From nobody Sun Oct 5 16:14:43 2025 Received: from mail-io1-f45.google.com (mail-io1-f45.google.com [209.85.166.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EE97C286436; Sun, 3 Aug 2025 03:59:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.45 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754193559; cv=none; b=VengCC5DVXzMSjf732O89HbZzxeOR2RGid8kQtN6nKIGM6NfTLT3wzoZXEgfiqE0C+FMnTKZUK3YVz213kKb+dM5bJaVQy8J/Y+9QXAQ84gyFkCZq9SBCOpsgpJBHXhhfKAzlTlS3e0FbYKZ72ZXei7i1P3YsxpHp6K+2BfWUJI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754193559; c=relaxed/simple; bh=Jj0f9JkUdyvI8rnvS13GD8oQmp6layChoeb3nY10K0s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DeQ7HT4J649SkusB2c4UjMFTdCqrVl/zo/JPwLu+NdonA6xNtmXQR+NKsJVx1UjR7RYUsdiVOfePTmev59UeMX5hbSLmTt4jxQt/r+NI862tCoFFvl9/gWPjGBhxQhXMWjdfj8tcMk9/zqK21y3Pbz/UmDYljvEMqKv/GORWdEw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=dboArhtb; arc=none smtp.client-ip=209.85.166.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dboArhtb" Received: by mail-io1-f45.google.com with SMTP id ca18e2360f4ac-8811ab2b559so242683939f.3; Sat, 02 Aug 2025 20:59:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1754193556; x=1754798356; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=HXquqH7KII4sF+LJ1AfrwTmzreYTzxHzyyy3sHAB95g=; b=dboArhtb6ZK1ql8BicZPTKKBT5Dt7lI2c3kKsuGoO9Ab4CUwtveJztosLMpqUFx5tN bEzTPYQqWG+4gFBcgTcSjKE9KBR5mo0i575LjZqYHWmHm+X1rTLNJ6TtZqlJoX2f/Q36 jkKCo7HEiFuIlryy1G83cVSwkcY/T16hohk1FuJN9tYVsijUUmFMOGvV3v4xNsAANzN8 OhBoBTranx50RlWyKAJUWretEFHGWzf46bVFpFLgAGjG+Z38nhLcrL68pEak+CjvTG0E Jc7GPAc3cc3I29WxcSnMzv31BsNo+n2cqpnc5xpL3Y88FI5pqVK7saukbmrXjB8RQNUd 0LZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754193556; x=1754798356; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=HXquqH7KII4sF+LJ1AfrwTmzreYTzxHzyyy3sHAB95g=; b=lvqUxrE40I5aIlzGHcEZ/2431lapJ4GPAIr/h4dUAoiXWCr+bL4PIeKz4FAuH0+rEw 0HS3U0CLwyfk6W/lbkEYVtBWOBd3YQpcOaVXaxfK4fYtrhyRgJwRrtUeS9a9IMhOZTNN vayarsvcMjtQvoRu6ecIxu814xTB/pYG7hyrqZj9meFC4MQeiyOkwPN7jjEVGMJ+XQPE dLyk5ViFHCcq1xpd/76evW5GZf1Tnnr+t53IXzy5CB32emR5ut8MJUHAO/ayluWhXFdY dAPjdg7wq8U9TIcLpxlz9M0iupXs46O8FUyQdIXR2o+F3V6LxsPGP44DPcVyRvcKJNMX SNow== X-Forwarded-Encrypted: i=1; AJvYcCX4lRxMbW1a76p0qvFzu4c81JuBYQa0CrhUuJN+VAVIQRozVYwdEdtD/yom2uU9+TUrYWmnq/7q9e30Fsk/@vger.kernel.org X-Gm-Message-State: AOJu0YwTh/JPFBsd9/45Nspb+TywqtVh+2kWBTTDm6lNgMgqEvssUAer L5bfV1xinR0T9USQEDz1Pq8XlDgHIKbZQJlruOYph1/Xej7H1cQJUC530jq0HVVfJxQ= X-Gm-Gg: ASbGncs+2Mq/BS+5dGUcMh1KbnB5mAmNohNx4bnC/4HCZom37e7lJEtsrp3KrbUVlBz YpTFPuajybMCPitLmDOiAeorkZv+gyGYtNxRSlJpf9osivKMF+v1n8OntedcY5Rpf9NlGDYAutg uwGw0d8yEVocfjMIkz8l4LpguMTDRepTbwwq5XSCbSw2SD7CEbdEE0xhaDCwRJz1v0klQ+Ryo0p k9UII5gqDTYjmF+8zCl4Om5mV/kw4iTCb972Z+ZeGZaxNt9hcCiBdd+fCB15EFNKWF7N6T4a98y 5BbfEWMSgGZjvzrxfS0ASDRJ+So1c0wRGBpyHjchwlGSkYZibrQ2B2cEUBCdAoKScdbTfy88BO4 H7oDwPHZT3MasXcTu4SLZl7pW+VxTd80Wc4Hu7te0RrrSmIZAuFRCh2lKptl5LkVISTwP2k7r/Z JJ8Q== X-Google-Smtp-Source: AGHT+IHEnyztiCzMLSKzxMv0/iqEKnGgfqHvaJUwVU2gtBDtmGy6WUb/KQqWprxWVGQiSsEBcFCLfQ== X-Received: by 2002:a05:6602:6b81:b0:87c:34e3:1790 with SMTP id ca18e2360f4ac-88168313db5mr806307439f.1.1754193555783; Sat, 02 Aug 2025 20:59:15 -0700 (PDT) Received: from frodo.raven-morpho.ts.net (c-67-165-245-5.hsd1.co.comcast.net. [67.165.245.5]) by smtp.googlemail.com with ESMTPSA id 8926c6da1cb9f-50a55df0940sm2268319173.106.2025.08.02.20.59.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Aug 2025 20:59:15 -0700 (PDT) From: Jim Cromie To: linux-kernel@vger.kernel.org, jbaron@akamai.com, gregkh@linuxfoundation.org, ukaszb@chromium.org, louis.chauvet@bootlin.com Cc: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, daniel.vetter@ffwll.ch, tvrtko.ursulin@linux.intel.com, jani.nikula@intel.com, ville.syrjala@linux.intel.com, seanpaul@chromium.org, robdclark@gmail.com, groeck@google.com, yanivt@google.com, bleung@google.com, quic_saipraka@quicinc.com, will@kernel.org, catalin.marinas@arm.com, quic_psodagud@quicinc.com, maz@kernel.org, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, mingo@redhat.com, jim.cromie@gmail.com Subject: [PATCH v4 28/58] dyndbg: restore classmap protection when theres a controlling_param Date: Sat, 2 Aug 2025 21:57:46 -0600 Message-ID: <20250803035816.603405-29-jim.cromie@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250803035816.603405-1-jim.cromie@gmail.com> References: <20250803035816.603405-1-jim.cromie@gmail.