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Peter Anvin" , Mathieu Desnoyers , Indu Bhagat , "Jose E. Marchesi" , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH 1/3] unwind_user: Enhance comments on get CFA, FP, and RA Date: Tue, 25 Nov 2025 17:43:47 +0100 Message-ID: <20251125164349.2592874-2-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251125164349.2592874-1-jremus@linux.ibm.com> References: <20251125164349.2592874-1-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-Spam-Details-Enc: AW1haW4tMjUxMTIyMDAxNiBTYWx0ZWRfX1KXu6t2wPS0R A+0SmgvR1GoitXoFU4Br1S7HBPaHUG3FmF5e4049NZKCjY+jjlXUUNEH+2oP2fBIxQs6Z7uQeBo cBJGaZvFVou6fs5PRSWfQZ0osy+VWYDTtWotHEp35Y9aOi6VSOI1tOTCdRB/Goc2Ynj7nJOD4Py cDQUBkxHkhTRyIvGGKBz8T7dcAGiyNRMsgqygCk0yaSx7Dt24d427Kvb6bBFthCZhaTw6/i/y5A e20CBjxAxedu1IpaHp40bspODwVslVPNbXxn8oNYf8J2+bASxcb170LsqwdFaJfh5I4XxqP0kwR hEW1PPPrIRBJBsGP2wwo5cPoXxsQ1SBC0bl7jQbnyM+K/S56f7iqRPAqHsmOkEGvqs3JNkw8I8R Rs71FuKdAKaTlmT4ZLx+hoAshNM2cQ== X-Proofpoint-ORIG-GUID: NOzabWbe7hh2k-PNGaQXU5L6shDSOH-e X-Authority-Analysis: v=2.4 cv=CcYFJbrl c=1 sm=1 tr=0 ts=6925dcd1 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=GRZQj7fo7pb9Qcd1f_cA:9 X-Proofpoint-GUID: NOzabWbe7hh2k-PNGaQXU5L6shDSOH-e 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=2025-11-25_02,2025-11-25_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 clxscore=1015 adultscore=0 spamscore=0 phishscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511220016 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