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Sat, 3 Feb 2024 08:56:45 -0500 (EST) Message-ID: Date: Sat, 3 Feb 2024 13:56:43 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/3] Handle delay slot for extable lookup To: Linus Torvalds 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 References: <20240202-exception_ip-v2-0-e6894d5ce705@flygoat.com> Content-Language: en-US From: Jiaxun Yang Autocrypt: addr=jiaxun.yang@flygoat.com; keydata= xsFNBFnp/kwBEADEHKlSYJNLpFE1HPHfvsxjggAIK3ZtHTj5iLuRkEHDPiyyiLtmIgimmD3+ XN/uu2k1FFbrYiYgMjpGCXeRtdCLqkd+g9V4kYMlgi4MPHLt3XEuHcoKD1Yd2qYPT/OiQeGM 6bPtGUZlgfOpze1XuqHQ2VMWATL+kLYzk6FUUL715t8J5J9TgZBvSy8zc6gvpp3awsCwjFSv X3fiPMTC2dIiiMh4rKQKGboI1c7svgu6blHpy/Q5pXlEVqfLc7tFTGnvUp95jsK639GD8Ht3 0fSBxHGrTslrT775Aqi+1IsbJKBOmxIuU9eUGBUaZ00beGE09ovxiz2n2JKXKKZklNqhzifb 6uyVCOKdckR8uGqzRuohxDS7vlDZfFD5Z5OhplFY/9q+2IjCrWMmbHGSWYs9VV52XGM+wiEG sM5bup03N2q1kDXUWJ+zNNYowuOJKN9uxF3jBjdXSDi3uJu/ZUL/mBqI58SkHq5NTaHypRoE 5BxVmgDMCGQe93adKHUNmt4HK28R506S7019+umg1bq5vA/ncmh/J2k8MFGPXqO8t1xVI2O5 qrRheRKu1oST46ZJ7vKET1UwgcXTZ1iwqFlA26/iKxXoL7R7/AqWrapokEsUzRblGcutGZ/b 4lJVOxxAWaRcajpWvwqscI2mUF++O7DxYbhOJ/EFY2rv0i6+/QARAQABzSVKaWF4dW4gWWFu ZyA8amlheHVuLnlhbmdAZmx5Z29hdC5jb20+wsGRBBMBCAA7AhsjAh4BAheABQsJCAcCBhUK CQgLAgQWAgMBFiEEmAN5vv6/v0d+oE75wRGUkHP8D2cFAmKcjj8CGQEACgkQwRGUkHP8D2fx LxAAuNjknjfMBXIwEDpY+L2KMMU4V5rvTBATQ0dHZZzTlmTJuEduj/YdlVo0uTClRr9qkfEr Nfdr/YIS6BN6Am1x6nF2PAqHu/MkTNNFSAFiABh35hcm032jhrZVqLgAPLeydwQguIR8KXQB pP6S/jL3c7mUvVkoYy2g5PE1eH1MPeBwkg/r/ib9qNJSTuJH3SXnfZ4zoynvf3ipqnHsn2Sa 90Ta0Bux6ZgXIVlTL+LRDU88LISTpjBITyzn5F6fNEArxNDQFm4yrbPNbpWJXml50AWqsywp q9jRpu9Ly4qX2szkruJ/EnnAuS/FbEd4Agx2KZFb6LxxGAr4useXn6vab9p1bwRVBzfiXzqR WeTRAqwmJtdvzyo3tpkLmNC/jC3UsjqgfyBtiDSQzq0pSu7baOjvCGiRgeDCRSWq/T3HGZug 02QAi0Wwt/k5DX7jJS4Z5AAkfimXG3gq2nhiA6R995bYRyO8nIa+jmkMlYRFkwWdead3i/a0 zrtUyfZnIyWxUOsqHrfsN45rF2b0wHGpnFUfnR3Paa4my1uuwfp4BI6ZDVSVjz0oFBJ5y39A DCvFSpJkiJM/q71Erhyqn6c1weRnMok3hmG0rZ8RCSh5t7HllmyUUWe4OT97d5dhI7K/rnhc