configure: Replace -Wl,-r,-d with -Wl,-r and add -fno-common

In GNU ld and ld.lld, -d is used with -r to allocate space to COMMON symbols.
This behavior is presumably to work around legacy projects which inspect
relocatable output by themselves and do not handle COMMON symbols. The GRUB
does not do this.

See llvm/llvm-project#53660
-d is quite useless and ld.lld 15.0.0 will make -d no-op.

COMMON symbols have special symbol resolution semantics which can cause surprise
(see https://maskray.me/blog/2022-02-06-all-about-common-symbols). GCC<10 and
Clang<11 defaulted to -fcommon. Just use -fno-common to avoid COMMON symbols.

Signed-off-by: Fangrui Song <[email protected]>
Reviewed-by: Daniel Kiper <[email protected]>

Author: MaskRay

acinclude.m4

@@ -430,7 +430,7 @@ link_nopie_needed=no]
 AC_MSG_CHECKING([whether linker needs disabling of PIE to work])
 AC_LANG_CONFTEST([AC_LANG_SOURCE([[]])])
 
-[if eval "$ac_compile -Wl,-r,-d -nostdlib -Werror -o conftest.o" 2> /dev/null; then]
+[if eval "$ac_compile -Wl,-r -nostdlib -Werror -o conftest.o" 2> /dev/null; then]
   AC_MSG_RESULT([no])
   [# Should we clear up other files as well, having called `AC_LANG_CONFTEST'?
   rm -f conftest.o

conf/Makefile.common

@@ -41,7 +41,7 @@ CCASFLAGS_KERNEL = $(CCASFLAGS_CPU) $(CCASFLAGS_PLATFORM)
 STRIPFLAGS_KERNEL = -R .rel.dyn -R .reginfo -R .note -R .comment -R .drectve -R .note.gnu.gold-version -R .MIPS.abiflags -R .ARM.exidx
 
 CFLAGS_MODULE = $(CFLAGS_PLATFORM) -ffreestanding
-LDFLAGS_MODULE = $(LDFLAGS_PLATFORM) -nostdlib $(TARGET_LDFLAGS_OLDMAGIC) -Wl,-r,-d
+LDFLAGS_MODULE = $(LDFLAGS_PLATFORM) -nostdlib $(TARGET_LDFLAGS_OLDMAGIC) -Wl,-r
 CPPFLAGS_MODULE = $(CPPFLAGS_CPU) $(CPPFLAGS_PLATFORM)
 CCASFLAGS_MODULE = $(CCASFLAGS_CPU) $(CCASFLAGS_PLATFORM)
 

configure.ac

@@ -85,9 +85,9 @@ fi
 
 # Enable support for "restrict" keyword and other
 # features from gnu99 C language standard.
-BUILD_CFLAGS="-std=gnu99 $BUILD_CFLAGS"
-HOST_CFLAGS="-std=gnu99 $HOST_CFLAGS"
-TARGET_CFLAGS="-std=gnu99 $TARGET_CFLAGS"
+BUILD_CFLAGS="-std=gnu99 -fno-common $BUILD_CFLAGS"
+HOST_CFLAGS="-std=gnu99 -fno-common $HOST_CFLAGS"
+TARGET_CFLAGS="-std=gnu99 -fno-common $TARGET_CFLAGS"
 
 # Default HOST_CPPFLAGS
 HOST_CPPFLAGS="$HOST_CPPFLAGS -Wall -W"

grub-core/Makefile.core.def

@@ -49,26 +49,26 @@ kernel = {
 
   nostrip = emu;
 
-  emu_ldflags              = '-Wl,-r,-d';
-  i386_efi_ldflags         = '-Wl,-r,-d';
+  emu_ldflags              = '-Wl,-r';
+  i386_efi_ldflags         = '-Wl,-r';
   i386_efi_stripflags      = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
-  x86_64_efi_ldflags       = '-Wl,-r,-d';
+  x86_64_efi_ldflags       = '-Wl,-r';
   x86_64_efi_stripflags    = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
 
   ia64_efi_cflags = '-fno-builtin -fpic -minline-int-divide-max-throughput';
-  ia64_efi_ldflags = '-Wl,-r,-d';
+  ia64_efi_ldflags = '-Wl,-r';
   ia64_efi_stripflags = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
 
-  arm_efi_ldflags          = '-Wl,-r,-d';
+  arm_efi_ldflags          = '-Wl,-r';
   arm_efi_stripflags       = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
 
-  arm64_efi_ldflags          = '-Wl,-r,-d';
+  arm64_efi_ldflags          = '-Wl,-r';
   arm64_efi_stripflags       = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version -R .eh_frame';
 
-  riscv32_efi_ldflags      = '-Wl,-r,-d';
+  riscv32_efi_ldflags      = '-Wl,-r';
   riscv32_efi_stripflags   = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version -R .eh_frame';
 
-  riscv64_efi_ldflags      = '-Wl,-r,-d';
+  riscv64_efi_ldflags      = '-Wl,-r';
   riscv64_efi_stripflags   = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version -R .eh_frame';
 
   i386_pc_ldflags          = '$(TARGET_IMG_LDFLAGS)';
@@ -98,9 +98,9 @@ kernel = {
   i386_qemu_cppflags     = '-DGRUB_BOOT_MACHINE_LINK_ADDR=$(GRUB_BOOT_MACHINE_LINK_ADDR)';
   emu_cflags = '$(CFLAGS_GNULIB)';
   emu_cppflags = '$(CPPFLAGS_GNULIB)';
-  arm_uboot_ldflags       = '-Wl,-r,-d';
+  arm_uboot_ldflags       = '-Wl,-r';
   arm_uboot_stripflags    = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
-  arm_coreboot_ldflags       = '-Wl,-r,-d';
+  arm_coreboot_ldflags       = '-Wl,-r';
   arm_coreboot_stripflags    = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version';
 
   i386_pc_startup = kern/i386/pc/startup.S;

grub-core/genmod.sh.in

@@ -83,9 +83,9 @@ else
     for dep in $deps; do echo "char moddep_$dep[] __attribute__ ((section(\"_moddeps, _moddeps\"))) = \"$dep\";" >>$t2; done
 
     if test -n "$deps"; then
-	@TARGET_CC@ @TARGET_LDFLAGS@ -ffreestanding -nostdlib -o $tmpfile2 $t1 $t2 $tmpfile -Wl,-r,-d
+	@TARGET_CC@ @TARGET_LDFLAGS@ -ffreestanding -nostdlib -o $tmpfile2 $t1 $t2 $tmpfile -Wl,-r
     else
-	@TARGET_CC@ @TARGET_LDFLAGS@ -ffreestanding -nostdlib -o $tmpfile2 $t1 $tmpfile -Wl,-r,-d
+	@TARGET_CC@ @TARGET_LDFLAGS@ -ffreestanding -nostdlib -o $tmpfile2 $t1 $tmpfile -Wl,-r
     fi
     rm -f $t1 $t2 $tmpfile
     mv $tmpfile2 $tmpfile