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Wed, 24 Jun 2026 12:08:50 -0700 (PDT) Received: from hu-mojha-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-845a412e5e9sm2932120b3a.54.2026.06.24.12.08.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2026 12:08:50 -0700 (PDT) From: Mukesh Ojha To: Bjorn Andersson , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Robert Marko , Guru Das Srinagesh Cc: cros-qcom-dts-watchers@chromium.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mukesh Ojha Subject: [PATCH v4 03/19] firmware: qcom: scm: Fix missing smp_load_acquire() Date: Thu, 25 Jun 2026 00:38:14 +0530 Message-ID: <20260624190830.3131112-4-mukesh.ojha@oss.qualcomm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260624190830.3131112-1-mukesh.ojha@oss.qualcomm.com> References: <20260624190830.3131112-1-mukesh.ojha@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjI0MDE2MCBTYWx0ZWRfX4iwt/PDrVfpV pWPPOdbW0ULAsd9+jrWTuJMpiU2+rouJ+eN5JP7dTK/3JD1mmwVxkG9wQOJpR8sRTnxmwlaMFor nblnofc6itt/AGCEe7GlIB1oE3VyxFwbCMyOV2tVjL2v/NaiNUefExMg3BmCJJ/b9O9SYeW9TT6 cYUu+b28GkO6kbScd/AzgP8n6MrsEBB3OXaXt0al80pOLSzlA7Xqd1AxYzIKOfQaOwiGA3tt4i+ sLpY36mIlaHSb05JGttWk+lURQ1ZTsZbRKuh3pr0w1VFY8prEFAa/oJ44jKcwjPz+dyT9ItvbJI MA8kcSWahBTBVFwKmE1f/p5L6obCqd4Bp0gsJKl1s8W4VUvdxUIok5uZqqD3Uq3/ImPPJ2gSIDP f7v3JFUQ4Jj1hTUicW9eaVxQEG2kz6k7PTVIXIu5DefgR5QvgBtuYlvd0D7+yZpVTJxyRoC2yCP Mkafeo6mOflU3OsdQCw== X-Proofpoint-ORIG-GUID: 7nciikE4Ig1cBe_1ffV0FBGHuct7WBiq X-Authority-Analysis: v=2.4 cv=ZM7nX37b c=1 sm=1 tr=0 ts=6a3c2b44 cx=c_pps a=rz3CxIlbcmazkYymdCej/Q==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=FelO9ux0wxsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=EUspDBNiAAAA:8 a=NeVOsJV41uE9b8WGLD4A:9 a=bFCP_H2QrGi7Okbo017w:22 X-Proofpoint-GUID: 7nciikE4Ig1cBe_1ffV0FBGHuct7WBiq X-Proofpoint-Spam-Info: AW1haW4tMjYwNjI0MDE2MCBTYWx0ZWRfX50oJ82s7l123 UUUfgQLOOHZpcY7c875bhK6SR/LECwL9KrB3c+rnaoEr57uGF0JtvB3K4HuMq32Np+8GICjQEhG 9zswAhk+ZvDBpxC/ZxsQ5lKYnxhxmSQ= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-24_03,2026-06-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 impostorscore=0 clxscore=1015 suspectscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606240160 __scm is published in qcom_scm_probe() with smp_store_release() but qcom_scm_set_download_mode() reads it directly without smp_load_acquire(), creating a potential ordering violation where a CPU could observe a stale or partially initialised __scm pointer. Use smp_load_acquire() to acquire __scm in the qcom_scm_set_download_mode() function. Signed-off-by: Mukesh Ojha --- drivers/firmware/qcom/qcom_scm.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c index 6b601a4b89db..b78da40a4d60 100644 --- a/drivers/firmware/qcom/qcom_scm.c +++ b/drivers/firmware/qcom/qcom_scm.c @@ -551,23 +551,23 @@ static int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val return qcom_scm_io_writel(addr, new); } -static void qcom_scm_set_download_mode(u32 dload_mode) +static void qcom_scm_set_download_mode(struct qcom_scm *scm, u32 dload_mode) { int ret = 0; - if (__scm->dload_mode_addr) { - ret = qcom_scm_io_rmw(__scm->dload_mode_addr, QCOM_DLOAD_MASK, + if (scm->dload_mode_addr) { + ret = qcom_scm_io_rmw(scm->dload_mode_addr, QCOM_DLOAD_MASK, FIELD_PREP(QCOM_DLOAD_MASK, dload_mode)); - } else if (__qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_BOOT, + } else if (__qcom_scm_is_call_available(scm->dev, QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_SET_DLOAD_MODE)) { - ret = __qcom_scm_set_dload_mode(__scm->dev, !!dload_mode); + ret = __qcom_scm_set_dload_mode(scm->dev, !!dload_mode); } else if (dload_mode) { - dev_err(__scm->dev, + dev_err(scm->dev, "No available mechanism for setting download mode\n"); } if (ret) - dev_err(__scm->dev, "failed to set download mode: %d\n", ret); + dev_err(scm->dev, "failed to set download mode: %d\n", ret); } /** @@ -2705,6 +2705,7 @@ static int get_download_mode(char *buffer, const struct kernel_param *kp) static int set_download_mode(const char *val, const struct kernel_param *kp) { + struct qcom_scm *scm; bool tmp; int ret; @@ -2720,8 +2721,10 @@ static int set_download_mode(const char *val, const struct kernel_param *kp) } download_mode = ret; - if (__scm) - qcom_scm_set_download_mode(download_mode); + /* Pairs with smp_store_release() in qcom_scm_probe(). */ + scm = smp_load_acquire(&__scm); + if (scm) + qcom_scm_set_download_mode(scm, download_mode); return 0; } @@ -2842,7 +2845,7 @@ static int qcom_scm_probe(struct platform_device *pdev) * will cause the boot stages to enter download mode, unless * disabled below by a clean shutdown/reboot. */ - qcom_scm_set_download_mode(download_mode); + qcom_scm_set_download_mode(scm, download_mode); /* * Disable SDI if indicated by DT that it is enabled by default. @@ -2875,7 +2878,7 @@ static int qcom_scm_probe(struct platform_device *pdev) static void qcom_scm_shutdown(struct platform_device *pdev) { /* Clean shutdown, disable download mode to allow normal restart */ - qcom_scm_set_download_mode(QCOM_DLOAD_NODUMP); + qcom_scm_set_download_mode(__scm, QCOM_DLOAD_NODUMP); } static const struct of_device_id qcom_scm_dt_match[] = { -- 2.53.0