linux-kernel - Re: [PATCH 04/12] __wr_after_init: x86_64: __wr

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Date:   Thu, 20 Dec 2018 21:19:15 +0200
From:   Igor Stoppa <igor.stoppa@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>, igor.stoppa@...wei.com,
        Nadav Amit <nadav.amit@...il.com>,
        Kees Cook <keescook@...omium.org>,
        linux-integrity@...r.kernel.org,
        kernel-hardening@...ts.openwall.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/12] __wr_after_init: x86_64: __wr_op



On 20/12/2018 20:49, Matthew Wilcox wrote:

> I think you're causing yourself more headaches by implementing this "op"
> function.  

I probably misinterpreted the initial criticism on my first patchset, 
about duplication. Somehow, I'm still thinking to the endgame of having 
higher-level functions, like list management.

> Here's some generic code:

thank you, I have one question, below

> void *wr_memcpy(void *dst, void *src, unsigned int len)
> {
> 	wr_state_t wr_state;
> 	void *wr_poking_addr = __wr_addr(dst);
> 
> 	local_irq_disable();
> 	wr_enable(&wr_state);
> 	__wr_memcpy(wr_poking_addr, src, len);

Is __wraddr() invoked inside wm_memcpy() instead of being invoked 
privately within __wr_memcpy() because the code is generic, or is there 
some other reason?

> 	wr_disable(&wr_state);
> 	local_irq_enable();
> 
> 	return dst;
> }
> 
> Now, x86 can define appropriate macros and functions to use the temporary_mm
> functionality, and other architectures can do what makes sense to them.
> 

--
igor