[PATCH] efi/libstub: refactor cmd_stubcopy

[PATCH] efi/libstub: refactor cmd_stubcopy

[Masahiro Yamada]

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(-)

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

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Ard Biesheuvel]

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
>

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Masahiro Yamada]

On Tue, Feb 12, 2019 at 4:26 PM Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
>
> 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!


I tried that, and it failed as expected.


$ git diff
diff --git a/drivers/firmware/efi/libstub/arm32-stub.c
b/drivers/firmware/efi/libstub/arm32-stub.c
index becbda4..5ad7bbd 100644
--- a/drivers/firmware/efi/libstub/arm32-stub.c
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -28,6 +28,8 @@ efi_status_t
check_platform_features(efi_system_table_t *sys_table_arg)
        return EFI_SUCCESS;
 }

+void * foo = (void *)check_platform_features;
+
 static efi_guid_t screen_info_guid = LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID;

 struct screen_info *alloc_screen_info(efi_system_table_t *sys_table_arg)
$ make ARCH=arm  CROSS_COMPILE=arm-linux-gnueabihf- defconfig
drivers/firmware/efi/libstub/
*** Default configuration is based on 'multi_v7_defconfig'
#
# configuration written to .config
#
scripts/kconfig/conf  --syncconfig Kconfig
  CALL    scripts/checksyscalls.sh
  CC      drivers/firmware/efi/libstub/arm32-stub.o
  STUBCPY drivers/firmware/efi/libstub/arm32-stub.stub.o
00000000 R_ARM_ABS32       check_platform_features
drivers/firmware/efi/libstub/arm32-stub.stub.o: absolute symbol
references not allowed in the EFI stub
drivers/firmware/efi/libstub/Makefile:80: recipe for target
'drivers/firmware/efi/libstub/arm32-stub.stub.o' failed
make[3]: *** [drivers/firmware/efi/libstub/arm32-stub.stub.o] Error 1
make[3]: *** Deleting file 'drivers/firmware/efi/libstub/arm32-stub.stub.o'
Makefile:1705: recipe for target 'drivers/firmware/efi/libstub/' failed
make[2]: *** [drivers/firmware/efi/libstub/] Error 2
/home/masahiro/workspace/bsp/linux/Makefile:300: recipe for target
'__build_one_by_one' failed
make[1]: *** [__build_one_by_one] Error 2
Makefile:160: recipe for target 'sub-make' failed
make: *** [sub-make] Error 2





-- 
Best Regards
Masahiro Yamada

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Ard Biesheuvel]

On Fri, 15 Feb 2019 at 06:49, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Tue, Feb 12, 2019 at 4:26 PM Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
> >
> > 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!
>
>
> I tried that, and it failed as expected.
>

Great, thanks for double checking.

Are you taking this directly, or do you want me to take it via the EFI
tree? Either is fine with me


