x86: remove always-defined CONFIG_AS_* options

CONFIG_AS_CFI was introduced by commit e2414910f212 ("[PATCH] x86:
Detect CFI support in the assembler at runtime"), and extended by commit f0f12d85af85 ("x86_64: Check for .cfi_rel_offset in CFI probe").

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, which is always defined.

Signed-off-by Masahiro Yamada <[email protected]>

---

If this series is OK, we can do follwup cleanups.
We can hard-code the assembler code, and delete CFI_* macros entirely.

 arch/x86/Makefile             | 10 ++--------
 arch/x86/include/asm/dwarf2.h | 36 -----------------------------------
 2 files changed, 2 insertions(+), 44 deletions(-)

arch/x86/Makefile +2 -8

index 513a55562d75..72f8f744ebd7 100644
@@ -177,12 +177,6 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
        KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
 endif
 
-# Stackpointer is addressed different for 32 bit and 64 bit x86
-sp-$(CONFIG_X86_32) := esp
-sp-$(CONFIG_X86_64) := rsp
-
-# do binutils support CFI?
-cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_endproc,-DCONFIG_AS_CFI=1)
 # 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)

@@ -196,8 +190,8 @@ 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) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
-KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
+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_LDFLAGS := -m elf_$(UTS_MACHINE)
 

arch/x86/include/asm/dwarf2.h +0 -37

index 5a0502212bc5..90807583cad7 100644
@@ -6,15 +6,6 @@
 #warning "asm/dwarf2.h should be only included in pure assembly files"
 #endif
 
-/*
- * Macros for dwarf2 CFI unwind table entries.
- * See "as.info" for details on these pseudo ops. Unfortunately
- * they are only supported in very new binutils, so define them
- * away for older version.
- */
-
-#ifdef CONFIG_AS_CFI
-
 #define CFI_STARTPROC          .cfi_startproc
 #define CFI_ENDPROC            .cfi_endproc
 #define CFI_DEF_CFA            .cfi_def_cfa

@@ -55,31 +46,4 @@
 #endif
 #endif
 
-#else
-
-/*
- * Due to the structure of pre-exisiting code, don't use assembler line
- * comment character # to ignore the arguments. Instead, use a dummy macro.
- */
-.macro cfi_ignore a=0, b=0, c=0, d=0
-.endm
-
-#define CFI_STARTPROC          cfi_ignore
-#define CFI_ENDPROC            cfi_ignore
-#define CFI_DEF_CFA            cfi_ignore
-#define CFI_DEF_CFA_REGISTER   cfi_ignore
-#define CFI_DEF_CFA_OFFSET     cfi_ignore
-#define CFI_ADJUST_CFA_OFFSET  cfi_ignore
-#define CFI_OFFSET             cfi_ignore
-#define CFI_REL_OFFSET         cfi_ignore
-#define CFI_REGISTER           cfi_ignore
-#define CFI_RESTORE            cfi_ignore
-#define CFI_REMEMBER_STATE     cfi_ignore
-#define CFI_RESTORE_STATE      cfi_ignore
-#define CFI_UNDEFINED          cfi_ignore
-#define CFI_ESCAPE             cfi_ignore
-#define CFI_SIGNAL_FRAME       cfi_ignore
-
-#endif
-
 #endif /* _ASM_X86_DWARF2_H */
--

2.17.1

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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 <[email protected]>

---

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

arch/x86/Makefile +2 -4

index 72f8f744ebd7..dd275008fc59 100644
@@ -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)
 

arch/x86/include/asm/dwarf2.h +0 -0

index 90807583cad7..d6697aab5706 100644

arch/x86/include/asm/dwarf2.h +0 -4

-#else
-#define CFI_SIGNAL_FRAME
-#endif
 
 #if defined(CONFIG_AS_CFI_SECTIONS)
 #ifndef BUILD_VDSO
--

2.17.1

--

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 <[email protected]>

---

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

arch/x86/Makefile +2 -4

index dd275008fc59..e4a062313bb0 100644
@@ -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)
 

arch/x86/include/asm/dwarf2.h +0 -3

index d6697aab5706..5d3e7507cbbd 100644
@@ -22,7 +22,6 @@
 #define CFI_ESCAPE             .cfi_escape
 #define CFI_SIGNAL_FRAME       .cfi_signal_frame
 
-#if defined(CONFIG_AS_CFI_SECTIONS)
 #ifndef BUILD_VDSO
        /*
         * Emit CFI data in .debug_frame sections, not .eh_frame sections.

