efi/libstub: Refactor the cmd_stubcopy Makefile command

It took me a while to understand what is going on in the nested
if-blocks.

Simplify it by removing unneeded code.

  - if_changed automatically adds 'set -e', so any failure in the
    series of commands makes it immediately fail as a whole.
    So, the outer if block is entirely redundant.

  - Since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"),
    GNU Make automatically deletes the target on any failure
    in its recipe. The explicit 'rm -f $@' is redundant.

  - Surrounding commands with ( ) will spawn a subshell to execute them
    in it, but it is rarely useful to do so.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190328193429.21373-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index b0103e1..ae90819 100644 (file)
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -86,12 +86,13 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
 # this time, use objcopy and leave all sections in place.
 #
 quiet_cmd_stubcopy = STUBCPY $@
-      cmd_stubcopy = if $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<; \
-                    then if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); \
-                    then (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \
-                          rm -f $@; /bin/false);                         \
-                    else $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; fi        \
-                    else /bin/false; fi
+      cmd_stubcopy =                                                   \
+       $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<;               \
+       if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then            \
+               echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
+               /bin/false;                                             \
+       fi;                                                             \
+       $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@
 
 #
 # ARM discards the .data section because it disallows r/w data in the