x86: fix race to build arch/x86/efi/relocs-dummy.o

With $(TARGET).efi depending on efi/relocs-dummy.o, arch/x86/Makefile
will attempt to build that object. This may result in a dependency file
being generated that has relocs-dummy.o depending on efi/relocs-dummy.S.

Then, when arch/x86/efi/Makefile tries to build relocs-dummy.o, well
efi/relocs-dummy.S doesn't exist.

Have only one makefile responsible for building relocs-dummy.o.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
x86/Makefile: remove $(guard) use from $(TARGET).efi target

Following the patch 65d104984c04 ("x86: fix race to build
arch/x86/efi/relocs-dummy.o"), the error message
  nm: 'efi/relocs-dummy.o': No such file"
started to appear on system which can't build the .efi target. This is
because relocs-dummy.o isn't built anymore.
The error is printed by the evaluation of VIRT_BASE and ALT_BASE which
aren't use anyway.

But, we don't need that file as we don't want to build `$(TARGET).efi'
anyway.  On such system, $(guard) evaluate to the shell builtin ':',
which prevent any of the shell commands in `$(TARGET).efi' from been
executed.

Even if $(guard) is evaluated opon use, it depends on $(XEN_BUILD_PE)
which is evaluated at the assignment. So, we can replace $(guard) in
$(TARGET).efi by having two different rules depending on
$(XEN_BUILD_PE) instead.

The change with this patch is that none of the dependency of
$(TARGET).efi will be built if the linker doesn't support PE
and VIRT_BASE and ALT_BASE don't get evaluated anymore, so nm will not
complain about the missing relocs-dummy.o file anymore.

Since prelink-efi.o isn't built on system that can't build
$(TARGET).efi anymore, we can remove the $(guard) variable everywhere.

Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 65d104984c04e69234f77bd3b8f8c0ef85b3f7fa
master date: 2019-11-15 14:18:16 +0100
master commit: 7059afb202ff0d82a6fa94f7ef84e4bb3139914e
master date: 2019-11-20 17:12:12 +0100

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 4c82d9f71052882e3ac699268657d40f9156a673..ec02972f2b6a209985f7c7e85d606d134702af01 100644 (file)
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -111,20 +111,20 @@ prelink_lto.o: $(ALL_OBJS)
        $(LD_LTO) -r -o $@ $^
 
 prelink-efi_lto.o: $(ALL_OBJS) efi/runtime.o efi/compat.o
-       $(guard) $(LD_LTO) -r -o $@ $(filter-out %/efi/built_in.o,$^)
+       $(LD_LTO) -r -o $@ $(filter-out %/efi/built_in.o,$^)
 
 # Link it with all the binary objects
 prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o
        $(LD) $(LDFLAGS) -r -o $@ $^
 
 prelink-efi.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink-efi_lto.o efi/boot.init.o
-       $(guard) $(LD) $(LDFLAGS) -r -o $@ $^
+       $(LD) $(LDFLAGS) -r -o $@ $^
 else
 prelink.o: $(ALL_OBJS)
        $(LD) $(LDFLAGS) -r -o $@ $^
 
 prelink-efi.o: $(ALL_OBJS) efi/boot.init.o efi/runtime.o efi/compat.o
-       $(guard) $(LD) $(LDFLAGS) -r -o $@ $(filter-out %/efi/built_in.o,$^)
+       $(LD) $(LDFLAGS) -r -o $@ $(filter-out %/efi/built_in.o,$^)
 endif
 
 $(BASEDIR)/common/symbols-dummy.o:
@@ -172,8 +172,6 @@ CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
 
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')
 $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A ALT_START$$,,p')
-# Don't use $(wildcard ...) here - at least make 3.80 expands this too early!
-$(TARGET).efi: guard = $(if $(filter y,$(XEN_BUILD_PE)),,:)
 
 ifneq ($(build_id_linker),)
 ifeq ($(call ld-ver-build-id,$(LD) $(filter -m%,$(EFI_LDFLAGS))),y)
@@ -191,30 +189,34 @@ note_file :=
 endif
 note_file_option ?= $(note_file)
 
+ifeq ($(filter y,$(XEN_BUILD_PE)),y)
 $(TARGET).efi: prelink-efi.o $(note_file) efi.lds efi/relocs-dummy.o $(BASEDIR)/common/symbols-dummy.o efi/mkreloc
        $(foreach base, $(VIRT_BASE) $(ALT_BASE), \
-                 $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< efi/relocs-dummy.o \
+                 $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< efi/relocs-dummy.o \
                        $(BASEDIR)/common/symbols-dummy.o $(note_file_option) -o $(@D)/.$(@F).$(base).0 &&) :
-       $(guard) efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).0) >$(@D)/.$(@F).0r.S
-       $(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).0 \
-               | $(guard) $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).0s.S
-       $(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o
+       efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).0) >$(@D)/.$(@F).0r.S
+       $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).0 \
+               | $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).0s.S
+       $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o
        $(foreach base, $(VIRT_BASE) $(ALT_BASE), \
-                 $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< \
+                 $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< \
                        $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o $(note_file_option) -o $(@D)/.$(@F).$(base).1 &&) :
-       $(guard) efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).1) >$(@D)/.$(@F).1r.S
-       $(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).1 \
-               | $(guard) $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).1s.S
-       $(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o
-       $(guard) $(LD) $(call EFI_LDFLAGS,$(VIRT_BASE)) -T efi.lds -N $< \
+       efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).1) >$(@D)/.$(@F).1r.S
+       $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).1 \
+               | $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).1s.S
+       $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o
+       $(LD) $(call EFI_LDFLAGS,$(VIRT_BASE)) -T efi.lds -N $< \
                        $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o $(note_file_option) -o $@
-       if $(guard) false; then rm -f $@; echo 'EFI support disabled'; \
-       else $(NM) -pa --format=sysv $(@D)/$(@F) \
-               | $(BASEDIR)/tools/symbols --xensyms --sysv --sort >$(@D)/$(@F).map; fi
+       $(NM) -pa --format=sysv $(@D)/$(@F) \
+               | $(BASEDIR)/tools/symbols --xensyms --sysv --sort >$(@D)/$(@F).map
        rm -f $(@D)/.$(@F).[0-9]* $(@D)/..$(@F).[0-9]*
+else
+$(TARGET).efi: FORCE
+       rm -f $@; echo 'EFI support disabled'
+endif
 
-efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o: $(BASEDIR)/arch/x86/efi/built_in.o
-efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o: ;
+efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
+efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o efi/relocs-dummy.o: ;
 
 asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c
        $(CC) $(filter-out -Wa$(comma)% -flto,$(CFLAGS)) -S -o $@ $<