From nobody Wed Feb 11 01:25:49 2026 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 5F073396B71; Tue, 10 Feb 2026 17:34:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770744879; cv=none; b=rxgmASp0iswBohtt1uNwiuaVGQOyjoI5dg7B2GbyoVVVkK7SYi2aNwGa4sLz7hB7Cgg5wwTpKk374PQuvE1N7bkPmm4+inVj9BaUmSuIMXBsVuEarOCkHXc3dJgT13tkZmeiFPrXVZo+L3+7DeBUr2mZebxj7hbCqsbP9Gvufeg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770744879; c=relaxed/simple; bh=mChCLV73SfDyjkx1FnS/Bp4AcikarcmzTUZ+U8IvJ0w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HTtyNiAgMmv/vDONJdDXReLcYPu+ihdchPhM/F1CQaNM+sGM5TicXysf1ZbxCvyS+KMxKZVSoyPr3/+JtrjHq09kKY6gxLpkzhKRTcXTajYHry1Nlqf5oUsdlgColtnHrH7Dnn4UwzCxMb50BGM69QyPLtvAVgzH/Zot1wudDfY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=VJmFcoWV; arc=none smtp.client-ip=185.171.202.116 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="VJmFcoWV" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id 6259DC8F455; Tue, 10 Feb 2026 17:34:45 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 03175606BD; Tue, 10 Feb 2026 17:34:37 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 0420B10B9213C; Tue, 10 Feb 2026 18:34:34 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1770744876; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=yTNPBv983V3G10hN3xMTv91meECHpLrvslxwBaJ5IF8=; b=VJmFcoWV9zBZznwDaBWZN7O5NnhudKSRVamYIcWSJKf1bbf5HtXBOT3/bU12BjgiHIMCcZ 8kPrplPs7H8OWRQMkEW125lomkbSwWBrsWbK6t5n2+CDDj1p7wJqS8Ak3nXBOxIzhSwHbK SA0cWBTZskWQkcYO4CHAZzu/rijVnXREaMoOrxrmb6/T7OUJHXsLoqVD4sI3jM2EBKnWK3 ejPWCD5u/mzxVgyBUZ55u6zc8LZAz0gKzF6elPH/36arr0wDEzIaCCVBamY2tng2Nf3H+f y5/6nFmIYoEtHFbZIhwK5buF4Ft732Db+z9mmBeSJCwWKrajig9S4WjyKpUmkg== From: Herve Codina To: David Gibson , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Ayush Singh , Geert Uytterhoeven , devicetree-compiler@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree-spec@vger.kernel.org, Hui Pu , Ian Ray , Luca Ceresoli , Thomas Petazzoni , Herve Codina Subject: [RFC PATCH 11/15] flattree: Handle unknown tags Date: Tue, 10 Feb 2026 18:33:39 +0100 Message-ID: <20260210173349.636766-12-herve.codina@bootlin.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260210173349.636766-1-herve.codina@bootlin.com> References: <20260210173349.636766-1-herve.codina@bootlin.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-Last-TLS-Session-Version: TLSv1.3 Content-Type: text/plain; charset="utf-8" The structured tag value definition introduced recently gives the ability to ignore unknown tags without any error when they are read. Handle those structured tag. Signed-off-by: Herve Codina --- flattree.c | 65 ++++++++++++++++++++-- tests/run_tests.sh | 5 ++ tests/unknown_tags_can_skip.dtb.dts.expect | 19 +++++++ 3 files changed, 84 insertions(+), 5 deletions(-) create mode 100644 tests/unknown_tags_can_skip.dtb.dts.expect diff --git a/flattree.c b/flattree.c index f3b698c..23813e2 100644 --- a/flattree.c +++ b/flattree.c @@ -579,7 +579,8 @@ static void flat_read_chunk(struct inbuf *inb, void *p,= int len) if ((inb->ptr + len) > inb->limit) die("Premature end of data parsing flat device tree\n"); =20 - memcpy(p, inb->ptr, len); + if (p) + memcpy(p, inb->ptr, len); =20 inb->ptr +=3D len; } @@ -604,6 +605,61 @@ static void flat_realign(struct inbuf *inb, int align) die("Premature end of data parsing flat device tree\n"); } =20 +static bool flat_skip_unknown_tag(struct inbuf *inb, uint32_t tag) +{ + uint32_t lng; + + if (!