elf_loader.c

linux下从网卡远程启动

	estate.loc += len + (estate.skip & ~0x1ff);
	skip_sectors = estate.skip >> 9;
	estate.skip &= 0x1ff;
	
	if (eof) {
		unsigned long entry;
		unsigned long machine;
elf_startkernel:
		entry = estate.e.elf32.e_entry;
		machine = estate.e.elf32.e_machine;

#if ELF_NOTES
		if (estate.check_ip_checksum) {
			unsigned long bytes = 0;
			uint16_t sum, new_sum;

			sum = ipchksum(&estate.e.elf32, sizeof(estate.e.elf32));
			bytes = sizeof(estate.e.elf32);
#if ELF_DEBUG
			printf("Ehdr: %hx %hx sz: %lx bytes: %lx\n",
				sum, sum, bytes, bytes);
#endif

			new_sum = ipchksum(estate.p.phdr32, sizeof(estate.p.phdr32[0]) * estate.e.elf32.e_phnum);
			sum = add_ipchksums(bytes, sum, new_sum);
			bytes += sizeof(estate.p.phdr32[0]) * estate.e.elf32.e_phnum;
#if ELF_DEBUG
			printf("Phdr: %hx %hx sz: %lx bytes: %lx\n",
				new_sum, sum,
				sizeof(estate.p.phdr32[0]) * estate.e.elf32.e_phnum, bytes);
#endif

			for(i = 0; i < estate.e.elf32.e_phnum; i++) {
				if (estate.p.phdr32[i].p_type != PT_LOAD)
					continue;
				new_sum = ipchksum(phys_to_virt(estate.p.phdr32[i].p_paddr),
						estate.p.phdr32[i].p_memsz);
				sum = add_ipchksums(bytes, sum, new_sum);
				bytes += estate.p.phdr32[i].p_memsz;
#if ELF_DEBUG
			printf("seg%d: %hx %hx sz: %x bytes: %lx\n",
				i, new_sum, sum,
				estate.p.phdr32[i].p_memsz, bytes);
#endif

			}
			if (estate.ip_checksum != sum) {
				printf("\nImage checksum: %hx != computed checksum: %hx\n",
					estate.ip_checksum, sum);
				longjmp(restart_etherboot, -2);
			}
		}
#endif
		done();
		/* Fixup the offset to the program header so you can find the program headers from
		 * the ELF header mknbi needs this.
		 */
		estate.e.elf32.e_phoff = (char *)&estate.p - (char *)&estate.e;
		elf_freebsd_boot(entry);
		elf_boot(machine,entry);
	}
	return skip_sectors;
}
#endif /* ELF_IMAGE */

