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Message-ID: <53b7257e-b192-07da-9dd3-06497ce826f0@petrovitsch.priv.at>
Date:   Mon, 12 Oct 2020 18:54:30 +0000
From:   Bernd Petrovitsch <bernd@...rovitsch.priv.at>
To:     Ujjwal Kumar <ujjwalkumar0501@...il.com>
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH v2 2/2] kbuild: use interpreters to invoke scripts

Hi all!

On 12/10/2020 18:42, Ujjwal Kumar wrote:
> On 12/10/20 11:50 pm, Lukas Bulwahn wrote:
>>
>>
>> On Mon, 12 Oct 2020, Ujjwal Kumar wrote:
>>
>>> We cannot rely on execute bits to be set on files in the repository.
>>> The build script should use the explicit interpreter when invoking any
>>> script from the repository.
>>>
>>> Link: https://lore.kernel.org/lkml/20200830174409.c24c3f67addcce0cea9a9d4c@linux-foundation.org/
>>> Link: https://lore.kernel.org/lkml/202008271102.FEB906C88@keescook/
>>>
>>> Suggested-by: Andrew Morton <akpm@...ux-foundation.org>
>>> Suggested-by: Kees Cook <keescook@...omium.org>
>>> Suggested-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
>>> Signed-off-by: Ujjwal Kumar <ujjwalkumar0501@...il.com>
>>> ---
>>>  Makefile                          | 4 ++--
>>>  arch/arm64/kernel/vdso/Makefile   | 2 +-
>>>  arch/arm64/kernel/vdso32/Makefile | 2 +-
>>>  arch/ia64/Makefile                | 4 ++--
>>>  arch/nds32/kernel/vdso/Makefile   | 2 +-
>>>  scripts/Makefile.build            | 2 +-
>>>  scripts/Makefile.package          | 4 ++--
>>>  7 files changed, 10 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/Makefile b/Makefile
>>> index 0af7945caa61..df20e71dd7c8 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -1256,7 +1256,7 @@ include/generated/utsrelease.h: include/config/kernel.release FORCE
>>>  PHONY += headerdep
>>>  headerdep:
>>>  	$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
>>> -	$(srctree)/scripts/headerdep.pl -I$(srctree)/include
>>> +	$(PERL) $(srctree)/scripts/headerdep.pl -I$(srctree)/include
>>>
>>>  # ---------------------------------------------------------------------------
>>>  # Kernel headers
>>> @@ -1312,7 +1312,7 @@ PHONY += kselftest-merge
>>>  kselftest-merge:
>>>  	$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
>>>  	$(Q)find $(srctree)/tools/testing/selftests -name config | \
>>> -		xargs $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
>>> +		xargs $(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
>>>  	$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
>>>
>>>  # ---------------------------------------------------------------------------
>>> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
>>> index edccdb77c53e..fb07804b7fc1 100644
>>> --- a/arch/arm64/kernel/vdso/Makefile
>>> +++ b/arch/arm64/kernel/vdso/Makefile
>>> @@ -65,7 +65,7 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
>>>  # Generate VDSO offsets using helper script
>>>  gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
>>>  quiet_cmd_vdsosym = VDSOSYM $@
>>> -      cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
>>> +      cmd_vdsosym = $(NM) $< | $(CONFIG_SHELL) $(gen-vdsosym) | LC_ALL=C sort > $@
>>>
>>>  include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
>>>  	$(call if_changed,vdsosym)
