linux-kernel - Re: [PATCH 2/4] arm64/process: Make loading of 32bit processes depend on aarch32

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Message-ID: <ZS_VJ29tFbEwNHAS@FVFF77S0Q05N.cambridge.arm.com>
Date:   Wed, 18 Oct 2023 13:52:55 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Andrea della Porta <andrea.porta@...e.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        nik.borisov@...e.com
Subject: Re: [PATCH 2/4] arm64/process: Make loading of 32bit processes
 depend on aarch32_enabled()

On Wed, Oct 18, 2023 at 01:13:20PM +0200, Andrea della Porta wrote:
> Major aspect of Aarch32 emulation is the ability to load 32bit
> processes.
> That's currently decided (among others) by compat_elf_check_arch().
> 
> Make the macro use aarch32_enabled() to decide if Aarch32 compat is
> enabled before loading a 32bit process.
> 
> Signed-off-by: Andrea della Porta <andrea.porta@...e.com>

Why can't you make system_supports_32bit_el0() take the option into account
instead?

Mark.

> ---
>  arch/arm64/kernel/process.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 657ea273c0f9..96832f1ec3ee 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -601,7 +601,7 @@ unsigned long arch_align_stack(unsigned long sp)
>  #ifdef CONFIG_COMPAT
>  int compat_elf_check_arch(const struct elf32_hdr *hdr)
>  {
> -	if (!system_supports_32bit_el0())
> +	if (!system_supports_32bit_el0() || !aarch32_enabled())
>  		return false;
>  
>  	if ((hdr)->e_machine != EM_ARM)
> -- 
> 2.35.3
>