On Mon, Jun 22, 2020 at 10:33 PM Nick Desaulniers
<ndesaulniers@xxxxxxxxxx> wrote:
>
> On Mon, Jun 22, 2020 at 8:50 AM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >
> > When building with LLVM_IAS=1 means using Clang's Integrated Assembly (IAS)
> > from LLVM/Clang >= v10.0.1-rc1+ instead of GNU/as from GNU/binutils
> > I see the following breakage in Debian/testing AMD64:
> >
> > <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
>
> === I think from here to...
>
>
> >
> > Craig Topper suggested me in ClangBuiltLinux issue #1050:
> >
> > > I think the "too many positional arguments" is because the parser isn't able
> > > to handle the trailing commas.
> > >
> > > The "unknown use of instruction mnemonic" is because the macro was named
> > > GHASH_4_ENCRYPT_4_PARALLEL_DEC but its being instantiated with
> > > GHASH_4_ENCRYPT_4_PARALLEL_dec I guess gas ignores case on the
> > > macro instantiation, but llvm doesn't.
>
> Yep, see also:
> commit 6f5459da2b87 ("arm64: alternative: fix build with clang
> integrated assembler")
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6f5459da2b8736720afdbd67c4bd2d1edba7d0e3
>
> >
> > First, I removed the trailing comma in the PRECOMPUTE line.
> >
> > Second, I substituted:
> > 1. GCM_ENC_DEC dec -> GCM_ENC_DEC DEC
> > 2. GCM_ENC_DEC enc -> GCM_ENC_DEC ENC
> >
> > With these changes I was able to build with LLVM_IAS=1 and boot on bare metal.
> >
> > As llvm-toolchain I used v10.0.1-rc1+ and v11.0.0-git pre-releases:
> > 1. release/10.x Git: 2dc664d578f0e9c8ea5975eed745e322fa77bffe
> > 2. master Git: 8da5b9083691b557f50f72ab099598bb291aec5f (default)
> >
> > Just for the sake of completeness:
> > 1. CONFIG_DEBUG_INFO_DWARF4=y
> > 2. OBJDUMP=llvm-objdump (passed to my make-line)
> >
> > Please have a look into "llvm.rst" kernel-doc for further informations and
> > how to pass LLVM kbuild-options to your make-line.
> >
> > I confirmed that this works with Linux-kernel v5.7.3 and v5.7.5 final.
> >
> > NOTE: This patch is on top of Linux v5.7 final.
> >
> > Thanks to Craig and the folks from the ClangBuiltLinux project.
>
> ===...here can be cut out from the commit message.
>
> >
> > Cc: Craig Topper <craig.topper@xxxxxxxxx>
> > Cc: Craig Topper <craig.topper@xxxxxxxxx>
>
> I'd pick one or the other email addresses, and just use that one.
> Craig seems to commit to LLVM with craig.topper@xxxxxxxxx, so I
> recommend that one.
>
> > Cc: Nick Desaulniers ndesaulniers@xxxxxxxxxx
>
> Thanks for the explicit CC, though I do monitor the below list actively.
>
> > Cc: "ClangBuiltLinux" <clang-built-linux@xxxxxxxxxxxxxxxx>
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1050
> > Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/kbuild/llvm.rst
>
> ^ probably don't need that link either.
>
> >
> > ---
> > arch/x86/crypto/aesni-intel_asm.S | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
> > index cad6e1bfa7d5..983eb2eec51a 100644
> > --- a/arch/x86/crypto/aesni-intel_asm.S
> > +++ b/arch/x86/crypto/aesni-intel_asm.S
> > @@ -266,7 +266,7 @@ ALL_F: .octa 0xffffffffffffffffffffffffffffffff
> > PSHUFB_XMM %xmm2, %xmm0
> > movdqu %xmm0, CurCount(%arg2) # ctx_data.current_counter = iv
> >
> > - PRECOMPUTE \SUBKEY, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7,
> > + PRECOMPUTE \SUBKEY, %xmm1, %xmm2, %xmm3, %xmm4, %xmm5, %xmm6, %xmm7
> > movdqu HashKey(%arg2), %xmm13
> >
> > CALC_AAD_HASH %xmm13, \AAD, \AADLEN, %xmm0, %xmm1, %xmm2, %xmm3, \
>
>
> There's a comparison on L386
> 386 .ifc \operation, dec
> Also, L407, L393, L672, L808, L841, L935, L941, L947,
>
> If we change the `\operation` macro parameter to be `DEC` instead of
> `dec`, does this comparison still hold true? I would expect not if
> LLVM's integrated assembler is case sensitive? Otherwise we're
> probably missing instructions for the case of `DEC`. In that case,
> that should probably get fixed.
