Re: [PATCH v3] kbuild: Show marked Kconfig fragments in "help"

Nicolas Schier
2023-09-02T18:18:29Z

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On Thu, Aug 31, 2023 at 12:13:39PM -0700 Kees Cook wrote:
> Currently the Kconfig fragments in kernel/configs and arch/*/configs
> that aren't used internally aren't discoverable through "make help",
> which consists of hard-coded lists of config fragments. Instead, list
> all the fragment targets that have a "# Help: " comment prefix so the
> targets can be generated dynamically.
>
> Add logic to the Makefile to search for and display the fragment and
> comment. Add comments to fragments that are intended to be direct targets.
>
> Cc: Nicolas Schier <nicolas@fjasle.eu>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: linux-kernel@vger.kernel.org
> Cc: x86@kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-riscv@lists.infradead.org
> Cc: linux-s390@vger.kernel.org
> Cc: linux-kbuild@vger.kernel.org
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Co-developed-by: Masahiro Yamada <masahiroy@kernel.org>
> ---

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

> v3:
> - Use Makefile logic from Masahiro Yamada
> - Use "# Help: " prefix, but only on desired fragment targets
> v2: https://lore.kernel.org/all/20230825194329.gonna.911-kees@kernel.org
> v1: https://lore.kernel.org/all/20230824223606.never.762-kees@kernel.org
> ---
> Makefile | 1 -
> arch/arm/configs/dram_0x00000000.config | 1 +
> arch/arm/configs/dram_0xc0000000.config | 1 +
> arch/arm/configs/dram_0xd0000000.config | 1 +
> arch/arm/configs/lpae.config | 1 +
> arch/arm64/configs/virt.config | 1 +
> arch/powerpc/configs/disable-werror.config | 1 +
> arch/powerpc/configs/security.config | 4 +++-
> arch/riscv/configs/32-bit.config | 1 +
> arch/riscv/configs/64-bit.config | 1 +
> arch/s390/configs/btf.config | 1 +
> arch/s390/configs/kasan.config | 1 +
> arch/x86/Makefile | 4 ----
> kernel/configs/debug.config | 2 ++
> kernel/configs/kvm_guest.config | 1 +
> kernel/configs/nopm.config | 2 ++
> kernel/configs/rust.config | 1 +
> kernel/configs/tiny.config | 2 ++
> kernel/configs/x86_debug.config | 1 +
> kernel/configs/xen.config | 2 ++
> scripts/kconfig/Makefile | 15 ++++++++++++---
> 21 files changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4739c21a63e2..91c90ce8e0e3 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1674,7 +1674,6 @@ help:
> @echo ' mrproper - Remove all generated files + config + various backup files'
> @echo ' distclean - mrproper + remove editor backup and patch files'
> @echo ''
> - @echo 'Configuration targets:'
> @$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
> @echo ''
> @echo 'Other generic targets:'
> diff --git a/arch/arm/configs/dram_0x00000000.config b/arch/arm/configs/dram_0x00000000.config
> index db96dcb420ce..8803a0f58343 100644
> --- a/arch/arm/configs/dram_0x00000000.config
> +++ b/arch/arm/configs/dram_0x00000000.config
> @@ -1 +1,2 @@
> +# Help: DRAM base at 0x00000000
> CONFIG_DRAM_BASE=0x00000000
> diff --git a/arch/arm/configs/dram_0xc0000000.config b/arch/arm/configs/dram_0xc0000000.config
> index 343d5333d973..aab8f864686b 100644
> --- a/arch/arm/configs/dram_0xc0000000.config
> +++ b/arch/arm/configs/dram_0xc0000000.config
> @@ -1 +1,2 @@
> +# Help: DRAM base at 0xc0000000
> CONFIG_DRAM_BASE=0xc0000000
> diff --git a/arch/arm/configs/dram_0xd0000000.config b/arch/arm/configs/dram_0xd0000000.config
> index 61ba7045f8a1..4aabce4ea3d4 100644
> --- a/arch/arm/configs/dram_0xd0000000.config
> +++ b/arch/arm/configs/dram_0xd0000000.config
> @@ -1 +1,2 @@
> +# Help: DRAM base at 0xd0000000
> CONFIG_DRAM_BASE=0xd0000000
> diff --git a/arch/arm/configs/lpae.config b/arch/arm/configs/lpae.config
> index a6d6f7ab3c01..1ab94da8345d 100644
> --- a/arch/arm/configs/lpae.config
