Add section header parsing and use it in the mk-payload step

This completes the improvements to the ELF file parsing code.  We can
now parse section headers too, across all 4 combinations of word size
and endianness. I had hoped to completely remove the use of htonl
until I found it in cbfs_image.c. That's a battle for another day.

There's now a handy macro to create magic numbers in host byte order.
I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe
we can use it for the others too, but this is sensitive code and
I'd rather change one thing at a time.

To maximize the ease of use for users, elf parsing is accomplished with
just one function:

int
elf_headers(const struct buffer *pinput,
	    Elf64_Ehdr *ehdr,
	    Elf64_Phdr **pphdr,
	    Elf64_Shdr **pshdr)

which requires the ehdr and pphdr pointers to be non-NULL, but allows
the pshdr to be NULL. If pshdr is NULL, the code will not try to read
in section headers.

To satisfy our powerful scripts, I had to remove the ^M from an unrelated
microcode file.

BUG=None
TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos.
BRANCH=None

Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889
Signed-off-by: Ronald G. Minnich <rminnich@google.com>
Reviewed-on: https://chromium-review.googlesource.com/181272
Reviewed-by: Ronald Minnich <rminnich@chromium.org>
Commit-Queue: Ronald Minnich <rminnich@chromium.org>
Tested-by: Ronald Minnich <rminnich@chromium.org>
Signed-off-by: Ronald G. Minnich <rminnich@google.com>
Reviewed-on: http://review.coreboot.org/5098
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

