selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/scripts/livepatch/Makefile b/scripts/livepatch/Makefile
new file mode 100644
index 000000000..17b590213
--- /dev/null
+++ b/scripts/livepatch/Makefile
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0
+# Standalone Makefile for developer tooling (not part of kbuild).
+
+SHELLCHECK := $(shell which shellcheck 2> /dev/null)
+
+SRCS := \
+  klp-build
+
+.DEFAULT_GOAL := help
+.PHONY: help
+help:
+	@echo "  check      - Run shellcheck on $(SRCS)"
+	@echo "  help       - Show this help message"
+
+.PHONY: check
+check:
+ifndef SHELLCHECK
+	$(error shellcheck is not installed. Please install it to run checks)
+endif
+	@$(SHELLCHECK) $(SHELLCHECK_OPTIONS) $(SRCS)