Status: Building with Clang's integrated assembler aka LLVM_IAS=1

[dileks]

@nickdesaulniers @nathanchance @tpimh

Hi,

what combination of recent Linux-kernel and recent llvm-toolchain is safe to build with enabled Clang's (I)ntegrated (AS)sembler aka set make-option LLVM_IAS=1?

kernel-doc llvm.rst [1] says:

Currently, the integrated assembler is disabled by default. You can pass LLVM_IAS=1 to enable it.

I am here on Debian/testing AMD64 with Linux v5.7.2 and llvm-toolchain-10 (release/10.x Git branch):

$ clang-10 --version
clang version 10.0.1 (https://github.com/llvm/llvm-project b6efa2365812f31667485c8948d49621ebf952f2)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/dileks/src/llvm-toolchain/install/bin

I have cherry-picked commit 51da9dfb7f20911ae4e79e9b412a9c2d4c373d4b from upstream:

$ git branch --show-current
for-5.7/elfnote-llvm-ias-ndesaulniers

$ git log --oneline v5.7.2..
604f98ca53d6 (HEAD -> for-5.7/elfnote-llvm-ias-ndesaulniers) elfnote: mark all .note sections SHF_ALLOC

Is this enough to have good chances for a successful build?

Thanks in advance.

Regards,

• Sedat -

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/kbuild/llvm.rst#n62

[dileks]

FYI: I have added LLVM_IAS=1 to my make-options and cherry-picked elfnote: mark all .note sections SHF_ALLOC. Let's see...

[dileks]

Short intermezzo:

  clang-10 -Wp,-MD,arch/x86/crypto/.aesni-intel_asm.o.d -nostdinc -isystem /home/dileks/src/llvm-toolchain/install/lib/clang/10.0.1/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -D__KERNEL__ -Qunused-arguments -D__ASSEMBLY__ -fno-PIE -Werror=unknown-warning-option -m64 -Wa,-gdwarf-2 -Wa,--compress-debug-sections=zlib -DCC_USING_FENTRY  -DMODULE  -c -o arch/x86/crypto/aesni-intel_asm.o arch/x86/crypto/aesni-intel_asm.S
arch/x86/crypto/aesni-intel_asm.S:47:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.gf128mul_x_ble_mask, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:51:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.POLY, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:54:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.TWOONE, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:58:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.SHUF_MASK, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:61:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.MASK1, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:64:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.MASK2, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:67:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.ONE, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:70:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.F_MIN_MASK, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:73:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.dec, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:76:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata.cst16.enc, "aM", @progbits, 16
^
arch/x86/crypto/aesni-intel_asm.S:83:1: warning: DWARF2 only supports one section per compilation unit
.section .rodata, "a", @progbits
^
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1598:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1599:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1686:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1687:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:15:67: error: too many positional arguments
 PRECOMPUTE %rcx, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                  ^
arch/x86/crypto/aesni-intel_asm.S:1707:2: note: while in macro instantiation
 GCM_INIT %rdx, %rcx,%r8, %r9
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1722:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1737:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
<instantiation>:2:2: warning: DWARF2 only supports one section per compilation unit
 .pushsection .discard.ignore_alts
 ^
<instantiation>:2:2: note: while in macro instantiation
 ANNOTATE_IGNORE_ALTERNATIVE
 ^
arch/x86/crypto/aesni-intel_asm.S:2761:2: note: while in macro instantiation
 CALL_NOSPEC %r11
 ^
<instantiation>:2:2: warning: DWARF2 only supports one section per compilation unit
 .pushsection .discard.retpoline_safe
 ^
<instantiation>:2:2: note: while in macro instantiation
 ANNOTATE_RETPOLINE_SAFE; call *%r11
 ^
<instantiation>:3:2: note: while in macro instantiation
 ALTERNATIVE_2 "ANNOTATE_RETPOLINE_SAFE; call *%r11", "RETPOLINE_CALL %r11", ( 7*32+12), "lfence; ANNOTATE_RETPOLINE_SAFE; call *%r11", ( 7*32+13)
 ^
arch/x86/crypto/aesni-intel_asm.S:2761:2: note: while in macro instantiation
 CALL_NOSPEC %r11
 ^
<instantiation>:8:2: warning: DWARF2 only supports one section per compilation unit
 .pushsection .altinstructions,"a"
 ^
<instantiation>:3:2: note: while in macro instantiation
 ALTERNATIVE_2 "ANNOTATE_RETPOLINE_SAFE; call *%r11", "RETPOLINE_CALL %r11", ( 7*32+12), "lfence; ANNOTATE_RETPOLINE_SAFE; call *%r11", ( 7*32+13)
 ^
arch/x86/crypto/aesni-intel_asm.S:2761:2: note: while in macro instantiation
 CALL_NOSPEC %r11
 ^
<instantiation>:13:2: warning: DWARF2 only supports one section per compilation unit
 .pushsection .altinstr_replacement,"ax"
 ^
<instantiation>:3:2: note: while in macro instantiation
 ALTERNATIVE_2 "ANNOTATE_RETPOLINE_SAFE; call *%r11", "RETPOLINE_CALL %r11", ( 7*32+12), "lfence; ANNOTATE_RETPOLINE_SAFE; call *%r11", ( 7*32+13)
 ^
arch/x86/crypto/aesni-intel_asm.S:2761:2: note: while in macro instantiation
 CALL_NOSPEC %r11
 ^
make[5]: *** [scripts/Makefile.build:349: arch/x86/crypto/aesni-intel_asm.o] Error 1
make[4]: *** [scripts/Makefile.build:488: arch/x86/crypto] Error 2
make[4]: *** Waiting for unfinished jobs....

