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x86_64: Remove unneeded static PIE check for undefined weak diagnostic

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https://sourceware.org/bugzilla/show_bug.cgi?id=21782 dropped an ld
diagnostic for R_X86_64_PC32 referencing an undefined weak symbol in
-pie links.  Arguably keeping the diagnostic like other ports is more
correct, since statically resolving movl foo(%rip), %eax to the
link-time zero address produces a corrupted output.

It turns out that --enable-static-pie builds do not depend on the ld
behavior. GCC generates GOT indirection for weak declarations for
-fPIE/-fPIC, so what ld does with the PC-relative relocation doesn't
really matter.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Fangrui Song 2021-07-08 14:26:22 -07:00 committed by Fangrui Song
parent 2d20ffe431
commit a21d58a0dc
2 changed files with 0 additions and 58 deletions
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33
sysdeps/x86_64/configure vendored Normal file → Executable file
View File

@ -85,39 +85,6 @@ if test x"$build_mathvec" = xnotset; then
build_mathvec=yes
fi
if test "$static_pie" = yes; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker static PIE support" >&5
$as_echo_n "checking for linker static PIE support... " >&6; }
if ${libc_cv_ld_static_pie+:} false; then :
$as_echo_n "(cached) " >&6
else
cat > conftest.s <<\EOF
.text
.global _start
.weak foo
_start:
leaq foo(%rip), %rax
EOF
libc_cv_pie_option="-Wl,-pie"
if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles -nostdlib $no_ssp $libc_cv_pie_option -o conftest conftest.s 1>&5'
{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
test $ac_status = 0; }; }; then
libc_cv_ld_static_pie=yes
else
libc_cv_ld_static_pie=no
fi
rm -f conftest*
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ld_static_pie" >&5
$as_echo "$libc_cv_ld_static_pie" >&6; }
if test "$libc_cv_ld_static_pie" != yes; then
as_fn_error $? "linker support for static PIE needed" "$LINENO" 5
fi
fi
$as_echo "#define PI_STATIC_AND_HIDDEN 1" >>confdefs.h

25
sysdeps/x86_64/configure.ac
View File

@ -44,31 +44,6 @@ if test x"$build_mathvec" = xnotset; then
build_mathvec=yes
fi
dnl Check if linker supports static PIE with the fix for
dnl
dnl https://sourceware.org/bugzilla/show_bug.cgi?id=21782
dnl
if test "$static_pie" = yes; then
AC_CACHE_CHECK(for linker static PIE support, libc_cv_ld_static_pie, [dnl
cat > conftest.s <<\EOF
.text
.global _start
.weak foo
_start:
leaq foo(%rip), %rax
EOF
libc_cv_pie_option="-Wl,-pie"
if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles -nostdlib $no_ssp $libc_cv_pie_option -o conftest conftest.s 1>&AS_MESSAGE_LOG_FD); then
libc_cv_ld_static_pie=yes
else
libc_cv_ld_static_pie=no
fi
rm -f conftest*])
if test "$libc_cv_ld_static_pie" != yes; then
AC_MSG_ERROR([linker support for static PIE needed])
fi
fi
dnl It is always possible to access static and hidden symbols in an
dnl position independent way.
AC_DEFINE(PI_STATIC_AND_HIDDEN)