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Subject: Re: [RFC 0/2] Consolidate patch_instruction
To: Balbir Singh <bsingharora@gmail.com>, linuxppc-dev@lists.ozlabs.org,
 mpe@ellerman.id.au
References: <20170516034913.21163-1-bsingharora@gmail.com>
Cc: naveen.n.rao@linux.vnet.ibm.com
From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Date: Tue, 16 May 2017 10:56:10 +0530
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On 05/16/2017 09:19 AM, Balbir Singh wrote:
> patch_instruction is enhanced in this RFC to support
> patching via a different virtual address (text_poke_area).

Why writing instruction directly into the address is not
sufficient and need to go through this virtual address ?

> The mapping of text_poke_area->addr is RW and not RWX.
> This way the mapping allows write for patching and then we tear
> down the mapping. The downside is that we introduce a spinlock
> which serializes our patching to one patch at a time.

So whats the benifits we get otherwise in this approach when
we are adding a new lock into the equation.