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Date:   Tue, 9 Jun 2020 21:35:03 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Will Deacon <will@kernel.org>, Stephen Boyd <swboyd@google.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Dave Martin <Dave.Martin@arm.com>,
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        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
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        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH v2] arm64: vdso32: add CONFIG_THUMB2_COMPAT_VDSO
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On Mon, Jun 08, 2020 at 01:57:08PM -0700, Nick Desaulniers wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7f9d38444d6d..fe9e6b231cac 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1299,6 +1299,14 @@ config COMPAT_VDSO
>  	  You must have a 32-bit build of glibc 2.22 or later for programs
>  	  to seamlessly take advantage of this.
>  
> +config THUMB2_COMPAT_VDSO
> +	bool "Compile the vDSO in THUMB2 mode"
> +	depends on COMPAT_VDSO
> +	default y
> +	help
> +	  Compile the compat vDSO with -mthumb -fomit-frame-pointer if y, otherwise
> +	  as -marm.

Now that we understood the issue (I think), do we actually need this
choice? Why not going for -mthumb -fomit-frame-pointer always for the
compat vdso?

-- 
Catalin