Patchwork efi/libstub: refactor cmd_stubcopy

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Submitter Masahiro Yamada
Date Feb. 12, 2019, 3:44 a.m.
Message ID <1549943095-10956-1-git-send-email-yamada.masahiro@socionext.com>
Download mbox | patch
Permalink /patch/723497/
State New
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Comments

Masahiro Yamada - Feb. 12, 2019, 3:44 a.m.
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>
---

 drivers/firmware/efi/libstub/Makefile | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
Ard Biesheuvel - Feb. 12, 2019, 7:23 a.m.
On Tue, 12 Feb 2019 at 04:45, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> 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>

Assuming that it still works as expected:

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

You can test this by adding a statically initialized global function
pointer to any of the libstub source files that get built for ARM.

Thanks!

> ---
>
>  drivers/firmware/efi/libstub/Makefile | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index d984509..7788e8a 100644
> --- 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
> --
> 2.7.4
>

Patch

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d984509..7788e8a 100644
--- 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