[PATCH 1/7] efi/riscv: libstub: mark when compiling libstub

[Heiko Stübner]

Am Sonntag, 13. November 2022, 18:16:10 CET schrieb Conor Dooley:
> On Thu, Nov 10, 2022 at 05:49:18PM +0100, Heiko Stuebner wrote:
> > From: Heiko Stuebner <heiko.stuebner at vrull.eu>
> > 
> > We want to runtime-optimize some core functions (str*, mem*)
> > but not have this leak into libstub. Instead libstub
> > for the short while it's running should just use the generic
> 
> Totally pedantic reword, mostly b/c I am an eejit and confused myself
> the first time reading this:
> 
> "Instead, libstub, for the short while it's running, should just use
> the generic implementation."
> 
> > implementation.
> > 
> > To be able to determine whether functions are getting compiled
> > as part of libstub or not, add a compile-flag we can check
> > via #ifdef.
> 
> Exempting the stub makes sense to me given when it runs. What's the
> actual downside of not exempting it though?

You run into build-errors.

I.e. the alternatives (zbb-variants in this case) get compiled
so there is the reference to the _strlen_zbb function in the efi-stub,
which of course is not fullfillable, hence the "magic" in patch6 :-) .


Heiko


> > Signed-off-by: Heiko Stuebner <heiko.stuebner at vrull.eu>
> > ---
> >  drivers/firmware/efi/libstub/Makefile | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> > index b1601aad7e1a..39c8e3da1937 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -25,7 +25,7 @@ cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> >  				   -fno-builtin -fpic \
> >  				   $(call cc-option,-mno-single-pic-base)
> >  cflags-$(CONFIG_RISCV)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > -				   -fpic
> > +				   -fpic -DRISCV_EFISTUB
> >  cflags-$(CONFIG_LOONGARCH)	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> >  				   -fpie
> >  
>