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X-CSE-ConnectionGUID: yKzYXCCFTrikhEobbtXXqA== X-CSE-MsgGUID: 2rquRciUTGqXpLJThT/YuA== X-IronPort-AV: E=McAfee;i="6800,10657,11455"; a="51255403" X-IronPort-AV: E=Sophos;i="6.16,212,1744095600"; d="scan'208";a="51255403" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2025 07:54:50 -0700 X-CSE-ConnectionGUID: cRINZ1aTRkyvZx+8o4uwiQ== X-CSE-MsgGUID: dITcnuoFTrqZNjre82ZpFw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,212,1744095600"; d="scan'208";a="150410911" Received: from spandruv-desk1.amr.corp.intel.com (HELO [10.125.111.0]) ([10.125.111.0]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2025 07:54:49 -0700 Message-ID: Date: Thu, 5 Jun 2025 07:54:48 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/virt/tdx: Add ENDBR for low level SEAMCALL assembly functions To: Peter Zijlstra , Kai Huang Cc: tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, hpa@zytor.com, kirill.shutemov@linux.intel.com, rick.p.edgecombe@intel.com, x86@kernel.org, samitolvanen@google.com, linux-kernel@vger.kernel.org References: <20250604003848.13154-1-kai.huang@intel.com> <20250605140739.GS39944@noisy.programming.kicks-ass.net> <20250605142124.GT39944@noisy.programming.kicks-ass.net> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/5/25 07:21, Peter Zijlstra wrote: > -static inline u64 sc_retry(sc_func_t func, u64 fn, > - struct tdx_module_args *args) > +static __always_inline u64 sc_retry(const sc_func_t func, u64 fn, > + struct tdx_module_args *args) > { > int retry = RDRAND_RETRY_LOOPS; Practically, I can see how this works. If the compiler doesn't inline sc_retry(), it stops being able to guarantee that the function pointer value is known. My only worry is that the compiler decides to be stupid for some other reason, it could start generating indirect calls again. Are we confident that __always_inline will keep the compiler from generating indirect calls?