From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.81]) by mx.groups.io with SMTP id smtpd.web11.130.1589990400760024998 for ; Wed, 20 May 2020 09:00:02 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=Awdg1oA8; spf=pass (domain: redhat.com, ip: 207.211.31.81, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589990399; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XYeXbRk5CERECD25BhKlAoQ0aBXiISbfRaPsEuHGUiE=; b=Awdg1oA8jpagfbIG8a1gtGoADl5KZKuWQw2nrYDxgNJUUY/ZRHYwCJ63XBPONzrFgDyfRM JcG5I2I2b0qXGNXgWOfkW+2JMah0Kjd0QkMp+E2bCB4W0DsPUCuU3gVZljL6525JdrZYno jBdlGbTSVDEUqsR6+JAOqesQ2y2um/A= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-81-LOhCqBVZM3m2C0-BG0tIfQ-1; Wed, 20 May 2020 11:59:56 -0400 X-MC-Unique: LOhCqBVZM3m2C0-BG0tIfQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EC85EC1A5; Wed, 20 May 2020 15:59:55 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-115-121.ams2.redhat.com [10.36.115.121]) by smtp.corp.redhat.com (Postfix) with ESMTP id CDA5762932; Wed, 20 May 2020 15:59:53 +0000 (UTC) Subject: Re: [PATCH v2] ArmPkg/CompilerIntrinsicsLib: provide atomics intrinsics To: Ard Biesheuvel , devel@edk2.groups.io Cc: glin@suse.com, leif@nuviainc.com, liming.gao@intel.com References: <20200520114448.26104-1-ard.biesheuvel@arm.com> From: "Laszlo Ersek" Message-ID: <8a9ba25c-c277-be2f-5bc7-94d05e3f0d1e@redhat.com> Date: Wed, 20 May 2020 17:59:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200520114448.26104-1-ard.biesheuvel@arm.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 05/20/20 13:44, Ard Biesheuvel wrote: > Gary reports the GCC 10 will emit calls to atomics intrinsics routines > unless -mno-outline-atomics is specified. This means GCC-10 introduces > new intrinsics, and even though it would be possible to work around this > by specifying the command line option, this would require a new GCC10 > toolchain profile to be created, which we prefer to avoid. > > So instead, add the new intrinsics to our library so they are provided > when necessary. > > Signed-off-by: Ard Biesheuvel > --- > v2: > - add missing .globl to export the functions from the object file > - add function end markers so the size of each is visible in the ELF metadata > - add some comments to describe what is going on > > ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf | 3 + > ArmPkg/Library/CompilerIntrinsicsLib/AArch64/Atomics.S | 142 ++++++++++++++++++++ > 2 files changed, 145 insertions(+) I can't review this patch at any technical level, unfortunately. However, I certainly agree with (and am thankful for) this approach. Acked-by: Laszlo Ersek If new versions are needed, please carry forward the A-b. Thanks! Laszlo > diff --git a/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf b/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf > index d5bad9467758..fcf48c678119 100644 > --- a/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf > +++ b/ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf > @@ -79,6 +79,9 @@ [Sources.ARM] > Arm/ldivmod.asm | MSFT > Arm/llsr.asm | MSFT > > +[Sources.AARCH64] > + AArch64/Atomics.S | GCC > + > [Packages] > MdePkg/MdePkg.dec > ArmPkg/ArmPkg.dec > diff --git a/ArmPkg/Library/CompilerIntrinsicsLib/AArch64/Atomics.S b/ArmPkg/Library/CompilerIntrinsicsLib/AArch64/Atomics.S > new file mode 100644 > index 000000000000..dc61d6bb8e52 > --- /dev/null > +++ b/ArmPkg/Library/CompilerIntrinsicsLib/AArch64/Atomics.S > @@ -0,0 +1,142 @@ > +#------------------------------------------------------------------------------ > +# > +# Copyright (c) 2020, Arm, Limited. All rights reserved.
