Re: [PATCH v2 1/4] common: remove -fno-stack-protector from EMBEDDED_EXTRA_CFLAGS

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.11.2024 02:10, Volodymyr Babchuk wrote:
> This patch is preparation for making stack protector
> configurable. First step is to remove -fno-stack-protector flag from
> EMBEDDED_EXTRA_CFLAGS so separate projects (Hypervisor in this case)
> can enable/disable this feature by themselves.

s/projects/components/ ?

> --- a/stubdom/Makefile
> +++ b/stubdom/Makefile
> @@ -54,6 +54,8 @@ TARGET_CFLAGS += $(CFLAGS)
>  TARGET_CPPFLAGS += $(CPPFLAGS)
>  $(call cc-options-add,TARGET_CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
>  
> +$(call cc-option-add,TARGET_CFLAGS,CC,-fno-stack-protector)
> +
>  # Do not use host headers and libs
>  GCC_INSTALL = $(shell LANG=C gcc -print-search-dirs | sed -n -e 's/install: 
> \(.*\)/\1/p')
>  TARGET_CPPFLAGS += -U __linux__ -U __FreeBSD__ -U __sun__
> --- a/tools/firmware/Rules.mk
> +++ b/tools/firmware/Rules.mk
> @@ -15,6 +15,8 @@ $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
>  
>  $(call cc-option-add,CFLAGS,CC,-fcf-protection=none)
>  
> +$(call cc-option-add,CFLAGS,CC,-fno-stack-protector)
> +
>  # Do not add the .note.gnu.property section to any of the firmware objects: 
> it
>  # breaks the rombios binary and is not useful for firmware anyway.
>  $(call cc-option-add,CFLAGS,CC,-Wa$$(comma)-mx86-used-note=no)
> --- a/tools/tests/x86_emulator/testcase.mk
> +++ b/tools/tests/x86_emulator/testcase.mk
> @@ -4,6 +4,8 @@ include $(XEN_ROOT)/tools/Rules.mk
>  
>  $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
>  
> +$(call cc-option-add,CFLAGS,CC,-fno-stack-protector)

Is use of cc-option-add really necessary throughout here, when ...

> --- a/xen/Makefile
> +++ b/xen/Makefile
> @@ -432,6 +432,8 @@ else
>  CFLAGS_UBSAN :=
>  endif
>  
> +CFLAGS += -fno-stack-protector

... is isn't needed here? Iirc the compiler version ranges supported don't
vary between components. Then again afaics $(EMBEDDED_EXTRA_CFLAGS) is used
by x86 only right now, and with cc-options-add, so perhaps it (a) needs
using cc-options-add here, too, and (b) it wants explaining why this needs
generalizing from x86 to all architectures. Quite possibly hypervisor use
of $(EMBEDDED_EXTRA_CFLAGS) may want generalizing separately, up front?

Jan