From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (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 E9A143C73CC; Thu, 9 Apr 2026 11:55:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775735703; cv=none; b=uCB/VsnPz6otzcaKU4v1FJ3R+6u12gCjTPMgKqbXypn9JzTakqknCu4DrIsYnhIOulYLCO0fU4MRb4kxaE+9XOlDyvhWCl/MaQ3pEJG9OzTzry8dHWbfqS1BSi2VPZ9Fzr0u+eRNkF08eVIhWmj0/+MYkZQFDkELTFkMUVCzC3Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775735703; c=relaxed/simple; bh=WlzaFeZff72ObXgtJ/TH8EF7ZB1ghVzKs9A8f2dv4Qc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ddh/MNbU4dWFPFm2tRX8X8v6JMHj+dFZKeaX7QnHivjQKS7Gc5yi71hm3pcVS9dYJKtvmvgmcfVPlCUzyj+t4scUPLWpXa6um6kMuI0WvLpeph5u76znzyKjid45xn3yR0fyxlGDQrRr1kpwK4PtPjItZxqS4YvF5Sdnob95kAs= 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=VQCTjIQ9; arc=none smtp.client-ip=185.246.84.56 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="VQCTjIQ9" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id B25DA1A3247; Thu, 9 Apr 2026 11:55:00 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 88F0D5FDEB; Thu, 9 Apr 2026 11:55:00 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 99746104500B2; Thu, 9 Apr 2026 13:54:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1775735699; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=cjcEgTR+EjskL2q0GwAsLq5wbNbj6oOnMcMqw7miUFM=; b=VQCTjIQ9gGuRf9GJ8xBtlHfS/AV9xkn1qDgWgIsZbZkfwrLfw+O8DG6Mzt0stf9+PKOO9U x9NCUEFWcrKLZvbU9Aa0/QvQen5pB/Hsxt8qNpK4oaBXVzRxlU4Yp5FKY/wQwG+5duKwdA AWQMHxU7USLiPGzD8eaH1XRNGDqvhJFSsBwMAbrWYPcOk4c7a9FaJhsFy6ejMrbYhHGiBG S+QcRuDe05B98uYrZTgj6CoVH+s2Ln13RsPh0TtVQOlGk4b4ft6W73ebhsqjjNY45uNIZo c9xxjVLBC1klGMEOttZHD8gCLP4lUUMkBlXYh/HoDsmFxpGTxMlxWrUibbYReg== 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: [PATCH v2 06/10] flattree: Handle unknown tags Date: Thu, 9 Apr 2026 13:54:22 +0200 Message-ID: <20260409115426.352214-7-herve.codina@bootlin.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260409115426.352214-1-herve.codina@bootlin.com> References: <20260409115426.352214-1-herve.codina@bootlin.com> Precedence: bulk X-Mailing-List: devicetree@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 --- 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..88dbfa7 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 f2855dd..d147011 100755 --- a/tests/run_tests.sh +++ b/tests/run_tests.sh @@ -881,6 +881,11 @@ 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 0000000..a11ee57 --- /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-int = <0x64023 0x64024>; + }; + }; +}; -- 2.53.0