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[209.85.208.172]) by smtp.gmail.com with ESMTPSA id o2-20020a2e9b42000000b002d093cb1c62sm45860ljj.97.2024.02.02.10.39.30 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Feb 2024 10:39:30 -0800 (PST) Received: by mail-lj1-f172.google.com with SMTP id 38308e7fff4ca-2d04c0b1cacso29963331fa.0 for ; Fri, 02 Feb 2024 10:39:30 -0800 (PST) X-Received: by 2002:a2e:8882:0:b0:2d0:8225:919d with SMTP id k2-20020a2e8882000000b002d08225919dmr1794857lji.21.1706899169784; Fri, 02 Feb 2024 10:39:29 -0800 (PST) MIME-Version: 1.0 References: <20240202-exception_ip-v2-0-e6894d5ce705@flygoat.com> In-Reply-To: <20240202-exception_ip-v2-0-e6894d5ce705@flygoat.com> From: Linus Torvalds Date: Fri, 2 Feb 2024 10:39:13 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 0/3] Handle delay slot for extable lookup To: Jiaxun Yang Cc: Oleg Nesterov , Thomas Bogendoerfer , Andrew Morton , Ben Hutchings , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, Xi Ruoyao Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 460E416000A X-Stat-Signature: mrx7n1pgxg5aasx5xetmb1duysthenw1 X-HE-Tag: 1706899172-551659 X-HE-Meta: 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 /33soGf/ 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 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: On Fri, 2 Feb 2024 at 04:30, Jiaxun Yang wrote: > > ptrace: Introduce exception_ip arch hook > MIPS: Clear Cause.BD in instruction_pointer_set > mm/memory: Use exception ip to search exception tables Just to clarify: does that second patch fix the problem that __isa_exception_epc() does a __get_user()? Because that mm/memory.c use of "exception_ip()" most definitely cannot take a page fault. So if MIPS cannot do that whole exception IP thing without potentially touching user space, I do worry that we might just have to add a #ifndef __MIPS__ around this all. Possibly somehow limited to just the microMIPS/MIPS16e case in Kconfig instead? Linus