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>

3 files changed, 74 insertions, 0 deletions

diff --git a/arch/mips/pic32/common/Makefile b/arch/mips/pic32/common/Makefile
new file mode 100644
index 000000000..a60750ab7
--- /dev/null
+++ b/arch/mips/pic32/common/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Joshua Henderson, <joshua.henderson@microchip.com>
+# Copyright (C) 2015 Microchip Technology, Inc.  All rights reserved.
+#
+obj-y = reset.o irq.o
diff --git a/arch/mips/pic32/common/irq.c b/arch/mips/pic32/common/irq.c
new file mode 100644
index 000000000..fb00b797b
--- /dev/null
+++ b/arch/mips/pic32/common/irq.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
+ */
+#include <linux/init.h>
+#include <linux/irqchip.h>
+#include <asm/irq.h>
+
+void __init arch_init_irq(void)
+{
+	irqchip_init();
+}
diff --git a/arch/mips/pic32/common/reset.c b/arch/mips/pic32/common/reset.c
new file mode 100644
index 000000000..230db4bad
--- /dev/null
+++ b/arch/mips/pic32/common/reset.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
+ */
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_data/pic32.h>
+#include <linux/pm.h>
+#include <asm/reboot.h>
+
+#define PIC32_RSWRST		0x10
+
+static void pic32_halt(void)
+{
+	while (1) {
+		__asm__(".set push;\n"
+			".set arch=r4000;\n"
+			"wait;\n"
+			".set pop;\n"
+		);
+	}
+}
+
+static void pic32_machine_restart(char *command)
+{
+	void __iomem *reg =
+		ioremap(PIC32_BASE_RESET + PIC32_RSWRST, sizeof(u32));
+
+	pic32_syskey_unlock();
+
+	/* magic write/read */
+	__raw_writel(1, reg);
+	(void)__raw_readl(reg);
+
+	pic32_halt();
+}
+
+static void pic32_machine_halt(void)
+{
+	local_irq_disable();
+
+	pic32_halt();
+}
+
+static int __init mips_reboot_setup(void)
+{
+	_machine_restart = pic32_machine_restart;
+	_machine_halt = pic32_machine_halt;
+	pm_power_off = pic32_machine_halt;
+
+	return 0;
+}
+
+arch_initcall(mips_reboot_setup);