Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 15/15] riscv: add binfmt_flat support
To:     Christoph Hellwig <hch@lst.de>, Greg Ungerer <gerg@linux-m68k.org>
Cc:     uclinux-h8-devel@lists.sourceforge.jp,
        linux-xtensa@linux-xtensa.org, Michal Simek <monstr@monstr.eu>,
        linux-c6x-dev@linux-c6x.org, linux-sh@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
        linux-riscv@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
References: <20190610212015.9157-1-hch@lst.de>
 <20190610212015.9157-16-hch@lst.de>
From:   Vladimir Murzin <vladimir.murzin@arm.com>
Message-ID: <d8d81820-8f0d-d5d0-fa3d-3376ddcc5358@arm.com>
Date:   Tue, 11 Jun 2019 09:16:43 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.0
MIME-Version: 1.0
In-Reply-To: <20190610212015.9157-16-hch@lst.de>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 6/10/19 10:20 PM, Christoph Hellwig wrote:
> Use the generic support with arguments are on the stack.  Same as arm
> and m68k.

Out of curiosity, what is reason for keeping arguments on the stack?

ARM port of uClibc has following comment around manipulating of argv/argc:

        /*
         * uClinux/arm stacks look a little different from normal
         * MMU-full Linux/arm stacks (for no good reason)
         */

So I though it is kind of legacy.

Thanks
Vladimir

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/riscv/Kconfig            | 2 ++
>  arch/riscv/include/asm/Kbuild | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 0c4b12205632..2e3b60cdeef4 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -17,7 +17,9 @@ config RISCV
>  	select OF
>  	select OF_EARLY_FLATTREE
>  	select OF_IRQ
> +	select ARCH_HAS_BINFMT_FLAT
>  	select ARCH_WANT_FRAME_POINTERS
> +	select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
>  	select CLONE_BACKWARDS
>  	select COMMON_CLK
>  	select GENERIC_CLOCKEVENTS
> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
> index 5ee646619cc3..1efaeddf1e4b 100644
> --- a/arch/riscv/include/asm/Kbuild
> +++ b/arch/riscv/include/asm/Kbuild
> @@ -5,6 +5,7 @@ generic-y += compat.h
>  generic-y += device.h
>  generic-y += div64.h
>  generic-y += extable.h
> +generic-y += flat.h
>  generic-y += dma.h
>  generic-y += dma-contiguous.h
>  generic-y += dma-mapping.h
>