>
> Interesting, looks like GAS *is* case sensitive for `.ifc` directives?
> ```
> $ cat foo.s
> .macro foo op
> .ifc \op, dec
> subq r8, r9
> .else
> addq $0, r8
> .endif
> .endm
> foo DEC
>
> $ clang foo.s -c
> $ llvm-objdump -d foo.o
> ...
> 0: 48 83 04 25 00 00 00 00 00 addq $0, 0
> $ as foo.s -c
> $ llvm-objdump -d foo.o
> ...
> 0: 48 83 04 25 00 00 00 00 00 addq $0, 0
> ```
> In that case, it seems that this patch probably breaks the DEC case
> for both toolchains.
>
> Just to triple check, forgetting LLVM for a minute, let's compare the
> disassembly before and after.
>
> $ make -j71 defconfig
> $ make -j71 menuconfig
> <enable CRYPTO_AES_NI_INTEL>
> $ make -j71 arch/x86/crypto/aesni-intel_asm.o
> $ llvm-objdump -dr arch/x86/crypto/aesni-intel_asm.o > prepatch.txt
> <apply your patch>
> $ make -j71 arch/x86/crypto/aesni-intel_asm.o
> $ llvm-objdump -dr arch/x86/crypto/aesni-intel_asm.o > postpatch.txt
> $ diff -u <(cat prepatch.txt | tr -s ' ' | cut -d ' ' -f 2-) <(cat
> postpatch.txt| tr -s ' ' | cut -d ' ' -f 2-) | less
>
> It's not the easiest to tell, since I should have left off `-r` for
> relocations from objdump, but you can clearly see cases of different
> disassembly. Even the address of labels changes due to missing
> instructions.
>
> In that case, it's probably a smaller change to just renamed the macros
> GHASH_4_ENCRYPT_4_PARALLEL_ENC
> GHASH_4_ENCRYPT_4_PARALLEL_DEC
>
> to
>
> GHASH_4_ENCRYPT_4_PARALLEL_enc
> GHASH_4_ENCRYPT_4_PARALLEL_dec
>
> respectively, though using ALL CAPS is likely more consistent at the
> cost of more lines changed. Also, sorry I didn't catch this on the
> earlier thread; my mistake.
>
> > @@ -1596,7 +1596,7 @@ SYM_FUNC_START(aesni_gcm_dec)
> > FUNC_SAVE
> >
> > GCM_INIT %arg6, arg7, arg8, arg9
> > - GCM_ENC_DEC dec
> > + GCM_ENC_DEC DEC
> > GCM_COMPLETE arg10, arg11
> > FUNC_RESTORE
> > ret
> > @@ -1684,7 +1684,7 @@ SYM_FUNC_START(aesni_gcm_enc)
> > FUNC_SAVE
> >
> > GCM_INIT %arg6, arg7, arg8, arg9
> > - GCM_ENC_DEC enc
> > + GCM_ENC_DEC ENC
> >
> > GCM_COMPLETE arg10, arg11
> > FUNC_RESTORE
> > @@ -1719,7 +1719,7 @@ SYM_FUNC_END(aesni_gcm_init)
> > */
> > SYM_FUNC_START(aesni_gcm_enc_update)
> > FUNC_SAVE
> > - GCM_ENC_DEC enc
> > + GCM_ENC_DEC ENC
> > FUNC_RESTORE
> > ret
> > SYM_FUNC_END(aesni_gcm_enc_update)
> > @@ -1734,7 +1734,7 @@ SYM_FUNC_END(aesni_gcm_enc_update)
> > */
> > SYM_FUNC_START(aesni_gcm_dec_update)
> > FUNC_SAVE
> > - GCM_ENC_DEC dec
> > + GCM_ENC_DEC DEC
> > FUNC_RESTORE
> > ret
> > SYM_FUNC_END(aesni_gcm_dec_update)
> > --
>
Thanks for your feedback and double-checking Nick.
I have submitted a v3 of my patch - should have all relevant material.
- Sedat -
[1] https://lore.kernel.org/lkml/20200623030600.18848-1-sedat.dilek@xxxxxxxxx/
[2] https://lore.kernel.org/patchwork/patch/1261340/
[3] https://github.com/ClangBuiltLinux/linux/issues/1050#issuecomment-647879758
