From 115c628cc44f89207858d0c79e970e43da75c772 Mon Sep 17 00:00:00 2001
From: Yingkun Meng <mengyingkun@loongson.cn>
Date: Tue, 5 Dec 2023 19:22:14 +0800
Subject: [PATCH] loongarch: Disable relaxation relocations

commit 87247635c0d583cfbc1947107d23b40877d107b8 upstream.

A working GRUB cannot be built with upcoming binutils and GCC, because linker
relaxation was added [1] causing new unsupported relocations to appear in modules.

So we pass -mno-relax to GCC if it is supported, to disable relaxation and make
GRUB forward-compatible with new toolchains.

While similar code already exists for sparc64 in configure.ac, sparc64 sets
LDFLAGS while LoongArch requires CFLAGS to be set. If we only set LDFLAGS on
LoongArch, GCC will still generate relaxation relocations in the .o files, so
the sparc64 code cannot be reused.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b

Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Signed-off-by: Yingkun Meng <mengyingkun@loongson.cn>
Change-Id: I09ef306dc8a0f8a59e9b7dbc53ae3fd3cc09ec55
---
 configure.ac | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/configure.ac b/configure.ac
index 0db9d7d111b8..e010bc0db465 100644
--- a/configure.ac
+++ b/configure.ac
@@ -908,6 +908,29 @@ if test "x$target_cpu" = xloongarch64; then
     TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt"
     TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs -fno-plt"
   fi
+
+  AC_CACHE_CHECK([for no-relax options], grub_cv_target_cc_mno_relax, [
+    grub_cv_target_cc_mno_relax=no
+    for cand in "-mno-relax" "-Wa,-mno-relax"; do
+      if test x"$grub_cv_target_cc_mno_relax" != xno ; then
+        break
+      fi
+      CFLAGS="$TARGET_CFLAGS $cand -Werror"
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+            asm (".globl start; start:");
+            void __main (void);
+            void __main (void) {}
+            int main (void);
+            ]], [[]])], [grub_cv_target_cc_mno_relax="$cand"], [])
+    done
+  ])
+  CFLAGS="$TARGET_CFLAGS"
+
+  if test x"$grub_cv_target_cc_mno_relax" != xno ; then
+    TARGET_CFLAGS="$TARGET_CFLAGS $grub_cv_target_cc_mno_relax"
+    TARGET_CCASFLAGS="$TARGET_CCASFLAGS $grub_cv_target_cc_mno_relax"
+  fi
+
   TARGET_CFLAGS="$TARGET_CFLAGS -Wa,-mla-global-with-abs"
   TARGET_CCASFLAGS="$TARGET_CCASFLAGS -Wa,-mla-global-with-abs"
 fi
-- 
2.33.0

