Rainer Orth <r...@cebitec.uni-bielefeld.de> writes:
> Beyond the reasons for the bundled Solaris CRTs already cited in
>
> https://gcc.gnu.org/ml/gcc-patches/2015-09/msg01638.html
>
> they need to be PIC to support position independent executables (PIE).
>
> While linker support for PIE has existed in Solaris ld since at least
> Solaris 11.2 and GNU ld has just gotten the last (mostly cosmetic) bit
> for binutils 2.26, there were no usable CRTs before.
>
> Now those pieces are in place, this patch enables PIE if the necessary
> support (linker and CRTs) is detected. It's mostly straightforward,
> adapting specs changes in gnu-user.h and allowing for differences in
> linker options.
>
> crtp.o, crtpg.o, and gmon.o are now compiled as PIC to also work with
> PIE. I don't thing there's any point to have separate PIC and non-PIC
> versions here.
>
> During early development of the patch, I found that gmon.c includes the
> trailing NULs in error messages it prints. Now corrected, though not
> strictly related to the patch.
>
> Contrary to other targets, where -pie seems to be silently ignored if
> PIE support is missing, I've decided to have gcc error out on Solaris in
> this situation. This also allows to easily distinguish between
> configurations with and without PIE support in the testsuite.
>
> Tested on i386-pc-solaris2.1[012] and sparc-sun-solaris2.1[012] with
> both as/ld and gas/gld, and x86_64-unknown-linux-gnu.
>
> I've also bootstrapped on i386-pc-solaris2.12 and sparc-sun-solaris2.12
> with --enable-default-pie. There are a couple of new failures, but they
> also occur on Linux/x86_64 and I've already filed PRs for (most of?)
> them.
>
> Again, perhaps with exception of the obvious hunk in gcc.c, this patch
> is purely Solaris-specific, so I'll commit it in a couple of days. I'd
> also like to backport it to the gcc-5 branch after some soak time on
> mainline.
I've now installed both the previous Solaris CRTs patch and this one. A
final round of testing revealed a problem with gld PIE support
detection, though: by mistake I initially did the gas/gld testing with
an unmodified gld 2.25. While this works just fine on Solaris/x86 (with
the exception of the PIE executables not being marked with DF_1_PIE in
DF_FLAGS_1, a purely informational thing), Solaris/SPARC was different:
even in a default build, many PIE tests failed with
gld-2.25: read-only segment has dynamic relocations.
which doesn't happen with a gld 2.25.51 with the Solaris PIE patch.
Also, Solaris ld links those exact same objects just fine.
Therefore I'm now requiring gld 2.26 on Solaris for PIE support, as in
the following patchlet. Tested by configuring with ld, gld 2.25 and a
gld 2.25.51 faked to call itself gld 2.26 on i386-pc-solaris2.11 and the
bundled gld 2.23.2 on x86_64-pc-linux-gnu and checking the HAVE_LD_PIE
is set correctly.
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4751,7 +4751,12 @@ AC_MSG_RESULT($gcc_cv_ld_eh_frame_ciev3)
AC_MSG_CHECKING(linker position independent executable support)
gcc_cv_ld_pie=no
if test $in_tree_ld = yes ; then
- if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 15 -o "$gcc_cv_gld_major_version" -gt 2 \
+ case "$target" in
+ # Full PIE support on Solaris was only introduced in gld 2.26.
+ *-*-solaris2*) gcc_gld_pie_min_version=26 ;;
+ *) gcc_gld_pie_min_version=15 ;;
+ esac
+ if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge "$gcc_gld_pie_min_version" -o "$gcc_cv_gld_major_version" -gt 2 \
&& test $in_tree_ld_is_elf = yes; then
gcc_cv_ld_pie=yes
fi
@@ -4759,6 +4764,14 @@ elif test x$gcc_cv_ld != x; then
# Check if linker supports -pie option
if $gcc_cv_ld --help 2>/dev/null | grep -- -pie > /dev/null; then
gcc_cv_ld_pie=yes
+ case "$target" in
+ *-*-solaris2*)
+ if echo "$ld_ver" | grep GNU > /dev/null \
+ && test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 26; then
+ gcc_cv_ld_pie=no
+ fi
+ ;;
+ esac
else
case "$target" in
*-*-solaris2.1[[1-9]]*)
@@ -4772,7 +4785,7 @@ elif test x$gcc_cv_ld != x; then
fi
if test x"$gcc_cv_ld_pie" = xyes; then
AC_DEFINE(HAVE_LD_PIE, 1,
-[Define if your linker supports -pie option.])
+[Define if your linker supports PIE option.])
fi
AC_MSG_RESULT($gcc_cv_ld_pie)
Despite that patch, with --enable-default-pie, there are many failures
on sparc-sun-solaris2.12 with gas/gld 2.26, both the same error as above
and execution failures in boehm-gc, libgomp, and libjava. Given that
those errors don't occur with as/ld or on i386-pc-solaris2.12, ISTM that
there's something amiss with gld on Solaris/SPARC. Given that this is a
non-recommended and niche configuration, I'm committing the patch
anyway.
Rainer
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University
