diff options
| -rw-r--r-- | ChangeLog | 9 | ||||
| -rw-r--r-- | INSTALL | 9 | ||||
| -rw-r--r-- | NEWS | 9 | ||||
| -rw-r--r-- | config.h.in | 3 | ||||
| -rwxr-xr-x | configure | 42 | ||||
| -rw-r--r-- | configure.ac | 33 | ||||
| -rw-r--r-- | manual/install.texi | 8 |
7 files changed, 113 insertions, 0 deletions
@@ -1,3 +1,12 @@ +2016-10-07 Stefan Liebler <stli@linux.vnet.ibm.com> + + * config.h.in (HAVE_GCC_IFUNC): New undef. + * configure.ac: Add check if gcc supports attribute ifunc feature. + * configure: Regenerated. + * manual/install.texi: Add recommendation for gcc with + indirect-function support. + * INSTALL: Regenerated. + 2016-10-06 Joseph Myers <joseph@codesourcery.com> * math/math.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (iseqsig): New @@ -359,6 +359,15 @@ build the GNU C Library: better code. As of release time, GCC 5.3 is the newest compiler verified to work to build the GNU C Library. + For multi-arch support it is recommended to use a GCC which has + been built with support for GNU indirect functions. This ensures + that correct debugging information is generated for functions + selected by IFUNC resolvers. This support can either be enabled by + configuring GCC with '--enable-gnu-indirect-function', or by + enabling it by default by setting 'default_gnu_indirect_function' + variable for a particular architecture in the GCC source file + 'gcc/config.gcc'. + You can use whatever compiler you like to compile programs that use the GNU C Library. @@ -76,6 +76,15 @@ Version 2.25 The glibc stub resolver did not support these hooks, but the header file did not reflect that. +* For multi-arch support it is recommended to use a GCC which has + been built with support for GNU indirect functions. This ensures + that correct debugging information is generated for functions + selected by IFUNC resolvers. This support can either be enabled by + configuring GCC with '--enable-gnu-indirect-function', or by + enabling it by default by setting 'default_gnu_indirect_function' + variable for a particular architecture in the GCC source file + 'gcc/config.gcc'. + Security related changes: On ARM EABI (32-bit), generating a backtrace for execution contexts which diff --git a/config.h.in b/config.h.in index 8cd08b0e89..33757bd553 100644 --- a/config.h.in +++ b/config.h.in @@ -174,6 +174,9 @@ /* Define to 1 if STT_GNU_IFUNC support actually works. */ #define HAVE_IFUNC 0 +/* Define if gcc supports attribute ifunc. */ +#undef HAVE_GCC_IFUNC + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START @@ -3916,6 +3916,36 @@ fi { $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ld_gnu_indirect_function" >&5 $as_echo "$libc_cv_ld_gnu_indirect_function" >&6; } +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute ifunc support" >&5 +$as_echo_n "checking for gcc attribute ifunc support... " >&6; } +if ${libc_cv_gcc_indirect_function+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +extern int func (int); +int used_func (int a) +{ + return a; +} +static void *resolver () +{ + return &used_func; +} +extern __typeof (func) func __attribute__ ((ifunc ("resolver"))); +EOF +libc_cv_gcc_indirect_function=no +if ${CC-cc} -c conftest.c -o conftest.o 1>&5 \ + 2>&5 ; then + if $READELF -s conftest.o | grep IFUNC >/dev/null 2>&5; then + libc_cv_gcc_indirect_function=yes + fi +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_indirect_function" >&5 +$as_echo "$libc_cv_gcc_indirect_function" >&6; } + if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then if test x"$multi_arch" = xyes; then as_fn_error $? "--enable-multi-arch support requires assembler and linker support" "$LINENO" 5 @@ -3923,6 +3953,13 @@ if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then multi_arch=no fi fi +if test x"$libc_cv_gcc_indirect_function" != xyes && + test x"$multi_arch" = xyes; then + { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: --enable-multi-arch support recommends a gcc with gnu-indirect-function support. +Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function" >&5 +$as_echo "$as_me: WARNING: --enable-multi-arch support recommends a gcc with gnu-indirect-function support. +Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function" >&2;} +fi multi_arch_d= if test x"$multi_arch" != xno; then multi_arch_d=/multiarch @@ -6518,6 +6555,11 @@ if test x"$libc_cv_ld_gnu_indirect_function" = xyes; then fi +if test x"$libc_cv_gcc_indirect_function" = xyes; then + $as_echo "#define HAVE_GCC_IFUNC 1" >>confdefs.h + +fi + # This is far from the AC_ARG_ENABLE that sets it so that a sysdeps # configure fragment can override the value to prevent this AC_DEFINE. diff --git a/configure.ac b/configure.ac index 9938ab0dc2..a64aeb9979 100644 --- a/configure.ac +++ b/configure.ac @@ -634,6 +634,30 @@ if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS \ fi rm -f conftest*]) +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +AC_CACHE_CHECK([for gcc attribute ifunc support], + libc_cv_gcc_indirect_function, [dnl +cat > conftest.c <<EOF +extern int func (int); +int used_func (int a) +{ + return a; +} +static void *resolver () +{ + return &used_func; +} +extern __typeof (func) func __attribute__ ((ifunc ("resolver"))); +EOF +libc_cv_gcc_indirect_function=no +if ${CC-cc} -c conftest.c -o conftest.o 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + if $READELF -s conftest.o | grep IFUNC >/dev/null 2>&AS_MESSAGE_LOG_FD; then + libc_cv_gcc_indirect_function=yes + fi +fi +rm -f conftest*]) + if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then if test x"$multi_arch" = xyes; then AC_MSG_ERROR([--enable-multi-arch support requires assembler and linker support]) @@ -641,6 +665,11 @@ if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then multi_arch=no fi fi +if test x"$libc_cv_gcc_indirect_function" != xyes && + test x"$multi_arch" = xyes; then + AC_MSG_WARN([--enable-multi-arch support recommends a gcc with gnu-indirect-function support. +Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function]) +fi multi_arch_d= if test x"$multi_arch" != xno; then multi_arch_d=/multiarch @@ -1782,6 +1811,10 @@ if test x"$libc_cv_ld_gnu_indirect_function" = xyes; then AC_DEFINE(HAVE_IFUNC) fi +if test x"$libc_cv_gcc_indirect_function" = xyes; then + AC_DEFINE(HAVE_GCC_IFUNC) +fi + # This is far from the AC_ARG_ENABLE that sets it so that a sysdeps # configure fragment can override the value to prevent this AC_DEFINE. AC_SUBST(use_nscd) diff --git a/manual/install.texi b/manual/install.texi index 663f8d59fb..de1c2030d3 100644 --- a/manual/install.texi +++ b/manual/install.texi @@ -402,6 +402,14 @@ the newest version of the compiler that is known to work for building release time, GCC 5.3 is the newest compiler verified to work to build @theglibc{}. +For multi-arch support it is recommended to use a GCC which has been built with +support for GNU indirect functions. This ensures that correct debugging +information is generated for functions selected by IFUNC resolvers. This +support can either be enabled by configuring GCC with +@samp{--enable-gnu-indirect-function}, or by enabling it by default by setting +@samp{default_gnu_indirect_function} variable for a particular architecture in +the GCC source file @file{gcc/config.gcc}. + You can use whatever compiler you like to compile programs that use @theglibc{}. |