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[PATCH] PowerPC: incorrect library search order?


Hi,

The problem below resulted in failures of some PowerPC sample toolchains in crosstool-ng.

As far as I understand, the code in ld/emulparams/elf32ppccommon.sh attempts to use /lib32 or /lib64 if the endianness of the selected emulation matches the endianness of the machine, and use the directories with explicit endianness (such as /lib32le, /lib32be, /lib64le, /lib64be) otherwise. However, there are two issues with that code:

First, it checks for *host's* triplet, not target. The host may not be using 'le' suffix to designate its endianness - for example, it may be little-endian by default. It also doesn't seem to make much sense to check the host for default layout - why would the expected sysroot layout on a big-endian host differ from that on a little-endian host?

Second, the check itself is flawed: it should be checking just the CPU part of the triplet, not the whole string. In its current form, the check compares $host against "*le-*" pattern - which matches "x86_64-apple-darwin16.0".

This results in ld configured for powerpc64le-unknown-linux target on x86_64-unknown-linux host behaving as follows:
- without -m, or with -melf64lppc it searches /lib64le first
- with '-melf64ppc' it searches /lib64 first - which seems to run counter to the intended purpose of that code, as the target is configured as little-endian!

'ld' works ok with libraries in /lib (which is always searched as the last fallback, regardless of the host and selected emulation). Once the libraries are placed in /lib64 (default gcc's directory for this target), ld fails to find them.

This erroneous code first appeared in binutils 2.24.

Patch attached.

Regards,
Alexey.



>From cf2cf4ea661b8527d0fe48a9ffda1b02154d0c67 Mon Sep 17 00:00:00 2001
From: Alexey Neyman <stilor@att.net>
Date: Sat, 11 Mar 2017 17:27:09 -0800
Subject: [PATCH] Fix library paths on PowerPC

First, need to match against just the CPU name, not the whole triplet.
Otherwise, the test picks up "*le-*" pattern from x86_64-apple-darwin
triplet.

Second, it should be testing for $target, not $host. Host may be
little endian by default, and the sysroot directory layout shouldn't
depend on whether it is built on LE or BE machine.

Signed-off-by: Alexey Neyman <stilor@att.net>
---
 ld/emulparams/elf32ppccommon.sh | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/ld/emulparams/elf32ppccommon.sh b/ld/emulparams/elf32ppccommon.sh
index 1f54ef8..d00cf68 100644
--- a/ld/emulparams/elf32ppccommon.sh
+++ b/ld/emulparams/elf32ppccommon.sh
@@ -44,11 +44,11 @@ fi
 
 # Look for 64 bit target libraries in /lib64, /usr/lib64 etc., first.
 # Similarly, look for 32 bit libraries in /lib32, /usr/lib32 etc.
-case "$host":"$EMULATION_NAME" in
-  *le-*:*64lppc*) LIBPATH_SUFFIX=64 ;;
-  *le-*:*32lppc*) LIBPATH_SUFFIX=32 ;;
-  *le-*:*64*) LIBPATH_SUFFIX=64be ;;
-  *le-*:*32*) LIBPATH_SUFFIX=32be ;;
+case `echo "$target" | sed -e 's/-.*//'`:"$EMULATION_NAME" in
+  *le:*64lppc*) LIBPATH_SUFFIX=64 ;;
+  *le:*32lppc*) LIBPATH_SUFFIX=32 ;;
+  *le:*64*) LIBPATH_SUFFIX=64be ;;
+  *le:*32*) LIBPATH_SUFFIX=32be ;;
   *:*64lppc*) LIBPATH_SUFFIX=64le ;;
   *:*32lppc*) LIBPATH_SUFFIX=32le ;;
   *:*64*) LIBPATH_SUFFIX=64 ;;
-- 
2.9.3



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