1 files changed, 2 insertions, 239 deletions

diff --git a/util/cbfstool/cbfs-mkstage.c b/util/cbfstool/cbfs-mkstage.c
index 5c8014f072a4..6a5f6f74ca6e 100644
--- a/util/cbfstool/cbfs-mkstage.c
+++ b/util/cbfstool/cbfs-mkstage.c
@@ -24,246 +24,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "elf.h"
 #include "common.h"
 #include "cbfs.h"
-#include "elf.h"
-
-/*
- * Short form: this is complicated, but we've tried making it simple
- * and we keep hitting problems with our ELF parsing.
- *
- * The ELF parsing situation has always been a bit tricky.  In fact,
- * we (and most others) have been getting it wrong in small ways for
- * years. Recently this has caused real trouble for the ARM V8 build.
- * In this file we attempt to finally get it right for all variations
- * of endian-ness and word size and target architectures and
- * architectures we might get run on. Phew!. To do this we borrow a
- * page from the FreeBSD NFS xdr model (see elf_ehdr and elf_phdr),
- * the Plan 9 endianness functions (see xdr.c), and Go interfaces (see
- * how we use buffer structs in this file). This ends up being a bit
- * wordy at the lowest level, but greatly simplifies the elf parsing
- * code and removes a common source of bugs, namely, forgetting to
- * flip type endianness when referencing a struct member.
- *
- * ELF files can have four combinations of data layout: 32/64, and
- * big/little endian.  Further, to add to the fun, depending on the
- * word size, the size of the ELF structs varies. The coreboot SELF
- * format is simpler in theory: it's supposed to be always BE, and the
- * various struct members allow room for growth: the entry point is
- * always 64 bits, for example, so the size of a SELF struct is
- * constant, regardless of target architecture word size.  Hence, we
- * need to do some transformation of the ELF files.
- *
- * A given architecture, realistically, only supports one of the four
- * combinations at a time as the 'native' format. Hence, our code has
- * been sprinkled with every variation of [nh]to[hn][sll] over the
- * years. We've never quite gotten it all right, however, and a quick
- * pass over this code revealed another bug.  It's all worked because,
- * until now, all the working platforms that had CBFS were 32 LE. Even then,
- * however, bugs crept in: we recently realized that we're not
- * transforming the entry point to big format when we store into the
- * SELF image.
- *
- * The problem is essentially an XDR operation:
- * we have something in a foreign format and need to transform it.
- * It's most like XDR because:
- * 1) the byte order can be wrong
- * 2) the word size can be wrong
- * 3) the size of elements in the stream depends on the value
- *    of other elements in the stream
- * it's not like XDR because:
- * 1) the byte order can be right
- * 2) the word size can be right
- * 3) the struct members are all on a natural alignment
- *
- * Hence, this new approach.  To cover word size issues, we *always*
- * transform the two structs we care about, the file header and
- * program header, into a native struct in the 64 bit format:
- *
- * [32,little] -> [Elf64_Ehdr, Elf64_Phdr]
- * [64,little] -> [Elf64_Ehdr, Elf64_Phdr]
- * [32,big] -> [Elf64_Ehdr, Elf64_Phdr]
- * [64,big] -> [Elf64_Ehdr, Elf64_Phdr]
- * Then we just use those structs, and all the need for inline ntoh* goes away,
- * as well as all the chances for error.
- * This works because all the SELF structs have fields large enough for
- * the largest ELF 64 struct members, and all the Elf64 struct members
- * are at least large enough for all ELF 32 struct members.
- * We end up with one function to do all our ELF parsing, and two functions
- * to transform the headers. For the put case, we also have
- * XDR functions, and hopefully we'll never again spend 5 years with the
- * wrong endian-ness on an output value :-)
- * This should work for all word sizes and endianness we hope to target.
- * I *really* don't want to be here for 128 bit addresses.
- *
- * The parse functions are called with a pointer to an input buffer
- * struct. One might ask: are there enough bytes in the input buffer?
- * We know there need to be at *least* sizeof(Elf32_Ehdr) +
- * sizeof(Elf32_Phdr) bytes. Realistically, there has to be some data
- * too.  If we start to worry, though we have not in the past, we
- * might apply the simple test: the input buffer needs to be at least
- * sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) bytes because, even if it's
- * ELF 32, there's got to be *some* data! This is not theoretically
- * accurate but it is actually good enough in practice. It allows the
- * header transformation code to ignore the possibility of underrun.
- *
- * We also must accomodate different ELF files, and hence formats,
- * in the same cbfs invocation. We might load a 64-bit payload
- * on a 32-bit machine; we might even have a mixed armv7/armv8
- * SOC or even a system with an x86/ARM!
- *
- * A possibly problematic (though unlikely to be so) assumption
- * is that we expect the BIOS to remain in the lowest 32 bits
- * of the physical address space. Since ARMV8 has standardized