@@ -39,6 +38,5 @@
          */
        .cfi_sections .eh_frame, .debug_frame
 #endif
-#endif
 
 #endif /* _ASM_X86_DWARF2_H */
--

2.17.1

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lib/raid6/algos.c +0 -0

index bf1b4765c8f6..77457ea5a239 100644

Quoted 5 lines · Masahiro Yamada

lib/raid6/algos.c +0 -0

index bf1b4765c8f6..77457ea5a239 100644

lib/raid6/algos.c const struct raid6_recov_calls *const raid6_recov_algos[] = { · line 109

Quoted 9 lines

lib/raid6/algos.c +0 -2

@@ -103,9 +103,7 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = {
 #ifdef CONFIG_AS_AVX2
        &raid6_recov_avx2,
 #endif
-#ifdef CONFIG_AS_SSSE3
        &raid6_recov_ssse3,
-#endif
 #ifdef CONFIG_S390
        &raid6_recov_s390xc,
 #endif

algos.c is compiled on all platforms, so you'll need to ifdef that x86 section where SSSE3 is no longer guarding it. The pattern in the rest of the file, if you want to follow it, is "#if defined(__x86_64__) && !defined(__arch_um__)". That seems ugly and like there are better ways, but in the interest of uniformity and a lack of desire to rewrite all the raid6 code, I went with that in this cleanup:

https://git.zx2c4.com/linux-dev/commit/?h=jd/kconfig-assembler-support&id=512a00ddebbe5294a88487dcf1dc845cf56703d9

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Quoted 24 lines · Jason A. Donenfeld

Quoted 5 lines · Masahiro Yamada

lib/raid6/algos.c +0 -0

index bf1b4765c8f6..77457ea5a239 100644

lib/raid6/algos.c const struct raid6_recov_calls *const raid6_recov_algos[] = { · line 109

Quoted 9 lines

lib/raid6/algos.c +0 -2

@@ -103,9 +103,7 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = {
 #ifdef CONFIG_AS_AVX2
        &raid6_recov_avx2,
 #endif
-#ifdef CONFIG_AS_SSSE3
        &raid6_recov_ssse3,
-#endif
 #ifdef CONFIG_S390
        &raid6_recov_s390xc,
 #endif

algos.c is compiled on all platforms, so you'll need to ifdef that x86 section where SSSE3 is no longer guarding it. The pattern in the rest of the file, if you want to follow it, is "#if defined(__x86_64__) && !defined(__arch_um__)". That seems ugly and like there are better ways, but in the interest of uniformity and a lack of desire to rewrite all the raid6 code, I went with that in this cleanup:

Quoted 1 line

https://git.zx2c4.com/linux-dev/commit/?h=jd/kconfig-assembler-support&id=512a00ddebbe5294a88487dcf1dc845cf56703d9

Thanks for the pointer,
but I think guarding with CONFIG_X86 makes more sense.

raid6_recov_ssse3 is defined in lib/raid6/recov_ssse3.c, which is guarded by like this:

raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o avx512.o recov_avx512.o

Indeed,

#if defined(__x86_64__) && !defined(__arch_um__)

is ugly.

I wonder why the code was written like that.

I rather want to check a single CONFIG option.
Please see the attached patch.

By the way, it looks like 5.7 will be raising the minimum binutils to 2.23: https://lore.kernel.org/lkml/[email protected]/ In light of this, I'll place another patch on top of my branch handling that transition.

Hi again,

I've consolidated your patches and rebased mine on top, and incorporated your useful binutils comments. The result lives here:

https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support

I can submit all of those to the list, if you want, or maybe you can just pull them out of there, include them in your v2, and put them in your tree for 5.7? However you want is fine with me.

Hi Jason,

Quoted 8 lines · Jason A. Donenfeld

Hi again,

I've consolidated your patches and rebased mine on top, and incorporated your useful binutils comments. The result lives here:

https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support

Quoted 3 lines

I can submit all of those to the list, if you want, or maybe you can just pull them out of there, include them in your v2, and put them in your tree for 5.7? However you want is fine with me.

Your series does not work correctly.

I will comment why later.

Quoted 17 lines · Masahiro Yamada

Hi Jason,

Quoted 11 lines · Jason A. Donenfeld

Hi again,

I've consolidated your patches and rebased mine on top, and incorporated your useful binutils comments. The result lives here:

https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support

I can submit all of those to the list, if you want, or maybe you can just pull them out of there, include them in your v2, and put them in your tree for 5.7? However you want is fine with me.

Quoted 3 lines

Your series does not work correctly.

I will comment why later.

Bummer, okay. Looking forward to learning what's up. Also, if some parts of it are useful (like the resorting and organizing of arch/x86/crypto/Makefile), feel free to cannibalize it, keeping what's useful and discarding what's not.

Hi Jason,
I have not checked your Kconfig changes are really working, especially I looked at [2] and comment on this.

I would have expected your arch/x86/Kconfig.assembler file as arch/x86/crypto/Kconfig (source include needs to be adapted in arch/x86/Kconfig).

What about a commit subject like "x86: crypto: Probe assembler options via Kconfig instead of makefile"?

