From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 93AD8C3DA5D for ; Thu, 25 Jul 2024 15:59:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=PFXxQwtLMQAZ09YUAD/h38uGSZ+1yapP3Vz2F1glEGE=; b=O+P5AsZBpYGHbUUsxRDojANtyn Tzt1ZKS3gQ3uWTJfaGE/IHAkegKIY8fAXDpuN8tZd19kEHzkhd+UCP1JwIvQyHDbVb3Zh7majJfwe GlW/ax8L4s4h9c+ivKinn9z6LEN0RdIOq8YWhNiCP5NH6nhRTt8BXux24IxO79qB88zFbwTuD8ar1 bWbz0RA89rIjJp9Xacv1WCSOwZe4Q9V+MMWYT5uyw5cAuPgSF8q0zu/qkWvxctJTRuMoTFRCBekkK NAszNqeFqSoCIJ4uFGhSqAKW4YiGDLcW3T1kGRS2Gh+5ION6uR8Cw6vcpoVYQ9s4DvDcUkTMfKWEe zgfiCqOA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sX0rs-00000001UmA-1CF8; Thu, 25 Jul 2024 15:59:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sX0rT-00000001UfN-17II for linux-arm-kernel@lists.infradead.org; Thu, 25 Jul 2024 15:58:36 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 22CF21007; Thu, 25 Jul 2024 08:58:59 -0700 (PDT) Received: from e133380.arm.com (e133380.arm.com [10.1.197.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C07A83F5A1; Thu, 25 Jul 2024 08:58:29 -0700 (PDT) Date: Thu, 25 Jul 2024 16:58:27 +0100 From: Dave Martin To: Amit Daniel Kachhap Cc: Mark Brown , Joey Gouly , linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, aneesh.kumar@kernel.org, aneesh.kumar@linux.ibm.com, bp@alien8.de, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, hpa@zytor.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, oliver.upton@linux.dev, shuah@kernel.org, szabolcs.nagy@arm.com, tglx@linutronix.de, will@kernel.org, x86@kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v4 18/29] arm64: add POE signal support Message-ID: References: <20240503130147.1154804-1-joey.gouly@arm.com> <20240503130147.1154804-19-joey.gouly@arm.com> <229bd367-466e-4bf9-9627-24d2d0821ff4@arm.com> <7789da64-34e2-49db-b203-84b80e5831d5@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240725_085835_500625_B8FF2B02 X-CRM114-Status: GOOD ( 24.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 03, 2024 at 02:51:46PM +0530, Amit Daniel Kachhap wrote: > > > On 5/31/24 22:09, Mark Brown wrote: > > On Tue, May 28, 2024 at 12:26:54PM +0530, Amit Daniel Kachhap wrote: > > > On 5/3/24 18:31, Joey Gouly wrote: > > > > > > +#define POE_MAGIC 0x504f4530 > > > > +struct poe_context { > > > > + struct _aarch64_ctx head; > > > > + __u64 por_el0; > > > > +}; > > > > > There is a comment section in the beginning which mentions the size > > > of the context frame structure and subsequent reduction in the > > > reserved range. So this new context description can be added there. > > > Although looks like it is broken for za, zt and fpmr context. > > > > Could you be more specific about how you think these existing contexts > > are broken? The above looks perfectly good and standard and the > > existing contexts do a reasonable simulation of working. Note that the > > ZA and ZT contexts don't generate data payload unless userspace has set > > PSTATE.ZA. > > Sorry for not being clear on this as I was only referring to the > comments in file arch/arm64/include/uapi/asm/sigcontext.h and no code > as such is broken. > > * Allocation of __reserved[]: > * (Note: records do not necessarily occur in the order shown here.) > * > * size description > * > * 0x210 fpsimd_context > * 0x10 esr_context > * 0x8a0 sve_context (vl <= 64) (optional) > * 0x20 extra_context (optional) > * 0x10 terminator (null _aarch64_ctx) > * > * 0x510 (reserved for future allocation) > > Here I think that optional context like za, zt, fpmr and poe should have > size mentioned here to make the description consistent.As you said ZA > and ZT context are enabled by userspace so some extra details can be > added for them too. Regarding this, __reserved[] is looking very full now. I'll post a draft patch separately, since I think the update could benefit from separate discussion, but my back-of-the-envelope calculation suggests that (before this patch) we are down to 0x90 bytes of free space (i.e., over 96% full). I wonder whether it is time to start pushing back on adding a new _foo_context for every individual register, though? Maybe we could add some kind of _misc_context for miscellaneous 64-bit regs. [...] Cheers ---Dave