From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="XG1UMych" Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E4AAD5F for ; Wed, 6 Dec 2023 13:09:03 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id d9443c01a7336-1d048d38881so1590035ad.2 for ; Wed, 06 Dec 2023 13:09:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1701896943; x=1702501743; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=r0jZIh33WJZDOGC0jgw5Fc4RYCqpyNHwEvNXaQB/Zzg=; b=XG1UMychDGvLI1nGeQMU7BYFeIanHRqEH9y4oH8/imC6Cqc2MFi9PryXlhFGgWYOaW suBK0gYzw4jzb8IHEieNdqvqZKLH3+X4dNQ5KJdi3wOh40PA1gaOUt4cy6P/6w5c1GQU wWyTaUxjwVZIT9ZrxRV/NiYy16u4AF7yi1xVk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701896943; x=1702501743; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=r0jZIh33WJZDOGC0jgw5Fc4RYCqpyNHwEvNXaQB/Zzg=; b=S0ErCcITyB8SrbqW0QamEnO/YJX3YzYoUWDokye6bM3lGkC1volqIDR6bG2tt2fd0j l3Ly8pRwVspOCoEYV8lLi8ujrHgW5WmkJSsAOPsFj/zPj6ag0fc8c1IKMpne/GyIGzsN jH3Dz8XdRSI3+LlrFSY27NPvBQU5cXZkNA8UuZAdHqh8ARLKz/+SoJ5AJ9vSDbvNRekc 2o5ZaLsGMjNcfgxTAnuXgC7UvsQ3hE0LROl/mu0PniyszbGlg3c/ohZgZGlVwmInQLSj JaHcH0BKGnzDnOcPe7GfW2aQDaAEvFxgiWuHDD0il5hYB+JKDKdLr3Vix8bIDpE8PXCc rv5A== X-Gm-Message-State: AOJu0YziK4bTnjeoopbDy7yTsn0pXWkmrHFKjW7FfKSsmuRIhbQ+b2L+ C3fC63YbMU96LyNE7xlVscNksA== X-Google-Smtp-Source: AGHT+IFQfQna/1EdVH0X+3X9HH+a9W9KXtDeaY2iTQz/5U8JSAc0AgMNRHkYjwLaZszqnToXGMyAxQ== X-Received: by 2002:a17:903:22cd:b0:1d0:7165:3faf with SMTP id y13-20020a17090322cd00b001d071653fafmr1374702plg.63.1701896942889; Wed, 06 Dec 2023 13:09:02 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id jm21-20020a17090304d500b001d06b93c66dsm244368plb.233.2023.12.06.13.09.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 13:09:02 -0800 (PST) Date: Wed, 6 Dec 2023 13:09:01 -0800 From: Kees Cook To: Florian Weimer Cc: Alexey Dobriyan , Andrew Morton , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2] ELF: supply userspace with available page shifts (AT_PAGE_SHIFT_MASK) Message-ID: <202312061308.630C56CCA@keescook> References: <6b399b86-a478-48b0-92a1-25240a8ede54@p183> <87v89dvuxg.fsf@oldenburg.str.redhat.com> <1d679805-8a82-44a4-ba14-49d4f28ff597@p183> <202312061236.DE847C52AA@keescook> <87edfzavof.fsf@oldenburg.str.redhat.com> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87edfzavof.fsf@oldenburg.str.redhat.com> On Wed, Dec 06, 2023 at 10:05:36PM +0100, Florian Weimer wrote: > * Kees Cook: > > > On Tue, Dec 05, 2023 at 07:01:34PM +0300, Alexey Dobriyan wrote: > >> Report available page shifts in arch independent manner, so that > >> userspace developers won't have to parse /proc/cpuinfo hunting > >> for arch specific strings: > >> > >> Note! > >> > >> This is strictly for userspace, if some page size is shutdown due > >> to kernel command line option or CPU bug workaround, than is must not > >> be reported in aux vector! > > > > Given Florian in CC, I assume this is something glibc would like to be > > using? Please mention this in the commit log. > > Nope, I just wrote a random drive-by comment on the first version. Ah, okay. Then Alexey, who do you expect to be the consumer of this new AT value? -- Kees Cook