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X-powerpc-patch-notification: thanks
X-powerpc-patch-commit: 51c9c0843993528bffc920c54c2121d9e6f8b090
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To: Anju T <anju@linux.vnet.ibm.com>, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
From: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: ananth@in.ibm.com, mahesh@linux.vnet.ibm.com, paulus@samba.org,
        mhiramat@kernel.org, naveen.n.rao@linux.vnet.ibm.com,
        hemant@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com
Subject: Re: [v4,1/2] arch/powerpc: Implement Optprobes
Message-Id: <3vN27w1vFGz9s74@ozlabs.org>
Date: Tue, 14 Feb 2017 23:40:28 +1100 (AEDT)
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On Wed, 2017-02-08 at 09:50:51 UTC, Anju T wrote:
> Current infrastructure of kprobe uses the unconditional trap instruction
> to probe a running kernel. Optprobe allows kprobe to replace the trap with
> a branch instruction to a detour buffer. Detour buffer contains instructions
> to create an in memory pt_regs. Detour buffer also has a call to
> optimized_callback() which in turn call the pre_handler().
> After the execution of the pre-handler, a call is made for instruction
> emulation. The NIP is determined in advanced through dummy instruction
> emulation and a branch instruction is created to the NIP at the end of
> the trampoline.
> 
> To address the limitation of branch instruction in POWER architecture,
> detour buffer slot is allocated from a reserved area. For the time being,
> 64KB is reserved in memory for this purpose.
> 
> Instructions which can be emulated using analyse_instr() are the candidates
> for optimization. Before optimization ensure that the address range
> between the detour buffer allocated and the instruction being probed
> is within +/- 32MB.
> 
> Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/51c9c0843993528bffc920c54c2121

cheers