gzip.c

EFI（Extensible Firmware Interface)是下一代BIOS

	
	offs  = bswap64(elf->e_phoff);
	phnum = bswap16(elf->e_phnum);

	VERB_PRT(3, { 
			Print(L"ELF file is %s\n", elf_is_big_endian ? L"big endian" : L"little endian");
			Print(L"Entry point 0x%lx\n", bswap64(elf->e_entry));
			Print(L"%d program headers\n", phnum);
			Print(L"%d segment headers\n", bswap16(elf->e_shnum));
		   });


	/* XXX: need to check on this */
	if (offs + phnum * sizeof(*phdrs) > (unsigned) blocksize) {
		ERR_PRT((L"%s : ELF program headers not in first block (%ld)\n", LD_NAME, offs));
		return -1;
	}

	kernel_entry = (void *)bswap64(elf->e_entry);

	if (((UINTN)kernel_entry >> 61) != 0) {
		ERR_PRT((L"%s:  <<ERROR>> entry point is a virtual address 0x%lx : not supported anymore\n", LD_NAME, kernel_entry));
	}

	phdrs = (Elf64_Phdr *) (buf + offs);

	low_addr = ~0;
	max_addr = 0;

	/*
	 * allocate chunk table
	 * Convention: a segment that does not need loading will
	 * have chunk[].addr = 0.
	 */
	chunks = (void *)alloc(sizeof(struct segment)*phnum, 0);
    	if (chunks == NULL) {
        	ERR_PRT((L"%s : failed alloc chunks %r\n", LD_NAME));
		return -1;
    	}
	nchunks = phnum;
	/*
	 * find lowest and higest virtual addresses
	 * don't assume FULLY sorted !
	 */
	for (i = 0; i < phnum; ++i) {

		/* 
		 * record chunk no matter what because no load may happen
		 * anywhere in archive, not just as the last segment
		 */
		paddr = bswap64(phdrs[i].p_paddr);
		memsz = bswap64(phdrs[i].p_memsz),

		chunks[i].addr   = paddr;
		chunks[i].offset = bswap64(phdrs[i].p_offset);
		chunks[i].size   = bswap64(phdrs[i].p_filesz);
		chunks[i].bss_sz = bswap64(phdrs[i].p_memsz) - bswap64(phdrs[i].p_filesz);

		CHUNK_VALIDATE(i);

		if (bswap32(phdrs[i].p_type) != PT_LOAD) {
			CHUNK_NO_LOAD(i); /* mark no load chunk */
			DBG_PRT((L"%s : skipping segment %ld\n", LD_NAME, i));
			continue;
		}

		CHUNK_CAN_LOAD(i); /* mark no load chunk */

		VERB_PRT(3, 
		Print(L"\n%s : segment %ld vaddr [0x%lx-0x%lx] offset %ld filesz %ld memsz=%ld bss_sz=%ld\n",
				LD_NAME,
				1+i, 
				chunks[i].addr, 
				chunks[i].addr+bswap64(phdrs[i].p_filesz), 
				chunks[i].offset, 
				chunks[i].size,
				memsz,
				chunks[i].bss_sz));
		
		if (paddr < low_addr) low_addr = paddr;

		if (paddr + memsz > max_addr) max_addr = paddr + memsz;
	}

	if (low_addr & (EFI_PAGE_SIZE - 1)) {
		ERR_PRT((L"%s : low_addr not page aligned 0x%lx\n", LD_NAME, low_addr));
		goto error;
	}

	analyze_chunks();

	DBG_PRT((L"%s : %d program headers entry=0x%lx\nlowest_addr=0x%lx highest_addr=0x%lx\n", 
			LD_NAME,
			phnum, kernel_entry, low_addr, max_addr));

	total_size = (UINTN)max_addr - (UINTN)low_addr;
	pages = EFI_SIZE_TO_PAGES(total_size);

	/*
	 * Record end of kernel for initrd
	 */
	kernel_base = (void *)low_addr;
	kernel_end  = (void *)(low_addr + (pages << EFI_PAGE_SHIFT));

	/* allocate memory for the kernel */
	if (alloc_kmem((void *)low_addr, pages) == -1) {
		VOID *new_addr;

		ERR_PRT((L"%s : AllocatePages(%d, 0x%lx) for kernel failed\n", LD_NAME, pages, low_addr));

		if (ia64_can_relocate() == 0) {
			ERR_PRT((L"relocation is disabled, cannot load kernel"));
			goto error;
		}

		/*
		 * could not allocate at requested spot, try to find a
		 * suitable location to relocate the kernel
		 *
		 * The maximum sized Itanium TLB translation entry is 256 MB.
		 * If we relocate the kernel by this amount we know for sure
		 * that alignment constraints will be satisified, regardless
		 * of the kernel used.
		 */
		VERB_PRT(1, Print(L"Attempting to relocate kernel.\n"));

		if (find_kernel_memory((VOID*) low_addr, (VOID*) max_addr, 256*MB, &new_addr) == -1) {
			ERR_PRT((L"%s : find_kernel_memory(0x%lx, 0x%lx, 0x%lx, 0x%lx) failed\n", LD_NAME, low_addr, max_addr, 256*MB, &load_offset));
			goto error;
		}
		/* unsigned arithmetic */
                load_offset = (UINTN) (new_addr - ROUNDDOWN((UINTN) low_addr,256*MB));

