GCC can generate bogus dwarf attributes with DW_AT_byte_size
set to 0xFFFFFFFF.
The issue was originaly detected in NetBSD but it has been
adapted for portability and to avoid compiler warnings.
Reference:
https://www.illumos.org/issues/3776
Obtained from: NetBSD
MFC after: 1 month
CTF format is not cross-platform by design, e.g. it is not guaranteed
that data generated by ctfconvert/ctfmerge on one architecture will
be successfuly read on another. CTF structures are saved/restored
using naive approach. Roughly it looks like:
write(fd, &ctf_struct, sizeof(ctf_struct))
read(fd, &ctf_struct, sizeof(ctf_struct))
By sheer luck memory layout of all type-related CTF structures is the same
on amd64/i386/mips32/mips64. It's different on ARM though. sparc, ia64,
powerpc, and powerpc64 were not tested. So in order to get file compatible
with dtrace on ARM it should be compiled on ARM. Alternative solution would
be to have "signatures" for every platform and ctfmerge should convert host's
reperesentation of CTF structure to target's one using "signature" as template.
This patch checks byte order of ELF files used for generating CTF record
and makes sure that byte order of data written to resulting files is the same
as target's byte order.
CTF can not represent enums with more than CTF_MAX_VLEN members, but
ctfconvert will happily ignore that limitation and create CTF section no
other tool can interpret.
This change is different from similar change from upstream, which just
returns an error if big enum is encountered. Doing that means that
every FreeBSD kernel with compiled in hwpmc will have no useable CTF
information due to pmc_event enum having 1236+ members.
