Re: [Xen-devel] [Qemu-devel] [Bug 1257099] [NEW] QEMU fails to build on CentOS 5.10 with relocation R_X86_64_PC32 error

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 12/14/13 15:21, Don Slutz wrote:

On 12/09/13 08:22, Paolo Bonzini wrote:

Il 09/12/2013 13:47, Don Slutz ha scritto:

On 12/05/13 22:20, Don Slutz wrote:

On 12/05/13 16:24, Richard Henderson wrote:

On 12/06/2013 04:18 AM, Paolo Bonzini wrote:

$ gcc -shared -o f.so f.c -fPIE -fPIC
/usr/bin/ld: /tmp/ccQc9els.o: relocation R_X86_64_PC32 against `f'
can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status


The bug is simply that "-fPIE -fPIC" counts as -fPIE rather than -fPIC:

$ gcc -S -o - f.c -fPIE |grep call
    call    f                      # PC32 relocation
$ gcc -S -o - f.c -fPIC |grep call
    call    f@PLT                  # PLT32 relocation

The easy workaround is to drop -fPIE when we're adding -fPIC.


r~

[snip]

Attached is a much better version.  It drops -fPIE and adds -fPIC for
libtool.

It's not much better, because using position-independent code for shared
libraries is really platform-dependent knowledge of the kind that
libtool is supposed to hide.

For example, on Mac OS X everything is position-independent by default.
 And on some platforms you have -fpic instead of -fPIC.

So I prefer the patch you had that disabled libtool if the platform is
buggy.

Paolo

Well, the detection code is too simple:

FC17 system:

dcs-xen-52:~/tmp/libtool>uname -a
Linux dcs-xen-52 3.8.11-100.fc17.x86_64 #1 SMP Wed May 1 19:31:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
dcs-xen-52:~/tmp/libtool>gcc -shared -fPIE -DPIE f.c  -fPIC -DPIC -o f.so
/usr/bin/ld: /tmp/ccl4By1r.o: relocation R_X86_64_PC32 against symbol `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
dcs-xen-52:~/tmp/libtool>libtool --mode=compile gcc -g -c -fPIE -DPIE f.c
libtool: compile:  gcc -g -c -DPIE f.c  -fPIC -DPIC -o .libs/f.o
libtool: compile:  gcc -g -c -DPIE f.c -fPIE -o f.o >/dev/null 2>&1
dcs-xen-52:~/tmp/libtool>libtool --mode=link gcc -g -o libf.la f.lo -rpath /usr/local/lib
libtool: link: gcc -shared  -fPIC -DPIC  .libs/f.o      -Wl,-soname -Wl,libf.so.0 -o .libs/libf.so.0.0.0
libtool: link: (cd ".libs" && rm -f "libf.so.0" && ln -s "libf.so.0.0.0" "libf.so.0")
libtool: link: (cd ".libs" && rm -f "libf.so" && ln -s "libf.so.0.0.0" "libf.so")
libtool: link: ar cru .libs/libf.a  f.o
libtool: link: ranlib .libs/libf.a
libtool: link: ( cd ".libs" && rm -f "libf.la" && ln -s "../libf.la" "libf.la" )

CentOS 5.10:

dcs-xen-53:~/tmp/libtool>uname -a
Linux dcs-xen-53 2.6.18-371.el5xen #1 SMP Tue Oct 1 09:15:30 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux
dcs-xen-53:~/tmp/libtool>gcc -shared -fPIE -DPIE f.c  -fPIC -DPIC -o f.so
/usr/bin/ld: /tmp/ccAy1vZK.o: relocation R_X86_64_PC32 against `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status
dcs-xen-53:~/tmp/libtool>libtool --mode=compile gcc -g -c -fPIE -DPIE f.c
mkdir .libs
 gcc -g -c -fPIE -DPIE f.c  -fPIC -DPIC -o .libs/f.o
 gcc -g -c -fPIE -DPIE f.c -o f.o >/dev/null 2>&1
dcs-xen-53:~/tmp/libtool>libtool --mode=link gcc -g -o libf.la f.lo -rpath /usr/local/lib
gcc -shared  .libs/f.o   -Wl,-soname -Wl,libf.so.0 -o .libs/libf.so.0.0.0
/usr/bin/ld: .libs/f.o: relocation R_X86_64_PC32 against `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status

I have attached a patch that uses libtool to determine if gcc & libtool is broken.
     -Don

Early today it hit me that the new check was a little to early in configure.  Needs to be after PIE check.
Attached is a v2 of the patch.