Quoted 3 lines

I would have expected your arch/x86/Kconfig.assembler file as arch/x86/crypto/Kconfig (source include needs to be adapted in arch/x86/Kconfig).

CONFIG_AS_* is required for more than just the crypto.

Quoted 2 lines

What about a commit subject like "x86: crypto: Probe assembler options via Kconfig instead of makefile"?

Thanks. Will fix silly verbiage and update branch.

Quoted 17 lines · Masahiro Yamada

Hi Jason,

Quoted 11 lines · Jason A. Donenfeld

Hi again,

I've consolidated your patches and rebased mine on top, and incorporated your useful binutils comments. The result lives here:

https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support

I can submit all of those to the list, if you want, or maybe you can just pull them out of there, include them in your v2, and put them in your tree for 5.7? However you want is fine with me.

Quoted 3 lines

Your series does not work correctly.

I will comment why later.

Bummer, okay. Looking forward to learning what's up. Also, if some parts of it are useful (like the resorting and organizing of arch/x86/crypto/Makefile), feel free to cannibalize it, keeping what's useful and discarding what's not.

Hi Jason,

Quoted 19 lines · Jason A. Donenfeld

Quoted 17 lines · Masahiro Yamada

Hi Jason,

Quoted 11 lines · Jason A. Donenfeld

Hi again,

I've consolidated your patches and rebased mine on top, and incorporated your useful binutils comments. The result lives here:

https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support

I can submit all of those to the list, if you want, or maybe you can just pull them out of there, include them in your v2, and put them in your tree for 5.7? However you want is fine with me.

Quoted 9 lines

Quoted 3 lines

Your series does not work correctly.

I will comment why later.

Bummer, okay. Looking forward to learning what's up. Also, if some parts of it are useful (like the resorting and organizing of arch/x86/crypto/Makefile), feel free to cannibalize it, keeping what's useful and discarding what's not.

The answer is mostly in my previous reply to Linus:
https://lkml.org/lkml/2020/3/13/27

I think this problem would happen for CONFIG_AS_CFI and CONFIG_AS_ADX since the register in instruction code is machine-bit dependent.

The former is OK wince we are planning to remove it.

We need to handle -m64 for the latter. Otherwise, a problem like commit 3a7c733165a4799fa1 would happen.

So, I think we should merge this
https://lore.kernel.org/patchwork/patch/1214332/
then, fix-up CONFIG_AS_ADX on top of it.

(Or, if we do not need to rush,
we can delete CONFIG_AS_ADX entirely after we bump the binutils version to 2.23)

arch/x86/Makefile tests instruction code by $(call as-instr, ...)

Some of them are very old.
For example, the check for CONFIG_AS_CFI dates back to 2006.

We raise GCC versions from time to time, and we clean old code away. The same policy applied to binutils.

The current minimal supported version of binutils is 2.21

This is new enough to recognize the instruction in most of as-instr calls.

Masahiro Yamada (7):
x86: remove unneeded defined(__ASSEMBLY__) check from asm/dwarf2.h
x86: remove always-defined CONFIG_AS_CFI
x86: remove always-defined CONFIG_AS_CFI_SIGNAL_FRAME
x86: remove always-defined CONFIG_AS_CFI_SECTIONS
x86: remove always-defined CONFIG_AS_SSSE3
x86: remove always-defined CONFIG_AS_AVX
x86: add comments about the binutils version to support code in
as-instr

 arch/x86/Makefile                             | 21 +++------
 arch/x86/crypto/Makefile                      | 32 ++++++--------
 arch/x86/crypto/aesni-intel_avx-x86_64.S      |  3 --
 arch/x86/crypto/aesni-intel_glue.c            | 14 +-----
 arch/x86/crypto/blake2s-core.S                |  2 -
 arch/x86/crypto/poly1305-x86_64-cryptogams.pl |  8 ----
 arch/x86/crypto/poly1305_glue.c               |  6 +--
 arch/x86/crypto/sha1_ssse3_asm.S              |  4 --
 arch/x86/crypto/sha1_ssse3_glue.c             |  9 +---
 arch/x86/crypto/sha256-avx-asm.S              |  3 --
 arch/x86/crypto/sha256_ssse3_glue.c           |  8 +---
 arch/x86/crypto/sha512-avx-asm.S              |  2 -
 arch/x86/crypto/sha512_ssse3_glue.c           |  7 +--
 arch/x86/include/asm/dwarf2.h                 | 43 -------------------
 arch/x86/include/asm/xor_avx.h                |  9 ----
 lib/raid6/algos.c                             |  2 -
 lib/raid6/recov_ssse3.c                       |  6 ---
 lib/raid6/test/Makefile                       |  3 --
 18 files changed, 26 insertions(+), 156 deletions(-)

--
2.17.1

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