>
> $ git diff
> diff --git a/drivers/firmware/efi/libstub/arm32-stub.c
> b/drivers/firmware/efi/libstub/arm32-stub.c
> index becbda4..5ad7bbd 100644
> --- a/drivers/firmware/efi/libstub/arm32-stub.c
> +++ b/drivers/firmware/efi/libstub/arm32-stub.c
> @@ -28,6 +28,8 @@ efi_status_t
> check_platform_features(efi_system_table_t *sys_table_arg)
>         return EFI_SUCCESS;
>  }
>
> +void * foo = (void *)check_platform_features;
> +
>  static efi_guid_t screen_info_guid = LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID;
>
>  struct screen_info *alloc_screen_info(efi_system_table_t *sys_table_arg)
> $ make ARCH=arm  CROSS_COMPILE=arm-linux-gnueabihf- defconfig
> drivers/firmware/efi/libstub/
> *** Default configuration is based on 'multi_v7_defconfig'
> #
> # configuration written to .config
> #
> scripts/kconfig/conf  --syncconfig Kconfig
>   CALL    scripts/checksyscalls.sh
>   CC      drivers/firmware/efi/libstub/arm32-stub.o
>   STUBCPY drivers/firmware/efi/libstub/arm32-stub.stub.o
> 00000000 R_ARM_ABS32       check_platform_features
> drivers/firmware/efi/libstub/arm32-stub.stub.o: absolute symbol
> references not allowed in the EFI stub
> drivers/firmware/efi/libstub/Makefile:80: recipe for target
> 'drivers/firmware/efi/libstub/arm32-stub.stub.o' failed
> make[3]: *** [drivers/firmware/efi/libstub/arm32-stub.stub.o] Error 1
> make[3]: *** Deleting file 'drivers/firmware/efi/libstub/arm32-stub.stub.o'
> Makefile:1705: recipe for target 'drivers/firmware/efi/libstub/' failed
> make[2]: *** [drivers/firmware/efi/libstub/] Error 2
> /home/masahiro/workspace/bsp/linux/Makefile:300: recipe for target
> '__build_one_by_one' failed
> make[1]: *** [__build_one_by_one] Error 2
> Makefile:160: recipe for target 'sub-make' failed
> make: *** [sub-make] Error 2
>
>
>
>
>
> --
> Best Regards
> Masahiro Yamada

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Masahiro Yamada]

On Sat, Feb 16, 2019 at 12:38 AM Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
>
> On Fri, 15 Feb 2019 at 06:49, Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> >
> > On Tue, Feb 12, 2019 at 4:26 PM Ard Biesheuvel
> > <ard.biesheuvel@linaro.org> wrote:
> > >
> > > 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!
> >
> >
> > I tried that, and it failed as expected.
> >
>
> Great, thanks for double checking.
>
> Are you taking this directly, or do you want me to take it via the EFI
> tree? Either is fine with me
>
>

Could you apply it to your EFI tree?
Thanks.



-- 
Best Regards
Masahiro Yamada

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Masahiro Yamada]

Hi Ard,



On Sat, Feb 16, 2019 at 11:07 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Sat, Feb 16, 2019 at 12:38 AM Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
> >
> > On Fri, 15 Feb 2019 at 06:49, Masahiro Yamada
> > <yamada.masahiro@socionext.com> wrote:
> > >
> > > On Tue, Feb 12, 2019 at 4:26 PM Ard Biesheuvel
> > > <ard.biesheuvel@linaro.org> wrote:
> > > >
> > > > 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!
> > >
> > >
> > > I tried that, and it failed as expected.
> > >
> >
> > Great, thanks for double checking.
> >
> > Are you taking this directly, or do you want me to take it via the EFI
> > tree? Either is fine with me
> >
> >
>
> Could you apply it to your EFI tree?
> Thanks.



Will you pick it up?



-- 
Best Regards
Masahiro Yamada

Re: [PATCH] efi/libstub: refactor cmd_stubcopy

[Ard Biesheuvel]

On Tue, 26 Mar 2019 at 07:06, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> Hi Ard,
>
>
>
> On Sat, Feb 16, 2019 at 11:07 AM Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> >
> > On Sat, Feb 16, 2019 at 12:38 AM Ard Biesheuvel
> > <ard.biesheuvel@linaro.org> wrote:
> > >
> > > On Fri, 15 Feb 2019 at 06:49, Masahiro Yamada
> > > <yamada.masahiro@socionext.com> wrote:
> > > >
> > > > On Tue, Feb 12, 2019 at 4:26 PM Ard Biesheuvel
> > > > <ard.biesheuvel@linaro.org> wrote:
> > > > >
> > > > > 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!
> > > >
> > > >
> > > > I tried that, and it failed as expected.
> > > >
> > >
> > > Great, thanks for double checking.
> > >
> > > Are you taking this directly, or do you want me to take it via the EFI
> > > tree? Either is fine with me
> > >
> > >
> >
> > Could you apply it to your EFI tree?
> > Thanks.
>
>
>
> Will you pick it up?
>

Yes, it's on my list for v5.2