		ERR_PRT((L"low_addr=0x%lx new_addr=0x%lx offset=0x%lx", low_addr, new_addr, load_offset));

		/*
		 * correct various addresses for non-zero load_offset
		 */
		kernel_base = (void *) ((UINTN) kernel_base + load_offset);
		kernel_end  = (void *) ((UINTN) kernel_end + load_offset);
		kernel_entry = (void*) ((UINTN) kernel_entry + load_offset);

		for (i = 0; i < phnum; ++i) {
			chunks[i].addr += load_offset;
			phdrs[i].p_paddr = (Elf64_Addr) ((UINT64) phdrs[i].p_paddr + load_offset);
		}

		/*
		 * try one last time to get memory for the kernel
		 */
		if (alloc_kmem((void *)low_addr+load_offset, pages) == -1) {
			ERR_PRT((L"%s : AllocatePages(%d, 0x%lx) for kernel failed\n", LD_NAME, pages, low_addr+load_offset));
			ERR_PRT((L"Relocation by 0x%lx bytes failed.\n", load_offset));
			goto error;
		}
	}
	return 0;
error:
	if (chunks) free(chunks);
	return -1;
}

/*
 * Determine which chunk in the Elf file will be coming out of the expand
 * code next.
 */
static void
nextchunk(void)
{
	int i;
	segment_t *cp;

	cp = NULL;
	for(i=0; i < nchunks; i++) {

		if (!CHUNK_IS_VALID(i) || !CHUNK_IS_LOAD(i)) continue;

		if (file_offset > chunks[i].offset) continue;

		if (cp == NULL || chunks[i].offset < cp->offset) cp = &chunks[i];
	}
	cur_chunk = cp;
}


/*
 * Write the output window window[0..outcnt-1] holding uncompressed
 * data and update crc.
 */
void
flush_window(void)
{
	static const CHAR8 helicopter[4] = { '|' , '/' , '-' , '\\' };
	static UINTN heli_count;
	struct segment *cp;
	char	*src, *dst;
	long	cnt;

	if (!outcnt) return;

	DBG_PRT((L"%s : flush_window outnct=%d file_offset=%ld\n", LD_NAME, outcnt, file_offset));

	Print(L"%c\b",helicopter[heli_count++%4]);

	updcrc(window, outcnt);

	/*
	 * first time, we extract the headers
	 */
	if (!bytes_out) {
		if (first_block(window, outcnt) < 0) error("invalid exec header"); 
		nextchunk();
	}

	bytes_out += outcnt;
	src = window;
tail:
	/* check if user wants to abort */
	if (check_abort() == EFI_SUCCESS) goto load_abort;

	cp = cur_chunk;
	if (cp == NULL || file_offset + outcnt <= cp->offset) {
		file_offset += outcnt;
		return;
	}

	// Does this window begin before the current chunk?
	if (file_offset < cp->offset) {
		unsigned long skip = cp->offset - file_offset;

		src         += skip;
		file_offset += skip;
		outcnt      -= skip;
	}
	dst = (char *)cp->addr + (file_offset - cp->offset);

	cnt = cp->offset + cp->size - file_offset;

	if (cnt > outcnt) cnt = outcnt;

	Memcpy(dst, src, cnt);

	file_offset += cnt;
	outcnt      -= cnt;
	src         += cnt;

	/* See if we are at the end of this chunk */
	if (file_offset == cp->offset + cp->size) {
		if (cp->bss_sz) {
			dst = (char *)cp->addr + cp->size;
			Memset(dst, 0, cp->bss_sz);
		}
		nextchunk();
		/* handle remaining bytes */
		if (outcnt) goto tail; 
	}
	return;
load_abort:
	free_kmem();
	error_return = ELILO_LOAD_ABORTED;
	longjmp(jbuf, 1);
}

static void
error(char *x)
{
	ERR_PRT((L"%s : %a", LD_NAME, x));
	/* will eventually exit with error from gunzip() */
	longjmp(jbuf,1);
}

INT32
decompress_kernel(VOID)
{
	INT32 ret;

	clear_bufs();
	makecrc();
	Print(L"Uncompressing Linux... ");
	ret = gunzip();
	if (ret == 0) Print(L"done\n");
	return ret == 0 ? 0 : -1;
}

int
gunzip_kernel(fops_fd_t fd, kdesc_t *kd)
{
	int ret = -1;

	error_return = ELILO_LOAD_ERROR;
	
	window = (void *)alloc(WSIZE, 0);
    	if (window == NULL) {
        	ERR_PRT((L"%s : allocate output window failed\n", LD_NAME));
		return -1;
    	}

	inbuf = (void *)alloc(INBUFSIZE, 0);
    	if (inbuf == NULL) {
        	ERR_PRT((L"%s : allocate input window failedr\n", LD_NAME));
		goto error;
    	}

	input_fd   = fd;
	insize     = 0;
	bytes_out  = 0;

	if (setjmp(jbuf) == 1) goto error;


	ret = decompress_kernel();

error:
	if (window) free(window);
	if (inbuf) free(inbuf);

	if (ret == 0) {
		kd->kentry = kernel_entry;
		kd->kend   = kernel_end;
		kd->kstart = kernel_base;
		error_return = ELILO_LOAD_SUCCESS;
	}
	return error_return;
}