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 Content-Type: text/plain; charset="utf-8" DRM has always had /sys/module/drm/parameters/debug (ie drm.debug). Without dyndbg, this is their only control point. One could presume they like it - in any case its a system/user interface, ie ABI. With dyndbg enabled, drm calls DYNAMIC_DEBUG_CLASSMAP_PARAM() to create the drm.debug kparam, wired to our param-handler, which writes a "class FOO" query for each bit in the classmap. Since no new interface was ever contemplated, this is using >control. Since drm.debug is ABI, we should not allow class-less queries to alter our implementation of its settings. This patch provides that protection, *only* when theres a PARAM. This is the user, expressing their wish for easy control of their entire classmap. They also wish to trust its settings. Classes without a PARAM are unprotected, allowing admins their shortcuts. No such use-cases exist yet. Anyway, this patch does: 1. adds struct _ddebug_class_map.controlling_param 2. set it in ddebug_match_apply_kparam(), during modprobe/init, when options like drm.debug are handled. 3. ddebug_class_has_param() checks .controlling_param 4. ddebug_class_wants_protection() macro renames 3. 5. ddebug_change() calls 4 when needed. IE when applying a class-less query to a class'd pr_debug / drm_dbg_ Historical Summary: -v0 - before classmaps. no special case keywords -v1 - "class DEFAULT" is assumed if not mentioned. this protects classes from class-less queries -v2.pre-this-patch - protection macro'd to false -v2.with-this-patch - sysfs knob decides -v2.speculative - module decides wrt classmap protection seems unneeded now, TBD NOTE: protection is only against class-less queries, explicit "class FOO" adjustments are allowed (that is the mechanism). Signed-off-by: Jim Cromie --- v3 - new patch --- include/linux/dynamic_debug.h | 16 ++++++---- lib/dynamic_debug.c | 55 ++++++++++++++++++++++++++--------- 2 files changed, 52 insertions(+), 19 deletions(-) diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index 2d959f1f8cd30..bc26bc9128c1c 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -100,8 +100,9 @@ enum ddebug_class_map_type { * __pr_debug_cls(0, "fake CORE msg") in any part of DRM would "work" * __pr_debug_cls(22, "no such class") would compile, but not "work" */ - +struct _ddebug_class_param; struct _ddebug_class_map { + struct _ddebug_class_param *controlling_param; const struct module *mod; /* NULL for builtins */ const char *mod_name; const char **class_names; @@ -231,7 +232,12 @@ struct _ddebug_class_param { * * Creates a sysfs-param to control the classes defined by the * exported classmap, with bits 0..N-1 mapped to the classes named. - * This version keeps class-state in a private long int. + * + * Since sysfs-params are ABI, this also protects the classmap'd + * pr_debugs from un-class'd `echo -p > /proc/dynamic_debug/control` + * changes. + * + * This keeps class-state in a private long int. */ #define DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _var, _flags) \ static unsigned long _name##_bvec; \ @@ -244,10 +250,8 @@ struct _ddebug_class_param { * @_var: name of the (exported) classmap var defining the classes/bits * @_flags: flags to be toggled, typically just 'p' * - * Creates a sysfs-param to control the classes defined by the - * exported clasmap, with bits 0..N-1 mapped to the classes named. - * This version keeps class-state in user @_bits. This lets drm check - * __drm_debug elsewhere too. + * Like DYNAMIC_DEBUG_CLASSMAP_PARAM, but maintains param-state in + * extern @_bits. This lets DRM check __drm_debug elsewhere too. */ #define DYNAMIC_DEBUG_CLASSMAP_PARAM_REF(_name, _bits, _var, _flags) \ __DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _bits, _var, _flags) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 548a82a178d49..c3e27637d9357 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -198,16 +198,26 @@ ddebug_find_valid_class(struct _ddebug_info const *di= , const char *query_class, } =20 /* - * classmaps-v1 protected classes from changes by legacy commands - * (those selecting _DPRINTK_CLASS_DFLT by omission), v2 undoes that - * special treatment. State so explicitly. Later we could give - * modules the choice to protect their classes or to keep v2 behavior. + * classmaps-V1 protected classes from changes by legacy commands + * (those selecting _DPRINTK_CLASS_DFLT by omission). This had the + * downside that saying "class FOO" for every change can get tedious. + * + * V2 is smarter, it protects class-maps if the defining module also + * calls DYNAMIC_DEBUG_CLASSMAP_PARAM to create a sysfs parameter. + * Since they want the knob, we should assume they intend to use it + * (in preference to "class FOO +p" >control), and want to trust its + * settings. + * This gives protection when its useful, and not when its just tedious. */ -static inline bool ddebug_client_module_protects_classes(const struct ddeb= ug_table *dt) +static inline bool ddebug_class_has_param(const struct _ddebug_class_map *= map) { - return false; + return !!(map->controlling_param); } =20 +/* re-framed as a policy choice */ +#define ddebug_class_wants_protection(map) \ + ddebug_class_has_param(map) + /* * Search the tables for _ddebug's which match the given `query' and * apply the `flags' and `mask' to them. Returns number of matching @@ -250,7 +260,7 @@ static int ddebug_change(const struct ddebug_query *que= ry, struct flag_settings /* site.class !=3D given class */ continue; /* legacy query, class'd site */ - else if (ddebug_client_module_protects_classes(dt)) + else if (ddebug_class_wants_protection(map)) continue; /* allow change on class'd pr_debug */ } @@ -650,6 +660,7 @@ static int ddebug_exec_queries(char *query, const char = *modname) } =20 /* apply a new class-param setting */ + static int ddebug_apply_class_bitmap(const struct _ddebug_class_param *dcp, const unsigned long *new_bits, const unsigned long old_bits, @@ -1228,25 +1239,36 @@ static void ddebug_sync_classbits(const struct kern= el_param *kp, const char *mod } } =20 -static void ddebug_match_apply_kparam(const struct kernel_param *kp, - const struct _ddebug_class_map *map, - const char *mod_name) +static struct _ddebug_class_param * +ddebug_get_classmap_kparam(const struct kernel_param *kp, + const struct _ddebug_class_map *map) { struct _ddebug_class_param *dcp; =20 if (kp->ops !=3D ¶m_ops_dyndbg_classes) - return; + return false; =20 dcp =3D (struct _ddebug_class_param *)kp->arg; =20 - if (map =3D=3D dcp->map) { + return (map =3D=3D dcp->map) + ? dcp : (struct _ddebug_class_param *)NULL; +} + +static void ddebug_match_apply_kparam(const struct kernel_param *kp, + struct _ddebug_class_map *map, + const char *mod_name) +{ + struct _ddebug_class_param *dcp =3D ddebug_get_classmap_kparam(kp, map); + + if (dcp) { + map->controlling_param =3D dcp; v2pr_info(" kp:%s.%s =3D0x%lx", mod_name, kp->name, *dcp->bits); vpr_cm_info(map, " %s mapped to: ", mod_name); ddebug_sync_classbits(kp, mod_name); } } =20 -static void ddebug_apply_params(const struct _ddebug_class_map *cm, const = char *mod_name) +static void ddebug_apply_params(struct _ddebug_class_map *cm, const char *= mod_name) { const struct kernel_param *kp; #if IS_ENABLED(CONFIG_MODULES) @@ -1266,6 +1288,13 @@ static void ddebug_apply_params(const struct _ddebug= _class_map *cm, const char * } } =20 +/* + * called from add_module, ie early. it can find controlling kparams, + * which can/does? enable protection of this classmap from class-less + * queries, on the grounds that the user created the kparam, means to + * use it, and expects it to reflect reality. We should oblige him, + * and protect those classmaps from classless "-p" changes. + */ static void ddebug_apply_class_maps(const struct _ddebug_info *di) { struct _ddebug_class_map *cm; --=20 2.50.1