--- /dev/null
+/*
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/**
+ * @file
+ *
+ * SYSLINUX COMBOOT (16-bit) 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 <ipxe/uaccess.h>
+#include <ipxe/image.h>
+#include <ipxe/segment.h>
+#include <ipxe/init.h>
+#include <ipxe/features.h>
+
+FEATURE ( FEATURE_IMAGE, "COMBOOT", DHCP_EB_FEATURE_COMBOOT, 1 );
+
+/**
+ * COMBOOT PSP, copied to offset 0 of code segment
+ */
+struct comboot_psp {
+ /** INT 20 instruction, executed if COMBOOT image returns with RET */
+ uint16_t int20;
+ /** Segment of first non-free paragraph of memory */
+ uint16_t first_non_free_para;
+};
+
+/** Offset in PSP of command line */
+#define COMBOOT_PSP_CMDLINE_OFFSET 0x81
+
+/** Maximum length of command line in PSP
+ * (127 bytes minus space and CR) */
+#define COMBOOT_MAX_CMDLINE_LEN 125
+
+
+/**
+ * Copy command line to PSP
+ *
+ * @v image COMBOOT image
+ */
+static void comboot_copy_cmdline ( struct image * image, userptr_t seg_userptr ) {
+ const char *cmdline = ( image->cmdline ? image->cmdline : "" );
+ int cmdline_len = strlen ( cmdline );
+ if( cmdline_len > COMBOOT_MAX_CMDLINE_LEN )
+ cmdline_len = COMBOOT_MAX_CMDLINE_LEN;
+ uint8_t len_byte = cmdline_len;
+ char spc = ' ', cr = '\r';
+
+ /* Copy length to byte before command line */
+ copy_to_user ( seg_userptr, COMBOOT_PSP_CMDLINE_OFFSET - 1,
+ &len_byte, 1 );
+
+ /* Command line starts with space */
+ copy_to_user ( seg_userptr,
+ COMBOOT_PSP_CMDLINE_OFFSET,
+ &spc, 1 );
+
+ /* Copy command line */
+ copy_to_user ( seg_userptr,
+ COMBOOT_PSP_CMDLINE_OFFSET + 1,
+ cmdline, cmdline_len );
+
+ /* Command line ends with CR */
+ copy_to_user ( seg_userptr,
+ COMBOOT_PSP_CMDLINE_OFFSET + cmdline_len + 1,
+ &cr, 1 );
+}
+
+/**
+ * Initialize PSP
+ *
+ * @v image COMBOOT image
+ * @v seg_userptr segment to initialize
+ */
+static void comboot_init_psp ( struct image * image, userptr_t seg_userptr ) {
+ struct comboot_psp psp;
+
+ /* Fill PSP */
+
+ /* INT 20h instruction, byte order reversed */
+ psp.int20 = 0x20CD;
+
+ /* get_fbms() returns BIOS free base memory counter, which is in
+ * kilobytes; x * 1024 / 16 == x * 64 == x << 6 */
+ psp.first_non_free_para = get_fbms() << 6;
+
+ DBGC ( image, "COMBOOT %p: first non-free paragraph = 0x%x\n",
+ image, psp.first_non_free_para );
+
+ /* Copy the PSP to offset 0 of segment.
+ * The rest of the PSP was already zeroed by
+ * comboot_prepare_segment. */
+ copy_to_user ( seg_userptr, 0, &psp, sizeof( psp ) );
+
+ /* Copy the command line to the PSP */
+ comboot_copy_cmdline ( image, seg_userptr );
+}
+
+/**
+ * Execute COMBOOT image
+ *
+ * @v image COMBOOT image
+ * @ret rc Return status code
+ */
+static int comboot_exec_loop ( struct image *image ) {
+ userptr_t seg_userptr = real_to_user ( COMBOOT_PSP_SEG, 0 );
+ int state;
+
+ state = rmsetjmp ( comboot_return );
+
+ switch ( state ) {
+ case 0: /* First time through; invoke COMBOOT program */
+
+ /* Initialize PSP */
+ comboot_init_psp ( image, seg_userptr );
+
+ /* Hook COMBOOT API interrupts */
+ hook_comboot_interrupts();
+
+ DBGC ( image, "executing 16-bit COMBOOT image at %4x:0100\n",
+ COMBOOT_PSP_SEG );
+
+ /* 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 );
+
+ /* Store stack segment at 0x38 and stack pointer at 0x3A
+ * in the PSP and jump to the image */
+ __asm__ __volatile__ (
+ REAL_CODE ( /* Save return address with segment on old stack */
