From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 799B24F474D for ; Mon, 19 Oct 2026 13:28:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792416530; cv=none; b=naKdEnUBuOl4VBReT+wqxxcKSIbfPnlQwxYMqFlQFwdCnlhY5hzYg86J4yjhCeoRCF4k0HQtK3A34SmQNKFnfp69f3VyX0UWb5VbBCig3gksV/TpAztviwdPvrJDZn/aWe9e3LEZI7DYKAnT48bzM8rjcsJGTdAdPZRPbZvRJFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792416530; c=relaxed/simple; bh=GMqklCenpFaYaxcJvPNUFIppL+AjgLQQ3Ow/FoEWGV0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=WyHxNdd/VSM+7DXFEmAM9yKBSCKan9i4LyWWncQmfOPIfkdfuL6XR1vURsTzcNHBvwWrsgpQCFi5aNDCy1MjF55bSoXXG9weXrxujp1iGf6yQhjw+a67CCIOmypYGQIzwsugN/a8W1aCj70b0bbjYr+iUKOzDzwg0fuVA8Ok3S8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=RXO4FDEN; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="RXO4FDEN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792416529; x=1823952529; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=GMqklCenpFaYaxcJvPNUFIppL+AjgLQQ3Ow/FoEWGV0=; b=RXO4FDENirKyR5irl2MznkiNeWeLGn/AgOIj8b9bpDsA2YkbDPFs0Sxg fZ1RDE/RquJVlpzwJpbtN0NaRqAW+wV13gbddr9e/85lQBcMMamm1o28A efJamao0bXNA76qDqLitrgppbSFksDLEGuQquxXnNiSN1nyXszRoFUXQh CfPodU1tQ4RBUvc0tCt9TcVNosbIBEZ9BAncOhilsbeNgvLpthU+MytAE UprojQ31c/59sQmaaH9ahGUkXZgQfjjMvSyoZR38nmimpL+KZiONnZNSj E1RSuGpqS8P6TDPug5WrmJg0+obM7ZNkh6X/5pC1fh4E6CGzOlBLYqNVr w==; X-CSE-ConnectionGUID: wAMh9GlWQyiECexI2qzecg== X-CSE-MsgGUID: d3nLuP1rSHOE+KJ3QijBHQ== X-IronPort-AV: E=McAfee;i="6800,10657,11940"; a="995802" X-IronPort-AV: E=Sophos;i="6.27,167,1787036400"; d="scan'208";a="995802" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2026 06:28:48 -0700 X-CSE-ConnectionGUID: BQpdfbZKRlu92tPvzvxVUg== X-CSE-MsgGUID: 0qNzjuEDRCaKJgpO70C1rQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,167,1787036400"; d="scan'208";a="2413921" Received: from ettammin-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.244.21]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2026 06:28:44 -0700 From: Jani Nikula To: Arnd Bergmann , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: Arnd Bergmann , "Mario Limonciello (AMD)" , Chenyu Chen , Alex Deucher , Harry Wentland , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/edid: reduce update_display_info() stack usage In-Reply-To: <20261013205223.2396822-1-arnd@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland References: <20261013205223.2396822-1-arnd@kernel.org> Date: Mon, 19 Oct 2026 16:28:41 +0300 Message-ID: <6c18da11310ced4a7c85ac7862c3f5c67b39891a@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, 13 Oct 2026, Arnd Bergmann wrote: > From: Arnd Bergmann > > The drm_parse_cea_ext() calls into nine individual parser functions > based on the data format. If all of those get inlined and KASAN_STACK > is enabled, this can explode the combined stack usage beyond a > reasonable amount: > > drivers/gpu/drm/drm_edid.c: In function 'update_display_info': > drivers/gpu/drm/drm_edid.c:7040:1: error: the frame size of 1888 bytes is larger than 1536 bytes [-Werror=frame-larger-than=] > 7040 | } > | ^ > > Mark all of the individual parser functions as noinline_for_stack > to avoid this and keep their stack frames separate. This reduces > the stack usage for update_display_info/drm_parse_cea_ext to > a more manageable 744 bytes, while each parser only adds at most > 200 bytes on top. Is there really no way to tell the compiler to not do silly things in a more generic way? BR, Jani. > > Signed-off-by: Arnd Bergmann > --- > drivers/gpu/drm/drm_edid.c | 31 +++++++++++++++++-------------- > 1 file changed, 17 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 3148038747b6..913a8bbe8894 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -5341,8 +5341,9 @@ static int edid_hfeeodb_extension_block_count(const struct edid *edid) > * etc). For example, if the bit 0 in