Message-ID: <5539B782.8060507@huawei.com>
Date: Fri, 24 Apr 2015 11:24:50 +0800
From: Li Bin <huawei.libin@huawei.com>
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To: AKASHI Takahiro <takahiro.akashi@linaro.org>, <rostedt@goodmis.org>,
        <mingo@kernel.org>, <jpoimboe@redhat.com>, <sjenning@redhat.com>,
        <jkosina@suse.cz>, <vojtech@suse.cz>, <catalin.marinas@arm.com>,
        <will.deacon@arm.com>
CC: <broonie@kernel.org>, <masami.hiramatsu.pt@hitachi.com>,
        <live-patching@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linaro-kernel@lists.linaro.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 0/4] arm64: add livepatch support
References: <1429843449-7388-1-git-send-email-takahiro.akashi@linaro.org>
In-Reply-To: <1429843449-7388-1-git-send-email-takahiro.akashi@linaro.org>
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On 2015/4/24 10:44, AKASHI Takahiro wrote:
> This patchset enables livepatch support on arm64.
> 
> Livepatch was merged in v4.0, and allows replacying a function dynamically
> based on ftrace framework, but it also requires -mfentry option of gcc.
> Currently arm64 gcc doesn't support it, but by adding a helper function to
> ftrace, we will be able to support livepatch on arch's which don't support
> this option.
> 

This is not correct for the case that the prologue of the old and new function
is different.
Thanks,
	Li Bin

> I submit this patchset as RFC since I'm not quite sure that I'm doing
> in the right way, or we should definitely support -fentry instead.
> 
> Please note that I tested the feature only with livepatch-sample, and
> the code for DYNAMIC_TRACE_WITH_REGS is still rough-edged.
> 
> To: Steven Rostedt <rostedt@goodmis.org>
> To: Ingo Molnar <mingo@kernel.org>
> To: Josh Poimboeuf <jpoimboe@redhat.com>
> To: Seth Jennings <sjenning@redhat.com>
> To: Jiri Kosina <jkosina@suse.cz>
> To: Vojtech Pavlik <vojtech@suse.cz>
> To: Catalin Marinas <catalin.marinas@arm.com>
> To: Will Deacon <will.deacon@arm.com>
> 
> AKASHI Takahiro (4):
>   ftrace: add a helper function for livepatch
>   livepatch: adjust a patched function's address
>   arm64: ftrace: add DYNAMIC_TRACE_WITH_REGS version
>   arm64: add livepatch support
> 
>  arch/arm64/Kconfig                 |    4 ++
>  arch/arm64/include/asm/ftrace.h    |    4 ++
>  arch/arm64/include/asm/livepatch.h |   38 +++++++++++
>  arch/arm64/kernel/Makefile         |    1 +
>  arch/arm64/kernel/entry-ftrace.S   |  124 ++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/ftrace.c         |   24 ++++++-
>  arch/arm64/kernel/livepatch.c      |   68 ++++++++++++++++++++
>  arch/x86/include/asm/livepatch.h   |    5 ++
>  include/linux/ftrace.h             |    2 +
>  include/linux/livepatch.h          |    2 +
>  kernel/livepatch/core.c            |   16 +++--
>  kernel/trace/ftrace.c              |   26 ++++++++
>  12 files changed, 309 insertions(+), 5 deletions(-)
>  create mode 100644 arch/arm64/include/asm/livepatch.h
>  create mode 100644 arch/arm64/kernel/livepatch.c
> 


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