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Peter Anvin" , Mathieu Desnoyers , Indu Bhagat , "Jose E. Marchesi" , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v3 1/3] unwind_user: Enhance comments on get CFA, FP, and RA Date: Tue, 2 Dec 2025 16:08:11 +0100 Message-ID: <20251202150814.3505869-2-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251202150814.3505869-1-jremus@linux.ibm.com> References: <20251202150814.3505869-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: SVlJ4mMwXMYe1KhvuK4Dv1EETDjg7mqa X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTI5MDAxNiBTYWx0ZWRfX5FXSDTJFfssB 3Gm4oRmzAvmt0WuAIJafFXZ5kLI905Zhl/vKNaCOFhCgl9KUklHQEFBl56E1fKQXeea+L/4PAJX SaaI8mwdtVdjuOhwNCcnxb37jFn1gf1l8L5qK49eOxbvfrwe/IzjiQtTeoCNEOqINn3H70cz3lD +CpxjToMgw0B8IcSBQYzv57T5y9TTthj3cNJFUkrUJcBCzQPN61aS6QTKHrU4Ko6zydquJKmg4H HOl4vPQXYkwbHnY7fkHK5EnQPVbdUNfRH3vBDIL+xw+dERyDRJnGdC3MJIRALx+PVy51tzfRu/a 4AA7cT/TI5ALV84cyhTn5Ou3bdYeVCNFwnwUWmrniZyHa7QT00mYn8NTkpTS2KPU4zseSKPyBld 492cIFlxdeHK786c/JOe0dzNQk4sFg== X-Authority-Analysis: v=2.4 cv=UO7Q3Sfy c=1 sm=1 tr=0 ts=692f00e4 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=wP3pNCr1ah4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=GRZQj7fo7pb9Qcd1f_cA:9 X-Proofpoint-GUID: SVlJ4mMwXMYe1KhvuK4Dv1EETDjg7mqa X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-01_01,2025-11-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 bulkscore=0 adultscore=0 priorityscore=1501 impostorscore=0 spamscore=0 phishscore=0 clxscore=1015 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511290016 Content-Type: text/plain; charset="utf-8" Move the comment "Get the Canonical Frame Address (CFA)" to the top of the sequence of statements that actually get the CFA. Reword the comment "Find the Return Address (RA)" to "Get ...", as the statements actually get the RA. Add a respective comment to the statements that get the FP. This will be useful once future commits extend the logic to get the RA and FP. While at it align the comment on the "stack going in wrong direction" check to the following one on the "address is word aligned" check. Signed-off-by: Jens Remus --- kernel/unwind/user.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index 39e270789444..0ca434f86e73 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -31,6 +31,7 @@ static int unwind_user_next_common(struct unwind_user_sta= te *state, { unsigned long cfa, fp, ra; =20 + /* Get the Canonical Frame Address (CFA) */ if (frame->use_fp) { if (state->fp < state->sp) return -EINVAL; @@ -38,11 +39,9 @@ static int unwind_user_next_common(struct unwind_user_st= ate *state, } else { cfa =3D state->sp; } - - /* Get the Canonical Frame Address (CFA) */ cfa +=3D frame->cfa_off; =20 - /* stack going in wrong direction? */ + /* Make sure that stack is not going in wrong direction */ if (cfa <=3D state->sp) return -EINVAL; =20 @@ -50,10 +49,11 @@ static int unwind_user_next_common(struct unwind_user_s= tate *state, if (cfa & (state->ws - 1)) return -EINVAL; =20 - /* Find the Return Address (RA) */ + /* Get the Return Address (RA) */ if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) return -EINVAL; =20 + /* Get the Frame Pointer (FP) */ if (frame->fp_off && get_user_word(&fp, cfa, frame->fp_off, state->ws)) return -EINVAL; =20 --=20 2.51.0