[PATCH 4.17 37/67] x86/purgatory: add missing FORCE to Makefile target

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Philipp Rudo <prudo@xxxxxxxxxxxxx>

commit fa8cbda88db12e632a8987c94b66f5caf25bcec4 upstream.

- Build the kernel without the fix
- Add some flag to the purgatories KBUILD_CFLAGS,I used
  -fno-asynchronous-unwind-tables
- Re-build the kernel

When you look at makes output you see that sha256.o is not re-build in the
last step.  Also readelf -S still shows the .eh_frame section for
sha256.o.

With the fix sha256.o is rebuilt in the last step.

Without FORCE make does not detect changes only made to the command line
options.  So object files might not be re-built even when they should be.
Fix this by adding FORCE where it is missing.

Link: http://lkml.kernel.org/r/20180704110044.29279-2-prudo@xxxxxxxxxxxxx
Fixes: df6f2801f511 ("kernel/kexec_file.c: move purgatories sha256 to common code")
Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxxxxx>
Acked-by: Dave Young <dyoung@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[4.17+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/purgatory/Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -6,7 +6,7 @@ purgatory-y := purgatory.o stack.o setup
 targets += $(purgatory-y)
 PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
 
-$(obj)/sha256.o: $(srctree)/lib/sha256.c
+$(obj)/sha256.o: $(srctree)/lib/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
 LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib