	/* FIXME: stub */
	ix86->segs.es = rm_ds;
	ix86->regs.bx = ( ( unsigned ) __from_data16 ( syslinux_configuration_file ) );
	ix86->flags &= ~CF;
	break;

	case 0x000F: /* Get IPAPPEND strings */
	/* FIXME: stub */
	ix86->regs.cx = 0;
	ix86->segs.es = 0;
	ix86->regs.bx = 0;
	ix86->flags &= ~CF;
	break;

	case 0x0010: /* Resolve hostname */
	{
	userptr_t hostname_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
	int len = strlen_user ( hostname_u, 0 );
	char hostname[len];
	struct in_addr addr;

	copy_from_user ( hostname, hostname_u, 0, len + 1 );

	/* TODO:
	* "If the hostname does not contain a dot (.), the
	* local domain name is automatically appended."
	*/

	comboot_resolv ( hostname, &addr );

	ix86->regs.eax = addr.s_addr;
	ix86->flags &= ~CF;
	}
	break;

	case 0x0011: /* Maximum number of shuffle descriptors */
	ix86->regs.cx = COMBOOT_MAX_SHUFFLE_DESCRIPTORS;
	ix86->flags &= ~CF;
	break;

	case 0x0012: /* Cleanup, shuffle and boot */
	if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
	break;

	/* Perform final cleanup */
	shutdown ( SHUTDOWN_BOOT );

	/* Perform sequence of copies */
	shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );

	/* Jump to real-mode entry point */
	__asm__ __volatile__ (
	REAL_CODE (
	"pushw %0\n\t"
	"popw %%ds\n\t"
	"pushl %1\n\t"
	"lret\n\t"
	)
	:
	: "r" ( ix86->segs.ds ),
	"r" ( ix86->regs.ebp ),
	"d" ( ix86->regs.ebx ),
	"S" ( ix86->regs.esi ) );

	assert ( 0 ); /* Execution should never reach this point */

	break;

	case 0x0013: /* Idle loop call */
	step ( );
	ix86->flags &= ~CF;
	break;

	case 0x0015: /* Get feature flags */
	ix86->segs.es = rm_ds;
	ix86->regs.bx = ( ( unsigned ) __from_data16 ( &comboot_feature_flags ) );
	ix86->regs.cx = 1; /* Number of feature flag bytes */
	ix86->flags &= ~CF;
	break;

	case 0x0016: /* Run kernel image */
	{
	userptr_t file_u = real_to_user ( ix86->segs.ds, ix86->regs.si );
	userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
	int file_len = strlen_user ( file_u, 0 );
	int cmd_len = strlen_user ( cmd_u, 0 );
	char file[file_len + 1];
	char cmd[cmd_len + 1];

	copy_from_user ( file, file_u, 0, file_len + 1 );
	copy_from_user ( cmd, cmd_u, 0, cmd_len + 1 );

	DBG ( "COMBOOT: run kernel %s %s\n", file, cmd );
	comboot_fetch_kernel ( file, cmd );
	/* Technically, we should return if we
	* couldn't load the kernel, but it's not safe
	* to do that since we have just overwritten
	* part of the COMBOOT program's memory space.
	*/
	DBG ( "COMBOOT: exiting to run kernel...\n" );
	rmlongjmp ( comboot_return, COMBOOT_EXIT_RUN_KERNEL );
	}
	break;

	case 0x0017: /* Report video mode change */
	comboot_graphics_mode = ix86->regs.bx;
	ix86->flags &= ~CF;
	break;

	case 0x0018: /* Query custom font */
	/* FIXME: stub */
	ix86->regs.al = 0;
	ix86->segs.es = 0;
	ix86->regs.bx = 0;
	ix86->flags &= ~CF;
	break;

	case 0x001B: /* Cleanup, shuffle and boot to real mode */
	if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
	break;

	/* Perform final cleanup */
	shutdown ( SHUTDOWN_BOOT );

	/* Perform sequence of copies */
	shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );

	/* Copy initial register values to .text16 */
	memcpy_user ( real_to_user ( rm_cs, (unsigned) __from_text16 ( &comboot_initial_regs ) ), 0,
	real_to_user ( ix86->segs.ds, ix86->regs.si ), 0,
	sizeof(syslinux_rm_regs) );

	/* Load initial register values */
	__asm__ __volatile__ (
	REAL_CODE (
	/* Point SS:SP at the register value structure */
	"pushw %%cs\n\t"
	"popw %%ss\n\t"
	"movw $comboot_initial_regs, %%sp\n\t"

	/* Segment registers */
	"popw %%es\n\t"
	"popw %%ax\n\t" /* Skip CS */
	"popw %%ds\n\t"
	"popw %%ax\n\t" /* Skip SS for now */
	"popw %%fs\n\t"
	"popw %%gs\n\t"

	/* GP registers */
	"popl %%eax\n\t"
	"popl %%ecx\n\t"
	"popl %%edx\n\t"
	"popl %%ebx\n\t"
	"popl %%ebp\n\t" /* Skip ESP for now */
	"popl %%ebp\n\t"
	"popl %%esi\n\t"
	"popl %%edi\n\t"

	/* Load correct SS:ESP */
	"movw $(comboot_initial_regs + 6), %%sp\n\t"
	"popw %%ss\n\t"
	"movl %%cs:(comboot_initial_regs + 28), %%esp\n\t"

	"ljmp *%%cs:(comboot_initial_regs + 44)\n\t"
	)
	: : );

	break;

	case 0x001C: /* Get pointer to auxilliary data vector */
	/* FIXME: stub */
	ix86->regs.cx = 0; /* Size of the ADV */
	ix86->flags &= ~CF;
	break;

	case 0x001D: /* Write auxilliary data vector */
	/* FIXME: stub */
	ix86->flags &= ~CF;
	break;

	default:
	DBG ( "COMBOOT unknown int22 function %04x\n", ix86->regs.ax );
	break;
	}
	}

	/**
	* Hook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
	*/
	void hook_comboot_interrupts ( ) {

	__asm__ __volatile__ (
	TEXT16_CODE ( "\nint20_wrapper:\n\t"
	"pushl %0\n\t"
	"pushw %%cs\n\t"
	"call prot_call\n\t"
	"addw $4, %%sp\n\t"
	"iret\n\t" )
	: : "i" ( int20 ) );

	hook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
	&int20_vector );

	__asm__ __volatile__ (
	TEXT16_CODE ( "\nint21_wrapper:\n\t"
	"pushl %0\n\t"
	"pushw %%cs\n\t"
	"call prot_call\n\t"
	"addw $4, %%sp\n\t"
	"iret\n\t" )
	: : "i" ( int21 ) );

	hook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
	&int21_vector );

	__asm__ __volatile__ (
	TEXT16_CODE ( "\nint22_wrapper:\n\t"
	"pushl %0\n\t"
	"pushw %%cs\n\t"
	"call prot_call\n\t"
	"addw $4, %%sp\n\t"
	"iret\n\t" )
	: : "i" ( int22) );

	hook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
	&int22_vector );
	}

	/**
	* Unhook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
	*/
	void unhook_comboot_interrupts ( ) {

	unhook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
	&int20_vector );

	unhook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
	&int21_vector );

	unhook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
	&int22_vector );
	}