- * on that, and x86_64 also has, this seems a safe assumption.
- *
- * To repeat, ELF structs are different sizes because ELF struct
- * members are different sizes, depending on values in the ELF file
- * header. For this we use the functions defined in xdr.c, which
- * consume bytes, convert the endianness, and advance the data pointer
- * in the buffer struct.
- */
-
-/* Get the ident array, so we can figure out
- * endian-ness, word size, and in future other useful
- * parameters
- */
-static void
-elf_eident(struct buffer *input, Elf64_Ehdr *ehdr)
-{
-	memmove(ehdr->e_ident, input->data, sizeof(ehdr->e_ident));
-	input->data += sizeof(ehdr->e_ident);
-	input->size -= sizeof(ehdr->e_ident);
-}
-
-
-static void
-elf_ehdr(struct buffer *input, Elf64_Ehdr *ehdr, struct xdr *xdr, int bit64)
-{
-	ehdr->e_type = xdr->get16(input);
-	ehdr->e_machine = xdr->get16(input);
-	ehdr->e_version = xdr->get32(input);
-	if (bit64){
-		ehdr->e_entry = xdr->get64(input);
-		ehdr->e_phoff = xdr->get64(input);
-		ehdr->e_shoff = xdr->get64(input);
-	} else {
-		ehdr->e_entry = xdr->get32(input);
-		ehdr->e_phoff = xdr->get32(input);
-		ehdr->e_shoff = xdr->get32(input);
-	}
-	ehdr->e_flags = xdr->get32(input);
-	ehdr->e_ehsize = xdr->get16(input);
-	ehdr->e_phentsize = xdr->get16(input);
-	ehdr->e_phnum = xdr->get16(input);
-	ehdr->e_shentsize = xdr->get16(input);
-	ehdr->e_shnum = xdr->get16(input);
-	ehdr->e_shstrndx = xdr->get16(input);
-}
-
-static void
-elf_phdr(struct buffer *pinput, Elf64_Phdr *phdr,
-	 int entsize, struct xdr *xdr, int bit64)
-{
-	/*
-	 * The entsize need not be sizeof(*phdr).
-	 * Hence, it is easier to keep a copy of the input,
-	 * as the xdr functions may not advance the input
-	 * pointer the full entsize; rather than get tricky
-	 * we just advance it below.
-	 */
-	struct buffer input = *pinput;
-	if (bit64){
-		phdr->p_type = xdr->get32(&input);
-		phdr->p_flags = xdr->get32(&input);
-		phdr->p_offset = xdr->get64(&input);
-		phdr->p_vaddr = xdr->get64(&input);
-		phdr->p_paddr = xdr->get64(&input);
-		phdr->p_filesz = xdr->get64(&input);
-		phdr->p_memsz = xdr->get64(&input);
-		phdr->p_align = xdr->get64(&input);
-	} else {
-		phdr->p_type = xdr->get32(&input);
-		phdr->p_offset = xdr->get32(&input);
-		phdr->p_vaddr = xdr->get32(&input);
-		phdr->p_paddr = xdr->get32(&input);
-		phdr->p_filesz = xdr->get32(&input);
-		phdr->p_memsz = xdr->get32(&input);
-		phdr->p_flags = xdr->get32(&input);
-		phdr->p_align = xdr->get32(&input);
-	}
-	pinput->size -= entsize;
-	pinput->data += entsize;
-}
-
-/* Get the headers from the buffer.
- * Return -1 in the event of an error.
- */
-static int
-elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr)
-{
-	int i;
-	struct xdr *xdr = &xdr_le;
-	int bit64 = 0;
-	struct buffer input = *(struct buffer *)pinput;
-	struct buffer phdr_buf;
-	Elf64_Phdr *phdr;
-
-	if (!iself((unsigned char *)pinput->data)) {
-		ERROR("The stage file is not in ELF format!\n");
-		return -1;
-	}
-
-	elf_eident(&input, ehdr);
-	bit64 = ehdr->e_ident[EI_CLASS] == ELFCLASS64;
-	/* Assume LE unless we are sure otherwise.
-	 * We're not going to take on the task of
-	 * fully validating the ELF file. That way
-	 * lies madness.
-	 */
-	if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
-		xdr = &xdr_be;
-
-	elf_ehdr(&input, ehdr, xdr, bit64);
-
-	// The tool may work in architecture-independent way.
-	if (arch != CBFS_ARCHITECTURE_UNKNOWN &&
-	    !((ehdr->e_machine == EM_ARM) && (arch == CBFS_ARCHITECTURE_ARMV7)) &&
-	    !((ehdr->e_machine == EM_386) && (arch == CBFS_ARCHITECTURE_X86))) {
-		ERROR("The stage file has the wrong architecture\n");
-		return -1;
-	}
-
-	if (pinput->size < ehdr->e_phoff){
-		ERROR("The program header offset is greater than "
-		      "the remaining file size."
-		      "%ld bytes left, program header offset is %ld \n",
-		      pinput->size, ehdr->e_phoff);
-		return -1;
-	}
-	/* cons up an input buffer for the headers.
-	 * Note that the program headers can be anywhere,
-	 * per the ELF spec, You'd be surprised how many ELF
-	 * readers miss this little detail.
-	 */
-	phdr_buf.data = &pinput->data[ehdr->e_phoff];
-	phdr_buf.size = ehdr->e_phentsize * ehdr->e_phnum;
-	if (phdr_buf.size > (pinput->size - ehdr->e_phoff)){
-		ERROR("The file is not large enough for the program headers."
-		      "%ld bytes left, %ld bytes of headers\n",
-		      pinput->size - ehdr->e_phoff, phdr_buf.size);
-		return -1;
-	}
-	/* gather up all the phdrs.
-	 * We do them all at once because there is more
-	 * than one loop over all the phdrs.
-	 */
-	phdr = calloc(sizeof(*phdr), ehdr->e_phnum);
-	for (i = 0; i < ehdr->e_phnum; i++)
-		elf_phdr(&phdr_buf, &phdr[i], ehdr->e_phentsize, xdr, bit64);
-	*pphdr = phdr;
-	return 0;
-}
 
 /* returns size of result, or -1 if error.
  * Note that, with the new code, this function
@@ -287,7 +50,7 @@ int parse_elf_to_stage(const struct buffer *input, struct buffer *output,
 
 	DEBUG("start: parse_elf_to_stage(location=0x%x)\n", *location);
 
-	if (elf_headers(input, &ehdr, &phdr) < 0)
+	if (elf_headers(input, &ehdr, &phdr, NULL) < 0)
 		return -1;
 
 	headers = ehdr.e_phnum;