From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (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 E14B03B71B8; Wed, 26 Aug 2026 08:32:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787733179; cv=none; b=EWzmLTB6b2vOIU8CFdTc+1hZRGHt4tyk4CBKRQ8BOf7SJCHaXg1UUbZ1kv1M1MyYiOedbEfLELi+9g/lV4ed57bG3XEfVg4YVaWcT3Oxd+3xASAdB9lc/TFGp0b7A09LPcqadwpRX1gT9iFWfg6lrdqfqNhkeQBrDbnpm+BMEgU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787733179; c=relaxed/simple; bh=QpN4qCEt7hYwfnpdO4a5K03B/9xVWyqMhVF9158lw10=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Nwo+SDlXv0KWvwoXafSY0T/FRHrBNCsBIyUqZ99CPmnMNKmJAffeUnZjvIBBYs0QY6kxp918t4q9De0US78UEma/NBNhXevIhREjduznwk2RicGwufkErI39YcNb6I8ME8SPHnweLUmytWjxDheRZxIZr9wYAzrV3YbacSRpbNs= 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=gsqEE0Sn; arc=none smtp.client-ip=185.246.85.4 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="gsqEE0Sn" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 7A9CB4E413C1; Wed, 26 Aug 2026 08:32:56 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 4E78F604EC; Wed, 26 Aug 2026 08:32:56 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 655C511C7AC5A; Wed, 26 Aug 2026 10:32:53 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1787733175; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=D7Zzba+aoynELITCEBt8J/Zswm9vFahDLREpmOs5caI=; b=gsqEE0Snv8tqiXD49byCdDSB/UMboSB2y+I9kDtXFJSMuOwchg0LUAs9O1t5CQMHZ2DRSH VpictovkXdMDS1WJdsRCupfQDrAlHSaZ52qHlbByE+RgJ4eku8v8DEYGXjrfmb0u+q29Tp u1Hh41TYaIntguvuOEkafs9bbD6U90aOMib4QdYG+HSEePh3PBKLz8WjYC9XKDIbMH27Cs MaxIjnPraGNawRaK+io8O6SF0jqwDrBCZ/hAgb5TR/gYOg76jnPJgBx62ouaXFxnRGqcGY rR6hp9Ot2q5oTadF0+PDCTo9HBqwfydJHE9GDmmKfx1HAvMhzHr1xR/Jo1AxLQ== From: Herve Codina To: David Gibson , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Laurent Pinchart , David Lechner , 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 , Frank Li Subject: [PATCH v3 08/15] flattree: Handle unknown tags Date: Wed, 26 Aug 2026 10:31:39 +0200 Message-ID: <20260826083146.304291-9-herve.codina@bootlin.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260826083146.304291-1-herve.codina@bootlin.com> References: <20260826083146.304291-1-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: 8bit X-Last-TLS-Session-Version: TLSv1.3 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 Reviewed-by: Luca Ceresoli Reviewed-by: Frank Li --- 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 f3b698c1..88dbfa7e 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"); - memcpy(p, inb->ptr, len); + if (p) + memcpy(p, inb->ptr, len); inb->ptr += len; } @@ -604,6 +605,61 @@ static void flat_realign(struct inbuf *inb, int align) die("Premature end of data parsing flat device tree\n"); } +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_VARLEN: + /* Get the length */ + lng = 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 = 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 = 0; @@ -750,7 +806,7 @@ static struct node *unflatten_tree(struct inbuf *dtbuf, struct property *prop; struct node *child; - val = flat_read_word(dtbuf); + val = 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) reservelist = flat_read_mem_reserve(&memresvbuf); - val = flat_read_word(&dtbuf); - + val = flat_read_tag(&dtbuf); if (val != FDT_BEGIN_NODE) die("Device tree blob doesn't begin with FDT_BEGIN_NODE (begins with 0x%08x)\n", val); tree = unflatten_tree(&dtbuf, &strbuf, "", flags); - val = flat_read_word(&dtbuf); + val = flat_read_tag(&dtbuf); if (val != FDT_END) die("Device tree blob doesn't end with FDT_END\n"); diff --git a/tests/run_tests.sh b/tests/run_tests.sh index f3647e63..8fc23cb7 100755 --- a/tests/run_tests.sh +++ b/tests/run_tests.sh @@ -882,6 +882,11 @@ dtc_tests () { # 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_tags_can_skip.dtb + base_run_test check_diff unknown_tags_can_skip.dtb.dts "$SRCDIR/unknown_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 } cmp_tests () { diff --git a/tests/unknown_tags_can_skip.dtb.dts.expect b/tests/unknown_tags_can_skip.dtb.dts.expect new file mode 100644 index 00000000..2194025b --- /dev/null +++ b/tests/unknown_tags_can_skip.dtb.dts.expect @@ -0,0 +1,19 @@ +/dts-v1/; + +/ { + prop-int = <0x3201>; + prop-str = "abcd"; + + subnode1 { + prop-int = <0x6401 0x6402>; + }; + + subnode2 { + prop-int1 = <0x64020 0x64021>; + prop-int2 = <0x32022>; + + subsubnode { + prop-bool; + }; + }; +}; -- 2.55.0