[dileks]

I try with:

scripts/config -e DEBUG_INFO_DWARF4

[dileks]

I tried with:

diff --git a/Makefile b/Makefile
index 812f4f1ee764..4d946b996e29 100644
--- a/Makefile
+++ b/Makefile
@@ -803,10 +803,12 @@ DEBUG_CFLAGS      += -gsplit-dwarf
 else
 DEBUG_CFLAGS   += -g
 endif
-KBUILD_AFLAGS  += -Wa,-gdwarf-2
-endif
 ifdef CONFIG_DEBUG_INFO_DWARF4
 DEBUG_CFLAGS   += -gdwarf-4
+KBUILD_AFLAGS  += -Wa,-gdwarf-4
+else
+KBUILD_AFLAGS  += -Wa,-gdwarf-2
+endif
 endif

 ifdef CONFIG_DEBUG_INFO_REDUCED

In my build-log I see:

  clang-10 -Wp,-MD,arch/x86/crypto/.aesni-intel_asm.o.d -nostdinc -isystem /home/dileks/src/llvm-toolchain/install/lib/clang/10.0.1/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -D__KERNEL__ -Qunused-arguments -D__ASSEMBLY__ -fno-PIE -Werror=unknown-warning-option -m64 -Wa,-gdwarf-4 -Wa,--compress-debug-sections=zlib -DCC_USING_FENTRY  -DMODULE  -c -o arch/x86/crypto/aesni-intel_asm.o arch/x86/crypto/aesni-intel_asm.S
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1598:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1599:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1686:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
   ./tools/objtool/objtool orc generate  --no-fp --retpoline --uaccess kernel/user.o
  if objdump -h kernel/user.o | grep -q __ksymtab; then clang-10 -E -D__GENKSYMS__ -Wp,-MD,kernel/.user.o.d -nostdinc -isystem /home/dileks/src/llvm-toolchain/install/lib/clang/10.0.1/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 -Werror=unknown-warning-option -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mstack-alignment=8 -mtune=generic -mno-red-zone -mcmodel=kernel -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -g -gdwarf-4 -gz=zlib -pg -mfentry -DCC_USING_FENTRY -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-array-bounds -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -fmacro-prefix-map=./= -fcf-protection=none -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-tautological-constant-out-of-range-compare    -DKBUILD_MODFILE='"kernel/user"' -DKBUILD_BASENAME='"user"' -DKBUILD_MODNAME='"user"' kernel/user.c | scripts/genksyms/genksyms    -r /dev/null > kernel/.tmp_user.ver; ld.lld-10 -m elf_x86_64  -z max-page-size=0x200000 --compress-debug-sections=zlib -r -o kernel/.tmp_user.o kernel/user.o -T kernel/.tmp_user.ver; mv -f kernel/.tmp_user.o kernel/user.o; rm -f kernel/.tmp_user.ver; fi
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1687:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:15:67: error: too many positional arguments
 PRECOMPUTE %rcx, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                  ^
arch/x86/crypto/aesni-intel_asm.S:1707:2: note: while in macro instantiation
 GCM_INIT %rdx, %rcx,%r8, %r9
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1722:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1737:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
make[5]: *** [scripts/Makefile.build:349: arch/x86/crypto/aesni-intel_asm.o] Error 1

[dileks]

I jumped to latest Linus Git and installed clang-11 and ld.lld-11 from :

$ git describe 
v5.7-14029-gb29482fde649

$ clang-11 --version
Debian clang version 11.0.0-++20200610100654+51a822724da-1~exp1~20200610201314.3290 
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

$ ld.lld-11 --version
LLD 11.0.0 (compatible with GNU linkers)

Instructions:

MAKE="make V=1" ; COMPILER="clang-11" ; LINKER="ld.lld-11" ; MAKE_OPTS="CC=$COMPILER HOSTCC=$COMPILER LD=$LINKER HOSTLD=$LINKER LLVM_IAS=1"

echo $MAKE $MAKE_OPTS
make V=1 CC=clang-11 HOSTCC=clang-11 LD=ld.lld-11 HOSTLD=ld.lld-11 LLVM_IAS=1

$MAKE $MAKE_OPTS defconfig

scripts/config -e CRYPTO_AES_NI_INTEL

scripts/config -s CRYPTO_AES_NI_INTEL
y

$MAKE $MAKE_OPTS arch/x86/crypto/aesni-intel_asm.o 2>&1 | tee ../make-log_clang-11_ld_lld-11_CRYPTO_AES_NI_INTEL-y_LLVM_IAS-1.txt

From my make-log.txt:

  clang-11 -Wp,-MMD,arch/x86/crypto/.aesni-intel_asm.o.d -nostdinc -isystem /usr/lib/llvm-11/lib/clang/11.0.0/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -D__KERNEL__ -Qunused-arguments -D__ASSEMBLY__ -fno-PIE -Werror=unknown-warning-option -m64    -c -o arch/x86/crypto/aesni-intel_asm.o arch/x86/crypto/aesni-intel_asm.S
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1598:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1599:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
<instantiation>:15:74: error: too many positional arguments
 PRECOMPUTE 8*3+8(%rsp), %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                         ^
arch/x86/crypto/aesni-intel_asm.S:1686:2: note: while in macro instantiation
 GCM_INIT %r9, 8*3 +8(%rsp), 8*3 +16(%rsp), 8*3 +24(%rsp)
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1687:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:15:67: error: too many positional arguments
 PRECOMPUTE %rcx, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
                                                                  ^
arch/x86/crypto/aesni-intel_asm.S:1707:2: note: while in macro instantiation
 GCM_INIT %rdx, %rcx,%r8, %r9
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_enc %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1722:2: note: while in macro instantiation
 GCM_ENC_DEC enc
 ^
<instantiation>:47:2: error: unknown use of instruction mnemonic without a size suffix
 GHASH_4_ENCRYPT_4_PARALLEL_dec %xmm9, %xmm10, %xmm11, %xmm12, %xmm13, %xmm14, %xmm0, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7, %xmm8, enc
 ^
arch/x86/crypto/aesni-intel_asm.S:1737:2: note: while in macro instantiation
 GCM_ENC_DEC dec
 ^
make[2]: *** [scripts/Makefile.build:361: arch/x86/crypto/aesni-intel_asm.o] Error 1
make[1]: *** [scripts/Makefile.build:497: arch/x86/crypto] Error 2