   -Don Slutz

From bb68898eb787cbb1748d4aeb31a4184339d38300 Mon Sep 17 00:00:00 2001
From: Don Slutz <dslutz@xxxxxxxxxxx>
Date: Sat, 14 Dec 2013 19:43:56 +0000
Subject: [PATCH] configure: Disable libtool if -fPIE does not work with it
 (bug #1257099)

Adjust TMPO and added TMPB, TMPL, and TMPA.  libtool needs the names
to be fixed (TMPB).

Add new functions do_libtool and libtool_prog.

Add check for broken gcc and libtool.

Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
---
 configure | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index edfea95..852d021 100755
--- a/configure
+++ b/configure
@@ -12,7 +12,10 @@ else
 fi
 
 TMPC="${TMPDIR1}/qemu-conf-${RANDOM}-$$-${RANDOM}.c"
-TMPO="${TMPDIR1}/qemu-conf-${RANDOM}-$$-${RANDOM}.o"
+TMPB="qemu-conf-${RANDOM}-$$-${RANDOM}"
+TMPO="${TMPDIR1}/${TMPB}.o"
+TMPL="${TMPDIR1}/${TMPB}.lo"
+TMPA="${TMPDIR1}/lib${TMPB}.la"
 TMPE="${TMPDIR1}/qemu-conf-${RANDOM}-$$-${RANDOM}.exe"
 
 # NB: do not call "exit" in the trap handler; this is buggy with some shells;
@@ -86,6 +89,38 @@ compile_prog() {
   do_cc $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC $LDFLAGS $local_ldflags
 }
 
+do_libtool() {
+    local mode=$1
+    shift
+    # Run the compiler, capturing its output to the log.
+    echo $libtool $mode --tag=CC $cc "$@" >> config.log
+    $libtool $mode --tag=CC $cc "$@" >> config.log 2>&1 || return $?
+    # Test passed. If this is an --enable-werror build, rerun
+    # the test with -Werror and bail out if it fails. This
+    # makes warning-generating-errors in configure test code
+    # obvious to developers.
+    if test "$werror" != "yes"; then
+        return 0
+    fi
+    # Don't bother rerunning the compile if we were already using -Werror
+    case "$*" in
+        *-Werror*)
+           return 0
+        ;;
+    esac
+    echo $libtool $mode --tag=CC $cc -Werror "$@" >> config.log
+    $libtool $mode --tag=CC $cc -Werror "$@" >> config.log 2>&1 && return $?
+    error_exit "configure test passed without -Werror but failed with -Werror." \
+        "This is probably a bug in the configure script. The failing command" \
+        "will be at the bottom of config.log." \
+        "You can run configure with --disable-werror to bypass this check."
+}
+
+libtool_prog() {
+    do_libtool --mode=compile $QEMU_CFLAGS -c -fPIE -DPIE -o $TMPO $TMPC || return $?
+    do_libtool --mode=link $LDFLAGS -o $TMPA $TMPL -rpath /usr/local/lib
+}
+
 # symbolically link $1 to $2.  Portable version of "ln -sf".
 symlink() {
   rm -rf "$2"
@@ -1367,6 +1402,32 @@ EOF
   fi
 fi
 
+# check for broken gcc and libtool in RHEL5
+if test -n "$libtool" -a "$pie" != "no" ; then
+  cat > $TMPC <<EOF
+
+void *f(unsigned char *buf, int len);
+void *g(unsigned char *buf, int len);
+
+void *
+f(unsigned char *buf, int len)
+{
+    return (void*)0L;
+}
+
+void *
+g(unsigned char *buf, int len)
+{
+    return f(buf, len);
+}
+
+EOF
+  if ! libtool_prog; then
+    echo "Disabling libtool due to broken toolchain support"
+    libtool=
+  fi
+fi
+
 ##########################################
 # __sync_fetch_and_and requires at least -march=i486. Many toolchains
 # use i686 as default anyway, but for those that don't, an explicit
--
1.8.2.1

Attachment: 0001-configure-Disable-libtool-if-fPIE-does-not-work-with.patch
Description: Text Data

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