/* * Copyright (C) 2008 Daniel Verkamp . * * 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 API * */ FILE_LICENCE ( GPL2_OR_LATER ); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /** The "SYSLINUX" version string */ static char __bss16_array ( syslinux_version, [32] ); #define syslinux_version __use_data16 ( syslinux_version ) /** The "SYSLINUX" copyright string */ static char __data16_array ( syslinux_copyright, [] ) = " http://ipxe.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; /* 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; struct image *initrd; 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 ); /* Fetch initrd */ if ( ( rc = imgdownload_string ( initrd_file, 0, &initrd ) ) != 0 ) { DBG ( "COMBOOT: could not fetch initrd: %s\n", strerror ( rc ) ); return rc; } /* Restore space after initrd name, if applicable */ if ( initrd_end ) *initrd_end = ' '; } DBG ( "COMBOOT: fetching kernel '%s'\n", kernel_file ); /* Fetch kernel */ if ( ( rc = imgdownload_string ( kernel_file, 0, &kernel ) ) != 0 ) { DBG ( "COMBOOT: could not fetch kernel: %s\n", strerror ( rc ) ); return rc; } /* Replace comboot image with kernel */ if ( ( rc = image_replace ( kernel ) ) != 0 ) { DBG ( "COMBOOT: could not replace with kernel: %s\n", strerror ( rc ) ); return rc; } return 0; } /** * 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 */ if ( serial_console.base ) { uart_transmit ( &serial_console, 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; } } /** * Dispatch PXE API call weakly * * @v ix86 Registers for PXE call * @ret present Zero if the PXE stack is present, nonzero if not * * A successful return only indicates that the PXE stack was available * for dispatching the call; it says nothing about the success of * whatever the call asked for. */ __weak int pxe_api_call_weak ( struct i386_all_regs *ix86 __unused ) { return -1; } /** * 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_IPXE; /* SYSLINUX version */ snprintf ( syslinux_version, sizeof ( syslinux_version ), "\r\niPXE %s", product_version ); /* 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 iPXE 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 */ /* iPXE has its own derivative ID, so there is no defined * output here; just return AL for now */ ix86->regs.al = BZI_LOADER_TYPE_IPXE; ix86->flags &= ~CF; break; case 0x000B: /* Get Serial Console Configuration */ if ( serial_console.base ) { ix86->regs.dx = ( ( intptr_t ) serial_console.base ); ix86->regs.cx = serial_console.divisor; ix86->regs.bx = 0; ix86->flags &= ~CF; } break; case 0x000C: /* Perform final cleanup */ shutdown_boot(); 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_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_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" VIRT_CALL ( int20 ) "clc\n\t" "call patch_cf\n\t" "iret\n\t" ) : ); hook_bios_interrupt ( 0x20, ( intptr_t ) int20_wrapper, &int20_vector ); __asm__ __volatile__ ( TEXT16_CODE ( "\nint21_wrapper:\n\t" VIRT_CALL ( int21 ) "clc\n\t" "call patch_cf\n\t" "iret\n\t" ) : ); hook_bios_interrupt ( 0x21, ( intptr_t ) int21_wrapper, &int21_vector ); __asm__ __volatile__ ( TEXT16_CODE ( "\nint22_wrapper:\n\t" VIRT_CALL ( int22 ) "clc\n\t" "call patch_cf\n\t" "iret\n\t" ) : ); hook_bios_interrupt ( 0x22, ( intptr_t ) int22_wrapper, &int22_vector ); } /** * Unhook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h) */ void unhook_comboot_interrupts ( ) { unhook_bios_interrupt ( 0x20, ( intptr_t ) int20_wrapper, &int20_vector ); unhook_bios_interrupt ( 0x21, ( intptr_t ) int21_wrapper, &int21_vector ); unhook_bios_interrupt ( 0x22, ( intptr_t ) int22_wrapper, &int22_vector ); } /* Avoid dragging in serial console support unconditionally */ struct uart serial_console __attribute__ (( weak ));