>>> diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
>>> index 7f96a1a9f68c..617c9ac58156 100644
>>> --- a/arch/arm64/kernel/vdso32/Makefile
>>> +++ b/arch/arm64/kernel/vdso32/Makefile
>>> @@ -205,7 +205,7 @@ quiet_cmd_vdsomunge = MUNGE   $@
>>>  gen-vdsosym := $(srctree)/$(src)/../vdso/gen_vdso_offsets.sh
>>>  quiet_cmd_vdsosym = VDSOSYM $@
>>>  # The AArch64 nm should be able to read an AArch32 binary
>>> -      cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
>>> +      cmd_vdsosym = $(NM) $< | $(CONFIG_SHELL) $(gen-vdsosym) | LC_ALL=C sort > $@
>>>
>>>  # Install commands for the unstripped file
>>>  quiet_cmd_vdso_install = INSTALL32 $@
>>> diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile
>>> index 703b1c4f6d12..86d42a2d09cb 100644
>>> --- a/arch/ia64/Makefile
>>> +++ b/arch/ia64/Makefile
>>> @@ -27,8 +27,8 @@ cflags-y	:= -pipe $(EXTRA) -ffixed-r13 -mfixed-range=f12-f15,f32-f127 \
>>>  		   -falign-functions=32 -frename-registers -fno-optimize-sibling-calls
>>>  KBUILD_CFLAGS_KERNEL := -mconstant-gp
>>>
>>> -GAS_STATUS	= $(shell $(srctree)/arch/ia64/scripts/check-gas "$(CC)" "$(OBJDUMP)")
>>> -KBUILD_CPPFLAGS += $(shell $(srctree)/arch/ia64/scripts/toolchain-flags "$(CC)" "$(OBJDUMP)" "$(READELF)")
>>> +GAS_STATUS	= $(shell $(CONFIG_SHELL) $(srctree)/arch/ia64/scripts/check-gas "$(CC)" "$(OBJDUMP)")
>>> +KBUILD_CPPFLAGS += $(shell $(CONFIG_SHELL) $(srctree)/arch/ia64/scripts/toolchain-flags "$(CC)" "$(OBJDUMP)" "$(READELF)")
>>
>> Here is an instance of what Masahiro-san pointed out being wrong.
>>
>> Ujjwal, will you send a v3?
> 
> Following is the quoted text from the reply mail from Masahiro
> 
>>> -GAS_STATUS     = $(shell $(srctree)/arch/ia64/scripts/check-gas "$(CC)" "$(OBJDUMP)")
>>> -KBUILD_CPPFLAGS += $(shell $(srctree)/arch/ia64/scripts/toolchain-flags "$(CC)" "$(OBJDUMP)" "$(READELF)")
>>> +GAS_STATUS     = $($(CONFIG_SHELL) $(srctree)/arch/ia64/scripts/check-gas "$(CC)" "$(OBJDUMP)")
>>> +KBUILD_CPPFLAGS += $($(CONFIG_SHELL) $(srctree)/arch/ia64/scripts/toolchain-flags "$(CC)" "$(OBJDUMP)" "$(READELF)")
>>
>>
>>
>> These changes look wrong to me.
>>
>> $($(CONFIG_SHELL)    ->  $(shell $(CONFIG_SHELL)
>>
> 
> From the above text, I understand as follows:

Did you actually *test* that (expecially) these lines work
afterwards as good as before?

> That my proposed change:
> $(shell $(src...)    ->  $($(CONFIG_SHELL) $(src...)
> 
> is WRONG

Yup, as it's in a Makefile and that's a Makefile construct.

> and in the next line he suggested the required correction.
> That being:
> $($(CONFIG_SHELL)    ->  $(shell $(CONFIG_SHELL)

Such stuff should generally not be needed as the to-be-used
shell can be set in Makefiles via a "SHELL = " assignment
(defaulting to /bin/sh - what else;-).
Flags for the shell can BTW set with ".SHELLFLAGS = ".

So please
-) learn basic "Makefile" + "make" before brainlessly patching
   a Makefile.
-) actually testy your changes to make sure the patch didn't
   broke anything
-) and - last but not least - check if there isn't a shell
   already set (and which).

MfG,
	Bernd
-- 
There is no cloud, just other people computers.
-- https://static.fsf.org/nosvn/stickers/thereisnocloud.svg

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