[dileks]

Tried with adding LLVM=1 manually:

$ echo $MAKE $MAKE_OPTS
make V=1 CC=clang-11 LD=ld.lld-11 AR=llvm-ar-11 NM=llvm-nm-11 STRIP=llvm-strip-11 OBJCOPY=llvm-objcopy-11 OBJDUMP=llvm-objdump-11 OBJSIZE=llvm-size-11 READELF=llvm-readelf-11 HOSTCC=clang-11 HOSTCXX=clang++-11 HOSTAR=llvm-ar-11 HOSTLD=ld.lld-11 LLVM_IAS=1

The same BROKEN output like above.

[dileks]

@nickdesaulniers

With which version of llvm-toolchain did you had success with LLVM_IAS=1?

[dileks]

I will see how far I get with:

diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
--- a/arch/x86/crypto/Makefile
+++ b/arch/x86/crypto/Makefile
@@ -2,6 +2,8 @@
 #
 # x86 crypto algorithms

+KBUILD_CPPFLAGS += -no-integrated-as
+
 OBJECT_FILES_NON_STANDARD := y

[dileks]

I am building full DWARF4 now and my diff looks like this:

diff --git a/Makefile b/Makefile
index 812f4f1ee764..f37f393cdcf0 100644
--- a/Makefile
+++ b/Makefile
@@ -561,6 +561,10 @@ endif
 CLANG_FLAGS    += -Werror=unknown-warning-option
 KBUILD_CFLAGS  += $(CLANG_FLAGS)
 KBUILD_AFLAGS  += $(CLANG_FLAGS)
+ifdef CONFIG_DEBUG_INFO_DWARF4
+KBUILD_CFLAGS  += -gdwarf-4
+KBUILD_AFLAGS  += -Wa,-gdwarf-4
+endif
 export CLANG_FLAGS
 endif

@@ -803,10 +807,12 @@ DEBUG_CFLAGS      += -gsplit-dwarf
 else
 DEBUG_CFLAGS   += -g
 endif
-KBUILD_AFLAGS  += -Wa,-gdwarf-2
-endif
 ifdef CONFIG_DEBUG_INFO_DWARF4
 DEBUG_CFLAGS   += -gdwarf-4
+KBUILD_AFLAGS  += -Wa,-gdwarf-4
+else
+KBUILD_AFLAGS  += -Wa,-gdwarf-2
+endif
 endif

 ifdef CONFIG_DEBUG_INFO_REDUCED
diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
index a31de0c6ccde..a28810a6a489 100644
--- a/arch/x86/crypto/Makefile
+++ b/arch/x86/crypto/Makefile
@@ -2,6 +2,8 @@
 #
 # x86 crypto algorithms

+KBUILD_CPPFLAGS += -no-integrated-as
+
 OBJECT_FILES_NON_STANDARD := y

 obj-$(CONFIG_CRYPTO_GLUE_HELPER_X86) += glue_helper.o

[dileks]

@nickdesaulniers patch is queued up.

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/log/?h=queue/5.7

[dileks]

Cool, I was able to build with LLVM_IAS=1 and boot on bare metal:

$ cat start-build.txt 
dileks    374356  374337  0 16:45 pts/1    00:00:00 make V=1 CC=clang-10 HOSTCC=clang-10 LD=ld.lld-10 HOSTLD=ld.lld-10 LLVM_IAS=1 -j3 KBUILD_VERBOSE=1 KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@gmail.com KBUILD_BUILD_TIMESTAMP=2020-06-11 LOCALVERSION=-3-amd64-clang bindeb-pkg KDEB_PKGVERSION=5.7.2-3~bullseye+dileks1

$ cat /proc/version 
Linux version 5.7.2-3-amd64-clang (sedat.dilek@gmail.com@iniza) (clang version 10.0.1 (https://github.com/llvm/llvm-project b6efa2365812f31667485c8948d49621ebf952f2), LLD 10.0.1 (https://github.com/llvm/llvm-project b6efa2365812f31667485c8948d49621ebf952f2)) #3~bullseye+dileks1 SMP 2020-06-11

I needed a 2nd hunk to previous diff:

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 5246db42de45..af6cbb746cef 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -3,6 +3,8 @@
 # Makefile for x86 specific library files.
 #

+KBUILD_CPPFLAGS += -no-integrated-as
+
 # Produces uninteresting flaky coverage.
 KCOV_INSTRUMENT_delay.o        := n

En plus, I pulled from tip.git#tags/objtool-core-2020-06-01 and jpoimboe/linux.git#objtool/core to have a recent objtool.

I will see if I add CFLAGS_<objectfile> += -fno-integrated-as to arch/x86/crypto/aesni-intel_asm.o and arch/x86/lib/memcpy_64.o and see which files are really affected.

Sidenote: Without my wrapper-scripts to compiler (uses ccache) and linker ccache I could reduce the build-time by approx one hour.

[nickdesaulniers]

Thanks for the report. I've filed #1050 for the bug (requires additional config beyond defconfig).