ze8vkrTNT6/fOvyPFqpSgYRDXGz2qboX/P6MG3zOOARlnqgjEgorBgEEAZdVAQUBAQdAUBqi bYcf0EGVya3wlwRABMwYsMimlsLEzvE4cKwoZzEDAQgHwsF2BBgBCAAgFiEEmAN5vv6/v0d+ oE75wRGUkHP8D2cFAmWeqCMCGwwACgkQwRGUkHP8D2dXlw/8CGKNXDloh1d7v/jDgcPPmlXd lQ4hssICgi6D+9aj3qYChIyuaNncRsUEOYvTmZoCHgQ6ymUUUBDuuog1KpuP3Ap8Pa3r5Tr6 TXtOl6Zi23ZWsrmthuYtJ8Yn5brxs6KQ5k4vCTkbF8ukue4Xl4O0RVlaIgJihJHZTfd9rUZy QugM8X98iLuUqYHCq2bAXHOq9h+mTLrhdy09dUalFyhOVejWMftULGfoXnRVz6OaHSBjTz5P HwZDAFChOUUR6vh31Lac2exTqtY/g+TjiUbXUPDEzN4mENACF/Aw+783v5CSEkSNYNxrCdt8 5+MRdhcj7y1wGfnSsKubHTOkBQJSanNr0cZZlPsJK0gxB2YTG6Nin13oX8mV7sAa3vBqqwfj ZtjNA+Up9IJY4Iz5upykUDAtCcvm82UnJoe5bMuoiyVccuqd5K/058AAxWv8fIvB4bSgmGMM aAN9l7GLyi4NhsKCCcAGSc2YAsxFrH6whVqY6JIF+08n1kur5ULrEKHpTTeffwajCgZPWpFc 7Mg2PDpoOwdpKLKlmIpyDexGVH0Lj/ycBL8ujDYZ2tA9HhEaO4dW6zsQyt1v6mZffpWK+ZXb Cs8oFeACbrtNFF0nhNI6LUPH3oaVOkUoRQUYDuX6mIc4VTwMA8EoZlueKEHfZIKrRf2QYbOZ HVO98ZmbMeg= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: oxqhcn5jhh9114u4k66rg8ns5o4emgkw X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 5A5788000A X-HE-Tag: 1706968610-452506 X-HE-Meta: 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 ohcTD0LG d9ZcOD+Dr6wGdguf5Gk/qf8XtfHZA2FCmxitjzgn4f123H6YT9NnfjJjuN0k8lvawAxExaPSsjESc7WUItGLXH8sqxj//njPxlNzi7IMvDrNC91/IcUP8G2ljfZsynItQKD4Wbw/sBaqo2ivH9lVittcxQTHWBX/l43MCXf+98mEiSjzXgjURbOm5/sZiMIor+FQtZ+8kCS2Yr7BFgP5TcE/Aqk83jDPhjzZ3nArNG1h0tZk3C3Gl8YzFRhoikvhkFPLvkAoXkJr3MN/DWz36ZHXW0Hu6nVj7IFVomnOfbUqHOuw97vCqpTq4gLsF8IuSUnQ8TRgxtWjAxg87f76Quiq/HXjaY+MWz/7vB+HRLFFuyjywFnEnewZ7bGOOyKdDyeTEIHAwsXPW+ew= 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: 在 2024/2/2 18:39, Linus Torvalds 写道: > 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. I reconsidered this issue today and I believe that exception_ip() usage here won't trigger page_fault anyway. Given that exception_ip is guarded by !user_mode(regs), EPC must points to a kernel text address. There is no way accessing kernel text will generate such exception.. Thanks > > 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 -- --- Jiaxun Yang