From af9b9379fdad760589acddb186620dcc7d994e8e Mon Sep 17 00:00:00 2001
From: Simo Sorce <simo@redhat.com>
Date: Wed, 24 Apr 2019 16:13:59 -0400
Subject: [PATCH 2/4] Fix generation of build notes if supported

This is needed to build correctly on platfroms that use
hardening flags and build notes on .c files.

Signed-off-by: Simo Sorce <simo@redhat.com>
---
 Makefile.in  |  4 +++-
 configure.ac | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Makefile.in b/Makefile.in
index 440de9f7..4e603047 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -17,6 +17,8 @@ OPT_HOGWEED_OBJS = @OPT_HOGWEED_OBJS@
 
 OPT_NETTLE_SOURCES = @OPT_NETTLE_SOURCES@
 
+ASM_GEN_BUILD_NOTES = @ASM_GEN_BUILD_NOTES@
+
 SUBDIRS = tools testsuite examples
 
 include config.make
@@ -396,7 +398,7 @@ ecc-25519.$(OBJEXT): ecc-25519.h
 
 .asm.$(OBJEXT): $(srcdir)/asm.m4 machine.m4 config.m4
 	$(M4) $(srcdir)/asm.m4 machine.m4 config.m4 $< >$*.s
-	$(COMPILE) -c $*.s
+	$(COMPILE) -c $*.s $(ASM_GEN_BUILD_NOTES)
 	@echo "$@ : $< $(srcdir)/asm.m4 machine.m4 config.m4" >$@.d 
 
 # Texinfo rules
diff --git a/configure.ac b/configure.ac
index 00d2bf5d..ac921df0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -702,6 +702,7 @@ ASM_TYPE_FUNCTION='@function'
 ASM_TYPE_PROGBITS='@progbits'
 ASM_MARK_NOEXEC_STACK=''
 ASM_ALIGN_LOG=''
+ASM_GEN_BUILD_NOTES=''
 
 if test x$enable_assembler = xyes ; then
   AC_CACHE_CHECK([if globals are prefixed by underscore],
@@ -812,6 +813,26 @@ EOF
        [nettle_cv_asm_align_log=yes],
        [nettle_cv_asm_align_log=no])])
   ASM_ALIGN_LOG="$nettle_cv_asm_align_log"
+
+  AC_CACHE_CHECK([if --generate-missing-build-notes is supported],
+    nettle_cv_asm_build_notes,
+    [ # Default
+      nettle_cv_asm_build_notes=no
+
+      cat >conftest.s << EOF
+.text
+EOF
+      FLAG="-Wa,--generate-missing-build-notes=yes"
+      nettle_assemble="$CC $CFLAGS $CPPFLAGS -c conftest.s $FLAG >conftest.out 2>&1"
+      if AC_TRY_EVAL(nettle_assemble); then
+        nettle_cv_asm_build_notes=yes
+      else
+       nettle_cv_asm_build_notes=no
+      fi
+    rm -f conftest.*])
+  if test x$nettle_cv_asm_build_notes = xyes ; then
+    ASM_GEN_BUILD_NOTES='-Wa,--generate-missing-build-notes=yes'
+  fi
 fi
 
 AC_SUBST(ASM_SYMBOL_PREFIX)
@@ -823,6 +844,7 @@ AC_SUBST(ASM_MARK_NOEXEC_STACK)
 AC_SUBST(ASM_ALIGN_LOG)
 AC_SUBST(W64_ABI)
 AC_SUBST(ASM_WORDS_BIGENDIAN)
+AC_SUBST(ASM_GEN_BUILD_NOTES)
 AC_SUBST(EMULATOR)
 
 AC_SUBST(LIBNETTLE_MAJOR)
-- 
2.20.1