linux-kernel - [PATCH 3/7] x86: remove always-defined CONFIG_AS_CFI_SIGNAL

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Date:   Mon, 23 Mar 2020 11:08:40 +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>
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 3/7] x86: remove always-defined CONFIG_AS_CFI_SIGNAL_FRAME

CONFIG_AS_CFI_SIGNAL_FRAME was introduced by commit adf1423698f0
("[PATCH] i386/x86-64: Work around gcc bug with noreturn functions
in unwinder").

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_SIGNAL_FRAME, which is always defined.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 arch/x86/Makefile             | 6 ++----
 arch/x86/include/asm/dwarf2.h | 5 -----
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 72f8f744ebd7..dd275008fc59 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
 
-# is .cfi_signal_frame supported too?
-cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1)
 cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
 
 # does binutils support specific instructions?
@@ -190,8 +188,8 @@ 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-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
-KBUILD_CFLAGS += $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
+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_LDFLAGS := -m elf_$(UTS_MACHINE)
 
diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h
index 90807583cad7..d6697aab5706 100644
--- a/arch/x86/include/asm/dwarf2.h
+++ b/arch/x86/include/asm/dwarf2.h
@@ -20,12 +20,7 @@
 #define CFI_RESTORE_STATE	.cfi_restore_state
 #define CFI_UNDEFINED		.cfi_undefined
 #define CFI_ESCAPE		.cfi_escape
-
-#ifdef CONFIG_AS_CFI_SIGNAL_FRAME
 #define CFI_SIGNAL_FRAME	.cfi_signal_frame
-#else
-#define CFI_SIGNAL_FRAME
-#endif
 
 #if defined(CONFIG_AS_CFI_SECTIONS)
 #ifndef BUILD_VDSO
-- 
2.17.1