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Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , Madhavan Srinivasan , , , , , , , Guohanjun References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-5-tongtiangen@huawei.com> <69955002-c3b1-459d-9b42-8d07475c3fd3@huawei.com> <3b181285-2ff3-b77a-867b-725f38ea86d3@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemk500005.china.huawei.com (7.202.194.90) X-Rspamd-Queue-Id: D5C21A0012 X-Stat-Signature: qc9gp6njiup3qztbq4riq71co7joczz8 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1741097457-923127 X-HE-Meta: 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 OyG7MMBJ UK2JsktjP6fV9+Ep6QegZfTFEzm5sIp7kPCyM1DUjbBbLzFAe6u6lBVjCqjaOenrVap9gfxmRqOxrojk52lf70EABqG/BqWh93DwxveNOCzW+Hh5/5it+psBHwDqMtNxrLr6K8r0txzhQvshyvxuDPv8HTlyIquR+QiHDwhGsno5gMnm9v0vswMI2lK3AVlLOIRLOBunXyP3MfreRU8/DTf62Lip+sjdx6A0Y9fTJIr5VtMgBYnC3Oc6xC+H2xALGniYWq0EMeyNsTi4TVdQsJufcCQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi,Catalin: Kindly ping ... Thanks.:) 在 2025/2/19 3:42, Catalin Marinas 写道: > On Tue, Feb 18, 2025 at 07:51:10PM +0800, Tong Tiangen wrote: >>>>>> 在 2025/2/13 1:11, Catalin Marinas 写道: >>>>>>> On Mon, Dec 09, 2024 at 10:42:56AM +0800, Tong Tiangen wrote: >>>>>>>> Currently, many scenarios that can tolerate memory errors when copying page >>>>>>>> have been supported in the kernel[1~5], all of which are implemented by >>>>>>>> copy_mc_[user]_highpage(). arm64 should also support this mechanism. >>>>>>>> >>>>>>>> Due to mte, arm64 needs to have its own copy_mc_[user]_highpage() >>>>>>>> architecture implementation, macros __HAVE_ARCH_COPY_MC_HIGHPAGE and >>>>>>>> __HAVE_ARCH_COPY_MC_USER_HIGHPAGE have been added to control it. >>>>>>>> >>>>>>>> Add new helper copy_mc_page() which provide a page copy implementation with >>>>>>>> hardware memory error safe. The code logic of copy_mc_page() is the same as >>>>>>>> copy_page(), the main difference is that the ldp insn of copy_mc_page() >>>>>>>> contains the fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, therefore, the >>>>>>>> main logic is extracted to copy_page_template.S. In addition, the fixup of >>>>>>>> MOPS insn is not considered at present. >>>>>>> >>>>>>> Could we not add the exception table entry permanently but ignore the >>>>>>> exception table entry if it's not on the do_sea() path? That would save >>>>>>> some code duplication. > [...] >> So we need another way to distinguish the different processing of the >> same exception type on SEA and non-SEA path. > > Distinguishing whether the fault is SEA or non-SEA is already done by > the exception handling you are adding. What we don't have though is > information about whether the caller invoked copy_highpage() or > copy_mc_highpage(). That's where the code duplication comes in handy. > > It's a shame we need to duplicate identical functions just to have > different addresses to look up in the exception table. We are also short > of caller saved registers to track this information (e.g. an extra > argument to those functions that the exception handler interprets). > > I need to think a bit more, we could in theory get the arm64 memcpy_mc() > to return an error code depending on what type of fault it got (e.g. > -EHWPOISON for SEA, -EFAULT for non-SEA). copy_mc_highpage() would > interpret this one and panic if -EFAULT. But we lose some fault details > we normally get on a faulty access like some of the registers. > > Well, maybe the simples is still to keep the function duplication. I'll > have another look at the series tomorrow. >