Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled

From	Will Deacon <will.deacon@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled
Date	2015-12-21 13:40 +0100
Message-ID	<qI7US-6vn-9@gated-at.bofh.it> (permalink)
References	<qHh9T-6J4-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote:
> The problem here is that GCC 6 and above emits .arch now
> for each function so now the global .arch_extension has
> no effect.  This fixes the problem by putting
> .arch_extension inside ARM64_LSE_ATOMIC_INSN so
> it is enabled for each place where LSE is used.

Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64.
.arch_extension is used for virt, mp and sec over there, and it may be
tricky to isolate the actual instruction usage (at least, virt looks
lost in kvm/arm.c).

Why can't gas have an option to accept all instruction encodings that it
knows about, inspite of any .arch directives?

Will

> Signed-off-by: Andrew Pinski <apinski@cavium.com>
> ---
>  arch/arm64/include/asm/lse.h |    4 +---
>  1 files changed, 1 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h
> index 3de42d6..625601f 100644
> --- a/arch/arm64/include/asm/lse.h
> +++ b/arch/arm64/include/asm/lse.h
> @@ -17,8 +17,6 @@
>  
>  #else	/* __ASSEMBLER__ */
>  
> -__asm__(".arch_extension	lse");
> -
>  /* Move the ll/sc atomics out-of-line */
>  #define __LL_SC_INLINE
>  #define __LL_SC_PREFIX(x)	__ll_sc_##x
> @@ -29,7 +27,7 @@ __asm__(".arch_extension	lse");
>  
>  /* In-line patching at runtime */
>  #define ARM64_LSE_ATOMIC_INSN(llsc, lse)				\
> -	ALTERNATIVE(llsc, lse, ARM64_HAS_LSE_ATOMICS)
> +	ALTERNATIVE(".arch_extension        lse\n" llsc, lse, ARM64_HAS_LSE_ATOMICS)
>  
>  #endif	/* __ASSEMBLER__ */
>  #else	/* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
> -- 
> 1.7.2.5
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
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Thread

[PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Andrew Pinski <apinski@cavium.com> - 2015-12-19 05:20 +0100
  Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Will Deacon <will.deacon@arm.com> - 2015-12-21 13:40 +0100
    Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-12-21 13:50 +0100
      Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-12-21 14:00 +0100
        Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Will Deacon <will.deacon@arm.com> - 2015-12-21 14:40 +0100
      Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Will Deacon <will.deacon@arm.com> - 2015-12-21 14:00 +0100
      Re: [PATCH] ARM64: Fix compiling with GCC 6 and Atomics enabled Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-21 14:10 +0100

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