From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2F702457E70 for ; Thu, 1 Oct 2026 08:38:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790843920; cv=none; b=u/cP5Z4QXlkvVTyMoGUbHJDfC+htnrBkAjZe+nR1KRkyzcmHYXlkexEbEXt0GysL66+cDq4v0qsGrDYAWf21VzUwgmpDO6tXBJAWpVjdpNwnPxxXPXDCqWEHVRXHR1hWQOTAY9Zji++89pGFshPR42ULYyZazASNBX7cZINcei0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790843920; c=relaxed/simple; bh=is/ngq975mUjUBzTdIqiNV/aCl6skLZgP+5C7ZZcfo4=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=bJCt5xto/xRLUEGfH6aFKTsNmJ8jx6Xwp8E5IZn+lPaF33lLmyhLKAEUxJ1pyCzzvM3DnArRugzgjo4W5pR8G9P+6z41NQZHBMcw71Wyn+jgN50Gu87nV/dm+ctcRfnwlzNHk76FmuszN2RTvWYlTvnZEuf0mNAek35UuoxU5JU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DXx/PLNR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DXx/PLNR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B79ED1F0089C for ; Thu, 1 Oct 2026 08:38:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790843918; bh=is/ngq975mUjUBzTdIqiNV/aCl6skLZgP+5C7ZZcfo4=; h=References:In-Reply-To:From:Date:Subject:To:Cc; b=DXx/PLNR9NqnLC//mCAWY7SvbPVzN9mfq49qG89mVN0TfrXV0kuS9EyELgzXqMYAh Uk8cbxTo5s1FgIPUFJa+JoN7BZ3NvCv308v7z+01wFzBOAB/uNWnJ3SbjxwaCc1Ld1 A1fgmFU6fm3tFtrCbgp8RkvPoAK1F8Ce/VL8JbL16bAi8ANRemcKTL2IDSKp/a6qN+ l1I88K2Q0eUhehJYOnWqMwDtESK6CC0B/U2TCf5E6PPxS9gIAXID1RfG3QIyLEe8mU 5FVpXaIALhbXY9prgI7QkNwFJ2SJXsJeV9bAP6n96OXi/S4HWrj254KUxw4LdKbxH5 stKAyn+TJm9YA== Received: by mail-oo2-f43.google.com with SMTP id 006d021491bc7-6de6b4c50f3so130154eaf.1 for ; Thu, 01 Oct 2026 01:38:38 -0700 (PDT) X-Forwarded-Encrypted: i=1; AKwUvBxd48TCZtii5uiSrnwxnC8p8SylCcrckIxpcXEGIumZPBAdDgozVKgQ3L8r4JSVkGxePKkzvlH1NgRVPhw=@vger.kernel.org X-Gm-Message-State: AFuF++kdVsKl1FSMdp4XZH2tMXhvCn+T1knxOyWyEtU7g2mZphRVrz48 3Cx7ntzqPGHzdkAfkZx21HVZXvjFaIdlh3WzazaeZRFNw5ZPIVMmhU2en+yIxp5LIihx/FTdpL4 fAbFUEXp8VthEW+e9jH/UicHb+vjN7n0= X-Received: by 2002:a05:6820:1806:b0:6d9:bad0:8374 with SMTP id 006d021491bc7-6dcf1fa428amr3428672eaf.10.1790843918052; Thu, 01 Oct 2026 01:38:38 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20260918161407.2300-1-will@kernel.org> <20260918161407.2300-20-will@kernel.org> In-Reply-To: From: Linus Walleij Date: Thu, 1 Oct 2026 10:38:22 +0200 X-Gmail-Original-Message-ID: X-Gm-Features: AclHuK9bZYHoY_AXjKZDaH1MPRes_W7KUtKQxFuh8xG-8gqtKY6GBTng2OBvj8Q Message-ID: Subject: Re: [PATCH v2 19/21] arm64: entry: The great stack switcheroo To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Ard Biesheuvel , Ada Couprie Diaz , David Hildenbrand , Catalin Marinas , Vladimir Murzin , Mark Rutland , Mostafa Saleh , Lorenzo Stoakes , Oliver Upton , Marc Zyngier Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Oct 1, 2026 at 9:27=E2=80=AFAM Will Deacon wrote: > On Wed, Sep 30, 2026 at 11:36:35PM +0200, Linus Walleij wrote: > > On Fri, Sep 18, 2026 at 6:15=E2=80=AFPM Will Deacon w= rote: > > > > > With the kernel stack pointer in SP_EL1 and the overflow stack pointe= r > > > in SP_EL0, it is now straightforward to switch between the two on > > > exception entry from EL1 by writing to SPSel. However, since exceptio= n > > > entry sets PSTATE.SP to 1 (selecting SP_EL1 as the stack pointer), > > > repurposing the overflow stack as a more general kernel exception sta= ck > > > would require writing to SPSel on every exception entry from the kern= el. > > > > > > Switch things around so that the overflow stack resides in SP_EL1, wi= th > > > the kernel stack residing in SP_EL0. > > > > > > Signed-off-by: Will Deacon > > > > This patch gives me panic, and as can be seen from the review > > comments need some love... > > Please can you share the panic message? I'll definitely be reworking > this based on the review comments, but if there's a bug it would be > great to see the details now! Haha. I was not referring to the kernel function but the emotion ;D Yours, Linus Walleij