[PATCH 1/4] aarch64: add configure checks for BTI support

[Yury Khrustalev]

---
 configure    | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac | 17 +++++++++
 2 files changed, 115 insertions(+)

diff --git a/configure b/configure
index 85bfeec8a9..40696cbc3d 100755
--- a/configure
+++ b/configure
@@ -9180,6 +9180,104 @@ printf "%s\n" "$libc_linker_feature" >&6; }
 config_vars="$config_vars
 load-address-ldflag = $libc_cv_load_address_ldflag"
 
+# Check if compilers support BTI in branch protection:
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking if compiler supports -mbranch-protection=bti" >&5
+printf %s "checking if compiler supports -mbranch-protection=bti... " >&6; }
+if test ${libc_cv_cc_bti+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) if { ac_try='${CC-cc} -Werror -mbranch-protection=bti -xc /dev/null -S -o /dev/null'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then :
+  libc_cv_cc_bti=yes
+else case e in #(
+  e) libc_cv_cc_bti=no ;;
+esac
+fi ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_cc_bti" >&5
+printf "%s\n" "$libc_cv_cc_bti" >&6; }
+if test "$TEST_CC" = "$CC"; then
+  libc_cv_test_cc_bti=$libc_cv_cc_bti
+else
+
+saved_CC="$CC"
+CC="$TEST_CC"
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking if compiler supports -mbranch-protection=bti in testing" >&5
+printf %s "checking if compiler supports -mbranch-protection=bti in testing... " >&6; }
+if test ${libc_cv_test_cc_bti+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) if { ac_try='${CC-cc} -Werror -mbranch-protection=bti -xc /dev/null -S -o /dev/null'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then :
+  libc_cv_test_cc_bti=yes
+else case e in #(
+  e) libc_cv_test_cc_bti=no ;;
+esac
+fi ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_test_cc_bti" >&5
+printf "%s\n" "$libc_cv_test_cc_bti" >&6; }
+
+CC="$saved_CC"
+
+fi
+
+config_vars="$config_vars
+have-cc-bti = $libc_cv_cc_bti"
+config_vars="$config_vars
+have-test-cc-bti = $libc_cv_test_cc_bti"
+
+# Check if linker supports BTI marking
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z force-bti" >&5
+printf %s "checking for linker that supports -z force-bti... " >&6; }
+libc_linker_feature=no
+cat > conftest.c <<EOF
+int _start (void) { return 42; }
+EOF
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
+		  -Wl,-z,force-bti -nostdlib -nostartfiles
+		  -fPIC -shared -o conftest.so conftest.c
+		  1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,-z,force-bti -nostdlib \
+      -nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \
+      | grep "warning: -z force-bti ignored" > /dev/null 2>&1; then
+    true
+  else
+    libc_linker_feature=yes
+  fi
+fi
+rm -f conftest*
+if test $libc_linker_feature = yes; then
+  libc_cv_ld_bti=yes
+else
+  libc_cv_ld_bti=no
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
+printf "%s\n" "$libc_linker_feature" >&6; }
+config_vars="$config_vars
+have-ld-bti = $libc_cv_ld_bti"
+
 # Check if compilers support GCS in branch protection:
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking if compiler supports -mbranch-protection=gcs" >&5
diff --git a/configure.ac b/configure.ac
index 2cb49f49bc..5475798dcc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2068,6 +2068,23 @@ LIBC_LINKER_FEATURE([-Ttext-segment=$libc_cv_pde_load_address],
 		    [libc_cv_load_address_ldflag=])
 LIBC_CONFIG_VAR([load-address-ldflag], [$libc_cv_load_address_ldflag])
 
+# Check if compilers support BTI in branch protection:
+LIBC_TRY_CC_AND_TEST_CC_OPTION([if compiler supports -mbranch-protection=bti],
+  [-Werror -mbranch-protection=bti],
+  libc_cv_cc_bti,
+  [libc_cv_cc_bti=yes],
+  [libc_cv_cc_bti=no],
+  libc_cv_test_cc_bti,
+  [libc_cv_test_cc_bti=yes],
+  [libc_cv_test_cc_bti=no])
+LIBC_CONFIG_VAR([have-cc-bti], [$libc_cv_cc_bti])
+LIBC_CONFIG_VAR([have-test-cc-bti], [$libc_cv_test_cc_bti])
+
+# Check if linker supports BTI marking
+LIBC_LINKER_FEATURE([-z force-bti], [-Wl,-z,force-bti],
+		    [libc_cv_ld_bti=yes], [libc_cv_ld_bti=no])
+LIBC_CONFIG_VAR([have-ld-bti], [$libc_cv_ld_bti])
+
 # Check if compilers support GCS in branch protection:
 LIBC_TRY_CC_AND_TEST_CC_OPTION([if compiler supports -mbranch-protection=gcs],
   [-Werror -mbranch-protection=gcs],
-- 
2.47.3