#ifdef  ELF64_IMAGE
static sector_t elf64_download(unsigned char *data, unsigned int len, int eof);
static inline os_download_t elf64_probe(unsigned char *data, unsigned int len)
{
	unsigned long phdr_size;
	if (len < sizeof(estate.e.elf64)) {
		return 0;
	}
	memcpy(&estate.e.elf64, data, sizeof(estate.e.elf64));
	if ((estate.e.elf64.e_ident[EI_MAG0] != ELFMAG0) ||
		(estate.e.elf64.e_ident[EI_MAG1] != ELFMAG1) ||
		(estate.e.elf64.e_ident[EI_MAG2] != ELFMAG2) ||
		(estate.e.elf64.e_ident[EI_MAG3] != ELFMAG3) ||
		(estate.e.elf64.e_ident[EI_CLASS] != ELFCLASS64) ||
		(estate.e.elf64.e_ident[EI_DATA] != ELFDATA_CURRENT) ||
		(estate.e.elf64.e_ident[EI_VERSION] != EV_CURRENT) ||
		(estate.e.elf64.e_type != ET_EXEC) ||
		(estate.e.elf64.e_version != EV_CURRENT) ||
		(estate.e.elf64.e_ehsize != sizeof(Elf64_Ehdr)) ||
		(estate.e.elf64.e_phentsize != sizeof(Elf64_Phdr)) ||
		!ELF_CHECK_ARCH(estate.e.elf64)) {
		return 0;
	}
	printf("(ELF64)... ");
	phdr_size = estate.e.elf64.e_phnum * estate.e.elf64.e_phentsize;
	if (estate.e.elf64.e_phoff + phdr_size > len) {
		printf("ELF header outside first block\n");
		return 0;
	}
	if (phdr_size > sizeof(estate.p.dummy)) {
		printf("Program header to big\n");
		return 0;
	}
	if (estate.e.elf64.e_entry > ULONG_MAX) {
		printf("ELF entry point exceeds address space\n");
		return 0;
	}
	memcpy(&estate.p.phdr64, data + estate.e.elf64.e_phoff, phdr_size);
#if ELF_NOTES
	/* Load ELF notes from the image */
	for(estate.segment = 0; estate.segment < estate.e.elf64.e_phnum; estate.segment++) {
		if (estate.p.phdr64[estate.segment].p_type != PT_NOTE)
			continue;
		if (estate.p.phdr64[estate.segment].p_offset + estate.p.phdr64[estate.segment].p_filesz > len) {
			/* Ignore ELF notes outside of the first block */
			continue;
		}
		process_elf_notes(data, 
			estate.p.phdr64[estate.segment].p_offset, estate.p.phdr64[estate.segment].p_filesz);
	}
#endif
	/* Check for Etherboot related limitations.  Memory
	 * between _text and _end is not allowed.  
	 * Reasons: the Etherboot code/data area.
	 */
	for (estate.segment = 0; estate.segment < estate.e.elf64.e_phnum; estate.segment++) {
		unsigned long start, mid, end, istart, iend;
		if (estate.p.phdr64[estate.segment].p_type != PT_LOAD) 
			continue;
		if ((estate.p.phdr64[estate.segment].p_paddr > ULONG_MAX) ||
			((estate.p.phdr64[estate.segment].p_paddr + estate.p.phdr64[estate.segment].p_filesz) > ULONG_MAX) ||
			((estate.p.phdr64[estate.segment].p_paddr + estate.p.phdr64[estate.segment].p_memsz) > ULONG_MAX)) {
			printf("ELF segment exceeds address space\n");
			return 0;
		}
		start = estate.p.phdr64[estate.segment].p_paddr;
		mid = start + estate.p.phdr64[estate.segment].p_filesz;
		end = start + estate.p.phdr64[estate.segment].p_memsz;
		istart = iend = ULONG_MAX;
		if ((estate.p.phdr64[estate.segment].p_offset < ULONG_MAX) &&
			((estate.p.phdr64[estate.segment].p_offset + estate.p.phdr64[estate.segment].p_filesz) < ULONG_MAX))
		{
			istart = estate.p.phdr64[estate.segment].p_offset;
			iend   = istart + estate.p.phdr64[estate.segment].p_filesz;
		} 
		if (!prep_segment(start, mid, end, istart, iend)) {
			return 0;
		}
		if (!elf_prep_segment(start, mid, end, istart, iend)) {
			return 0;
		}
	}
	estate.segment = -1;
	estate.loc = 0;
	estate.skip = 0;
	estate.toread = 0;
	return elf64_download;
}

static sector_t elf64_download(unsigned char *data, unsigned int len, int eof)
{
	unsigned long skip_sectors = 0;
	unsigned int offset;	/* working offset in the current data block */
	int i;

	offset = 0;
	do {
		if (estate.segment != -1) {
			if (estate.skip) {
				if (estate.skip >= len - offset) {
					estate.skip -= len - offset;
					break;
				}
				offset += estate.skip;
				estate.skip = 0;
			}
			
			if (estate.toread) {
				unsigned int cplen;
				cplen = len - offset;
				if (cplen >= estate.toread) {
					cplen = estate.toread;
				}
				memcpy(phys_to_virt(estate.curaddr), data+offset, cplen);
				estate.curaddr += cplen;
				estate.toread -= cplen;
				offset += cplen;
				if (estate.toread)
					break;
			}
		}
		
