From nobody Thu Sep 24 18:44:20 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C1EC735CB7F for ; Tue, 22 Sep 2026 01:14:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790039694; cv=none; b=OfFx66zynE/PE4HtTvVyVxc48ewp8IQEUYJcCpGbhAsgUHKcjYQlAFrle2Edw7h6C90zvT+Atufu3q+5K1y1SzTUMqckDCgOq6iJL9CuvNXsyV6QHSELhFAkYUOdpU7frbeOdIf8UwbiIA82zKlsDIBn20DPgejmB2an4oc3WxM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790039694; c=relaxed/simple; bh=m3LsZOYKXpBxu2jAlB5YJTHDy68xjmQ8m4RqAnY7buc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=S/m4xSxb60ArSf26fwNEGaDS/ms8AcMtqzD8Cv9BAUk0ZxHPs4ejEzHJUXeq+BsNAyWJLyM4p4RK/Zw69G4PZCLHJ/3KiTz3UbBR5OeZ+R0XWlK6T7azN0FD5kFVdfIaQ1fHlkCT83CY4MxRfoStSXl82HiJ2ggaMJyygxOTpHI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OshD3BQf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OshD3BQf" Received: by smtp.kernel.org (Postfix) with ESMTPS id 82C0BC2BCB3; Tue, 22 Sep 2026 01:14:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1790039694; bh=m3LsZOYKXpBxu2jAlB5YJTHDy68xjmQ8m4RqAnY7buc=; h=From:Date:Subject:To:Cc:Reply-To:From; b=OshD3BQfh9BhJu5uNQp2FG3/KqPInw+5i8WTKaJ43CSjwpWEPppk+JHwKLD0tV2DK WXO0iN3LmPo0mA7JMoLS1p/28CSZeD6A5yg6pk+GsaaICj5V/uiahLdjodn4FXKrkz rWkV8Fl66NWLd38Pk7Ek98gf97OqNm82xcqM+3EsoHnClZRC8u2cJN660XLz/ErUvU +Ks9wMJjqOkbBz74Z3af6x7EB3aUxKIlXypXYt0CgwvCuMUPl99pgshozZQ/QJVFzl SYdPYY/U/vXye+/ACk5m5r9cm8aQLhE3fuCoNMmc8mriV7rGF8fI1g9dciTFd1zOSe w50U7GrIVY+MQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E744C982FB; Tue, 22 Sep 2026 01:14:54 +0000 (UTC) From: Jaidev Shastri via B4 Relay Date: Mon, 21 Sep 2026 21:14:52 -0400 Subject: [PATCH] firmware: arm_sdei: publish sdei_entry_point with release semantics Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260921-mb-arm-sdei-v1-1-6d12d12a7cba@vt.edu> X-B4-Tracking: v=1; b=H4sIAIvWsWoC/yXMzQrCMBAE4Fcpe3YljVKNryIe8rOxKzTKrhah9 N1N6vEbZmYBJWFSuHQLCM2s/CwV/a6DOPpyJ+RUDdbYwTjb4xTQy4SaiDEPLjtjw7k3CeriJZT 5u71db3/rJzwovttFawSvhEF8iWOLNs6n/QElHmFdf6MD9r+PAAAA X-Change-ID: 20260921-mb-arm-sdei-f69f902b810d To: James Morse Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jaidev Shastri X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1790039693; l=3316; i=jaidevshastri@vt.edu; s=20260921; h=from:subject:message-id; bh=kwRV/aHBCufpjFjA3xGTlvIAqmYK7kG+Dzi8qsvpfdU=; b=Fgbe9A5j8oOXTX+D4bvOXfcOfpfGlHrCYiIHUVy5lzThSYDd/gVtl2n+KkwU/cSS5swWUe4rz cfIXERHDaG2CXS+vG1wOV/wF4ctaKXQuHdeBN2m3d9IcRLLINEGmlme X-Developer-Key: i=jaidevshastri@vt.edu; a=ed25519; pk=J7+xYJRlTPds+pv5hbqFFRqGCpDeJDzmZT1ggRwj7/0= X-Endpoint-Received: by B4 Relay for jaidevshastri@vt.edu/20260921 with auth_id=1044 X-Original-From: Jaidev Shastri Reply-To: jaidevshastri@vt.edu From: Jaidev Shastri sdei_probe() stores the SDEI entry point to the file-scope sdei_entry_point with a plain store after the platform reset. sdei_event_register(), the cross-call helper _local_event_register() and the re-registration path pass it to the firmware with plain loads. Keep it in a local and publish it with smp_store_release(). Read it through a new sdei_get_entry_point() accessor at the three call sites. Found with MBCheck, a static herd7-based memory consistency checker. Signed-off-by: Jaidev Shastri --- drivers/firmware/arm_sdei.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c index e8dd2f0f3..a75203469 100644 --- a/drivers/firmware/arm_sdei.c +++ b/drivers/firmware/arm_sdei.c @@ -43,6 +43,12 @@ static asmlinkage void (*sdei_firmware_call)(unsigned lo= ng function_id, /* entry point from firmware to arch asm code */ static unsigned long sdei_entry_point; =20 +static unsigned long sdei_get_entry_point(void) +{ + /* Pairs with the smp_store_release() in sdei_probe(). */ + return smp_load_acquire(&sdei_entry_point); +} + static int sdei_hp_state; =20 struct sdei_event { @@ -582,7 +588,7 @@ static void _local_event_register(void *data) struct sdei_crosscall_args *arg =3D data; =20 reg =3D per_cpu_ptr(arg->event->private_registered, smp_processor_id()); - err =3D sdei_api_event_register(arg->event->event_num, sdei_entry_point, + err =3D sdei_api_event_register(arg->event->event_num, sdei_get_entry_poi= nt(), reg, 0, 0); =20 sdei_cross_call_return(arg, err); @@ -612,7 +618,7 @@ int sdei_event_register(u32 event_num, sdei_event_callb= ack *cb, void *arg) cpus_read_lock(); if (event->type =3D=3D SDEI_EVENT_TYPE_SHARED) { err =3D sdei_api_event_register(event->event_num, - sdei_entry_point, + sdei_get_entry_point(), event->registered, SDEI_EVENT_REGISTER_RM_ANY, 0); } else { @@ -650,7 +656,7 @@ static int sdei_reregister_shared(void) =20 if (event->reregister) { err =3D sdei_api_event_register(event->event_num, - sdei_entry_point, event->registered, + sdei_get_entry_point(), event->registered, SDEI_EVENT_REGISTER_RM_ANY, 0); if (err) { pr_err("Failed to re-register event %u\n", @@ -978,6 +984,7 @@ static int sdei_get_conduit(struct platform_device *pde= v) =20 static int sdei_probe(struct platform_device *pdev) { + unsigned long entry_point; int err; u64 ver =3D 0; int conduit; @@ -1007,12 +1014,14 @@ static int sdei_probe(struct platform_device *pdev) if (err) return err; =20 - sdei_entry_point =3D sdei_arch_get_entry_point(conduit); - if (!sdei_entry_point) { + entry_point =3D sdei_arch_get_entry_point(conduit); + if (!entry_point) { /* Not supported due to hardware or boot configuration */ sdei_mark_interface_broken(); return 0; } + /* Pairs with the smp_load_acquire() in sdei_get_entry_point(). */ + smp_store_release(&sdei_entry_point, entry_point); =20 err =3D cpu_pm_register_notifier(&sdei_pm_nb); if (err) { --- base-commit: 93f51579e7df248780214094418f205253383cc5 change-id: 20260921-mb-arm-sdei-f69f902b810d Best regards, -- =20 Jaidev Shastri