x86: Set minimum x86-64 level marker [BZ #27318]

Since the full ISA set used in an ELF binary is unknown to compiler,
an x86-64 ISA level marker indicates the minimum, not maximum, ISA set
required to run such an ELF binary.  We never guarantee a library with
an x86-64 ISA level v3 marker doesn't contain other ISAs beyond x86-64
ISA level v3, like AVX VNNI.  We check the x86-64 ISA level marker for
the minimum ISA set.  Since -march=sandybridge enables only some ISAs
in x86-64 ISA level v3, we should set the needed ISA marker to v2.
Otherwise, libc is compiled with -march=sandybridge will fail to run on
Sandy Bridge:

$ ./elf/ld.so ./libc.so
./libc.so: (p) CPU ISA level is lower than required: needed: 7; got: 3

Set the minimum, instead of maximum, x86-64 ISA level marker should have
no impact on the glibc-hwcaps directory assignment logic in ldconfig nor
ld.so.
This commit is contained in:
H.J. Lu 2021-02-02 13:45:58 -08:00
parent 3c66792667
commit 339bf918ea
4 changed files with 64 additions and 11 deletions

View File

@ -275,4 +275,10 @@
/* Define if x86 ISA level should be included in shared libraries. */
#undef INCLUDE_X86_ISA_LEVEL
/* Define if -msahf is enabled by default on x86. */
#undef HAVE_X86_LAHF_SAHF
/* Define if -mmovbe is enabled by default on x86. */
#undef HAVE_X86_MOVBE
#endif

28
sysdeps/x86/configure vendored
View File

@ -126,6 +126,8 @@ cat > conftest2.S <<EOF
4:
EOF
libc_cv_include_x86_isa_level=no
libc_cv_have_x86_lahf_sahf=no
libc_cv_have_x86_movbe=no
if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest conftest1.S conftest2.S'
{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
(eval $ac_try) 2>&5
@ -135,6 +137,24 @@ if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest c
count=`LC_ALL=C $READELF -n conftest | grep NT_GNU_PROPERTY_TYPE_0 | wc -l`
if test "$count" = 1; then
libc_cv_include_x86_isa_level=yes
cat > conftest.c <<EOF
EOF
if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c'
{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
test $ac_status = 0; }; } | grep -q "\-msahf"; then
libc_cv_have_x86_lahf_sahf=yes
fi
if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c'
{ { eval echo "\"\$as_me\":${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; }; } | grep -q "\-mmovbe"; then
libc_cv_have_x86_movbe=yes
fi
fi
fi
rm -f conftest*
@ -144,6 +164,14 @@ $as_echo "$libc_cv_include_x86_isa_level" >&6; }
if test $libc_cv_include_x86_isa_level = yes; then
$as_echo "#define INCLUDE_X86_ISA_LEVEL 1" >>confdefs.h
fi
if test $libc_cv_have_x86_lahf_sahf = yes; then
$as_echo "#define HAVE_X86_LAHF_SAHF 1" >>confdefs.h
fi
if test $libc_cv_have_x86_movbe = yes; then
$as_echo "#define HAVE_X86_MOVBE 1" >>confdefs.h
fi
config_vars="$config_vars
enable-x86-isa-level = $libc_cv_include_x86_isa_level"

View File

@ -98,14 +98,30 @@ cat > conftest2.S <<EOF
4:
EOF
libc_cv_include_x86_isa_level=no
libc_cv_have_x86_lahf_sahf=no
libc_cv_have_x86_movbe=no
if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest conftest1.S conftest2.S); then
count=`LC_ALL=C $READELF -n conftest | grep NT_GNU_PROPERTY_TYPE_0 | wc -l`
if test "$count" = 1; then
libc_cv_include_x86_isa_level=yes
cat > conftest.c <<EOF
EOF
if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c) | grep -q "\-msahf"; then
libc_cv_have_x86_lahf_sahf=yes
fi
if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c) | grep -q "\-mmovbe"; then
libc_cv_have_x86_movbe=yes
fi
fi
fi
rm -f conftest*])
if test $libc_cv_include_x86_isa_level = yes; then
AC_DEFINE(INCLUDE_X86_ISA_LEVEL)
fi
if test $libc_cv_have_x86_lahf_sahf = yes; then
AC_DEFINE(HAVE_X86_LAHF_SAHF)
fi
if test $libc_cv_have_x86_movbe = yes; then
AC_DEFINE(HAVE_X86_MOVBE)
fi
LIBC_CONFIG_VAR([enable-x86-isa-level], [$libc_cv_include_x86_isa_level])

View File

@ -29,32 +29,35 @@
/* ELF program property for x86 ISA level. */
#ifdef INCLUDE_X86_ISA_LEVEL
# if defined __x86_64__ || defined __FXSR__ || !defined _SOFT_FLOAT \
|| defined __MMX__ || defined __SSE__ || defined __SSE2__
# if defined __SSE__ && defined __SSE2__
/* NB: ISAs, excluding MMX, in x86-64 ISA level baseline are used. */
# define ISA_BASELINE GNU_PROPERTY_X86_ISA_1_BASELINE
# else
# define ISA_BASELINE 0
# endif
# if defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 \
|| (defined __x86_64__ && defined __LAHF_SAHF__) \
|| defined __POPCNT__ || defined __SSE3__ \
|| defined __SSSE3__ || defined __SSE4_1__ || defined __SSE4_2__
# if ISA_BASELINE && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 \
&& defined HAVE_X86_LAHF_SAHF && defined __POPCNT__ \
&& defined __SSE3__ && defined __SSSE3__ && defined __SSE4_1__ \
&& defined __SSE4_2__
/* NB: ISAs in x86-64 ISA level v2 are used. */
# define ISA_V2 GNU_PROPERTY_X86_ISA_1_V2
# else
# define ISA_V2 0
# endif
# if defined __AVX__ || defined __AVX2__ || defined __F16C__ \
|| defined __FMA__ || defined __LZCNT__ || defined __MOVBE__ \
|| defined __XSAVE__
# if ISA_V2 && defined __AVX__ && defined __AVX2__ && defined __F16C__ \
&& defined __FMA__ && defined __LZCNT__ && defined HAVE_X86_MOVBE
/* NB: ISAs in x86-64 ISA level v3 are used. */
# define ISA_V3 GNU_PROPERTY_X86_ISA_1_V3
# else
# define ISA_V3 0
# endif
# if defined __AVX512F__ || defined __AVX512BW__ || defined __AVX512CD__ \
|| defined __AVX512DQ__ || defined __AVX512VL__
# if ISA_V3 && defined __AVX512F__ && defined __AVX512BW__ \
&& defined __AVX512CD__ && defined __AVX512DQ__ \
&& defined __AVX512VL__
/* NB: ISAs in x86-64 ISA level v4 are used. */
# define ISA_V4 GNU_PROPERTY_X86_ISA_1_V4
# else
# define ISA_V4 0