For -Wa,-gdwarf-4, that looks good, similar to my suggestion. I plan to fix that up with my local patch set for dwarf-5 support, since I need to modify it anyway.

Without my wrapper-scripts to compiler (uses ccache) and linker ccache I could reduce the build-time by approx one hour.

If you're getting cache misses (new compiler, or not using a deterministic build timestamp) then ccache should be slower than no ccache. The hope is following builds that don't change too much become hotter and build faster.

Also #1043 should be a blocker here as we disabled LLVM_IAS in https://github.com/ClangBuiltLinux/continuous-integration/pull/276 due to it.

Closing for now, we can still follow up here or in #1050

[dileks]

Unsetting above diff makes this visible Error 255:

   ./tools/objtool/objtool orc generate  --no-fp --retpoline --uaccess arch/x86/lib/memcpy_64.o

arch/x86/lib/memcpy_64.o: warning: objtool: memcpy_erms(): can't find starting instruction
make[4]: *** [scripts/Makefile.build:349: arch/x86/lib/memcpy_64.o] Error 255

   ./tools/objtool/objtool orc generate  --no-fp --retpoline --uaccess arch/x86/lib/memset_64.o

arch/x86/lib/memset_64.o: warning: objtool: memset_erms(): can't find starting instruction
make[4]: *** [scripts/Makefile.build:349: arch/x86/lib/memset_64.o] Error 255
make[4]: *** Deleting file 'arch/x86/lib/memset_64.o'
make[3]: *** [Makefile:1741: arch/x86/lib] Error 2

[dileks]

How can I see this is real DWARF4?

[dileks]

My latest diff:

diff --git a/Makefile b/Makefile
index 812f4f1ee764..68ae67cdde29 100644
--- a/Makefile
+++ b/Makefile
@@ -561,6 +561,10 @@ endif
 CLANG_FLAGS    += -Werror=unknown-warning-option
 KBUILD_CFLAGS  += $(CLANG_FLAGS)
 KBUILD_AFLAGS  += $(CLANG_FLAGS)
+ifdef LLVM_IAS
+KBUILD_CFLAGS  += -gdwarf-4
+KBUILD_AFLAGS  += -Wa,-gdwarf-4
+endif
 export CLANG_FLAGS
 endif

@@ -803,10 +807,15 @@ DEBUG_CFLAGS      += -gsplit-dwarf
 else
 DEBUG_CFLAGS   += -g
 endif
+ifndef LLVM_IAS
 KBUILD_AFLAGS  += -Wa,-gdwarf-2
 endif
+endif
 ifdef CONFIG_DEBUG_INFO_DWARF4
 DEBUG_CFLAGS   += -gdwarf-4
+ifdef LLVM_IAS
+KBUILD_AFLAGS  += -Wa,-gdwarf-4
+endif
 endif

 ifdef CONFIG_DEBUG_INFO_REDUCED
diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
index a31de0c6ccde..bd5be603fdf3 100644
--- a/arch/x86/crypto/Makefile
+++ b/arch/x86/crypto/Makefile
@@ -2,6 +2,10 @@
 #
 # x86 crypto algorithms

+ifdef LLVM_IAS
+KBUILD_CPPFLAGS += -no-integrated-as
+endif
+
 OBJECT_FILES_NON_STANDARD := y

 obj-$(CONFIG_CRYPTO_GLUE_HELPER_X86) += glue_helper.o
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 5246db42de45..619107bec0d9 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -3,6 +3,10 @@
 # Makefile for x86 specific library files.
 #

+ifdef LLVM_IAS
+KBUILD_CPPFLAGS += -no-integrated-as
+endif
+
 # Produces uninteresting flaky coverage.
 KCOV_INSTRUMENT_delay.o        := n

[nickdesaulniers]

How can I see this is real DWARF4?

llvm-dwarfdump will print the version as one of very first few lines it prints. Not easy to see, it in a list, IIRC.

[dileks]

Thanks.

I see with llvm-dwarfdump DWARF version = 0x0004 (here: vmlinux.o)

$ llvm-dwarfdump vmlinux.o | head -5
vmlinux.o:      file format ELF64-x86-64

.debug_info contents:
0x00000000: Compile Unit: length = 0x000003a3 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x000003a7)

[dileks]

@masahir0y commented in the thread [1]:

"x86/crypto: Set -no-integrated-as for specific object-file when building with LLVM_IAS=1"

The source file is .S (assembly file), so

AFLAGS_aes_ctrby8_avx-x86_64.o += -no-integrated-as

Or,

asflags-y += -no-integrated-as

, which is effective for all .S files in the directory.

Here you have another example I use to dig into LLVM_IAS=1 issues in arch/x86/lib:

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 619107bec0d9..2c07cc651d52 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -3,10 +3,6 @@
 # Makefile for x86 specific library files.
 #

-ifdef LLVM_IAS
-KBUILD_CPPFLAGS += -no-integrated-as
-endif
-
 # Produces uninteresting flaky coverage.
 KCOV_INSTRUMENT_delay.o        := n

@@ -39,6 +35,9 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 lib-y := delay.o misc.o cmdline.o cpu.o
 lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o
+ifdef LLVM_IAS
+AFLAGS_memcpy_$(BITS).o += -no-integrated-as
+endif
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
 lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
 lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
@@ -62,6 +61,9 @@ else
         lib-y += csum-partial_64.o csum-copy_64.o csum-wrappers_64.o
         lib-y += clear_page_64.o copy_page_64.o
         lib-y += memmove_64.o memset_64.o
+        ifndef LLVM_IAS
+        AFLAGS_memset_64.o += -no-integrated-as
+        endif
         lib-y += copy_user_64.o
        lib-y += cmpxchg16b_emu.o
 endif

[1] https://lore.kernel.org/r/CAK7LNAQuiuj5UifVBYEN7Xkp5GH0RNiWc5F3VyA1BAjGAUhqhw@mail.gmail.com/ [2] https://lore.kernel.org/r/CA+icZUX20_yarSs7fJWq6Sxy3xBaeUXSQjmMbjcQFXB4JnyijA@mail.gmail.com/

[dileks]

@nickdesaulniers

Can you comment on my DWARF-4 settings? I have seen doubles in the make-lines.