> +# > +# SPDX-License-Identifier: BSD-2-Clause-Patent > +# > +#------------------------------------------------------------------------------ > + > + /* > + * Provide the GCC intrinsics that are required when using GCC 9 or > + * later with the -moutline-atomics options (which became the default > + * in GCC 10) > + */ > + .arch armv8-a > + > + .macro reg_alias, pfx, sz > + r0_\sz .req \pfx\()0 > + r1_\sz .req \pfx\()1 > + tmp0_\sz .req \pfx\()16 > + tmp1_\sz .req \pfx\()17 > + .endm > + > + /* > + * Define register aliases of the right type for each size > + * (xN for 8 bytes, wN for everything smaller) > + */ > + reg_alias w, 1 > + reg_alias w, 2 > + reg_alias w, 4 > + reg_alias x, 8 > + > + .macro fn_start, name:req > + .section .text.\name > + .globl \name > + .type \name, %function > +\name\(): > + .endm > + > + .macro fn_end, name:req > + .size \name, . - \name > + .endm > + > + /* > + * Emit an atomic helper for \model with operands of size \sz, using > + * the operation specified by \insn (which is the LSE name), and which > + * can be implemented using the generic load-locked/store-conditional > + * (LL/SC) sequence below, using the arithmetic operation given by > + * \opc. > + */ > + .macro emit_ld_sz, sz:req, insn:req, opc:req, model:req, s, a, l > + fn_start __aarch64_\insn\()\sz\()\model > + mov tmp0_\sz, r0_\sz > +0: ld\a\()xr\s r0_\sz, [x1] > + .ifnc \insn, swp > + \opc tmp1_\sz, r0_\sz, tmp0_\sz > + .else > + \opc tmp1_\sz, tmp0_\sz > + .endif > + st\l\()xr\s w15, tmp1_\sz, [x1] > + cbnz w15, 0b > + ret > + fn_end __aarch64_\insn\()\sz\()\model > + .endm > + > + /* > + * Emit atomic helpers for \model for operand sizes in the > + * set {1, 2, 4, 8}, for the instruction pattern given by > + * \insn. (This is the LSE name, but this implementation uses > + * the generic LL/SC sequence using \opc as the arithmetic > + * operation on the target.) > + */ > + .macro emit_ld, insn:req, opc:req, model:req, a, l > + emit_ld_sz 1, \insn, \opc, \model, b, \a, \l > + emit_ld_sz 2, \insn, \opc, \model, h, \a, \l > + emit_ld_sz 4, \insn, \opc, \model, , \a, \l > + emit_ld_sz 8, \insn, \opc, \model, , \a, \l > + .endm > + > + /* > + * Emit the compare and swap helper for \model and size \sz > + * using LL/SC instructions. > + */ > + .macro emit_cas_sz, sz:req, model:req, uxt:req, s, a, l > + fn_start __aarch64_cas\sz\()\model > + \uxt tmp0_\sz, r0_\sz > +0: ld\a\()xr\s r0_\sz, [x2] > + cmp r0_\sz, tmp0_\sz > + bne 1f > + st\l\()xr\s w15, r1_\sz, [x2] > + cbnz w15, 0b > +1: ret > + fn_end __aarch64_cas\sz\()\model > + .endm > + > + /* > + * Emit compare-and-swap helpers for \model for operand sizes in the > + * set {1, 2, 4, 8, 16}. > + */ > + .macro emit_cas, model:req, a, l > + emit_cas_sz 1, \model, uxtb, b, \a, \l > + emit_cas_sz 2, \model, uxth, h, \a, \l > + emit_cas_sz 4, \model, mov , , \a, \l > + emit_cas_sz 8, \model, mov , , \a, \l > + > + /* > + * We cannot use the parameterized sequence for 16 byte CAS, so we > + * need to define it explicitly. > + */ > + fn_start __aarch64_cas16\model > + mov x16, x0 > + mov x17, x1 > +0: ld\a\()xp x0, x1, [x4] > + cmp x0, x16 > + ccmp x1, x17, #0, eq > + bne 1f > + st\l\()xp w15, x16, x17, [x4] > + cbnz w15, 0b > +1: ret > + fn_end __aarch64_cas16\model > + .endm > + > + /* > + * Emit the set of GCC outline atomic helper functions for > + * the memory ordering model given by \model: > + * - relax unordered loads and stores > + * - acq load-acquire, unordered store > + * - rel unordered load, store-release > + * - acq_rel load-acquire, store-release > + */ > + .macro emit_model, model:req, a, l > + emit_ld ldadd, add, \model, \a, \l > + emit_ld ldclr, bic, \model, \a, \l > + emit_ld ldeor, eor, \model, \a, \l > + emit_ld ldset, orr, \model, \a, \l > + emit_ld swp, mov, \model, \a, \l > + emit_cas \model, \a, \l > + .endm > + > + emit_model _relax > + emit_model _acq, a > + emit_model _rel,, l > + emit_model _acq_rel, a, l >