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Mon, 13 Mar 2023 18:10:35 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1678727435; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=nkKTq/4WyFVx6pB2Xg+q+iJ0RUH4l9vZi60hs/FYjRk=; b=c9pxxkI+7k7EHK3FvvIhyVXvpJdXznrzmK8aS32lEGgY/YvSl8mrdv6+RWUsTak5vUmrmg zG+mE+9padkduNFKg5PojdVsz5dqGOlR8cuCzm4Ku71Mx9Am59R9dH/HO79c1PQFx1rYWm BrqA28Maor8BpN0592FeDrSMMC4ZZqU= Date: Mon, 13 Mar 2023 18:10:31 +0100 From: Borislav Petkov To: "Edgecombe, Rick P" Cc: "david@redhat.com" , "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "peterz@infradead.org" , "rdunlap@infradead.org" , "keescook@chromium.org" , "Eranian, Stephane" , "kirill.shutemov@linux.intel.com" , "dave.hansen@linux.intel.com" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "nadav.amit@gmail.com" , "jannh@google.com" , "dethoma@microsoft.com" , "kcc@google.com" , "linux-arch@vger.kernel.org" , "pavel@ucw.cz" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "akpm@linux-foundation.org" , "Yang, Weijiang" , "Lutomirski, Andy" , "jamorris@linux.microsoft.com" , "arnd@arndb.de" , "tglx@linutronix.de" , "Schimpe, Christina" , "mike.kravetz@oracle.com" , "debug@rivosinc.com" , "linux-doc@vger.kernel.org" , "x86@kernel.org" , "andrew.cooper3@citrix.com" , "john.allen@amd.com" , "rppt@kernel.org" , "mingo@redhat.com" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" Subject: Re: [PATCH v7 38/41] x86/fpu: Add helper for initing features Message-ID: <20230313171031.GEZA9ZB01FRjCo98pr@fat_crate.local> References: <20230227222957.24501-1-rick.p.edgecombe@intel.com> <20230227222957.24501-39-rick.p.edgecombe@intel.com> <3385eaf888f4178607ce4621ae2103d08ba79994.camel@intel.com> <20230313110335.GAZA8DB6PNSMGOGHpw@fat_crate.local> <04f821e6d4a8a736e6df2eb73ce811022cd42537.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <04f821e6d4a8a736e6df2eb73ce811022cd42537.camel@intel.com> X-Rspam-User: X-Rspamd-Queue-Id: 7AF851C0005 X-Rspamd-Server: rspam01 X-Stat-Signature: 5dyokbwt4fzyfpsko84baa5h41trdwbp X-HE-Tag: 1678727437-426311 X-HE-Meta: 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 fylGqfwi Vs/WyHmYltzAzUTsywHf+RAwAO0Ia3zN4UutRzXChHLw8KUXDs6ER/eGe+/zyFtgKDqkSWUDdJUFqIAcdFdlb2tOSWO3iiWLHJYyB/iUI0MzKD2tTtcqrFsx0Yiey20DpRt9ScAO/qxizQ4toq7M2ponHJ2H4mOXwjOdpKp5X1tAFq5f3IYI5nV/Puj1DE1XNc+ue/ZrOaemTuCqsKploYcLHEXJEce1L5XnbKa/ncALHatF7tX12/vROSpY6GhDQuiWy7FxyYAQvKVyKS5pd2BL7cJFDhl95p7zGxDM3Aot5SVNKbzLJsNm2OaYP8PTBJQdEnQnYBzxTvhd8AN5rck/IUrj9td1C4uEb 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: On Mon, Mar 13, 2023 at 04:10:14PM +0000, Edgecombe, Rick P wrote: > This seems more clear. I'm sorry for the noise here though, because > this has made me realize that the initing logic should never be hit. We > used to support the full CET_U state in ptrace, but then dropped it to > just the SSP and only allowed it when shadow stack is active. Right, you do check that at function entry. > This means that CET_U will always have at least the CET_SHSTK_EN bit > set and so not be in the init state. So this can probably just warn > and bail if it sees an init state. I don't mind the additional checks as this is a security thing so sanity checks are good, especially if they're cheap. And you don't need to reinit the buffer - just scream loudly when get_xsave_addr() returns NULL. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette