On Wed, Jul 17, 2024 at 11:10:15PM +0700, Koakuma wrote:
> Remove all usage of -fcall-used* flags so that all flags used are
> portable between GCC and clang.
>
> The reasoning is as follows:
>
> In the (normal) 32-bit ABI, %g5 and %g7 is normally reserved, and in
> the 64-bit ABI, %g7 is the reserved one.
> Linux turns them into volatile registers by the way of -fcall-used-*,
> but on the other hand, omitting the flags shouldn't be harmful;
> compilers will now simply refuse to touch them, and any assembly
> code that happens to touch them would still work like usual (because
> Linux' conventions already treats them as volatile anyway).
>
> Signed-off-by: Koakuma <koachan@xxxxxxxxxxxxxx>
As before, I tested this series with the vDSO patch mentioned before and
a version of LLVM that supports the -m{,no-}v8plus flags and I was able
to successfully boot a kernel in QEMU :)
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> ---
> arch/sparc/Makefile | 4 ++--
> arch/sparc/vdso/Makefile | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
> index 757451c3ea1d..7318a8b452c3 100644
> --- a/arch/sparc/Makefile
> +++ b/arch/sparc/Makefile
> @@ -29,7 +29,7 @@ UTS_MACHINE := sparc
> # versions of gcc. Some gcc versions won't pass -Av8 to binutils when you
> # give -mcpu=v8. This silently worked with older bintutils versions but
> # does not any more.
> -KBUILD_CFLAGS += -m32 -mcpu=v8 -pipe -mno-fpu -fcall-used-g5 -fcall-used-g7
> +KBUILD_CFLAGS += -m32 -mcpu=v8 -pipe -mno-fpu
> KBUILD_CFLAGS += -Wa,-Av8
>
> KBUILD_AFLAGS += -m32 -Wa,-Av8
> @@ -45,7 +45,7 @@ export BITS := 64
> UTS_MACHINE := sparc64
>
> KBUILD_CFLAGS += -m64 -pipe -mno-fpu -mcpu=ultrasparc -mcmodel=medlow
> -KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
> +KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -Wno-sign-compare
> KBUILD_CFLAGS += -Wa,--undeclared-regs
> KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
> KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
> diff --git a/arch/sparc/vdso/Makefile b/arch/sparc/vdso/Makefile
> index 243dbfc4609d..e009443145af 100644
> --- a/arch/sparc/vdso/Makefile
> +++ b/arch/sparc/vdso/Makefile
> @@ -46,7 +46,7 @@ CFL := $(PROFILING) -mcmodel=medlow -fPIC -O2 -fasynchronous-unwind-tables -m64
> -fno-omit-frame-pointer -foptimize-sibling-calls \
> -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
>
> -SPARC_REG_CFLAGS = -ffixed-g4 -ffixed-g5 -fcall-used-g5 -fcall-used-g7
> +SPARC_REG_CFLAGS = -ffixed-g4 -ffixed-g5
>
> $(vobjs): KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
>
>
> --
> 2.45.2
>
