Hi Robert,
On 4 December 2015 at 15:13, Robert Schiele <rschi...@gmail.com> wrote:
> Hi,
>
> when working with the Linaro patches I found that a particular commit
> breaks our aarch64 kernel build.
>
> The patch in question is that one:
>
> commit be09330da9d0777c4a58568d137e3f8a3dbe0a0b
> Author: Yvan Roux <yvan.r...@linaro.org>
> Date: Tue Oct 27 21:18:19 2015 +0100
>
> One of the things it attempts to change apparently is moving the .arch
> specifiers in the assembler file from a global scope to individual
> functions. What also happens though is that they seem to lose some
> information after that transformation.
>
> I observed that when building arch/arm64/crypto/aes-ce-cipher.c from
> the Linux kernel. This code contains inline assembly like this:
>
> static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const
> src[])
> {
> struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
> struct aes_block *out = (struct aes_block *)dst;
> struct aes_block const *in = (struct aes_block *)src;
> void *dummy0;
> int dummy1;
>
> kernel_neon_begin_partial(4);
>
> __asm__(" ld1 {v0.16b}, %[in] ;"
> " ld1 {v1.2d}, [%[key]], #16 ;"
> " cmp %w[rounds], #10 ;"
> " bmi 0f ;"
> " bne 3f ;"
> " mov v3.16b, v1.16b ;"
> " b 2f ;"
> "0: mov v2.16b, v1.16b ;"
> " ld1 {v3.2d}, [%[key]], #16 ;"
> "1: aesd v0.16b, v2.16b ;"
> " aesimc v0.16b, v0.16b ;"
> "2: ld1 {v1.2d}, [%[key]], #16 ;"
> " aesd v0.16b, v3.16b ;"
> " aesimc v0.16b, v0.16b ;"
> "3: ld1 {v2.2d}, [%[key]], #16 ;"
> " subs %w[rounds], %w[rounds], #3 ;"
> " aesd v0.16b, v1.16b ;"
> " aesimc v0.16b, v0.16b ;"
> " ld1 {v3.2d}, [%[key]], #16 ;"
> " bpl 1b ;"
> " aesd v0.16b, v2.16b ;"
> " eor v0.16b, v0.16b, v3.16b ;"
> " st1 {v0.16b}, %[out] ;"
>
> : [out] "=Q"(*out),
> [key] "=r"(dummy0),
> [rounds] "=r"(dummy1)
> : [in] "Q"(*in),
> "1"(ctx->key_dec),
> "2"(num_rounds(ctx) - 2)
> : "cc");
>
> kernel_neon_end();
> }
>
> Now without this patch the compiler behaved like the following. It was
> invoked with:
>
> aarch64-linux-gnu-gcc -Wp,-MD,arch/arm64/crypto/.aes-ce-cipher.o.d
> -nostdinc -isystem
> /var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/bin/../lib/gcc/aarch64-linux-gnu/5.2.1/include
> -I/var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/arch/arm64/include
> -Iarch/arm64/include/generated/uapi -Iarch/arm64/include/generated
> -I/var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/include
> -Iinclude
> -I/var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/arch/arm64/include/uapi
> -Iarch/arm64/include/generated/uapi
> -I/var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/include/uapi
> -Iinclude/generated/uapi -include
> /var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/include/linux/kconfig.h
>
> -I/var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/arch/arm64/crypto
> -Iarch/arm64/crypto -D__KERNEL__ -mlittle-endian -Wall -Wundef
> -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common
> -Werror-implicit-function-declaration -Wno-format-security -std=gnu89
> -mgeneral-regs-only -fno-delete-null-pointer-checks -O2
> --param=allow-store-data-races=0 -Wframe-larger-than=2048
> -fno-stack-protector -Wno-unused-but-set-variable
> -fno-omit-frame-pointer -fno-optimize-sibling-calls
> -fno-var-tracking-assignments -g -Wdeclaration-after-statement
> -Wno-pointer-sign -fno-strict-overflow -fconserve-stack
> -Werror=implicit-int -Werror=strict-prototypes -Werror=date-time
> -DCC_HAVE_ASM_GOTO -Werror -march=armv8-a+crypto
> -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(aes_ce_cipher)"
> -D"KBUILD_MODNAME=KBUILD_STR(aes_ce_cipher)" -c -o
> arch/arm64/crypto/aes-ce-cipher.o
> /var/fpwork/rschiele/crossbuild/builds/aarch64-linux-gnu/linux-next/srcdir/src/linux/arch/arm64/crypto/aes-ce-cipher.c
>
> As a result it created a file for the assembler with the global
>
> .arch armv8-a+fp+simd+crypto
>
> at the beginning of the file.
>
> After the patch it created individual
>
> .arch armv8-a
>
> at individual places.
>
> It is not clear to me, why the extensions (fp+simd+crypto) got lost.
> Is that intended, such that the code needs special adaption for inline
> assembly using those extensions or is that loss of extensions a bug of
> that patch?
Hmmm, this seems to be triggered by -mgeneral-regs-only flag, at least
on my side, I've to investigate more to give you a real answer, this
backport is not a small one ;) But do you confirm that if you remove
that flag the .arch are correct ?
Thanks,
Yvan
> Greetings!
> Robert
> _______________________________________________
> linaro-toolchain mailing list
> linaro-toolchain@lists.linaro.org
> https://lists.linaro.org/mailman/listinfo/linaro-toolchain
_______________________________________________
linaro-toolchain mailing list
linaro-toolchain@lists.linaro.org
https://lists.linaro.org/mailman/listinfo/linaro-toolchain
