make-target-2.sh PIE failure on ppc64le and ppc64

[Thomas Fitzsimmons]

When building on a Debian sid system with the following package
versions:

Linux 5.8.0-3-powerpc64le #1 SMP Debian 5.8.14-1 (2020-10-10) ppc64le GNU/Linux
GNU assembler (GNU Binutils for Debian) 2.35.1
cc (Debian 9.3.0-18) 9.3.0
ldd (Debian GLIBC 2.30-8) 2.30

$ sh make.sh

results in:

 [...]
//entering make-target-2.sh
//doing warm init - compilation phase
./src/runtime/sbcl: error while loading shared libraries: R_PPC64_ADDR16_HI reloc at 0x0000000105532f68 for symbol `' out of range

real 0m0.003s
user 0m0.001s
sys 0m0.002s
$ echo $?
127
$

Likewise on a Debian 10 ppc64 system with the following package versions:

Linux 5.2.0-2-powerpc64 #1 SMP Debian 5.2.9-2 (2019-08-21) ppc64 GNU/Linux
GNU assembler (GNU Binutils for Debian) 2.35.1
cc (Debian 10.2.0-13) 10.2.0
ldd (Debian GLIBC 2.31-4) 2.31

$ sh make.sh --arch=ppc64

results in:

[...]

//entering make-target-2.sh
//doing warm init - compilation phase
./src/runtime/sbcl: error while loading shared libraries: R_PPC64_ADDR16_HI reloc at 0x000000013fbc6e02 for symbol `' out of range
$ echo $?
127
$

These failures started showing up due to:

   commit 78de8730813a8a2d0c7f5c125fff3cfaa129f63b
   Author: Douglas Katzman <email address hidden>
   Date: Mon Sep 21 22:05:19 2020 -0400

       Remove DISABLE_PIE

       Use the toolchain default everywhere, whether it makes a PIE or not.

which resulted in sbcl being built as a position-independent
executable by default.

The attached patches fix the build in both cases; do they look OK?

They change the linkage table entry size on ppc64 to accommodate
call_into_c loading the two high address bytes. There may be a better
approach that keeps the entry size to 24 bytes; if that matters, I can
attempt another version of the patch.

The patches also do not attempt to handle the PIE-disabled case, where
the extra instructions aren't needed, the same as before. I'm not
sure how much that matters since PIE seems to be encouraged and
default now.

[Stas Boukarev (stassats)]

Doesn't it have some pseudo-instruction for loading constants?

[Sébastien Villemot (sebastien-villemot)]

I confirm that this bug affects the official Debian package, see the build log:
https://buildd.debian.org/status/fetch.php?pkg=sbcl&arch=ppc64el&ver=2%3A2.0.9-1&stamp=1602961283&raw=0

[Thomas Fitzsimmons (fitzsim)]

I looked around and I can't find a pseudo-instruction or mnemonic to use for the "Calculate LRA" section. This page says to just wrap the five instructions in a macro:

https://developer.ibm.com/technologies/linux/articles/l-ppc/

but the sequence only occurs once in ppc64-assem.S so I think it might as well be inlined.

[Stas Boukarev (stassats)]

Couldn't find it either and a macro wouldn't be able to avoid unnecessary instructions (easily). Oh well.