> +++ b/arch/arm/configs/lpae.config
> @@ -1,2 +1,3 @@
> +# Help: Enable Large Physical Address Extension mode
> CONFIG_ARM_LPAE=y
> CONFIG_VMSPLIT_2G=y
> diff --git a/arch/arm64/configs/virt.config b/arch/arm64/configs/virt.config
> index 6865d54e68f8..c47c36f8f67b 100644
> --- a/arch/arm64/configs/virt.config
> +++ b/arch/arm64/configs/virt.config
> @@ -1,3 +1,4 @@
> +# Help: Virtualization guest
> #
> # Base options for platforms
> #
> diff --git a/arch/powerpc/configs/disable-werror.config b/arch/powerpc/configs/disable-werror.config
> index 6ea12a12432c..7776b91da37f 100644
> --- a/arch/powerpc/configs/disable-werror.config
> +++ b/arch/powerpc/configs/disable-werror.config
> @@ -1 +1,2 @@
> +# Help: Disable -Werror
> CONFIG_PPC_DISABLE_WERROR=y
> diff --git a/arch/powerpc/configs/security.config b/arch/powerpc/configs/security.config
> index 1c91a35c6a73..0d54e29e2cdf 100644
> --- a/arch/powerpc/configs/security.config
> +++ b/arch/powerpc/configs/security.config
> @@ -1,3 +1,5 @@
> +# Help: Common security options for PowerPC builds
> +
> # This is the equivalent of booting with lockdown=integrity
> CONFIG_SECURITY=y
> CONFIG_SECURITYFS=y
> @@ -12,4 +14,4 @@ CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
>
> # UBSAN bounds checking is very cheap and good for hardening
> CONFIG_UBSAN=y
> -# CONFIG_UBSAN_MISC is not set
> \ No newline at end of file
> +# CONFIG_UBSAN_MISC is not set
> diff --git a/arch/riscv/configs/32-bit.config b/arch/riscv/configs/32-bit.config
> index f6af0f708df4..16ee163847b4 100644
> --- a/arch/riscv/configs/32-bit.config
> +++ b/arch/riscv/configs/32-bit.config
> @@ -1,3 +1,4 @@
> +# Help: Build a 32-bit image
> CONFIG_ARCH_RV32I=y
> CONFIG_32BIT=y
> # CONFIG_PORTABLE is not set
> diff --git a/arch/riscv/configs/64-bit.config b/arch/riscv/configs/64-bit.config
> index 313edc554d84..d872a2d533f2 100644
> --- a/arch/riscv/configs/64-bit.config
> +++ b/arch/riscv/configs/64-bit.config
> @@ -1,2 +1,3 @@
> +# Help: Build a 64-bit image
> CONFIG_ARCH_RV64I=y
> CONFIG_64BIT=y
> diff --git a/arch/s390/configs/btf.config b/arch/s390/configs/btf.config
> index 39227b4511af..eb7f84f5925c 100644
> --- a/arch/s390/configs/btf.config
> +++ b/arch/s390/configs/btf.config
> @@ -1 +1,2 @@
> +# Help: Enable BTF debug info
> CONFIG_DEBUG_INFO_BTF=y
> diff --git a/arch/s390/configs/kasan.config b/arch/s390/configs/kasan.config
> index 700a8b25c3ff..84c2b551e992 100644
> --- a/arch/s390/configs/kasan.config
> +++ b/arch/s390/configs/kasan.config
> @@ -1,3 +1,4 @@
> +# Help: Enable KASan for debugging
> CONFIG_KASAN=y
> CONFIG_KASAN_INLINE=y
> CONFIG_KASAN_VMALLOC=y
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index fdc2e3abd615..c4b2a8a19fc8 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -335,9 +335,5 @@ define archhelp
> echo ' bzdisk/fdimage*/hdimage/isoimage also accept:'
> echo ' FDARGS="..." arguments for the booted kernel'
> echo ' FDINITRD=file initrd for the booted kernel'
> - echo ''
> - echo ' kvm_guest.config - Enable Kconfig items for running this kernel as a KVM guest'
> - echo ' xen.config - Enable Kconfig items for running this kernel as a Xen guest'
> - echo ' x86_debug.config - Enable tip tree debugging options for testing'
>
> endef
> diff --git a/kernel/configs/debug.config b/kernel/configs/debug.config
> index e8db8d938661..4722b998a324 100644
> --- a/kernel/configs/debug.config
> +++ b/kernel/configs/debug.config
> @@ -1,3 +1,5 @@
> +# Help: Debugging for CI systems and finding regressions
> +#
> # The config is based on running daily CI for enterprise Linux distros to
> # seek regressions on linux-next builds on different bare-metal and virtual
> # platforms. It can be used for example,
> diff --git a/kernel/configs/kvm_guest.config b/kernel/configs/kvm_guest.config
> index 208481d91090..d0877063d925 100644
