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 8423DC79F80 for ; Fri, 4 Sep 2026 16:19:16 +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=T2OcsfQB2rXyV+qEnim3LyzT5vfleOs/dQwzAKYIyC8=; b=2gG8H1G4682TkN AN86MCY3F2DVhIP6P7LZcs47AfsPeqjpI7GLkBKoHpMVoC2spIC8P/bqX20ZHl9ZBQ6K87XYYyG+S cMyegqyt1y0P+d1RN7weSkouOf4lFTLy2DlIAoFXo78wWwUnn/Zlry7Ejv7Z93weeKBOXdqfyuBqN 2Nbrl8XFjtPtqjakP5DssJNCGmdU5M84Ww+AAUavPmnXtUrAJy6T2rcIwWZ2aDY3xfVkaynTV2V7l c13f3dxE6VxhzQPLHtOGw4M0e9JN5iMh4vBKT1ZqnVybJfEIfuPaQAA03PhwHkXJ/sUNVTLaUGLiL gb/MuWyZVFWccK7s6/gg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x2Wd7-00000002hIp-1guy; Fri, 04 Sep 2026 16:19:05 +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 1x2Wd4-00000002hCe-2D5t for linux-arm-kernel@lists.infradead.org; Fri, 04 Sep 2026 16:19:03 +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 C9165153B; Fri, 4 Sep 2026 09:18:52 -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 822F23F8D6; Fri, 4 Sep 2026 09:18:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788538736; bh=pUyEkl4bH7bjN7cz2XbK3Pl6rivIm/Z5yqVzikq2V+0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rQhs7b3FjaUZd3YeBRcvwQCaIPNsMAYiIycOFk7VjmlIpt26wAOPUSLOlThOrUSlx btY/r2SeucKbi0Dwn5UsfCqT4euj/pDMewj/YEvm7troIiQjoG+90qr4oVV9zJtTjG MBzAG9jnJAdvmAa8NPinTIQr0iFLEHmbRCiJj6Ds= From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 12/21] arm64: entry: sdei: Restore all clobberable GPRs Date: Fri, 4 Sep 2026 17:17:49 +0100 Message-Id: <20260904161758.376504-13-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20260904161758.376504-1-mark.rutland@arm.com> References: <20260904161758.376504-1-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-20260904_091902_604294_227D52E0 X-CRM114-Status: GOOD ( 10.66 ) 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, 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, 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 Currently __sdei_asm_handler() avoids restoring x20 to x27, as these are not be clobbered by existing code. This is correct today, but it makes it awkward to rework __sdei_asm_handler(). Given the rarity of SDEI events, restoring x20 to x27 should not have a measurable impact. Restore x20 to x27 when returning from an SDEI event handler. This will free up those GPRs for usage in __sdei_asm_handler() prior to return. 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 | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f63049ac32dc6..a6ec5c5a2d29c 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1044,10 +1044,14 @@ SYM_CODE_START(__sdei_asm_handler) bl __sdei_handler msr sp_el0, x28 - /* restore regs >x17 that we clobbered */ + /* restore regs >x17 that firmware won't restore */ mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline - ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] + ldp x20, x21, [x4, #SDEI_EVENT_INTREGS + 16 * 10] + ldp x22, x23, [x4, #SDEI_EVENT_INTREGS + 16 * 11] + ldp x24, x25, [x4, #SDEI_EVENT_INTREGS + 16 * 12] + ldp x26, x27, [x4, #SDEI_EVENT_INTREGS + 16 * 13] + ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR] mov sp, x1 -- 2.30.2