220 lines
8.2 KiB
C
220 lines
8.2 KiB
C
/* SPDX-FileCopyrightText: 2023 Richard Masters <grick23@gmail.com> */
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/* SPDX-License-Identifier: MIT */
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "multiboot1.h"
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#define MULTIBOOT_MAGIC 0x2BADB002
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#define INITRD_MB 1152
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int main() {
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/* Read the kernel */
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printf("kexec-fiwix: starting...\n\n");
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FILE *fiwix_file = fopen("/boot/fiwix", "r");
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fseek(fiwix_file, 0, SEEK_END);
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int fiwix_len = ftell(fiwix_file);
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printf("kexec-fiwix: Fiwix kernel file length: %d\n", fiwix_len);
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puts("kexec-fiwix: Reading kernel...");
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fseek(fiwix_file, 0, SEEK_SET);
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char * fiwix_mem = malloc(fiwix_len);
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int read_len = fread(fiwix_mem, fiwix_len, 1, fiwix_file);
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fclose(fiwix_file);
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if (read_len < 1) {
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printf("kexec-fiwix: kernel fread error: %d\n", read_len);
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return EXIT_FAILURE;
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}
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/* Display info from ELF header */
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unsigned int e_entry = *((unsigned int *) (&fiwix_mem[0x18]));
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printf("ELF virtual entry point : 0x%x\n", e_entry);
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unsigned int e_phoff = *((unsigned int *) (&fiwix_mem[0x1C]));
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printf("ELF program header offset : 0x%x\n", e_phoff);
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unsigned int e_phnum = *((unsigned int *) (&fiwix_mem[0x2C]));
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e_phnum &= 0xFFFF;
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printf("ELF number of program headers: %d\n", e_phnum);
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unsigned int e_phentsize = *((unsigned int *) (&fiwix_mem[0x2A]));
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e_phentsize &= 0xFFFF;
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printf("ELF size of program headers : %d\n", e_phentsize);
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/* Load the kernel */
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puts("kexec-fiwix: Placing kernel in memory...");
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int header_num;
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for (header_num = 0; header_num < e_phnum; header_num++) {
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char * fiwix_prog_header = &fiwix_mem[e_phoff + header_num * e_phentsize];
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unsigned int p_offset = *((unsigned int *) (&fiwix_prog_header[0x04]));
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unsigned int p_vaddr = *((unsigned int *) (&fiwix_prog_header[0x08]));
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unsigned int p_paddr = *((unsigned int *) (&fiwix_prog_header[0x0C]));
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unsigned int p_filesz = *((unsigned int *) (&fiwix_prog_header[0x10]));
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unsigned int p_memsz = *((unsigned int *) (&fiwix_prog_header[0x14]));
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if (header_num == 0) {
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e_entry -= (p_vaddr - p_paddr);
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printf("ELF physical entry point : 0x%x\n", e_entry);
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}
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printf("header %d:\n", header_num);
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printf(" p_offset: 0x%08x\n", p_offset);
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printf(" p_paddr : 0x%08x\n", p_paddr);
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printf(" p_filesz: 0x%08x\n", p_filesz);
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printf(" p_memsz : 0x%08x\n", p_memsz);
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memset((void *)p_paddr, 0, p_memsz + 0x10000);
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memcpy((void *)p_paddr, &fiwix_mem[p_offset], p_filesz);
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}
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puts("Preparing multiboot info for kernel...");
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char cmdline[256];
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sprintf(cmdline, "fiwix console=/dev/ttyS0 root=/dev/ram0 ramdisksize=%d initrd=image.ext2", INITRD_MB * 1024);
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char * boot_loader_name = "kexec-fiwix";
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unsigned int next_avail_mem = 0x8000;
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multiboot_info_t * pmultiboot_info = (multiboot_info_t *) next_avail_mem;
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memset(pmultiboot_info, 0, sizeof(multiboot_info_t));
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pmultiboot_info->flags = MULTIBOOT_INFO_BOOT_LOADER_NAME
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| MULTIBOOT_INFO_MEMORY
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| MULTIBOOT_INFO_CMDLINE
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| MULTIBOOT_INFO_MODS
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| MULTIBOOT_INFO_MEM_MAP;
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next_avail_mem += sizeof(multiboot_info_t);
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pmultiboot_info->mem_lower = 0x0000027F;
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pmultiboot_info->mem_upper = 0x002FFB80;
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/* Set command line */
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pmultiboot_info->cmdline = next_avail_mem;
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strcpy((char *) next_avail_mem, cmdline);
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next_avail_mem += (strlen(cmdline) + 1);
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/* Set ramdrive info */
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pmultiboot_info->mods_count = 1;
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pmultiboot_info->mods_addr = next_avail_mem;
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multiboot_module_t *pmultiboot_module = (multiboot_module_t *) next_avail_mem;
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pmultiboot_module->mod_start = 0x1C6000;
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pmultiboot_module->mod_end = 0x1C6000 + (INITRD_MB * 1024 * 1024);
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next_avail_mem += sizeof(multiboot_module_t);
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pmultiboot_module->cmdline = next_avail_mem;
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strcpy((char *) next_avail_mem, "image.ext2");
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next_avail_mem += (strlen("image.ext2") + 1);
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/* Set memory map info */
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pmultiboot_info->mmap_addr = next_avail_mem;
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pmultiboot_info->mmap_length = 7 * sizeof(multiboot_memory_map_t);
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multiboot_memory_map_t *pmultiboot_memory_map = (multiboot_memory_map_t *) next_avail_mem;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x00000000;
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pmultiboot_memory_map->len = 0x0009FC00;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_AVAILABLE;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x0009FC00;
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pmultiboot_memory_map->len = 0x00000400;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x000F0000;
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pmultiboot_memory_map->len = 0x00010000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x00100000;
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pmultiboot_memory_map->len = 0xBFEE0000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_AVAILABLE;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XBFFE0000;
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pmultiboot_memory_map->len = 0x00020000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XFEFFC000;
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pmultiboot_memory_map->len = 0x00004000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XFFFC0000;
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pmultiboot_memory_map->len = 0x00040000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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next_avail_mem += pmultiboot_info->mmap_length;
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/* Set boot loader name */
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pmultiboot_info->boot_loader_name = next_avail_mem;
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strcpy((char *) next_avail_mem, boot_loader_name);
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/* next_avail_mem += (strlen(boot_loader_name) + 1); */
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/* Jump to kernel entry point */
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unsigned int magic = MULTIBOOT_BOOTLOADER_MAGIC;
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unsigned int dummy = 0;
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unsigned int multiboot_info_num = (unsigned int) pmultiboot_info;
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int filenum;
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unsigned int filename_addr;
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for (filenum = 4, filename_addr = 0x201000; filenum <= 14335; filenum++, filename_addr += 1024) {
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if (!strcmp((char *) filename_addr, "/sysa/lwext4-1.0.0-lb1/build/lwext4-1.0.0-lb1/src/image.ext2")) {
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printf("Found image at filenum %d\n", filenum);
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break;
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}
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}
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unsigned int initrd_src = *((unsigned int *) (0x01000000 + (16 * filenum) + 4));
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unsigned int initrd_len = *((unsigned int *) (0x01000000 + (16 * filenum) + 8));
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printf("initrd_src: 0x%08x\n", initrd_src);
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printf("initrd_len: 0x%08x\n", initrd_len);
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printf("Preparing trampoline...\n");
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/* The ramdrive needs to be written to a location that would overwrite this program.
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* Therfore, the code that copies the ram drive and jumps to the kernel needs to be
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* run from a safe location. So, we put that code into an array variable and
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* copy the code (called a "trampoline") to a safe location and then jump to it.
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* The 0x00000000 values below are place holders which are set below
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*/
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char trampoline[] = {
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0xBE, 0x00, 0x00, 0x00, 0x00, /* mov esi, 0x00000000 */
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0xBF, 0x00, 0x00, 0x00, 0x00, /* mov edi, 0x00000000 */
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0xB9, 0x00, 0x00, 0x00, 0x00, /* mov ecx, 0x00000000 */
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0xFC, /* cld */
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0xF3, 0xA4, /* rep movsb */
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0xB8, 0x00, 0x00, 0x00, 0x00, /* mov eax, 0x00000000 */
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0xBB, 0x00, 0x00, 0x00, 0x00, /* mov ebx, 0x00000000 */
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0xEA, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 /* jmp far 0x0008:0x00000000 */
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};
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/* Set place holder values */
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*((unsigned int *) &trampoline[1]) = initrd_src;
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*((unsigned int *) &trampoline[6]) = 0x001C6000;
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*((unsigned int *) &trampoline[11]) = INITRD_MB * 1024 * 1024;
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*((unsigned int *) &trampoline[19]) = magic;
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*((unsigned int *) &trampoline[24]) = multiboot_info_num;
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*((unsigned int *) &trampoline[29]) = e_entry;
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memcpy((void *)0x4000, trampoline, sizeof(trampoline));
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printf("kexec-fiwix: jumping to trampoline...\n");
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__asm__ __volatile__ (
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"ljmp $0x8, $0x00004000\n\t"
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);
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}
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