		/* Data left, but current segment finished - look for the next
		 * segment (in file offset order) that needs to be loaded. 
		 * We can only seek forward, so select the program headers,
		 * in the correct order.
		 */
		estate.segment = -1;
		for (i = 0; i < estate.e.elf64.e_phnum; i++) {
			if (estate.p.phdr64[i].p_type != PT_LOAD)
				continue;
			if (estate.p.phdr64[i].p_filesz == 0)
				continue;
			if (estate.p.phdr64[i].p_offset < estate.loc + offset)
				continue;	/* can't go backwards */
			if ((estate.segment != -1) &&
				(estate.p.phdr64[i].p_offset >= estate.p.phdr64[estate.segment].p_offset))
				continue;	/* search minimum file offset */
			estate.segment = i;
		}
		if (estate.segment == -1) {
			/* No more segments to be loaded, so just start the
			 * kernel.  This saves a lot of network bandwidth if
			 * debug info is in the kernel but not loaded.  */
			goto elf_startkernel;
			break;
		}
		estate.curaddr = estate.p.phdr64[estate.segment].p_paddr;
		estate.skip    = estate.p.phdr64[estate.segment].p_offset - (estate.loc + offset);
		estate.toread  = estate.p.phdr64[estate.segment].p_filesz;
#if ELF_DEBUG
		printf("PHDR %d, size %#lX, curaddr %#lX\n",
			estate.segment, estate.toread, estate.curaddr);
#endif
	} while (offset < len);
	
	estate.loc += len + (estate.skip & ~0x1ff);
	skip_sectors = estate.skip >> 9;
	estate.skip &= 0x1ff;
	
	if (eof) {
		unsigned long entry;
		unsigned long machine;
elf_startkernel:
		entry = estate.e.elf64.e_entry;
		machine = estate.e.elf64.e_machine;
#if ELF_NOTES
		if (estate.check_ip_checksum) {
			unsigned long bytes = 0;
			uint16_t sum, new_sum;

			sum = ipchksum(&estate.e.elf64, sizeof(estate.e.elf64));
			bytes = sizeof(estate.e.elf64);
#if ELF_DEBUG
			printf("Ehdr: %hx %hx sz: %lx bytes: %lx\n",
				sum, sum, bytes, bytes);
#endif

			new_sum = ipchksum(estate.p.phdr64, sizeof(estate.p.phdr64[0]) * estate.e.elf64.e_phnum);
			sum = add_ipchksums(bytes, sum, new_sum);
			bytes += sizeof(estate.p.phdr64[0]) * estate.e.elf64.e_phnum;
#if ELF_DEBUG
			printf("Phdr: %hx %hx sz: %lx bytes: %lx\n",
				new_sum, sum,
				sizeof(estate.p.phdr64[0]) * estate.e.elf64.e_phnum, bytes);
#endif

			for(i = 0; i < estate.e.elf64.e_phnum; i++) {
				if (estate.p.phdr64[i].p_type != PT_LOAD)
					continue;
				new_sum = ipchksum(phys_to_virt(estate.p.phdr64[i].p_paddr),
						estate.p.phdr64[i].p_memsz);
				sum = add_ipchksums(bytes, sum, new_sum);
				bytes += estate.p.phdr64[i].p_memsz;
#if ELF_DEBUG
			printf("seg%d: %hx %hx sz: %x bytes: %lx\n",
				i, new_sum, sum,
				estate.p.phdr64[i].p_memsz, bytes);
#endif

			}
			if (estate.ip_checksum != sum) {
				printf("\nImage checksum: %hx != computed checksum: %hx\n",
					estate.ip_checksum, sum);
				longjmp(restart_etherboot, -2);
			}
		}
#endif
		done();
		/* Fixup the offset to the program header so you can find the program headers from
		 * the ELF header mknbi needs this.
		 */
		estate.e.elf64.e_phoff = (char *)&estate.p - (char *)&estate.e;
		elf_boot(machine,entry);
	}
	return skip_sectors;
}

#endif /* ELF64_IMAGE */