uapi: import Linux kernel uAPI headers

This patch introduces uAPI headers import into the DPDK
repository. This import is possible thanks to Linux Kernel
licence exception for syscalls:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/LICENSES/exceptions/Linux-syscall-note

Header files have to be explicitly imported.

Guidelines are provided in the documentation, and helper
script is also provided to ensure proper import of the
headers (unmodified content from a released Kernel
version).

Signed-off-by: Maxime Coquelin <[email protected]>
Acked-by: Morten Brørup <[email protected]>
Reviewed-by: David Marchand <[email protected]>

3 files changed, 173 insertions, 0 deletions

diff --git a/devtools/check-spdx-tag.sh b/devtools/check-spdx-tag.sh
index 1ffccdaecc..b983268b1e 100755
--- a/devtools/check-spdx-tag.sh
+++ b/devtools/check-spdx-tag.sh
@@ -24,6 +24,7 @@ check_spdx() {
 	':^README' ':^MAINTAINERS' ':^VERSION' ':^ABI_VERSION' \
 	':^*/Kbuild' ':^*/README*' \
 	':^license/' ':^config/' ':^buildtools/' ':^*/poetry.lock' \
+	':^kernel/linux/uapi/.gitignore' ':^kernel/linux/uapi/version' \
 	':^*.cocci' ':^*.abignore' \
 	':^*.map' ':^*.ini' ':^*.data' ':^*.json' ':^*.cfg' ':^*.txt' \
 	':^*.svg' ':^*.png' \
diff --git a/devtools/linux-uapi.sh b/devtools/linux-uapi.sh
new file mode 100755
index 0000000000..ccd8b6816e
--- /dev/null
+++ b/devtools/linux-uapi.sh
@@ -0,0 +1,171 @@
+#!/bin/sh -e
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2024 Red Hat, Inc.
+
+#
+# Import and check Linux Kernel uAPI headers
+#
+
+base_url="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/include/uapi/"
+base_path="kernel/linux/uapi/"
+version=""
+file=""
+check_headers=0
+errors=0
+
+print_usage()
+{
+	echo "Usage: $(basename $0) [-h] [-i FILE] [-u VERSION] [-c]"
+	echo "-i FILE      import Linux header file. E.g. linux/vfio.h"
+	echo "-u VERSION   update imported list of Linux headers to a given version. E.g. v6.10"
+	echo "-c           check headers are valid"
+}
+
+version_older_than() {
+    printf '%s\n%s' "$1" "$2" | sort -C -V
+}
+
+download_header()
+{
+	local header=$1
+	local path=$2
+
+	local url="${base_url}${header}?h=${version}"
+
+	if ! curl -s -f --create-dirs -o $path $url; then
+		echo "Failed to download $url"
+		return 1
+	fi
+
+	return 0
+}
+
+update_headers()
+{
+	local header
+	local url
+	local path
+
+	echo "Updating to $version"
+	for filename in $(find $base_path -name "*.h" -type f); do
+		header=${filename#$base_path}
+		download_header $header $filename || return 1
+	done
+
+	return 0
+}
+
+import_header()
+{
+	local include
+	local import
+	local header=$1
+
+	local path="${base_path}${header}"
+
+	download_header $header $path || return 1
+
+	for include in $(sed -ne 's/^#include <\(.*\)>$/\1/p' $path); do
+		if [ ! -f "${base_path}${include}" ]; then
+			read -p "Import $include (y/n): " import && [ "$import" = 'y' ] || continue
+			echo "Importing $include for $path"
+			import_header "$include" || return 1
+		fi
+	done
+
+	return 0
+}
+
+fixup_includes()
+{
+	local path=$1
+
+	sed -i "s|^#include <linux/compiler.h>||g" $path
+	sed -i "s|\<__user[[:space:]]||" $path
+
+	# Prepend include path with "uapi/" if the header is imported
+	for include in $(sed -ne 's/^#include <\(.*\)>$/\1/p' $path); do
+		if [ -f "${base_path}${include}" ]; then
+			sed -i "s|${include}|uapi/${include}|g" $path
+		fi
+	done
+}
+
+check_header() {
+	echo -n "Checking $1... "
+
+	if ! diff -q $1 $2 >/dev/null; then
+		echo "KO"
+		diff -u $1 $2
+		return 1
+	else
+		echo "OK"
+	fi
+
+	return 0
+}
+
+while getopts i:u:ch opt ; do
+	case ${opt} in
+		i ) file=$OPTARG ;;
+		u ) version=$OPTARG ;;
+		c ) check_headers=1 ;;
+		h ) print_usage ; exit 0 ;;
+		? ) print_usage ; exit 1 ;;
+	esac
+done
+
+shift $(($OPTIND - 1))
+if [ $# -ne 0 ]; then
+	print_usage
+	exit 1
+fi
+
+cd $(dirname $0)/..
+
+current_version=$(< ${base_path}/version)
+
+if [ -n "${version}" ]; then
+	if version_older_than "$version" "$current_version"; then
+		echo "Headers already up to date ($current_version >= $version)"
+		version=$current_version
+	else
+		update_headers || exit 1
+	fi
+else
+	echo "Version not specified, using current version ($current_version)"
+	version=$current_version
+fi
+
+if [ -n "${file}" ]; then
+	import_header $file || exit 1
+fi
+
+for filename in $(find $base_path -name "*.h" -type f); do
+	fixup_includes $filename || exit 1
+done
+
+echo $version > ${base_path}/version
+
+if [ $check_headers -eq 0 ]; then
+	exit 0
+fi
+
+tmpheader="$(mktemp -t dpdk.checkuapi.XXXXXX)"
+trap "rm -f '$tmpheader'" INT
+
+echo "Checking imported headers for version ${version}"
+
+for filename in $(find $base_path -name "*.h" -type f); do
+	header=${filename#$base_path}
+	download_header $header $tmpheader || exit 1
+	fixup_includes $tmpheader || exit 1
+	check_header $filename $tmpheader || errors=$((errors+1))
+done
+
+echo "$errors error(s) found"
+
+rm -f $tmpheader
+trap - INT
+
+exit $errors
diff --git a/devtools/words-case.txt b/devtools/words-case.txt
index 2257ce6201..bc35c160ba 100644
--- a/devtools/words-case.txt
+++ b/devtools/words-case.txt
@@ -104,6 +104,7 @@ TPID
 TSO
 TTL
 Tx
+uAPI
 UDM
 UDP
 ULP