(tag & FDT_TAG_STRUCTURED) || !(tag & FDT_TAG_SKIP_SAFE)) + return false; + + switch (tag & FDT_TAG_DATA_MASK) { + case FDT_TAG_DATA_NONE: + break; + + case FDT_TAG_DATA_1CELL: + flat_read_word(inb); + break; + + case FDT_TAG_DATA_2CELLS: + flat_read_word(inb); + flat_read_word(inb); + break; + + case FDT_TAG_DATA_LNG: + /* Get the length */ + lng =3D flat_read_word(inb); + + /* Skip the following length bytes */ + flat_read_chunk(inb, NULL, lng); + + flat_realign(inb, sizeof(uint32_t)); + break; + } + + return true; +} + +static uint32_t flat_read_tag(struct inbuf *inb) +{ + uint32_t tag; + + do { + tag =3D flat_read_word(inb); + switch (tag) { + case FDT_BEGIN_NODE: + case FDT_END_NODE: + case FDT_PROP: + case FDT_NOP: + case FDT_END: + return tag; + default: + break; + } + } while (flat_skip_unknown_tag(inb, tag)); + + die("Cannot skip unknown tag 0x%08x\n", tag); +} + static const char *flat_read_string(struct inbuf *inb) { int len =3D 0; @@ -750,7 +806,7 @@ static struct node *unflatten_tree(struct inbuf *dtbuf, struct property *prop; struct node *child; =20 - val =3D flat_read_word(dtbuf); + val =3D flat_read_tag(dtbuf); switch (val) { case FDT_PROP: if (node->children) @@ -905,14 +961,13 @@ struct dt_info *dt_from_blob(const char *fname) =20 reservelist =3D flat_read_mem_reserve(&memresvbuf); =20 - val =3D flat_read_word(&dtbuf); - + val =3D flat_read_tag(&dtbuf); if (val !=3D FDT_BEGIN_NODE) die("Device tree blob doesn't begin with FDT_BEGIN_NODE (begins with 0x%= 08x)\n", val); =20 tree =3D unflatten_tree(&dtbuf, &strbuf, "", flags); =20 - val =3D flat_read_word(&dtbuf); + val =3D flat_read_tag(&dtbuf); if (val !=3D FDT_END) die("Device tree blob doesn't end with FDT_END\n"); =20 diff --git a/tests/run_tests.sh b/tests/run_tests.sh index b69b61b..98fa4f4 100755 --- a/tests/run_tests.sh +++ b/tests/run_tests.sh @@ -881,6 +881,11 @@ dtc_tests () { =20 # Tests for overlay/plugin generation dtc_overlay_tests + + # Tests with "unknown tags" + run_dtc_test -I dtb -O dts -o unknown_tags_can_skip.dtb.dts unknown_ta= gs_can_skip.dtb + base_run_test check_diff unknown_tags_can_skip.dtb.dts "$SRCDIR/unknow= n_tags_can_skip.dtb.dts.expect" + run_wrap_error_test $DTC -I dtb -O dts -o unknown_tags_no_skip.dtb.dts= unknown_tags_no_skip.dtb } =20 cmp_tests () { diff --git a/tests/unknown_tags_can_skip.dtb.dts.expect b/tests/unknown_tag= s_can_skip.dtb.dts.expect new file mode 100644 index 0000000..94fa6d6 --- /dev/null +++ b/tests/unknown_tags_can_skip.dtb.dts.expect @@ -0,0 +1,19 @@ +/dts-v1/; + +/ { + prop-int =3D <0x01>; + prop-str =3D "abcd"; + + subnode1 { + prop-int =3D <0x01 0x02>; + }; + + subnode2 { + prop-int1 =3D <0x01 0x02>; + prop-int2 =3D <0x01 0x02>; + + subsubnode { + prop-int =3D <0x01 0x02>; + }; + }; +}; --=20 2.52.0