/* * Copyright (C) 2007 Michael Brown . * * 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 * * Linux bzImage image format * */ #include #include #include #include #include #include #include #include #include #include #include #include #include FEATURE ( FEATURE_IMAGE, "bzImage", DHCP_EB_FEATURE_BZIMAGE, 1 ); struct image_type bzimage_image_type __image_type ( PROBE_NORMAL ); /** * bzImage load context */ struct bzimage_load_context { /** Real-mode kernel portion load segment address */ unsigned int rm_kernel_seg; /** Real-mode kernel portion load address */ userptr_t rm_kernel; /** Real-mode kernel portion file size */ size_t rm_filesz; /** Real-mode heap top (offset from rm_kernel) */ size_t rm_heap; /** Command line (offset from rm_kernel) */ size_t rm_cmdline; /** Real-mode kernel portion total memory size */ size_t rm_memsz; /** Non-real-mode kernel portion load address */ userptr_t pm_kernel; /** Non-real-mode kernel portion file and memory size */ size_t pm_sz; }; /** * bzImage execution context */ struct bzimage_exec_context { /** Real-mode kernel portion load segment address */ unsigned int rm_kernel_seg; /** Real-mode kernel portion load address */ userptr_t rm_kernel; /** Real-mode heap top (offset from rm_kernel) */ size_t rm_heap; /** Command line (offset from rm_kernel) */ size_t rm_cmdline; /** Command line maximum length */ size_t cmdline_size; /** Video mode */ unsigned int vid_mode; /** Memory limit */ uint64_t mem_limit; /** Initrd address */ physaddr_t ramdisk_image; /** Initrd size */ physaddr_t ramdisk_size; }; /** * Parse kernel command line for bootloader parameters * * @v image bzImage file * @v exec_ctx Execution context * @v cmdline Kernel command line * @ret rc Return status code */ static int bzimage_parse_cmdline ( struct image *image, struct bzimage_exec_context *exec_ctx, const char *cmdline ) { char *vga; char *mem; /* Look for "vga=" */ if ( ( vga = strstr ( cmdline, "vga=" ) ) ) { vga += 4; if ( strcmp ( vga, "normal" ) == 0 ) { exec_ctx->vid_mode = BZI_VID_MODE_NORMAL; } else if ( strcmp ( vga, "ext" ) == 0 ) { exec_ctx->vid_mode = BZI_VID_MODE_EXT; } else if ( strcmp ( vga, "ask" ) == 0 ) { exec_ctx->vid_mode = BZI_VID_MODE_ASK; } else { exec_ctx->vid_mode = strtoul ( vga, &vga, 0 ); if ( *vga && ( *vga != ' ' ) ) { DBGC ( image, "bzImage %p strange \"vga=\"" "terminator '%c'\n", image, *vga ); } } } /* Look for "mem=" */ if ( ( mem = strstr ( cmdline, "mem=" ) ) ) { mem += 4; exec_ctx->mem_limit = strtoul ( mem, &mem, 0 ); switch ( *mem ) { case 'G': case 'g': exec_ctx->mem_limit <<= 10; case 'M': case 'm': exec_ctx->mem_limit <<= 10; case 'K': case 'k': exec_ctx->mem_limit <<= 10; break; case '\0': case ' ': break; default: DBGC ( image, "bzImage %p strange \"mem=\" " "terminator '%c'\n", image, *mem ); break; } exec_ctx->mem_limit -= 1; } return 0; } /** * Set command line * * @v image bzImage image * @v exec_ctx Execution context * @v cmdline Kernel command line * @ret rc Return status code */ static int bzimage_set_cmdline ( struct image *image, struct bzimage_exec_context *exec_ctx, const char *cmdline ) { size_t cmdline_len; /* Copy command line down to real-mode portion */ cmdline_len = ( strlen ( cmdline ) + 1 ); if ( cmdline_len > exec_ctx->cmdline_size ) cmdline_len = exec_ctx->cmdline_size; copy_to_user ( exec_ctx->rm_kernel, exec_ctx->rm_cmdline, cmdline, cmdline_len ); DBGC ( image, "bzImage %p command line \"%s\"\n", image, cmdline ); return 0; } /** * Load initrd * * @v image bzImage image * @v initrd initrd image * @v address Address at which to load, or UNULL * @ret len Length of loaded image, rounded up to 4 bytes */ static size_t bzimage_load_initrd ( struct image *image, struct image *initrd, userptr_t address ) { char *filename = initrd->cmdline; struct cpio_header cpio; size_t offset = 0; /* Do not include kernel image itself as an initrd */ if ( initrd == image ) return 0; /* Create cpio header before non-prebuilt images */ if ( filename && filename[0] ) { size_t name_len = ( strlen ( filename ) + 1 ); DBGC ( image, "bzImage %p inserting initrd %p as %s\n", image, initrd, filename ); memset ( &cpio, '0', sizeof ( cpio ) ); memcpy ( cpio.c_magic, CPIO_MAGIC, sizeof ( cpio.c_magic ) ); cpio_set_field ( cpio.c_mode, 0100644 ); cpio_set_field ( cpio.c_nlink, 1 ); cpio_set_field ( cpio.c_filesize, initrd->len ); cpio_set_field ( cpio.c_namesize, name_len ); if ( address ) { copy_to_user ( address, offset, &cpio, sizeof ( cpio ) ); } offset += sizeof ( cpio ); if ( address ) { copy_to_user ( address, offset, filename, name_len ); } offset += name_len; offset = ( ( offset + 0x03 ) & ~0x03 ); } /* Copy in initrd image body */ if ( address ) { DBGC ( image, "bzImage %p has initrd %p at [%lx,%lx)\n", image, initrd, address, ( address + offset ) ); memcpy_user ( address, offset, initrd->data, 0, initrd->len ); } offset += initrd->len; offset = ( ( offset + 0x03 ) & ~0x03 ); return offset; } /** * Load initrds, if any * * @v image bzImage image * @v exec_ctx Execution context * @ret rc Return status code */ static int bzimage_load_initrds ( struct image *image, struct bzimage_exec_context *exec_ctx ) { struct image *initrd; size_t total_len = 0; physaddr_t address; int rc; /* Add up length of all initrd images */ for_each_image ( initrd ) { total_len += bzimage_load_initrd ( image, initrd, UNULL ); } /* Give up if no initrd images found */ if ( ! total_len ) return 0; /* Find a suitable start address. Try 1MB boundaries, * starting from the downloaded kernel image itself and * working downwards until we hit an available region. */ for ( address = ( user_to_phys ( image->data, 0 ) & ~0xfffff ) ; ; address -= 0x100000 ) { /* Check that we're not going to overwrite the * kernel itself. This check isn't totally * accurate, but errs on the side of caution. */ if ( address <= ( BZI_LOAD_HIGH_ADDR + image->len ) ) { DBGC ( image, "bzImage %p could not find a location " "for initrd\n", image ); return -ENOBUFS; } /* Check that we are within the kernel's range */ if ( ( address + total_len - 1 ) > exec_ctx->mem_limit ) continue; /* Prepare and verify segment */ if ( ( rc = prep_segment ( phys_to_user ( address ), 0, total_len ) ) != 0 ) continue; /* Use this address */ break; } /* Record initrd location */ exec_ctx->ramdisk_image = address; exec_ctx->ramdisk_size = total_len; /* Construct initrd */ DBGC ( image, "bzImage %p constructing initrd at [%lx,%lx)\n", image, address, ( address + total_len ) ); for_each_image ( initrd ) { address += bzimage_load_initrd ( image, initrd, phys_to_user ( address ) ); } return 0; } /** * Execute bzImage image * * @v image bzImage image * @ret rc Return status code */ static int bzimage_exec ( struct image *image ) { struct bzimage_exec_context exec_ctx; struct bzimage_header bzhdr; const char *cmdline = ( image->cmdline ? image->cmdline : "" ); int rc; /* Initialise context */ memset ( &exec_ctx, 0, sizeof ( exec_ctx ) ); /* Retrieve kernel header */ exec_ctx.rm_kernel_seg = image->priv.ul; exec_ctx.rm_kernel = real_to_user ( exec_ctx.rm_kernel_seg, 0 ); copy_from_user ( &bzhdr, exec_ctx.rm_kernel, BZI_HDR_OFFSET, sizeof ( bzhdr ) ); exec_ctx.rm_cmdline = exec_ctx.rm_heap = ( bzhdr.heap_end_ptr + 0x200 ); exec_ctx.vid_mode = bzhdr.vid_mode; if ( bzhdr.version >= 0x0203 ) { exec_ctx.mem_limit = bzhdr.initrd_addr_max; } else { exec_ctx.mem_limit = BZI_INITRD_MAX; } if ( bzhdr.version >= 0x0206 ) { exec_ctx.cmdline_size = bzhdr.cmdline_size; } else { exec_ctx.cmdline_size = BZI_CMDLINE_SIZE; } DBG ( "cmdline_size = %zd\n", exec_ctx.cmdline_size ); /* Parse command line for bootloader parameters */ if ( ( rc = bzimage_parse_cmdline ( image, &exec_ctx, cmdline ) ) != 0) return rc; /* Store command line */ if ( ( rc = bzimage_set_cmdline ( image, &exec_ctx, cmdline ) ) != 0 ) return rc; /* Load any initrds */ if ( ( rc = bzimage_load_initrds ( image, &exec_ctx ) ) != 0 ) return rc; /* Update and store kernel header */ bzhdr.vid_mode = exec_ctx.vid_mode; bzhdr.ramdisk_image = exec_ctx.ramdisk_image; bzhdr.ramdisk_size = exec_ctx.ramdisk_size; copy_to_user ( exec_ctx.rm_kernel, BZI_HDR_OFFSET, &bzhdr, sizeof ( bzhdr ) ); /* Prepare for exiting */ shutdown ( SHUTDOWN_BOOT ); DBGC ( image, "bzImage %p jumping to RM kernel at %04x:0000 " "(stack %04x:%04zx)\n", image, ( exec_ctx.rm_kernel_seg + 0x20 ), exec_ctx.rm_kernel_seg, exec_ctx.rm_heap ); /* Jump to the kernel */ __asm__ __volatile__ ( REAL_CODE ( "movw %w0, %%ds\n\t" "movw %w0, %%es\n\t" "movw %w0, %%fs\n\t" "movw %w0, %%gs\n\t" "movw %w0, %%ss\n\t" "movw %w1, %%sp\n\t" "pushw %w2\n\t" "pushw $0\n\t" "lret\n\t" ) : : "r" ( exec_ctx.rm_kernel_seg ), "r" ( exec_ctx.rm_heap ), "r" ( exec_ctx.rm_kernel_seg + 0x20 ) ); /* There is no way for the image to return, since we provide * no return address. */ assert ( 0 ); return -ECANCELED; /* -EIMPOSSIBLE */ } /** * Load and parse bzImage header * * @v image bzImage file * @v load_ctx Load context * @v bzhdr Buffer for bzImage header * @ret rc Return status code */ static int bzimage_load_header ( struct image *image, struct bzimage_load_context *load_ctx, struct bzimage_header *bzhdr ) { /* Sanity check */ if ( image->len < ( BZI_HDR_OFFSET + sizeof ( *bzhdr ) ) ) { DBGC ( image, "bzImage %p too short for kernel header\n", image ); return -ENOEXEC; } /* Read and verify header */ copy_from_user ( bzhdr, image->data, BZI_HDR_OFFSET, sizeof ( *bzhdr ) ); if ( bzhdr->header != BZI_SIGNATURE ) { DBGC ( image, "bzImage %p bad signature %08lx\n", image, bzhdr->header ); return -ENOEXEC; } /* We don't support ancient kernels */ if ( bzhdr->version < 0x0200 ) { DBGC ( image, "bzImage %p version %04x not supported\n", image, bzhdr->version ); return -ENOTSUP; } /* Calculate load address and size of real-mode portion */ load_ctx->rm_kernel_seg = ( ( bzhdr->loadflags & BZI_LOAD_HIGH ) ? 0x1000 : /* 1000:0000 (bzImage) */ 0x9000 ); /* 9000:0000 (zImage) */ load_ctx->rm_kernel = real_to_user ( load_ctx->rm_kernel_seg, 0 ); load_ctx->rm_filesz = ( ( bzhdr->setup_sects ? bzhdr->setup_sects : 4 ) + 1 ) << 9; load_ctx->rm_memsz = BZI_ASSUMED_RM_SIZE; if ( load_ctx->rm_filesz > image->len ) { DBGC ( image, "bzImage %p too short for %zd byte of setup\n", image, load_ctx->rm_filesz ); return -ENOEXEC; } /* Calculate load address and size of non-real-mode portion */ load_ctx->pm_kernel = ( ( bzhdr->loadflags & BZI_LOAD_HIGH ) ? phys_to_user ( BZI_LOAD_HIGH_ADDR ) : phys_to_user ( BZI_LOAD_LOW_ADDR ) ); load_ctx->pm_sz = ( image->len - load_ctx->rm_filesz ); DBGC ( image, "bzImage %p version %04x RM %#zx bytes PM %#zx bytes\n", image, bzhdr->version, load_ctx->rm_filesz, load_ctx->pm_sz ); return 0; } /** * Load real-mode portion of bzImage * * @v image bzImage file * @v load_ctx Load context * @ret rc Return status code */ static int bzimage_load_real ( struct image *image, struct bzimage_load_context *load_ctx ) { int rc; /* Allow space for the stack and heap */ load_ctx->rm_memsz += BZI_STACK_SIZE; load_ctx->rm_heap = load_ctx->rm_memsz; /* Allow space for the command line */ load_ctx->rm_cmdline = load_ctx->rm_memsz; load_ctx->rm_memsz += BZI_CMDLINE_SIZE; /* Prepare, verify, and load the real-mode segment */ if ( ( rc = prep_segment ( load_ctx->rm_kernel, load_ctx->rm_filesz, load_ctx->rm_memsz ) ) != 0 ) { DBGC ( image, "bzImage %p could not prepare RM segment: %s\n", image, strerror ( rc ) ); return rc; } memcpy_user ( load_ctx->rm_kernel, 0, image->data, 0, load_ctx->rm_filesz ); return 0; } /** * Load non-real-mode portion of bzImage * * @v image bzImage file * @v load_ctx Load context * @ret rc Return status code */ static int bzimage_load_non_real ( struct image *image, struct bzimage_load_context *load_ctx ) { int rc; /* Prepare, verify and load the non-real-mode segment */ if ( ( rc = prep_segment ( load_ctx->pm_kernel, load_ctx->pm_sz, load_ctx->pm_sz ) ) != 0 ) { DBGC ( image, "bzImage %p could not prepare PM segment: %s\n", image, strerror ( rc ) ); return rc; } memcpy_user ( load_ctx->pm_kernel, 0, image->data, load_ctx->rm_filesz, load_ctx->pm_sz ); return 0; } /** * Update and store bzImage header * * @v image bzImage file * @v load_ctx Load context * @v bzhdr Original bzImage header * @ret rc Return status code */ static int bzimage_write_header ( struct image *image __unused, struct bzimage_load_context *load_ctx, struct bzimage_header *bzhdr ) { struct bzimage_cmdline cmdline; /* Update the header and copy it into the loaded kernel */ bzhdr->type_of_loader = BZI_LOADER_TYPE_GPXE; if ( bzhdr->version >= 0x0201 ) { bzhdr->heap_end_ptr = ( load_ctx->rm_heap - 0x200 ); bzhdr->loadflags |= BZI_CAN_USE_HEAP; } if ( bzhdr->version >= 0x0202 ) { bzhdr->cmd_line_ptr = user_to_phys ( load_ctx->rm_kernel, load_ctx->rm_cmdline ); } else { cmdline.magic = BZI_CMDLINE_MAGIC; cmdline.offset = load_ctx->rm_cmdline; copy_to_user ( load_ctx->rm_kernel, BZI_CMDLINE_OFFSET, &cmdline, sizeof ( cmdline ) ); bzhdr->setup_move_size = load_ctx->rm_memsz; } copy_to_user ( load_ctx->rm_kernel, BZI_HDR_OFFSET, bzhdr, sizeof ( *bzhdr ) ); return 0; } /** * Load bzImage image into memory * * @v image bzImage file * @ret rc Return status code */ int bzimage_load ( struct image *image ) { struct bzimage_load_context load_ctx; struct bzimage_header bzhdr; int rc; /* Initialise context */ memset ( &load_ctx, 0, sizeof ( load_ctx ) ); /* Load and verify header */ if ( ( rc = bzimage_load_header ( image, &load_ctx, &bzhdr ) ) != 0 ) return rc; /* This is a bzImage image, valid or otherwise */ if ( ! image->type ) image->type = &bzimage_image_type; /* Load real-mode portion */ if ( ( rc = bzimage_load_real ( image, &load_ctx ) ) != 0 ) return rc; /* Load non-real-mode portion */ if ( ( rc = bzimage_load_non_real ( image, &load_ctx ) ) != 0 ) return rc; /* Update and write out header */ if ( ( rc = bzimage_write_header ( image, &load_ctx, &bzhdr ) ) != 0 ) return rc; /* Record real-mode segment in image private data field */ image->priv.ul = load_ctx.rm_kernel_seg; return 0; } /** Linux bzImage image type */ struct image_type bzimage_image_type __image_type ( PROBE_NORMAL ) = { .name = "bzImage", .load = bzimage_load, .exec = bzimage_exec, };