Does KBUILD_AFLAGS += -Wa,-gdwarf-4 make sense to you? Is this only useful in the DEBUG section of the toplevel Makefile?

IMHO the settings in the first block can go away? I wanted to force DWARF-4 in the complete build.

What about the second block?

[ Makefile ]

ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
ifneq ($(CROSS_COMPILE),)
CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)
GCC_TOOLCHAIN   := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
endif
ifneq ($(GCC_TOOLCHAIN),)
CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN)
endif
ifneq ($(LLVM_IAS),1)
CLANG_FLAGS += -no-integrated-as
endif
CLANG_FLAGS += -Werror=unknown-warning-option
KBUILD_CFLAGS   += $(CLANG_FLAGS)
KBUILD_AFLAGS   += $(CLANG_FLAGS)
ifdef LLVM_IAS
KBUILD_CFLAGS   += -gdwarf-4
KBUILD_AFLAGS   += -Wa,-gdwarf-4
endif
export CLANG_FLAGS
endif

...

ifdef CONFIG_DEBUG_INFO
ifdef CONFIG_DEBUG_INFO_SPLIT
DEBUG_CFLAGS    += -gsplit-dwarf
else
DEBUG_CFLAGS    += -g
endif
ifndef LLVM_IAS
KBUILD_AFLAGS   += -Wa,-gdwarf-2
endif
endif
ifdef CONFIG_DEBUG_INFO_DWARF4
DEBUG_CFLAGS    += -gdwarf-4
ifdef LLVM_IAS
KBUILD_AFLAGS   += -Wa,-gdwarf-4
endif
endif

[dileks]

3.10 Options for Debugging Your Program [1] says:

-g

Produce debugging information in the operating system’s native format (stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging information.

On most systems that use stabs format, -g enables use of extra debugging information that only GDB can use; this extra information makes debugging work better in GDB but probably makes other debuggers crash or refuse to read the program. If you want to control for certain whether to generate the extra information, use -gstabs+, -gstabs, -gxcoff+, -gxcoff, or -gvms (see below).

-gdwarf -gdwarf-version

Produce debugging information in DWARF format (if that is supported). The value of version may be either 2, 3, 4 or 5; the default version for most targets is 4. DWARF Version 5 is only experimental.

Note that with DWARF Version 2, some ports require and always use some non-conflicting DWARF 3 extensions in the unwind tables.

Version 4 may require GDB 7.0 and -fvar-tracking-assignments for maximum benefit.

GCC no longer supports DWARF Version 1, which is substantially different than Version 2 and later. For historical reasons, some other DWARF-related options such as -fno-dwarf2-cfi-asm) retain a reference to DWARF Version 2 in their names, but apply to all currently-supported versions of DWARF.

[1] https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html

[E5ten]

With the patches to fix syntax in arch/x86/crypto/aes{ni-intel_asm,_ctrby8_avx-x86_64}.S, the patch to switch the use of movzxw->movzwq, and individually adding CFLAGS_initramfs.o += -no-integrated-as to init/Makefile and CFLAGS_elfcore.o += -no-integrated-as to kernel/Makefile to avoid https://github.com/ClangBuiltLinux/linux/issues/981, I can build an x86 kernel with LLVM_IAS=1, so once those changes are upstreamed and the linked issue is solved, we should be able to build an x86 kernel with integrated-as.

[dileks]

[ REPORT 2020-06-14 by dileks ]

[ DISCLAIMER ]

I collect here my experiences and want to share them with you. Please do not close this issue - thanks.

THIS IS STILL EXPERIMENTAL - USE AT YOUR OWN RISK!

My work is in collaboration with ClangBuiltLinux folks.

[ MY PERSONAL DISCLAIMER ]

To say with the words of the author of curl and DOH (keynote @ FOSDEM 2019): I do this for me - It has to work for me - in my environment - *first*.

Second, even experimental work has to boot on bare metal - my bare metal.

It has to build in my environment using latest "stable" Linux-Kernel and "stable" llvm-toolchain.

1. Debian/testing AMD64 with daily APT upgrades (plus selected packages from Debian/unstable)
2. Linux-kernel: v5.7.2 + queue-5.7 2020-06-11 includes @nickdesaulniers elfnote patch
3. llvm-toolchain: releas/10.x Git up to commit 2dc664d578f0e9c8ea5975eed745e322fa77bffe
4. apt.llvm.org: Debian packages version 1:10.0.1~++20200612013218+2dc664d578f-1~exp1~20200611233837.179

[ STATUS ]

This is the status from 14-Jun-2020.

