[PATCH] xfsprogs: remove retpoline support

[Eric Sandeen <sandeen@redhat.com>]

When it came up that xfsprogs was using retpolines by default,
the gcc folks inside Red Hat expressed ... alarm.  I'm not sure
of all the details, but I think the concern was that userspace
support for this is not really quite baked.

Unless/until there is a demonstrated side-channel which would
warrant retpolines here, let's just remove it for now.

Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

Getting this on the list so we can have a discussion with people who
understand the issues better than I do ...

diff --git a/configure.ac b/configure.ac
index 5fdf78e..41f1209 100644
--- a/configure.ac
+++ b/configure.ac
@@ -227,7 +227,6 @@ if test "$enable_lto" = "yes" && test "$have_lto" != "yes"; then
 	AC_MSG_ERROR([LTO not supported by compiler.])
 fi
 
-AC_PACKAGE_CHECK_RETPOLINE
 AC_CHECK_SIZEOF([long])
 AC_CHECK_SIZEOF([char *])
 AC_TYPE_UMODE_T
diff --git a/include/builddefs.in b/include/builddefs.in
index f7d39a4..fe529c6 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -166,13 +166,6 @@ LIBICU_CFLAGS = @libicu_CFLAGS@
 SANITIZER_CFLAGS += @addrsan_cflags@ @threadsan_cflags@ @ubsan_cflags@
 SANITIZER_LDFLAGS += @addrsan_ldflags@ @threadsan_ldflags@ @ubsan_ldflags@
 
-# Enable retpolines if available
-HAVE_RETPOLINE = @have_retpoline@
-ifeq ($(HAVE_RETPOLINE),yes)
-OPTIMIZER += @retpoline_cflags@
-LOADERFLAGS += @retpoline_ldflags@
-endif
-
 # Use special ar/ranlib wrappers if we have lto
 HAVE_LTO = @have_lto@
 ifeq ($(HAVE_LTO),yes)
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index 0a6b514..52ddac2 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -446,25 +446,3 @@ AC_DEFUN([AC_PACKAGE_CHECK_LTO],
     AC_SUBST(lto_cflags)
     AC_SUBST(lto_ldflags)
   ])
-
-AC_DEFUN([AC_PACKAGE_CHECK_RETPOLINE],
-  [ AC_MSG_CHECKING([if C compiler supports retpoline])
-    OLD_CFLAGS="$CFLAGS"
-    OLD_LDFLAGS="$LDFLAGS"
-    RETPOLINE_FLAGS="-mindirect-branch=thunk"
-    CFLAGS="$CFLAGS $RETPOLINE_FLAGS"
-    LDFLAGS="$LDFLAGS $RETPOLINE_FLAGS"
-    AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
-        [AC_MSG_RESULT([yes])]
-        [retpoline_cflags=$RETPOLINE_FLAGS]
-        [retpoline_ldflags=$RETPOLINE_FLAGS],
-        [AC_MSG_RESULT([no])])
-    if test -n "$retpoline_cflags"; then
-        have_retpoline=yes
-    fi
-    CFLAGS="${OLD_CFLAGS}"
-    LDFLAGS="${OLD_LDFLAGS}"
-    AC_SUBST(have_retpoline)
-    AC_SUBST(retpoline_cflags)
-    AC_SUBST(retpoline_ldflags)
-  ])