since commit c5e34dabbb, crt1.c has
provided a "mostly-C" implementation of the crt1 start file that
avoids the need for arch-specific symbol referencing, PIC/PIE-specific
code variants, etc. but for archs that had existing hand-written
versions, the new code was initially unused, and later only used as
the dynamic linker entry point. this commit switches all archs to
using the new code.
the code being removed was a recurring source of subtle errors, and
was still broken at least on arm, where it failed to properly align
the stack pointer before calling into C code.
it's naturally aligned when entered with the kernel argv array, but if
ld.so has been invoked explicitly to run a program, the stack will not
be aligned due to having thrown away argv[0].
since .init and .fini are not .text, the toolchain does not seem to
align them for code by default. this yields random breakage depending
on the object sizes the linker is dealing with.
basically, this version of the code was obtained by starting with
rdp's work from his ellcc source tree, adapting it to musl's build
system and coding style, auditing the bits headers for discrepencies
with kernel definitions or glibc/LSB ABI or large file issues, fixing
up incompatibility with the old binutils from aboriginal linux, and
adding some new special cases to deal with the oddities of sigaction
and pipe syscall interfaces on mips.
at present, minimal test programs work, but some interfaces are broken
or missing. threaded programs probably will not link.
Rich Felker