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 C2B21C79F82 for ; Tue, 8 Sep 2026 15:22:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-Id:Date :Subject:To:From:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=78tVDEHMcN/wIq05dXhyUqSnoyCcXNYXjHWpnw6Enmk=; b=X2QM3hR8ouEbVN j/DRfbfG+Rr0C7CLzbsYmOv7jPOBIskqw++4S7yyERbf/VExZY/71GqLvuW9YYrbQoQ9P/3V2c75g XRZp4wBxjdeoZJKzsCDk/OJsTbSBVm/I/iIRglsRojZUuyiAqWswDKtdy6aB4mvDFkUajg4aIAQVd OM2oswyBccIa9roCysHqW6/s/Wq8DO8WslsTXv50rt585MjthA3wS7e1+TmNsj44yFuTHG85iugyZ NK9SjeF1ftyg1YallbWlePnMJyIErunzYutxgSx7groeNMMl/nZOWUxCDiz57YUdCodUKyXO+E7rx pLqljiWduQJSu/BCOEQg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3xem-00000009Sqz-2Iba; Tue, 08 Sep 2026 15:22:47 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3xeh-00000009SpP-2ySH for linux-arm-kernel@lists.infradead.org; Tue, 08 Sep 2026 15:22:43 +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 501BE1C25; Tue, 8 Sep 2026 08:22:35 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 3C2B13F7B4; Tue, 8 Sep 2026 08:22:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788880959; bh=pUGiK76B/cGSXLCAJDeQJWe6X+z6/ttgCiv66ralV/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gskfN7qSBPy6MuEKz8Un2ZUKEgtO6KEC1SWbKnxWytEIDx8PPUQzFNihP42j5W7zq 0i5+xaHppTKDOkWBkdE3YzcShsEZah45LBGq8gPRcwXFPWMDn6yUTgS1YUkHKp5aZN mKuKlcfePaufoszVXlqhc5u+uTH15SqI7kx+nm6Q= From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 13/21] arm64: entry: sdei: Make 'tsk' available Date: Tue, 8 Sep 2026 16:17:33 +0100 Message-Id: <20260908151741.394589-14-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20260908151741.394589-1-mark.rutland@arm.com> References: <20260908151741.394589-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260908_082239_823645_1889CA02 X-CRM114-Status: GOOD ( 12.12 ) 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: , Cc: mark.rutland@arm.com, vladimir.murzin@arm.com, ryan.roberts@arm.com, usama.anjum@arm.com, peterz@infradead.org, catalin.marinas@arm.com, david.laight.linux@gmail.com, stable@vger.kernel.org, ruanjinjie@huawei.com, james.morse@arm.com, yang@os.amperecomputing.com, cl@gentwo.org, maz@kernel.org, david@kernel.org, ljs@kernel.org, will@kernel.org, ardb@kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org For regular entry/exit sequences, we use 'tsk' (x28) to hold the current task pointer, allowing this to be used by various assembly macros. The SDEI entry/exit sequence uses x28 to hold the value of the interrupted sp_el0, and doesn't retain the current task pointer in a register. These differences makes it awkward to share assembly macros across regular entry/exit and SDEI entry/exit, and risk surprises. Align the SDEI entry/exit sequence with regular entry/exit, keeping the current task pointer in 'tsk', and preserving the interrupted sp_el0 in another (callee-saved) register. I've used x20 as x19 was already in used for the relevant sdei_registered_event, and these are the lowest-numbered registers above x18 (which we must preserve for shadow call stack). Signed-off-by: Mark Rutland Tested-by: Muhammad Usama Anjum Cc: Ada Couprie Diaz Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse Cc: Jinjie Ruan Cc: Marc Zyngier Cc: Peter Zijlstra Cc: Vladimir Murzin Cc: Will Deacon Cc: Yang Shi --- arch/arm64/kernel/entry.S | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index a6ec5c5a2d29c..0902c1bd9dd3d 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1023,11 +1023,12 @@ SYM_CODE_START(__sdei_asm_handler) /* * We may have interrupted userspace, or a guest, or exit-from or - * return-to either of these. We can't trust sp_el0, restore it. + * return-to either of these. Preserve the interrupted sp_el0, and + * initialize sp_el0 to the current task. */ - mrs x28, sp_el0 - ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1 - msr sp_el0, x0 + mrs x20, sp_el0 + ldr_this_cpu dst=tsk, sym=__entry_task, tmp=x1 + msr sp_el0, tsk /* If we interrupted the kernel point to the previous stack/frame. */ and x0, x3, #0xc @@ -1043,7 +1044,7 @@ SYM_CODE_START(__sdei_asm_handler) mov x1, x19 bl __sdei_handler - msr sp_el0, x28 + msr sp_el0, x20 /* restore regs >x17 that firmware won't restore */ mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] -- 2.30.2