> --- a/kernel/configs/kvm_guest.config
> +++ b/kernel/configs/kvm_guest.config
> @@ -1,3 +1,4 @@
> +# Help: Bootable as a KVM guest
> CONFIG_NET=y
> CONFIG_NET_CORE=y
> CONFIG_NETDEVICES=y
> diff --git a/kernel/configs/nopm.config b/kernel/configs/nopm.config
> index 81ff07863576..ebfdc3d8aa9a 100644
> --- a/kernel/configs/nopm.config
> +++ b/kernel/configs/nopm.config
> @@ -1,3 +1,5 @@
> +# Help: Disable Power Management
> +
> CONFIG_PM=n
> CONFIG_SUSPEND=n
> CONFIG_HIBERNATION=n
> diff --git a/kernel/configs/rust.config b/kernel/configs/rust.config
> index 38a7c5362c9c..2c6e001a7284 100644
> --- a/kernel/configs/rust.config
> +++ b/kernel/configs/rust.config
> @@ -1 +1,2 @@
> +# Help: Enable Rust
> CONFIG_RUST=y
> diff --git a/kernel/configs/tiny.config b/kernel/configs/tiny.config
> index 00009f7d0835..60a4b6d80b36 100644
> --- a/kernel/configs/tiny.config
> +++ b/kernel/configs/tiny.config
> @@ -1,3 +1,5 @@
> +# Help: Size-optimized kernel image
> +#
> # CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE is not set
> CONFIG_CC_OPTIMIZE_FOR_SIZE=y
> # CONFIG_KERNEL_GZIP is not set
> diff --git a/kernel/configs/x86_debug.config b/kernel/configs/x86_debug.config
> index 6fac5b405334..35f48671b8d5 100644
> --- a/kernel/configs/x86_debug.config
> +++ b/kernel/configs/x86_debug.config
> @@ -1,3 +1,4 @@
> +# Help: Debugging options for tip tree testing
> CONFIG_X86_DEBUG_FPU=y
> CONFIG_LOCK_STAT=y
> CONFIG_DEBUG_VM=y
> diff --git a/kernel/configs/xen.config b/kernel/configs/xen.config
> index 436f806aa1ed..6878b9a49be8 100644
> --- a/kernel/configs/xen.config
> +++ b/kernel/configs/xen.config
> @@ -1,3 +1,5 @@
> +# Help: Bootable as a Xen guest
> +#
> # global stuff - these enable us to allow some
> # of the not so generic stuff below for xen
> CONFIG_PARAVIRT=y
> diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> index af1c96198f49..4eee155121a8 100644
> --- a/scripts/kconfig/Makefile
> +++ b/scripts/kconfig/Makefile
> @@ -93,11 +93,13 @@ endif
> %_defconfig: $(obj)/conf
> $(Q)$< $(silent) --defconfig=arch/$(SRCARCH)/configs/$@ $(Kconfig)
>
> -configfiles=$(wildcard $(srctree)/kernel/configs/$@ $(srctree)/arch/$(SRCARCH)/configs/$@)
> +configfiles = $(wildcard $(srctree)/kernel/configs/$(1) $(srctree)/arch/$(SRCARCH)/configs/$(1))
> +all-config-fragments = $(call configfiles,*.config)
> +config-fragments = $(call configfiles,$@)
>
> %.config: $(obj)/conf
> - $(if $(call configfiles),, $(error No configuration exists for this target on this architecture))
> - $(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m .config $(configfiles)
> + $(if $(config-fragments),, $(error $@ fragment does not exists on this architecture))
> + $(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m .config $(config-fragments)
> $(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
>
> PHONY += tinyconfig
> @@ -115,6 +117,7 @@ clean-files += tests/.cache
>
> # Help text used by make help
> help:
> + @echo 'Configuration targets:'
> @echo ' config - Update current config utilising a line-oriented program'
> @echo ' nconfig - Update current config utilising a ncurses menu based program'
> @echo ' menuconfig - Update current config utilising a menu based program'
> @@ -141,6 +144,12 @@ help:
> @echo ' default value without prompting'
> @echo ' tinyconfig - Configure the tiniest possible kernel'
> @echo ' testconfig - Run Kconfig unit tests (requires python3 and pytest)'
> + @echo ''
> + @echo 'Configuration topic targets:'
> + @$(foreach f, $(all-config-fragments), \
> + if help=$$(grep -m1 '^# Help: ' $(f)); then \
> + printf ' %-25s - %s\n' '$(notdir $(f))' "$${help#*: }"; \
> + fi;)
>
> # ===========================================================================
> # object files used by all kconfig flavours
> --
> 2.34.1

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