mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
9e1751e6d6
Return address signing requires unwinder support, which is present in libgcc since >=gcc-7, however due to bugs the support may be broken in <gcc-10 (and similarly there may be issues in custom unwinders), so pac-ret is not always safe to use. So in assembly code glibc should only use pac-ret if the compiler uses it too. Unfortunately there is no predefined feature macro for it set by the compiler so pac-ret is inferred from the code generation. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
64 lines
2.4 KiB
Plaintext
64 lines
2.4 KiB
Plaintext
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
|
|
# Local configure fragment for sysdeps/aarch64.
|
|
|
|
# We check to see if the compiler and flags are
|
|
# selecting the big endian ABI and if they are then
|
|
# we set libc_cv_aarch64_be to yes which causes
|
|
# HAVE_AARCH64_BE to be defined in config.h and
|
|
# in include/libc-symbols.h and thus available to
|
|
# shlib-versions to select the appropriate name for
|
|
# the dynamic linker via %ifdef.
|
|
AC_CACHE_CHECK([for big endian],
|
|
[libc_cv_aarch64_be],
|
|
[AC_EGREP_CPP(yes,[#ifdef __AARCH64EB__
|
|
yes
|
|
#endif
|
|
], libc_cv_aarch64_be=yes, libc_cv_aarch64_be=no)])
|
|
if test $libc_cv_aarch64_be = yes; then
|
|
AC_DEFINE(HAVE_AARCH64_BE)
|
|
LIBC_CONFIG_VAR([default-abi], [lp64_be])
|
|
else
|
|
LIBC_CONFIG_VAR([default-abi], [lp64])
|
|
fi
|
|
|
|
# Only consider BTI supported if -mbranch-protection=bti is
|
|
# on by default in the compiler and the linker produces
|
|
# binaries with GNU property notes in PT_GNU_PROPERTY segment.
|
|
AC_CACHE_CHECK([for BTI support], [libc_cv_aarch64_bti], [dnl
|
|
cat > conftest.c <<EOF
|
|
void foo (void) { }
|
|
EOF
|
|
libc_cv_aarch64_bti=no
|
|
if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles $no_ssp -shared -fPIC -o conftest.so conftest.c]) \
|
|
&& AC_TRY_COMMAND([$READELF -lW conftest.so | grep -q GNU_PROPERTY]) \
|
|
&& AC_TRY_COMMAND([$READELF -nW conftest.so | grep -q "NT_GNU_PROPERTY_TYPE_0.*AArch64 feature:.* BTI"])
|
|
then
|
|
libc_cv_aarch64_bti=yes
|
|
fi
|
|
rm -rf conftest.*])
|
|
LIBC_CONFIG_VAR([aarch64-bti], [$libc_cv_aarch64_bti])
|
|
if test $libc_cv_aarch64_bti = yes; then
|
|
AC_DEFINE(HAVE_AARCH64_BTI)
|
|
fi
|
|
|
|
# Check if glibc is built with return address signing, i.e.
|
|
# if -mbranch-protection=pac-ret is on. We need this because
|
|
# pac-ret relies on unwinder support so it's not safe to use
|
|
# it in assembly code unconditionally, but there is no
|
|
# feature test macro for it in gcc.
|
|
AC_CACHE_CHECK([if pac-ret is enabled], [libc_cv_aarch64_pac_ret], [dnl
|
|
cat > conftest.c <<EOF
|
|
int bar (void);
|
|
int foo (void) { return bar () + 1; }
|
|
EOF
|
|
libc_cv_aarch64_pac_ret=no
|
|
if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -o conftest.s conftest.c]) \
|
|
&& AC_TRY_COMMAND([grep -q -E '\''(hint( | )+25|paciasp)'\'' conftest.s])
|
|
then
|
|
libc_cv_aarch64_pac_ret=yes
|
|
fi
|
|
rm -rf conftest.*])
|
|
if test $libc_cv_aarch64_pac_ret = yes; then
|
|
AC_DEFINE(HAVE_AARCH64_PAC_RET)
|
|
fi
|