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 2FF962222A9; Fri, 21 Aug 2026 20:03:44 +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=1787342626; cv=none; b=E0bbJVOus2nPiPrKD6m3ycePsvoYYz9uvSWDtqg0Hv9BoJSkOOCzjdlG23SMUx/OFUYzEuKpj+cuLgJ97Ir4CKqw0tLhL9tikYW0qUHpimbhPvZUOLh7nB1GSVM3T8gPO9udDb6LCquqsI4MvDVnDAWwbGN1cGOOiqabd9yW5ec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787342626; c=relaxed/simple; bh=R9q7ruuhryKinMa5FLg1lRTqoUTmSzGU76W+eWgqqKw=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=n9oeZtW/0NwrZfakniAcV/OuAhswHdrr1DNOUT4tOPXwjUOmIkTI5TQChtKoaZvv2yfUcV+4pUYXFfR1tPGuhaqgeAriBqYgBTzma6N7kANgHL2w+Kk7nDLG26iksFu0rF50Nume8N4NMXrfXwTgA/DVr49yfF7AgrFKYQFG6Gk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MibtfTcM; 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="MibtfTcM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E5AA1F000E9; Fri, 21 Aug 2026 20:03:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787342624; bh=HdfvtvYPMrFT5OC9MSMaQdtdWBU+zkNaBqAFzWpxBHY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=MibtfTcMicJIMiOi8G0UcHOiiij2jWU7UXqfomnnYgOn63/sGqZQH6F6yG6OY7JM2 hNq2TZu34NIbUWmlFZFT/arUK6p3+lpNSrPouIprIH5ZU1h5jEIJYEtYXCKzyjqMhy 1USi84hBtnXivcNCE162PEOQ9qZ6FeIRqtDIj6hKnnbSo99Fq7d+kLbtnHc8b5lJFb uOgN5GIrcIVH4AWT22GEHeHZLEK4sVHvQIywqsSDpGzS/J8mo4S6a9rql1KIKuFe55 3KJ+cy3jMhVntvFr7jL3dC4T3sPh5A96Al5vlzby8TFuRLv7PeUhjUDJrnJ/+C2sV0 euLO2ccDuxsIA== From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH v2 06/24] unwind_user: Enable archs that define CFA = SP_callsite + offset Reply-To: sashiko-reviews@lists.linux.dev To: "Jens Remus" Cc: linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, "Heiko Carstens" , "Christian Borntraeger" , "Alexander Gordeev" , "Vasily Gorbik" In-Reply-To: <20260821195259.2688377-7-jremus@linux.ibm.com> References: <20260821195259.2688377-1-jremus@linux.ibm.com> <20260821195259.2688377-7-jremus@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 21 Aug 2026 20:03:44 +0000 Message-Id: <20260821200344.7E5AA1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Most architectures define their CFA as the value of the stack pointer > (SP) at the call site in the previous frame, as suggested by the DWARF > standard. Therefore the SP at call site can be unwound using an > implicitly assumed value offset from CFA rule with an offset of zero: >=20 > .cfi_val_offset , 0 >=20 > As a result the SP at call site computes as follows: >=20 > SP =3D CFA >=20 > Enable unwinding of user space for architectures, such as s390, which > define their CFA as the value of the SP at the call site in the previous > frame with an offset. Do so by enabling architectures to override the > default SP value offset from CFA of zero with an architecture-specific > one: >=20 > .cfi_val_offset , offset >=20 > So that the SP at call site computes as follows: >=20 > SP =3D CFA + offset >=20 > Signed-off-by: Jens Remus Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260821195259.2688= 377-1-jremus@linux.ibm.com?part=3D6