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Date: Thu, 7 Nov 2013 08:51:51 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        David Long <dave.long@linaro.org>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [GIT PULL] uprobes: preparations for arm port
Message-ID: <20131107075151.GB31560@gmail.com>
References: <20131106191913.GA18661@redhat.com>
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* Oleg Nesterov <oleg@redhat.com> wrote:

> --- a/arch/powerpc/include/asm/uprobes.h
> +++ b/arch/powerpc/include/asm/uprobes.h
> @@ -37,6 +37,7 @@ typedef ppc_opcode_t uprobe_opcode_t;
>  struct arch_uprobe {
>  	union {
>  		u8	insn[MAX_UINSN_BYTES];
> +		u8	ixol[MAX_UINSN_BYTES];
>  		u32	ainsn;
>  	};
>  };

> --- a/arch/x86/include/asm/uprobes.h
> +++ b/arch/x86/include/asm/uprobes.h
> @@ -35,7 +35,10 @@ typedef u8 uprobe_opcode_t;
>  
>  struct arch_uprobe {
>  	u16				fixups;
> -	u8				insn[MAX_UINSN_BYTES];
> +	union {
> +		u8			insn[MAX_UINSN_BYTES];
> +		u8			ixol[MAX_UINSN_BYTES];
> +	};
>  #ifdef CONFIG_X86_64
>  	unsigned long			rip_rela_target_address;
>  #endif

Btw., at least on the surface, the powerpc and x86 definitions seem rather 
similar, barring senseless variations. Would it make sense to generalize 
the data structure a bit more?

Also, we all hate data structures that are not self-documenting. What does 
'ixol' mean and what is its role? Is it obvious to the reader of that 
file?

Thanks,

	Ingo