| Message ID | 20200323215732.13339-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kconfig: allow to pass optional flag into as-instr macro | expand |
On Mon, Mar 23, 2020 at 3:58 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > Commit 42d519e3d0c0 ("kbuild: Add support for 'as-instr' to be used in > Kconfig files") introduced the Kconfig variant of as-instr. > > It is currently used in arch/arm64/Kconfig. > > arm and arm64 are simple cases because they are separated by directory, > and GCC also provides a single architecture. > > Such architectures as x86, powerpc, sparc, etc. support both 32 and > 64 bit kernel in the unified arch directory, and GCC can be biarch. > On such architectures, Kbuild passes -m32 / -m64 flag (or a proper > target triple for Clang) to select the target machine bit. > > This commit adds the second parameter to as-instr so you can optionally > pass a compiler flag to evaluate the instruction with. > > One example usage of this is for the conversion of the following code > in arch/x86/Makefile: > > adx_instr := $(call as-instr,adox %r10$(comma)%r10,-DCONFIG_AS_ADX=1) > > This instruction code should be evaluated by the 64-bit assembler > (r10 is a 64-bit register). > > If you use compiler that defaults to 32-bit for building the 64-bit > kernel, -m64 should be passed to invoke the 64-bit assembler. > > config AS_ADX > def_bool $(as-instr,adox %r10$(comma)%r10,$(m64-flags)) > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > > scripts/Kconfig.include | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include > index 496d11c92c97..9b8c98168ba9 100644 > --- a/scripts/Kconfig.include > +++ b/scripts/Kconfig.include > @@ -31,9 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -S -x c /dev/null -o /de > # Return y if the linker supports <flag>, n otherwise > ld-option = $(success,$(LD) -v $(1)) > > -# $(as-instr,<instr>) > +# $(as-instr,<instr>,[<flag>]) > # Return y if the assembler supports <instr>, n otherwise > -as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -) > +# You can pass optional <flag> to evaluate <instr> with > +as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) $(2) -c -x assembler -o /dev/null -) > > # check if $(CC) and $(LD) exist > $(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found) > -- > 2.17.1 This looks fine to me, and might be useful down the line in the future. But for the ADX situation, I wound up just going with the bicompatible register: https://git.zx2c4.com/linux-dev/commit/?h=jd/kconfig-assembler-support&id=c81d9c743d058ef9013fbf8661d071ac9d574472 +# binutils >= 2.23 +config AS_ADX + def_bool $(as-instr,adox %eax$(comma)%eax) This seems to work. But it also doesn't matter much, as it gets removed anyway during the binutils 2.23 bump: https://git.zx2c4.com/linux-dev/commit/?h=jd/kconfig-assembler-support&id=c95d6f2ce88722eeb86d54f206bd7599bdc51e1d
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include index 496d11c92c97..9b8c98168ba9 100644 --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -31,9 +31,10 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -S -x c /dev/null -o /de # Return y if the linker supports <flag>, n otherwise ld-option = $(success,$(LD) -v $(1)) -# $(as-instr,<instr>) +# $(as-instr,<instr>,[<flag>]) # Return y if the assembler supports <instr>, n otherwise -as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -) +# You can pass optional <flag> to evaluate <instr> with +as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) $(2) -c -x assembler -o /dev/null -) # check if $(CC) and $(LD) exist $(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
Commit 42d519e3d0c0 ("kbuild: Add support for 'as-instr' to be used in Kconfig files") introduced the Kconfig variant of as-instr. It is currently used in arch/arm64/Kconfig. arm and arm64 are simple cases because they are separated by directory, and GCC also provides a single architecture. Such architectures as x86, powerpc, sparc, etc. support both 32 and 64 bit kernel in the unified arch directory, and GCC can be biarch. On such architectures, Kbuild passes -m32 / -m64 flag (or a proper target triple for Clang) to select the target machine bit. This commit adds the second parameter to as-instr so you can optionally pass a compiler flag to evaluate the instruction with. One example usage of this is for the conversion of the following code in arch/x86/Makefile: adx_instr := $(call as-instr,adox %r10$(comma)%r10,-DCONFIG_AS_ADX=1) This instruction code should be evaluated by the 64-bit assembler (r10 is a 64-bit register). If you use compiler that defaults to 32-bit for building the 64-bit kernel, -m64 should be passed to invoke the 64-bit assembler. config AS_ADX def_bool $(as-instr,adox %r10$(comma)%r10,$(m64-flags)) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- scripts/Kconfig.include | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)