[ LLVM_IAS PATCHSET ]

1. PREREQ: @nickdesaulniers elfnote patch (in Linus tree and linux-stable-rc.git#queue-5.7)
2. Explicitly use DWARF version 4: CONFIG_DEBUG_INFO_DWARF4=y, /me has set assembler-option for dwarf4 when CONFIG_DEBUG_INFO_DWARF4=y
3. make: Use clang-10 compiler and ld.lld-10 linker plus LLVM_IAS=1 and new OBJDUMP=llvm-objdump (@arndb patch)
4. x86/crypto: All solved - with known patches or diffs from @nickdesaulniers, @tpimh, @arndb, @jcai19 and @dileks (with suggested-by @topperc)
5. x86/lib: Workaround objtool errors in memcpy_64 and memset_64 with -no-integrated-as assembler-option (thanks @masahir0y)

NOTE: Contacted Linux/objtool maintainers: Peter Zijlstra is inspecting my .o files NOTE: Dropped objtool stuff from upstream-5.8 + jpoimboe-Git (did not help - still see the same objtool errors)

[ KNOWN ISSUES @dileks ]

[ MINIMAL PATCHSET ]

XXX: TODO: Sort out relevant patches only XXX: TODO: Create patches for upstream - with help of CBL folks - respect credits XXX: TODO: Collect feedback - the more the better - Thanks @E5ten

NOTE: I started to label patches with "llvm-ias:" and/or add "when building with LLVM_IAS=1" which is IMHO too long.

[ SELFMADE TOOLCHAIN VS. APT.LLVM.ORG ]

NOTE: Same version!

XXX: TODO: Uninstall/Disable selfmade toolchain and use the Debian packages only - strategy?

[ KERN.LOG - c-index-test ]

When building a selfmade toolchain I see with c-index-test:

traps: clang[...] trap invalid opcode ip:[...] sp:[...] error:0 in clang-10[...+...]

XXX: REPRODUCIBLE

[ ZSTD-INITRAMFS ]

When creating a new initramfs with zstd-support under a LLVM_IAS+llvm-objdump kernel I see:

Message from syslogd@iniza at Jun 14 10:21:43 ... kernel:[ 2427.576669] traps: PANIC: double fault, error_code: 0x0

REPRODUCER: root# update-initramfs -c -k $(uname -r) -v 2>&1 | tee logupdate-initramfs$(uname -r).txt

XXX: REPRODUCIBLE

XXX: TODO: post syslog_20200614.txt (Call Trace: )

[ crypto/algapi.c - crypto_wait_for_test ]

WARNING: CPU: 2 PID: 255 at crypto/algapi.c:404 crypto_wait_for_test

NOTE: I have some crypto-algo kconfigs enabled as modules.

Tried to fix with cherry-picked upstream commits:

1. beeb460cd12ac9b91640b484b6a52dcba9d9fc8f ("crypto: algapi - Avoid spurious modprobe on LOADED")
2. ec6e2bf33b54cc3351bd702452e5d016b8f9d2f4 ("crypto: algapi - create function to add request in front of queue")

XXX: REPRODUCIBLE (seen on each boot; upstream-5.8 patches did not help)

XXX: TODO: Contact Linux/crypto maintainers XXX: TODO: post BROKEN_dmesg-x86-crypto-llvm_ias-1.txt

[ KDE/PLASMA ]

See several crashes "signald" shown in a infobox (see above zstd/initramfs etc.)

XXX: REPRODUCIBLE

[ CBL ISSUE-TRACKER ]

LINK: https://github.com/ClangBuiltLinux/linux/issues/1049 LINK: https://github.com/ClangBuiltLinux/linux/issues/1050 LINK: https://github.com/ClangBuiltLinux/linux/issues/1010 LINK: https://github.com/ClangBuiltLinux/linux/issues/1008 LINK: https://github.com/ClangBuiltLinux/continuous-integration/blob/master/patches/llvm-all/linux-next/arm64/silence-dwarf2-warnings.patch

[ THANKS ]

Thanks for using llvm-toolchain to build the Linux-kernel and your time and patience to answer my question.

My special thank-you to (in no preferential order): @nickdesaulniers, @tpimh, @arndb, @jcai19, @topperc, @masahir0y, @nathanchance, @E5ten

Of course not to forget the people behind cbl/continuous-ci and all contributors to llvm/clang/lld/llvm-tools... ...and the Linux/x86 coding monsters.

[ YOUR FEEDBACK ]

You are welcome.

[dileks]

This patchset is from my for-5.7/x86-llvm-ias-dileks-v3 Git branch (on top of Linux v5.7.2):

1. [PATCH] kbuild: llvm-ias: Silence dwarf-2 warning
2. [PATCH] kbuild: llvm-ias: Add -Wa,-gdwarf-4 assembler option when CONFIG_DEBUG_INFO_DWARF4=y
3. [PATCH] x86/crypto: aesni-intel: Fix build with LLVM_IAS=1
4. [PATCH] x86/64/crypto: aesni-intel: Fix build with LLVM_IAS=1
5. [PATCH] x86/64/crypto: crc32c-intel: Fix build with LLVM_IAS=1
6. [PATCH] x86/lib: memcpy_64: Build with -no-integrated-as assembler option when LLVM_IAS=1
7. [PATCH] x86/lib: memset_64: Build with -no-integrated-as assembler option when LLVM_IAS=1

NOTE: This patchset does not respect any credits yet - take it as-is - status: WIP.

Feedback is welcome.

@E5ten Can you test with this patchset? As said you need the patch from [1].