+ "popw %%ax\n\t"
+ "pushw %%cs\n\t"
+ "pushw %%ax\n\t"
+ /* Set DS=ES=segment with image */
+ "movw %w0, %%ds\n\t"
+ "movw %w0, %%es\n\t"
+ /* Set SS:SP to new stack (end of image segment) */
+ "movw %w0, %%ss\n\t"
+ "xor %%sp, %%sp\n\t"
+ "pushw $0\n\t"
+ "pushw %w0\n\t"
+ "pushw $0x100\n\t"
+ /* Zero registers (some COM files assume GP regs are 0) */
+ "xorw %%ax, %%ax\n\t"
+ "xorw %%bx, %%bx\n\t"
+ "xorw %%cx, %%cx\n\t"
+ "xorw %%dx, %%dx\n\t"
+ "xorw %%si, %%si\n\t"
+ "xorw %%di, %%di\n\t"
+ "xorw %%bp, %%bp\n\t"
+ "lret\n\t" )
+ : : "r" ( COMBOOT_PSP_SEG ) : "eax" );
+ DBGC ( image, "COMBOOT %p: returned\n", image );
+ break;
+
+ case COMBOOT_EXIT:
+ DBGC ( image, "COMBOOT %p: exited\n", image );
+ break;
+
+ case COMBOOT_EXIT_RUN_KERNEL:
+ assert ( image->replacement );
+ DBGC ( image, "COMBOOT %p: exited to run kernel %s\n",
+ image, image->replacement->name );
+ break;
+
+ case COMBOOT_EXIT_COMMAND:
+ DBGC ( image, "COMBOOT %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 COMBOOT image
+ * @ret rc Return status code
+ */
+static int comboot_identify ( struct image *image ) {
+ const char *ext;
+
+ ext = strrchr( image->name, '.' );
+
+ if ( ! ext ) {
+ DBGC ( image, "COMBOOT %p: no extension\n",
+ image );
+ return -ENOEXEC;
+ }
+
+ ++ext;
+
+ if ( strcasecmp( ext, "cbt" ) ) {
+ DBGC ( image, "COMBOOT %p: unrecognized extension %s\n",
+ image, ext );
+ return -ENOEXEC;
+ }
+
+ return 0;
+}
+
+/**
+ * Load COMBOOT image into memory, preparing a segment and returning it
+ * @v image COMBOOT image
+ * @ret rc Return status code
+ */
+static int comboot_prepare_segment ( struct image *image )
+{
+ userptr_t seg_userptr;
+ size_t filesz, memsz;
+ int rc;
+
+ /* Load image in segment */
+ seg_userptr = real_to_user ( COMBOOT_PSP_SEG, 0 );
+
+ /* Allow etra 0x100 bytes before image for PSP */
+ filesz = image->len + 0x100;
+
+ /* Ensure the entire 64k segment is free */
+ memsz = 0xFFFF;
+
+ /* Prepare, verify, and load the real-mode segment */
+ if ( ( rc = prep_segment ( seg_userptr, filesz, memsz ) ) != 0 ) {
+ DBGC ( image, "COMBOOT %p: could not prepare segment: %s\n",
+ image, strerror ( rc ) );
+ return rc;
+ }
+
+ /* Zero PSP */
+ memset_user ( seg_userptr, 0, 0, 0x100 );
+
+ /* Copy image to segment:0100 */
+ memcpy_user ( seg_userptr, 0x100, image->data, 0, image->len );
+
+ return 0;
+}
+
+/**
+ * Probe COMBOOT image
+ *
+ * @v image COMBOOT image
+ * @ret rc Return status code
+ */
+static int comboot_probe ( struct image *image ) {
+ int rc;
+
+ DBGC ( image, "COMBOOT %p: name '%s'\n",
+ image, image->name );
+
+ /* Check if this is a COMBOOT image */
+ if ( ( rc = comboot_identify ( image ) ) != 0 ) {
+
+ return rc;
+ }
+
+ return 0;
+}
+
+/**
+ * Execute COMBOOT image
+ *
+ * @v image COMBOOT image
+ * @ret rc Return status code
+ */
+static int comboot_exec ( struct image *image ) {
+ int rc;
+
+ /* Sanity check for filesize */
+ if( image->len >= 0xFF00 ) {
+ DBGC( image, "COMBOOT %p: image too large\n",
+ image );
+ return -ENOEXEC;
+ }
+
+ /* Prepare segment and load image */
+ if ( ( rc = comboot_prepare_segment ( image ) ) != 0 ) {
+ return rc;
+ }
+
+ return comboot_exec_loop ( image );
+}
+
+/** SYSLINUX COMBOOT (16-bit) image type */
+struct image_type comboot_image_type __image_type ( PROBE_NORMAL ) = {
+ .name = "COMBOOT",
+ .probe = comboot_probe,
+ .exec = comboot_exec,
+};
Code Review / kvmfornfv.git / blobdiff