Subject: [PATCH v5 2/2] arm64: Work around Falkor erratum 1009

From: [email-masked] (Will Deacon)
Date: Tue, 31 Jan 2017 14:38:44 +0000

On Mon, Jan 30, 2017 at 06:08:17PM -0500, Christopher Covington wrote:
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index deab52374119..fc434f421c7b 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -36,9 +36,21 @@
>   * not. The macros handles invoking the asm with or without the
>   * register argument as appropriate.
>   */
> -#define __TLBI_0(op, arg)		asm ("tlbi " #op)
> -#define __TLBI_1(op, arg)		asm ("tlbi " #op ", %0" : : "r" (arg))
> -#define __TLBI_N(op, arg, n, ...)	__TLBI_##n(op, arg)
> +#define __TLBI_0(op, arg) asm volatile ("tlbi " #op "\n"		       \
> +			    ALTERNATIVE("nop\n		nop",		       \
> +					"dsb ish\n	tlbi " #op,	       \
> +					ARM64_WORKAROUND_REPEAT_TLBI,	       \
> +					CONFIG_QCOM_FALKOR_ERRATUM_1009)       \
> +			    : : )
> +
> +#define __TLBI_1(op, arg) asm volatile ("tlbi " #op ", %0\n"		       \
> +			    ALTERNATIVE("nop\n		nop",		       \
> +					"dsb ish\n	tlbi " #op ", %0",     \
> +					ARM64_WORKAROUND_REPEAT_TLBI,	       \
> +					CONFIG_QCOM_FALKOR_ERRATUM_1009)       \
> +			    : : "r" (arg))
> +

Why are these now volatile? I asked the same question on the previous
version but didn't get a response:

http://lists.infradead.org/pipermail/linux-arm-kernel/2017-January/483579.html

Will