[1] https://git.kernel.org/linus/51da9dfb7f20911ae4e79e9b412a9c2d4c373d4b [2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/log/?h=queue/5.7 [3] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?h=queue/5.7&id=e5aa55eb3a10d354eb16af98a73bb448af623abf

0001-kbuild-llvm-ias-Silence-dwarf-2-warning_patch.txt 0002-kbuild-llvm-ias-Add-Wa-gdwarf-4-assembler-option-whe_patch.txt 0003-x86-crypto-aesni-intel-Fix-build-with-LLVM_IAS-1_patch.txt 0004-x86-64-crypto-aesni-intel-Fix-build-with-LLVM_IAS-1_patch.txt 0005-x86-64-crypto-crc32c-intel-Fix-build-with-LLVM_IAS-1_patch.txt 0006-x86-lib-memcpy_64-Build-with-no-integrated-as-assemb_patch.txt 0007-x86-lib-memset_64-Build-with-no-integrated-as-assemb_patch.txt

[dileks]

Add my latest Linux-kernel config.

config-5.7.2-7-amd64-clang.txt

[dileks]

Maybe this is shorter (commit-subject):

kbuild: Silence dwarf-2 warning when LLVM_IAS=1
kbuild: Add dwarf-4 assembler option when LLVM_IAS=1
x86/crypto: aesni: Fix build with LLVM_IAS=1
x86/64/crypto: aesni: Fix build with LLVM_IAS=1
x86/64/crypto: crc32c: Fix build with LLVM_IAS=1
x86/lib: memcpy_64: Build with -no-integrated-as when LLVM_IAS=1
x86/lib: memset_64: Build with -no-integrated-as when LLVM_IAS=1

UPDATE: Add patchset v5

0001-kbuild-Silence-dwarf-2-warning-when-LLVM_IAS-1_patch.txt 0002-kbuild-Add-dwarf-4-assembler-option-when-LLVM_IAS-1_patch.txt 0003-x86-crypto-aesni-Fix-build-with-LLVM_IAS-1_patch.txt 0004-x86-64-crypto-aesni-Fix-build-with-LLVM_IAS-1_patch.txt 0005-x86-64-crypto-crc32c-Fix-build-with-LLVM_IAS-1_patch.txt 0006-x86-lib-memcpy_64-Build-with-no-integrated-as-when-LLVM_IAS-1_patch.txt 0007-x86-lib-memset_64-Build-with-no-integrated-as-when-LLVM_IAS-1_patch.txt

[dileks]

CFLAGS_initramfs.o += -no-integrated-as

According to @masahir0y this should be:

AFLAGS_initramfs.o += -no-integrated-as

Why did you need this? What did you try to fix?

UPDATE: @E5ten you are right - it is an .o file not .S file (CFLAGS_initramfs.o line is correct).

[dileks]

@E5ten

I added init/Makefile: initramfs: Build with -no-integrated-as when LLVM_IAS=1to my patchset v6.

UPDATE: Add patch 0008 v2 (based on feedback from @E5ten)

0008-init-Makefile-initramfs-Build-with-no-integrated-as-when-LLVM_IAS-1-v2_patch.txt

[E5ten]

@dileks I think you'll need the same for kernel/elfcore.o, I get the same issue as init/initramfs.o (#981) with it.

[dileks]

@E5ten

Can you describe your build environment: Linux-kernel and llvm-toolchain versions? What versions of clang and llvm-tools like lld or llvm-objdump do you use? kernel-config?

You tried with @nickdesaulniers elfnote patch?

I do not see any Cannot find symbol for section 2: .text in my logs.

[E5ten]

@nathanchance in the linked issue described steps to reproduce

[dileks]

Sorry, I tried with your both workarounds - I still see the crypto/algapi call-trace in dmesg and on update-initramfs the syslog double faults.

BTW, I do not use LLVM=1 - only OBJDUMP=llvm-objdump.

Seems to me a different issue.

[dileks]

Out of curiosity I build with LLVM=1 and LLVM_IAS=1 and will report later.

Patchset on top of Linux v5.7.2:

elfnote: mark all .note sections SHF_ALLOC
kbuild: Silence dwarf-2 warning when LLVM_IAS=1
kbuild: Add dwarf-4 assembler option when LLVM_IAS=1
x86/crypto: aesni: Fix build with LLVM_IAS=1
x86/64/crypto: aesni: Fix build with LLVM_IAS=1
x86/64/crypto: crc32c: Fix build with LLVM_IAS=1
x86/lib: memcpy_64: Build with -no-integrated-as when LLVM_IAS=1
x86/lib: memset_64: Build with -no-integrated-as when LLVM_IAS=1
init: initramfs: Build with -no-integrated-as when LLVM=1 and LLVM_IAS=1
kernel: elfcore: Build with -no-integrated-as when LLVM=1 and LLVM_IAS=1

UPDATE: 2020-06-15: Awesome. Build and boot on bare metal OK.

[dileks]

Workaround makes the crypro-manager tests warnings go away:

scripts/config -e CRYPTO_MANAGER_DISABLE_TESTS

[dileks]

On spec of the traps: warnings in the syslog I cherry-picked:

lib/bsearch: Provide __always_inline variant
x86/int3: Inline bsearch()

Nope.

[dileks]

For now I did:

Revert "x86/64/crypto: aesni: Fix build with LLVM_IAS=1"
x86/64/crypto: aesni: Build with -no-integrated-as when LLVM_IAS=1

Unsure, if the patch is not correct or simply set scripts/config -e CRYPTO_MANAGER_DISABLE_TESTS.

See also #1003

[E5ten]

@dileks With the same list of changes that I successfully built with before, I just confirmed I could boot. I don't seem to need to disable integrated-as for mem{cpy,set}_64 though, I didn't have any build issues there. What's the problem you have building those with integrated-as?

