linux-kernel - [PATCH v2 5/9] x86: remove always-defined CONFIG_AS_CFI

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Date:   Tue, 24 Mar 2020 09:13:54 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     x86@...nel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, linux-crypto@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        "Jason A . Donenfeld" <Jason@...c4.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        clang-built-linux@...glegroups.com
Subject: [PATCH v2 5/9] x86: remove always-defined CONFIG_AS_CFI_SECTIONS

CONFIG_AS_CFI_SECTIONS was introduced by commit 9e565292270a ("x86:
Use .cfi_sections for assembly code").

We raise the minimal supported binutils version from time to time.
The last bump was commit 1fb12b35e5ff ("kbuild: Raise the minimum
required binutils version to 2.21").

I confirmed the code in $(call as-instr,...) can be assembled by the
binutils 2.21 assembler and also by LLVM integrated assembler.

Remove CONFIG_AS_CFI_SECTIONS, which is always defined.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
Acked-by: Jason A. Donenfeld <Jason@...c4.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
---

Changes in v2: None

 arch/x86/Makefile             | 6 ++----
 arch/x86/include/asm/dwarf2.h | 2 --
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index dd275008fc59..e4a062313bb0 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -177,8 +177,6 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
 	KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
 endif
 
-cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
-
 # does binutils support specific instructions?
 asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1)
 avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
@@ -188,8 +186,8 @@ sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=
 sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)
 adx_instr := $(call as-instr,adox %r10$(comma)%r10,-DCONFIG_AS_ADX=1)
 
-KBUILD_AFLAGS += $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
-KBUILD_CFLAGS += $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
+KBUILD_AFLAGS += $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
+KBUILD_CFLAGS += $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
 
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
 
diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h
index f440790f09f9..c1e0c315a622 100644
--- a/arch/x86/include/asm/dwarf2.h
+++ b/arch/x86/include/asm/dwarf2.h
@@ -21,7 +21,6 @@
 #define CFI_UNDEFINED		.cfi_undefined
 #define CFI_ESCAPE		.cfi_escape
 
-#if defined(CONFIG_AS_CFI_SECTIONS)
 #ifndef BUILD_VDSO
 	/*
 	 * Emit CFI data in .debug_frame sections, not .eh_frame sections.
@@ -38,6 +37,5 @@
 	  */
 	.cfi_sections .eh_frame, .debug_frame
 #endif
-#endif
 
 #endif /* _ASM_X86_DWARF2_H */
-- 
2.17.1