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X-CSE-ConnectionGUID: ZXx7eKAiSS6gk1dol0opYw== X-CSE-MsgGUID: RqENIS9TRcKdBv3nP+VbUQ== X-IronPort-AV: E=McAfee;i="6800,10657,11646"; a="93508936" X-IronPort-AV: E=Sophos;i="6.21,158,1763452800"; d="scan'208";a="93508936" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Dec 2025 08:34:38 -0800 X-CSE-ConnectionGUID: km/MzlcvQMSKtMba/hbKFQ== X-CSE-MsgGUID: 4LrMg2ZbSVqF+gAWjo3O8g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,158,1763452800"; d="scan'208";a="203525480" Received: from spandruv-mobl4.amr.corp.intel.com (HELO [10.125.111.56]) ([10.125.111.56]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Dec 2025 08:34:37 -0800 Message-ID: <6ddb3366-31a8-4d18-a553-908a035f7cf2@intel.com> Date: Thu, 18 Dec 2025 08:34:36 -0800 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v15 16/28] x86/txt: Intel Trusted eXecution Technology (TXT) definitions To: Ross Philipson , linux-kernel@vger.kernel.org, x86@kernel.org, linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, kexec@lists.infradead.org, linux-efi@vger.kernel.org, iommu@lists.linux.dev Cc: dpsmith@apertussolutions.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com, ardb@kernel.org, mjg59@srcf.ucam.org, James.Bottomley@hansenpartnership.com, peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, luto@amacapital.net, nivedita@alum.mit.edu, herbert@gondor.apana.org.au, davem@davemloft.net, corbet@lwn.net, ebiederm@xmission.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, kanth.ghatraju@oracle.com, andrew.cooper3@citrix.com, trenchboot-devel@googlegroups.com References: <20251215233316.1076248-1-ross.philipson@oracle.com> <20251215233316.1076248-17-ross.philipson@oracle.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/15/25 15:33, Ross Philipson wrote: > +static inline void *txt_sinit_mle_data_start(void *heap) > +{ > + return heap + txt_bios_data_size(heap) + > + txt_os_mle_data_size(heap) + > + txt_os_sinit_data_size(heap) + sizeof(u64); > +} So each one of these walks through the entire table? Maybe I'm naive, but wouldn't this all be a lot more sane if it was just parsed *once* into a table of pointers? enum { FIELD1, FIELD2, FIELD3, MAX_NR }; void *parseit(u8 *heap) { void *ptr_array[MAX_NR] = {}; void *place = heap; for (int i = 0; i < MAX_NR; i++) { // The buffer starts with the length: u32 *size_ptr = place; // Consume the length: place += sizeof(*size_ptr); // Point at the data: ptr_array[i] = place; // Consume the data: place += *size_ptr; } // along with some sanity checks } Then, to access FIELDs you do: struct field1_struct *f1s = ptr_array[FIELD1]; struct field2_struct *f1s = ptr_array[FIELD2]; Yeah, it means keeping that pointer array around. But . It's also not about performance. That ^ is a billion times easier to understand because it lays out the "heap" logic in one place. You don't have to recurse through half a dozen helpers to figure things out.