selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 98 insertions, 0 deletions

diff --git a/scripts/syscallhdr.sh b/scripts/syscallhdr.sh
new file mode 100755
index 000000000..22e34cd46
--- /dev/null
+++ b/scripts/syscallhdr.sh
@@ -0,0 +1,98 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Generate a syscall number header.
+#
+# Each line of the syscall table should have the following format:
+#
+# NR ABI NAME [NATIVE] [COMPAT]
+#
+# NR       syscall number
+# ABI      ABI name
+# NAME     syscall name
+# NATIVE   native entry point (optional)
+# COMPAT   compat entry point (optional)
+
+set -e
+
+usage() {
+	echo >&2 "usage: $0 [--abis ABIS] [--emit-nr] [--offset OFFSET] [--prefix PREFIX] INFILE OUTFILE" >&2
+	echo >&2
+	echo >&2 "  INFILE    input syscall table"
+	echo >&2 "  OUTFILE   output header file"
+	echo >&2
+	echo >&2 "options:"
+	echo >&2 "  --abis ABIS        ABI(s) to handle (By default, all lines are handled)"
+	echo >&2 "  --emit-nr          Emit the macro of the number of syscalls (__NR_syscalls)"
+	echo >&2 "  --offset OFFSET    The offset of syscall numbers"
+	echo >&2 "  --prefix PREFIX    The prefix to the macro like __NR_<PREFIX><NAME>"
+	exit 1
+}
+
+# default unless specified by options
+abis=
+emit_nr=
+offset=
+prefix=
+
+while [ $# -gt 0 ]
+do
+	case $1 in
+	--abis)
+		abis=$(echo "($2)" | tr ',' '|')
+		shift 2;;
+	--emit-nr)
+		emit_nr=1
+		shift 1;;
+	--offset)
+		offset=$2
+		shift 2;;
+	--prefix)
+		prefix=$2
+		shift 2;;
+	-*)
+		echo "$1: unknown option" >&2
+		usage;;
+	*)
+		break;;
+	esac
+done
+
+if [ $# -ne 2 ]; then
+	usage
+fi
+
+infile="$1"
+outfile="$2"
+
+guard=_UAPI_ASM_$(basename "$outfile" |
+	sed -e 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/' \
+	-e 's/[^A-Z0-9_]/_/g' -e 's/__/_/g')
+
+grep -E "^[0-9A-Fa-fXx]+[[:space:]]+$abis" "$infile" | {
+	echo "#ifndef $guard"
+	echo "#define $guard"
+	echo
+
+	max=0
+	while read nr abi name native compat ; do
+
+		max=$nr
+
+		if [ -n "$offset" ]; then
+			nr="($offset + $nr)"
+		fi
+
+		echo "#define __NR_$prefix$name $nr"
+	done
+
+	if [ -n "$emit_nr" ]; then
+		echo
+		echo "#ifdef __KERNEL__"
+		echo "#define __NR_${prefix}syscalls $(($max + 1))"
+		echo "#endif"
+	fi
+
+	echo
+	echo "#endif /* $guard */"
+} > "$outfile"