[uclibc-ng-devel] -static-pie and FDPIC

Christophe Lyon christophe.lyon at linaro.org
Mon May 20 16:42:12 CEST 2019


Hi,

My recent attempt at submitting the GCC patch series to add FDPIC
support for arm triggered a discussion about -static-pie support [1],
which continued on IRC.

The patch currently supports -static but the resulting binary still
needs the dynamic linker to prepare the parameters for __self_reloc,
and there are arguments that a static binary should not have a
PT_INTERP field.

At present, musl supports -static-pie for sh+FDPIC only.

I think other uclibc-ng targets with FDPIC (frv, bfin) do not support
-static, but I'm not sure how to build such toolchains, nor if they
are still supported.

It seems I have several options:
(a) add support for static-pie to uclibc-ng. This means creating a new
rcrt1.o or similar, which would embed parts of the dynamic linker into
static-pie executables. I'm not sure how big a task this is?

(b) add support for FDPIC on arm to musl, which I'm not familiar with

(c) declare -static not supported on arm-FDPIC

(d) gather consensus that -static with pt_interp is ok (my preference,
since that's what the current patches do :-)

So, my questions are:
- does uclibc-ng support -static on some FDPIC targets? which ones?
- how much work would option (a) mean?
- are uclibc-ng people opposed to option (d)?

Thanks,

Christophe

[1] https://gcc.gnu.org/ml/gcc-patches/2019-05/msg00820.html


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