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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id af79cd13be357-79bce92e6b4sm113770785a.100.2024.06.21.13.27.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Jun 2024 13:27:47 -0700 (PDT) Date: Fri, 21 Jun 2024 16:27:44 -0400 From: Peter Xu To: "Edgecombe, Rick P" Cc: "linux-mm@kvack.org" , "Hansen, Dave" , "linux-kernel@vger.kernel.org" , "hughd@google.com" , "willy@infradead.org" , "dave.hansen@linux.intel.com" , "vbabka@suse.cz" , "mpe@ellerman.id.au" , "akpm@linux-foundation.org" , "mingo@redhat.com" , "kirill@shutemov.name" , "christophe.leroy@csgroup.eu" , "Jiang, Dave" , "aneesh.kumar@linux.ibm.com" , "tglx@linutronix.de" , "riel@surriel.com" , "npiggin@gmail.com" , "osalvador@suse.de" , "linuxppc-dev@lists.ozlabs.org" , "bp@alien8.de" , "mgorman@techsingularity.net" , "Huang, Ying" , "x86@kernel.org" , "Williams, Dan J" Subject: Re: [PATCH 6/7] mm/x86: Add missing pud helpers Message-ID: References: <20240621142504.1940209-1-peterx@redhat.com> <20240621142504.1940209-7-peterx@redhat.com> <4fb4b087-cae2-4516-a34e-cb4c72be13eb@intel.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: CE0C0140011 X-Stat-Signature: phr499xbgu3mbpn8hg6m59c7fdwmquf1 X-HE-Tag: 1719001671-972810 X-HE-Meta: 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 6CyQ7sd6 Bz6Ol9CTQCUksNNw+nOmOPZwLHt5U4WHktOsgIU67dV7w53P5jy7jfcLxiNSwWae3euI2EXOSyDlM3VCRJ0c6t01EzbqmPIeRdN6J2SusJ6BTt9kj+HAbT5P35wCjROD3P+MYDZnchMUTBSDlFy5DqAimZbZT0M0rScKNVU8WjLKpYstm3dbNv3q/ArKdM+k1PfWF5DlDmYlUc8L3kSSAVomHrBzDIh5LwLcPoTgKudSqr5dTb9iydVyqVrdQ0Uhma+XeQ3ZYoB65B170PiXztkwU3gmI9cnki39klY8EM59Rz0oo+oa5s9nQ9Br3Phkk5euh/67YUWnJq3IAUPUmDj85QaI3WoWN1bSq3d3mdj/cm0MO3UrSMqfo750/Phyugx1/oy1VBefnQxUddeE/QwoVFdbYjyB+RwC0 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, Jun 21, 2024 at 07:36:30PM +0000, Edgecombe, Rick P wrote: > On Fri, 2024-06-21 at 07:51 -0700, Dave Hansen wrote: > > > > But, still, what if you take a Dirty=1,Write=1 pud and pud_modify() it > > to make it Dirty=1,Write=0?  What prevents that from being > > misinterpreted by the hardware as being a valid 1G shadow stack mapping? > > Hmm, it looks like we could use an arch_check_zapped_pud() that does a warning > like arch_check_zapped_pte/pmd() too. Not that we had no use for one before > this. I can definitely look into that, but this check only happens when zapping, and IIUC it means there can still be outliers floating around. I wonder whether it should rely on page_table_check_pxx_set() from that regard. Thanks, -- Peter Xu