[dileks]

With the above applied I see in my logs:

[Mon Jun 15 17:09:39 2020] AES CTR mode by8 optimization enabled
[Mon Jun 15 17:09:39 2020] alg: aead: rfc4106-gcm-aesni encryption test failed (wrong result) on test vector 0, cfg="two even aligned splits"
[Mon Jun 15 17:09:39 2020] alg: aead: generic-gcm-aesni encryption test failed (wrong result) on test vector 1, cfg="two even aligned splits"
[Mon Jun 15 17:09:40 2020] alg: No test for fips(ansi_cprng) (fips_ansi_cprng)

$ git grep -E 'generic-gcm-aesni|rfc4106-gcm-aesni' arch/x86/crypto/
arch/x86/crypto/aesni-intel_glue.c:             .cra_driver_name        = "__rfc4106-gcm-aesni",
arch/x86/crypto/aesni-intel_glue.c:             .cra_driver_name        = "__generic-gcm-aesni",

Maybe we should workaround -no-integrated-as for all aesni-intel*.o or only aesni-intel_glue.o:

[ arch/x86/crypto/Makefile ]

obj-$(CONFIG_CRYPTO_AES_NI_INTEL) += aesni-intel.o
aesni-intel-y := aesni-intel_asm.o aesni-intel_glue.o
aesni-intel-$(CONFIG_64BIT) += aesni-intel_avx-x86_64.o aes_ctrby8_avx-x86_64.o
ifdef LLVM_IAS
AFLAGS_aes_ctrby8_avx-x86_64.o += -no-integrated-as
AFLAGS_aesni-intel_glue.o += -no-integrated-as
endif

[dileks]

@dileks With the same list of changes that I successfully built with before, I just confirmed I could boot. I don't seem to need to disable integrated-as for mem{cpy,set}_64 though, I didn't have any build issues there. What's the problem you have building those with integrated-as?

objtool issues with mem{cpy,set}_64:

clang-10 -Wp,-MD,arch/x86/lib/.memset_64.o.d -nostdinc -isystem /home/dileks/src/llvm-toolchain/install/lib/clang/10.0.1/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -DKERNEL -Qunused-arguments -DASSEMBLY -fno-PIE -Werror=unknown-warning-option -Wa,-gdwarf-4 -m64 -Wa,-gdwarf-4 -Wa,--compress-debug-sections=zlib -DCC_USING_FENTRY -c -o arch/x86/lib/memset_64.o arch/x86/lib/memset_64.S ./tools/objtool/objtool orc generate --no-fp --retpoline --uaccess arch/x86/lib/memset_64.o arch/x86/lib/memset_64.o: warning: objtool: memset_erms(): can't find starting instruction make[4]: [scripts/Makefile.build:349: arch/x86/lib/memset_64.o] Error 255 make[4]: Deleting file 'arch/x86/lib/memset_64.o'

Which clang and llvm-tools version do you use? Which Linux-kernel version?

[E5ten]

llvm from git, it seems my current build is from commit https://github.com/llvm/llvm-project/commit/63959803702c66cbd72f6526f43914039c1a027b, nothing special about that commit, just when I happened to pull and build.

[dileks]

OK, I am here at latest release/10.x Git 2dc664d578f0e9c8ea5975eed745e322fa77bffe.

Thanks for the commit-id.

[1] https://github.com/llvm/llvm-project/commits/release/10.x [2] https://github.com/llvm/llvm-project/commit/2dc664d578f0e9c8ea5975eed745e322fa77bffe

[dileks]

@E5ten

You build your llvm-toolchain by yourself or do you use tc-build?

[1] https://github.com/ClangBuiltLinux/tc-build

[dileks]

@E5ten

You see any aesni and/or crc32c warnings in the logs?

If not, I should update my llvm-toolchain :-).

[E5ten]

Build it myself.

[dileks]

@E5ten

Linux? Today, I saw Linux v5.8-rc1 was released.

[E5ten]

5.7.2

[dileks]

@E5ten

You see no problems with the diff from #1008?

[dileks]

I switched over to latest known GOOD_REVISION = '8a5aea7b50429cd4a459511286a7a9f1a7f4f5e2' in tc-build.

tc-build says:

HEAD is now at 8a5aea7b5042 [X86][AVX] Fold extract_subvector(subv_broadcast(x),c) -> (x)

[1] https://github.com/ClangBuiltLinux/tc-build/blob/master/build-llvm.py#L20 [2] https://github.com/ClangBuiltLinux/tc-build/blob/master/build-llvm.py#L269

[dileks]

@E5ten

With llvm Git 8a5aea7b5042 memcpy_64/memset_64 is OK.

$ clang --version
clang version 11.0.0 (https://github.com/llvm/llvm-project 8a5aea7b50429cd4a459511286a7a9f1a7f4f5e2)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/dileks/src/llvm-toolchain/install/bin

$ ld.lld --version
LLD 11.0.0 (https://github.com/llvm/llvm-project 8a5aea7b50429cd4a459511286a7a9f1a7f4f5e2) (compatible with GNU linkers)

[dileks]

Ah I see CC_HAS_ASM_INLINE y with clang-11:

$ scripts/diffconfig /boot/config-5.7.2-1-amd64-clang .config
 BUILD_SALT "5.7.2-1-amd64-clang" -> "5.7.2-12-amd64-clang"
 CLANG_VERSION 100001 -> 110000
 DEBUG_INFO_DWARF4 n -> y
+CC_HAS_ASM_INLINE y
+TOOLS_SUPPORT_RELR y

[dileks]

I build with LLVM=1 and LLVM_IAS=1 using llvm-toolchain Git 8a5aea7b50429cd4a459511286a7a9f1a7f4f5e2 and this patchset:

elfnote: mark all .note sections SHF_ALLOC

kbuild: Silence dwarf-2 warning when LLVM_IAS=1
kbuild: Add dwarf-4 assembler option when LLVM_IAS=1
x86/crypto: aesni: Fix build with LLVM_IAS=1
x86/64/crypto: crc32c: Fix build with LLVM_IAS=1
x86/64/crypto: aesni: aes_ctrby8: Build with -no-integrated-as when LLVM_IAS=1

init: initramfs: Build with -no-integrated-as when LLVM=1 and LLVM_IAS=1
kernel: elfcore: Build with -no-integrated-as when LLVM=1 and LLVM_IAS=1