bitmap is set, first mode in VDB can > * support YCBCR420 output too. > */ > -static void parse_cta_y420cmdb(struct drm_connector *connector, > - const struct cea_db *db, u64 *y420cmdb_map) > +static noinline_for_stack void > +parse_cta_y420cmdb(struct drm_connector *connector, const struct cea_db *db, > + u64 *y420cmdb_map) > { > struct drm_display_info *info = &connector->display_info; > int i, map_len = cea_db_payload_len(db) - 1; > @@ -5515,7 +5516,7 @@ static uint8_t hdr_metadata_type(const u8 *edid_ext) > BIT(HDMI_STATIC_METADATA_TYPE1); > } > > -static void > +static noinline_for_stack void > drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db) > { > struct hdr_static_metadata *hdr_metadata = > @@ -6070,7 +6071,8 @@ drm_default_rgb_quant_range(const struct drm_display_mode *mode) > EXPORT_SYMBOL(drm_default_rgb_quant_range); > > /* CTA-861 Video Data Block (CTA VDB) */ > -static void parse_cta_vdb(struct drm_connector *connector, const struct cea_db *db) > +static noinline_for_stack void > +parse_cta_vdb(struct drm_connector *connector, const struct cea_db *db) > { > struct drm_display_info *info = &connector->display_info; > int i, vic_index, len = cea_db_payload_len(db); > @@ -6136,8 +6138,8 @@ static bool cta_vdb_has_vic(const struct drm_connector *connector, u8 vic) > } > > /* CTA-861-H YCbCr 4:2:0 Video Data Block (CTA Y420VDB) */ > -static void parse_cta_y420vdb(struct drm_connector *connector, > - const struct cea_db *db) > +static noinline_for_stack void > +parse_cta_y420vdb(struct drm_connector *connector, const struct cea_db *db) > { > struct drm_display_info *info = &connector->display_info; > struct drm_hdmi_info *hdmi = &info->hdmi; > @@ -6155,7 +6157,8 @@ static void parse_cta_y420vdb(struct drm_connector *connector, > } > } > > -static void drm_parse_vcdb(struct drm_connector *connector, const u8 *db) > +static noinline_for_stack void > +drm_parse_vcdb(struct drm_connector *connector, const u8 *db) > { > struct drm_display_info *info = &connector->display_info; > > @@ -6310,8 +6313,8 @@ static void drm_parse_dsc_info(struct drm_hdmi_dsc_cap *hdmi_dsc, > } > > /* Sink Capability Data Structure */ > -static void drm_parse_hdmi_forum_scds(struct drm_connector *connector, > - const u8 *hf_scds) > +static noinline_for_stack void > +drm_parse_hdmi_forum_scds(struct drm_connector *connector, const u8 *hf_scds) > { > struct drm_display_info *info = &connector->display_info; > struct drm_hdmi_info *hdmi = &info->hdmi; > @@ -6451,7 +6454,7 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector, > } > > /* HDMI Vendor-Specific Data Block (HDMI VSDB, H14b-VSDB) */ > -static void > +static noinline_for_stack void > drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db) > { > struct drm_display_info *info = &connector->display_info; > @@ -6486,8 +6489,8 @@ drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db) > * See EDID extension for head-mounted and specialized monitors, specified at: > * https://docs.microsoft.com/en-us/windows-hardware/drivers/display/specialized-monitors-edid-extension > */ > -static void drm_parse_microsoft_vsdb(struct drm_connector *connector, > - const u8 *db) > +static noinline_for_stack void > +drm_parse_microsoft_vsdb(struct drm_connector *connector, const u8 *db) > { > struct drm_display_info *info = &connector->display_info; > u8 version = db[4]; > @@ -6558,8 +6561,8 @@ static void drm_parse_amd_vsdb_v3(struct drm_display_info *info, > info->amd_vsdb.max_frame_rate = max_frame_rate; > } > > -static void drm_parse_amd_vsdb(struct drm_connector *connector, > - const struct cea_db *db) > +static noinline_for_stack void > +drm_parse_amd_vsdb(struct drm_connector *connector, const struct cea_db *db) > { > struct drm_display_info *info = &connector->display_info; > const u8 *data = cea_db_data(db); -- Jani Nikula, Intel