From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 79420 invoked by alias); 22 May 2019 15:06:51 -0000 Mailing-List: contact gnu-gabi-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Post: List-Help: List-Subscribe: Sender: gnu-gabi-owner@sourceware.org Received: (qmail 79288 invoked by uid 89); 22 May 2019 15:06:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.100.3 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-6.0 required=5.0 tests=AWL,BAYES_00,KAM_ASCII_DIVIDERS,KAM_NUMSUBJECT,SPF_HELO_PASS autolearn=no version=3.3.1 spammy=callee-saved, calleesaved, AAPCS64, aapcs64 X-Spam-Status: No, score=-6.0 required=5.0 tests=AWL,BAYES_00,KAM_ASCII_DIVIDERS,KAM_NUMSUBJECT,SPF_HELO_PASS autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on sourceware.org X-Spam-Level: X-Spam-User: qpsmtpd, 3 recipients X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 22 May 2019 15:06:50 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4615181E15; Wed, 22 May 2019 15:06:29 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-117-43.ams2.redhat.com [10.36.117.43]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7B325607CA; Wed, 22 May 2019 15:06:23 +0000 (UTC) From: Florian Weimer To: Szabolcs Nagy Cc: GNU C Library , Binutils , GCC Development , "gnu-gabi\@sourceware.org" , nd , Ramana Radhakrishnan , Richard Earnshaw , Tejas Belagod , Richard Sandiford , Steve Ellcey , Richard Henderson Subject: Re: [AArch64 ELF ABI] Vector calls and lazy binding on AArch64 References: <7be6eecc-9e36-c782-1c87-e608bb1b5678@arm.com> Date: Tue, 01 Jan 2019 00:00:00 -0000 In-Reply-To: <7be6eecc-9e36-c782-1c87-e608bb1b5678@arm.com> (Szabolcs Nagy's message of "Wed, 22 May 2019 14:42:05 +0000") Message-ID: <87y32y34wi.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 22 May 2019 15:06:49 +0000 (UTC) X-IsSubscribed: yes X-SW-Source: 2019-q2/txt/msg00001.txt.bz2 * Szabolcs Nagy: > AAELF64: in the Symbol Table section add > > st_other Values > The st_other member of a symbol table entry specifies the symbol's > visibility in the lowest 2 bits. The top 6 bits are unused in the > generic ELF ABI [SCO-ELF], and while there are no values reserved for > processor-specific semantics, many other architectures have used these > bits. > > The defined processor-specific st_other flag values are listed in > Table 4-5-1. > > Table 4-5-1, Processor specific st_other flags > +------------------------+------+---------------------+ > |Name | Mask | Comment | > +------------------------+------+---------------------+ > |STO_AARCH64_VARIANT_PCS | 0x80 | The function | > | | | associated with the | > | | | symbol may follow a | > | | | variant procedure | > | | | call standard with | > | | | different register | > | | | usage convention. | > +------------------------+------+---------------------+ > > A symbol table entry that is marked with the STO_AARCH64_VARIANT_PCS > flag set in its st_other field may be associated with a function that > follows a variant procedure call standard with different register > usage convention from the one defined in the base procedure call > standard for the list of argument, caller-saved and callee-saved > registers [AAPCS64]. The rules in the Call and Jump relocations > section still apply to such functions, and if a subroutine is called > via a symbol reference that is marked with STO_AARCH64_VARIANT_PCS > then code that runs between the calling routine and called subroutine > must preserve the contents of all registers except IP0, IP1 and the > condition code flags [AAPCS64]. Can you clarify if there has to be a valid stack at this point which can be used during the call transfer? What about the stack alignment requirement? Thanks, Florian